tag:theconversation.com,2011:/nz/topics/human-evolution-2687/articles
Human evolution – The Conversation
2024-03-14T03:55:30Z
tag:theconversation.com,2011:article/223646
2024-03-14T03:55:30Z
2024-03-14T03:55:30Z
Why is the male body the scientific default when the female body drives the reproductive success of our species?
<figure><img src="https://images.theconversation.com/files/581526/original/file-20240313-20-9ueone.jpg?ixlib=rb-1.1.0&rect=6%2C0%2C2038%2C1536&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Eve – Lucas Cranach the Elder (c.1510)</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Cranach_Adam_and_Eve_(detail)_3.jpg">Public domain, via Wikimedia Commons</a></span></figcaption></figure><p>American essayist Cat Bohannon loves a bit of pop culture to contextualise her ideas. <a href="https://www.penguin.com.au/books/eve-9781529151244">Eve: How the Female Body Drove 200 Million Years of Human Evolution</a> – her ambitious, funny, intelligent history of female evolution – is threaded with it. </p>
<p>The book opens with a futuristic scene from <a href="https://www.imdb.com/title/tt1446714/">Prometheus</a>, the 2012 prequel to <a href="https://www.imdb.com/title/tt0078748/">Alien</a>. Archaeologist Elizabeth Shaw is in an AI surgery pod, seeking a life-saving caesarean (she has been impregnated with an alien squid) when an affectless voice gives her an error message: “This medpod is calibrated for male patients only.” </p>
<p>Crash-test dummies, heart-attack symptoms, anti-depressant dosages, air-conditioning systems in large office buildings: we are all pretty aware by now that these are “calibrated for male bodies only”. Alien Prometheus is set in 2093; one can only hope the scientific technology of the late 21st-century turns out to have, at least, a “female-registering” option.</p>
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<p><em>Eve: How the Female Body Drove 200 Million Years of Human Evolution – Cat Bohannon (Hutchinson Heinemann)</em> </p>
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<p>While women’s hormonal cycles have made us messy in the arena of “clean science” – not good controls, not good at being controlled for – Bohannon reminds us that an understanding of the female body cannot be retrofitted to an understanding of the male body. Women are not just men with extra fleshy bits and confounding hormones. </p>
<p>Bohannon also reminds us those “fleshy bits” have a function beyond providing a curvaceous silhouette. </p>
<p>Female adipose tissue, 600 million years old, stored around our butts and thighs, is necessary to the development of babies’ brains. It is so necessary that girls begin storing it in childhood and when women liposuction it out of their lower bodies it returns in unexpected places: the armpits, for example. Bohannon points out that the possible repercussions of liposuction on the brain health of future offspring has not yet been studied.</p>
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<h2>Reproductive success</h2>
<p>The salient question here is: why is the male body the scientific default when it is the female body that crucially drives the evolution and reproductive success of our species? Eve is both a rectification of this immense blind spot and, in Bohannon’s own words, “a user’s manual for the female mammal”. </p>
<p>Yet how to collapse 200 million years of evolutionary history into 500 pages (let alone 1500 words)? </p>
<p>Bohannon does this by organising her book into a series of “Eves” from whom we inherited our current biological functions, creating an often diverging, often interlocking chronology. There is the Eve of milk, “the real Madonna”; placental Eve, “an HR Giger fever-dream meat factory” (Bohannon has fun with language); Donna, Eve of the uterus; and Pergi, the tree-dwelling Eve of perception. </p>
<p>This structure allows Bohannon to move from microbiology to paleoanthropology, evolutionary biology to gynaecology, anatomy to social history. I learnt much about my own body in her sprawling, illuminating discussions, but also about animal reproductive biology in general — from monotremal cloacas (platypuses and echidnas have them) to squamation hemipenises (snakes and lizards) and “notoriously foldy” anti-rape duck vaginas designed to circumvent corkscrew penises. </p>
<p>It was some small relief to learn the fairly straightforward design of the human penis is testament to a “not-particularly rapey” human evolutionary history. </p>
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<a href="https://images.theconversation.com/files/581824/original/file-20240314-18-pjj64q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/581824/original/file-20240314-18-pjj64q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581824/original/file-20240314-18-pjj64q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581824/original/file-20240314-18-pjj64q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581824/original/file-20240314-18-pjj64q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581824/original/file-20240314-18-pjj64q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581824/original/file-20240314-18-pjj64q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581824/original/file-20240314-18-pjj64q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">‘Notoriously foldy.’</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Detailed_white_duck.jpg">Image: Roger Heslop, via Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Bohannon writes with tender care of her “Eves”. She manages to both penetrate and animate deep time for the reader, a textual equivalent perhaps of Walking with Dinosaurs. She describes the Jurassic insect-eater <a href="https://museum.wales/blog/1895/Meet-Morgie/">Morgie</a> (my favourite), one of the earliest known mammals, skittering over the feet of dinosaurs to get home to her burrow, where she sweats milk through mammary patches to feed her hidden brood. Morgie comes vividly alive in her small precarious existence: “funny, warm, heart-fluttering Eve”, Bohannon writes. </p>
<p>For a female with a uterus, who has twice given birth and twice breastfed, Bohannon’s book demystified many of the mysterious goings-on of my reproductive system. I had no idea, for instance, that lactation was such an intensive co-production between mother and baby. </p>
<p>I knew it enabled a baby’s gut to be colonised with good maternal bacteria, and I knew the basic mechanics of the let-down reflex. But I didn’t know that the composition of the milk itself is informed by a baby’s needs. These needs, codified in a baby’s saliva, are registered by the mother’s body, which then customises its milk accordingly, so it is full of the particular bacteria- or virus-fighting agents required.</p>
<p>This recriprocity is also apparent in the biological wonder that is the placenta. Built out of both endometrial and embryonic tissue, the placenta is “one of the only organs in the animal world made out of two separate organisms”. </p>
<p>Did you know this? I certainly didn’t. </p>
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<a href="https://images.theconversation.com/files/581827/original/file-20240314-30-yukxv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/581827/original/file-20240314-30-yukxv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581827/original/file-20240314-30-yukxv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581827/original/file-20240314-30-yukxv4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581827/original/file-20240314-30-yukxv4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581827/original/file-20240314-30-yukxv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=369&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581827/original/file-20240314-30-yukxv4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=369&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581827/original/file-20240314-30-yukxv4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=369&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">‘Morgie’ – Morganucodon, one of the earliest known mammals.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Morganucodon.jpg">FunkMonk (Michael B.H.), via Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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Read more:
<a href="https://theconversation.com/a-raunchy-new-big-history-tells-the-story-of-sex-but-raises-some-unanswered-questions-213538">A raunchy new 'Big History' tells the story of sex, but raises some unanswered questions</a>
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<h2>Life: a user’s manual</h2>
<p>In this sense, Eve really is a user’s manual. At the risk of sounding “miracle of life” about it, Bohannon’s book puts wonder into the commonplace by explaining not only how our reproductive systems work, but how they came to be.</p>
<p>Women’s bodies are not just about babies, of course. Bohannon charts new political territory, tracing her anatomical discoveries through to their social outcomes. Truisms of human and social evolution are turned on their heads and gynaecology gets its rightful place in the story. </p>
<p>Milk again: the population growth that enabled humans to become the ferocious planet-hogs we are today might be down to the humble wet-nurse of ancient civilisations. The prevalence of wet-nursing meant the natural contraceptive properties of breastfeeding were not in play for many women. This meant women had much shorter spaces between pregnancies and had more babies. Wet-nurses, those under-sung footnotes in history, might well have catalysed the growth of modern cities.</p>
<p>Bipedalism? It might just be that we stood up on two feet not so we could better carry spears, but so we had free arms to carry babies while hunting and still cart as much food home with us as possible.</p>
<p>Tool-making? The seminal moment here may not have been a Kubrick-style raising of a femur bone to crunch down on a challenger’s head, or beat an animal to death for dinner (fossil remains show we really didn’t eat a particularly intensive paleo diet). Instead, it might have been a woman, baby on back, chewing a sapling to a neat point to hunt “<a href="https://www.nationalgeographic.com/animals/mammals/facts/bushbabies">bush-babies</a>” asleep in tree hollows. </p>
<p>Bohannon makes a good argument that it was women, not men, who most needed tools to hunt. Our biologically stronger male counterparts often needed only the heft of their bodies to bring down an animal. Women were inventors, she says, because, being smaller, being weaker, they had more need.</p>
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<a href="https://images.theconversation.com/files/581555/original/file-20240313-18-z1f8bf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/581555/original/file-20240313-18-z1f8bf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581555/original/file-20240313-18-z1f8bf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581555/original/file-20240313-18-z1f8bf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581555/original/file-20240313-18-z1f8bf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581555/original/file-20240313-18-z1f8bf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581555/original/file-20240313-18-z1f8bf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581555/original/file-20240313-18-z1f8bf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Cave painting depicting a woman giving birth, Serra da Capivara national park, Brazil.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Serra_da_Capivara_-_Painting_8.JPG">Vitor 1234, via Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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Read more:
<a href="https://theconversation.com/friday-essay-matrilineal-societies-exist-around-the-world-its-time-to-look-beyond-the-patriarchy-200825">Friday essay: matrilineal societies exist around the world – it's time to look beyond the patriarchy</a>
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<h2>Womb triumphalism</h2>
<p>Our most important invention, though – and this is the overarching thesis of Bohannan’s book – is gynaecology. “What got us here,” she writes, “is not tool triumphalism but womb triumphalism.” </p>
<p>Considering how hard it is for the human female body to get pregnant, stay pregnant, deliver a baby (without us or it dying), and then look after it through its protracted childhood, it is a miracle that humans populate – and over-populate — the planet in the way we have come to. Gynaecology, Bohannon writes, </p>
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<p>is absolutely essential for our species’ evolutionary fitness. Without it, it’s doubtful we would have made it this far […] The arrival of midwifery is one of those moments when we can truly say, “Here is when we become human” […] No other mammals on the planet have been observed regularly helping one another give birth.</p>
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<p>With gynaecology comes contraception, reproductive choice and birth-spacing. Knowledge about the properties of herbs and plants, about labour, about delivering a breech or posterior baby, or really <em>any</em> baby (they are all life and death situations) – all of these combine to enable the flourishing of humans, in spite of our large heads, narrow pelvises, complex gestation and birthing trajectories. </p>
<p>“Women had their hands on the actual machinery of evolution,” Bohannon writes. And while she notes that “[m]odern female coalitions are scattered, vulnerable, brittle”, her book celebrates the ancient collaboration between women and the spirit of cooperation over competition that got us here. </p>
<p>Bohannon repositions this as profound in its significance for the human race. A failure to fully apprehend the different workings of male and female bodies and not provide for these differences – or to provide comprehensively for one sex, and neglect the other – doesn’t just mean there will be no caesarean option in a future surgery-pod. </p>
<p>It means limiting human possibility and opportunity. It represents a failure to grasp the whole human story and its potential.</p>
<p>Bohannon ends her book with a practical feminist statement about the importance – and boon to society – of educating women, feeding them properly (not last), and putting financial means in their hands. </p>
<p>Smart humans of the future – who might want to flourish without destroying the means of their flourishing – will require women with adipose fat to feed the brains of their suckling babies, with reproductive choices to plan and space those babies, and with life choices which enable them to contribute their full potential to the world. </p>
<img src="https://counter.theconversation.com/content/223646/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Edwina Preston has received funding from Creative Victoria and the Australia Council for the Arts. She works for the Australian Education Union</span></em></p>
The story of human evolution is inextricable from the story of gynaecology.
Edwina Preston, PhD Candidate, The University of Melbourne
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/222762
2024-02-06T18:06:12Z
2024-02-06T18:06:12Z
How long did Neanderthals and modern humans co-exist in Europe? Evidence is growing it may have been at least 10,000 years
<figure><img src="https://images.theconversation.com/files/573551/original/file-20240205-21-v9koj7.jpeg?ixlib=rb-1.1.0&rect=3%2C0%2C1222%2C775&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A human bone fragment from the new excavations at Ranis in Germany.</span> <span class="attribution"><span class="source">Tim Schüler TLDA. </span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>The idea that two different human species, <em>Homo sapiens</em> (us) and Neanderthals, co-existed in western Eurasia 50–40,000 years ago has long captured the imagination of academics and the public alike.</p>
<p>It is therefore not surprising that this time period – the Middle-to-Upper Palaeolithic transition – has been a focus of research for many archaeologists, physical anthropologists and, more recently, geneticists. </p>
<p>Various scenarios have been explored over the years, from those positing tens of thousands of years of co-existence between the two groups of humans, to those seeing a much more rapid replacement of Neanderthals by <em>H. sapiens</em> – whether through the active or coincidental displacement of our cousins, or through outcompeting them for resources. </p>
<p>Both positions allow for the occasional interbreeding that has resulted in a little bit of Neanderthal being present in many of us, <a href="https://www.cell.com/current-biology/pdf/S0960-9822(16)30247-0.pdf">especially those of European and East Asian ancestry</a>.</p>
<p>However, there are many challenges to exploring this distant time. Human skeletal remains are comparatively rare, with many of the best-known fossils having been excavated under less than ideal conditions in the 19th and early 20th centuries.</p>
<p>When skeletal remains are found, there are often questions over their precise relationship to other archaeological remains at the same site – such as stone and bone tools, animal remains and other finds. Connections between a particular species of human and finds from an excavation have often been assumed, only to be later found <a href="https://www.pnas.org/doi/abs/10.1073/pnas.1709235114">spurious in a number of instances</a>.</p>
<h2>Major revisions</h2>
<p>The transition period of 50–40,000 years ago is within the lower limits of radiocarbon dating – a technique that only works on organic remains up to about 50,000 years old. This means the smallest amounts of more recent contamination from the burial environment, or from museum conservation materials, can make dating finds from these sites extremely challenging. </p>
<p>This has resulted in major revisions to the chronology of early human occupation over the past decade, shifting some dates on Neanderthal and modern human remains <a href="https://www.pnas.org/doi/10.1073/pnas.2022466118">by many thousands of years</a>. </p>
<p>This is obviously crucial to the debate, since it is impossible to speak of overlap or replacement without a robust chronology. There is also the matter of spatial scale. Does the persistence of Neanderthals after 40,000 years ago in southern Iberia, for example, represent a lengthy period of overlap and co-existence, or a <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/jqs.3252">“last stand”</a> at the margins of the continent, expressly avoiding contact with the newcomers?</p>
<p>The most recent entry into the fray comes from the cave of Ilsenhöhle in Ranis, east-central Germany, wonderfully situated at the base of a 16th-century Renaissance castle with earlier medieval origins. </p>
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<img alt="Ilsenhohle caves beneath the castle of Ranis." src="https://images.theconversation.com/files/573553/original/file-20240205-19-z1mrgq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/573553/original/file-20240205-19-z1mrgq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=903&fit=crop&dpr=1 600w, https://images.theconversation.com/files/573553/original/file-20240205-19-z1mrgq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=903&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/573553/original/file-20240205-19-z1mrgq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=903&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/573553/original/file-20240205-19-z1mrgq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1135&fit=crop&dpr=1 754w, https://images.theconversation.com/files/573553/original/file-20240205-19-z1mrgq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1135&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/573553/original/file-20240205-19-z1mrgq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1135&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The cave site of Ilsenhöhle.</span>
<span class="attribution"><span class="source">© Tim Schüler TLDA</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>An international, multidisciplinary team has identified human (<em>H. sapiens</em>) remains from both early 20th-century and more recent excavations in the cave, dating them to <a href="https://www.nature.com/articles/s41586-023-06923-7">around 45,000 years ago</a>. The authors say that, when combined with <a href="https://www.science.org/doi/10.1126/sciadv.abj9496">early dates of <em>H. sapiens</em> in France</a> and a variety of dates for Neanderthals being present at 45,000 years around Europe, this allows a potential period of overlap between the two species lasting some 10,000 years.</p>
<p><a href="https://www.nature.com/articles/s41559-023-02318-z">In a companion paper</a>, the researchers reported the results of their analysis of stable oxygen isotopes (different chemical forms of an element) that came from teeth belonging to mammals in the horse family (equids). These teeth came from the same sediment levels as the human remains. The results place the people in a particularly cold snap around 45–43,000 years ago. </p>
<p>The <em>H. sapiens</em> remains are associated with what was previously considered an ambiguous stone tool industry (a particular way of making tools) called the <a href="https://en.wikipedia.org/wiki/Lincombian-Ranisian-Jerzmanowician">Lincombian–Ranisian–Jerzmanowician</a> (LRJ). But it has been unclear whether these were made by Neanderthals or modern humans. </p>
<h2>Mystery toolmakers</h2>
<p>Other transitional Middle-Upper Palaeolithic stone tool industries have a long history of the same problem – we’re not sure who made them. Most notable is the <a href="https://www.britannica.com/topic/Chatelperronian-stage">Châtelperronian</a> of southern France and northern Spain: do the Neanderthal remains accompanying some of these “modern-looking” tool industries mean they were the toolmakers, or is the association fortuitous?</p>
<p>This debate continues apace, with a possible <em>H. sapiens</em> newborn child’s <a href="https://www.britannica.com/science/ilium">ilium</a> having recently been identified in a Châtelperronian assemblage at the Grotte du Renne in Arcy-sur-Cure, central France. Here, only Neanderthal remains <a href="https://www.nature.com/articles/s41598-023-39767-2">had previously been identified</a>.</p>
<p>Most caves with Palaeolithic deposits saw intermittent occupation, often by both Neanderthals and <em>H. sapiens</em>, over millennia. Materials can easily become mixed together and so, short of finding tools buried in a modern human grave, it is difficult to say who made them. Ranis does seem to have an advantage in this regard, though, as the levels containing the human remains and the LRJ tools were sealed together by a rockfall.</p>
<p>However, even here a cautionary note should be sounded. The dates for the levels under consideration still span several millennia, during which there may well have been short-term visits by both camps.</p>
<h2>New archaeological techniques</h2>
<p>The results from Ranis, as well as contributing important new data to our understanding of the Middle-Upper Palaeolithic transition, highlight the contributions of recent developments in archaeological science.</p>
<p>Far from unearthing a complete skeleton or skull that traditionally would have heralded an important new hominin fossil, Ranis yielded only a few small fragments of bone that were recognisable as human. Some other small bone fragments were identified as belonging to hominins (the wider human family) using a technique known as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8473418/#:%7E:text=The%20word%20proteome%20was%20created,of%20the%20organism%20than%20genomics.">proteomics</a> – the study of protein structures that are unique to genera and sometimes to species. This technique was also applied to the site’s fauna <a href="https://www.nature.com/articles/s41559-023-02303-6">in another companion paper</a>.</p>
<p>Then, relatively high-precision radiocarbon dates were obtained for both the sediment level and the human remains themselves. The precision of these dates was further improved through statistical modelling.</p>
<p>But most importantly for the question at hand, ancient DNA analysis – in this case, mitochondrial DNA (mtDNA) – confirmed the identification as <em>H. sapiens</em>. The mtDNA results link Ranis with other <a href="https://en.wikipedia.org/wiki/Initial_Upper_Paleolithic">Initial Upper Palaeolithic</a> human remains at Zlatý kůň in the Czech Republic and the Grotta di Fumane in Italy. </p>
<p>As the authors of the Ranis study note, an intriguing twist to the tale is that recent genetic studies suggest the <em>H. sapiens</em> conducting these early forays into Europe appear to have themselves been <a href="https://www.nature.com/articles/s41586-023-05726-0">replaced by other <em>H. sapiens</em> populations</a> later in the Upper Palaeolithic.</p>
<p>So, the focus on the Middle-Upper Palaeolithic transition and its replacement of one hominin population by another may have to be extended to consider similar, subsequent events that have remained far less visible, because they all involved <em>H. sapiens</em>.</p><img src="https://counter.theconversation.com/content/222762/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rick Schulting does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
A new discovery is shedding more light on the overlap between the two species of human, despite the challenges of exploring this distant time
Rick Schulting, Professor of Scientific and Prehistoric Archaeology, University of Oxford
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/220218
2024-02-04T22:56:09Z
2024-02-04T22:56:09Z
Our ancient primate ancestors had an appetite for soft fruits – and their diet shaped human evolution
<p>The diet of early anthropoids – the ancestors of apes and monkeys – has long been debated. Did these early primates display behaviours and diets similar to modern species, or did they have much humbler beginnings? </p>
<p>Research on early anthropoids has often suggested a diet high in soft fruits. But some species seem to have had a more varied diet, containing harder foods such as seeds and nuts. </p>
<p>Our <a href="https://doi.org/10.1002/ajpa.24884">latest research</a> reveals a different story, one that highlights the dominant role of soft fruits. This likely encompassed various types that were ripe and high in sugar, as evidenced by the presence of tooth decay in some individuals.</p>
<p>This has important implications for understanding how our earliest ancestors adapted and evolved.</p>
<h2>Tracking anthropoid evolution</h2>
<p>When discussing the primate family tree, it is crucial to address the common confusion arising from the everyday use of terms such as “ape” and “monkey”. </p>
<p>Humans, for instance, are typically excluded from the ape category, and apes are not generally considered monkeys. Yet humans are nested within the ape family tree, which in turn is nested within the broader monkey group, however this is defined.</p>
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<strong>
Read more:
<a href="https://theconversation.com/revelations-from-17-million-year-old-ape-teeth-could-lead-to-new-insights-on-early-human-evolution-187996">Revelations from 17-million-year-old ape teeth could lead to new insights on early human evolution</a>
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<p>All of these primates (humans, apes, and monkeys) are collectively called anthropoids, and we all share a common anthropoid ancestor that lived around 40 million years ago.</p>
<p><a href="https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1001342">Genetic and molecular studies</a>, along with <a href="https://www.pnas.org/doi/abs/10.1073/pnas.0908320107">fossil evidence</a>, indicate the period from 40 to 25 million years ago was a critical phase for the evolution and spread of anthropoid primates. </p>
<p>The early portion of this period marks when Afro-Eurasian monkeys and apes (Catarrhini) diverged from monkeys native to the Americas (Platyrrhini). The latter part of this period witnessed further divergence between Afro-Eurasian monkeys (Cercopithecoidea) and apes (Hominoidea).</p>
<h2>Fossils of our earliest ancestors</h2>
<p>The <a href="https://link.springer.com/chapter/10.1007/978-3-319-65661-8_12">Fayum Depression</a> in the Western Desert of Egypt offers one of the largest and best-preserved collections of fossil primates from this time frame. Between 35 and 29.2 million years ago (when the fossils used in this study were deposited), the Fayum sat on the lush northern coast of Africa. </p>
<p>The terrestrial rocks of the Fayum preserve the remnants of ecosystems that laid the groundwork for Africa’s modern biodiversity. They also capture a pivotal window in primate evolution. </p>
<p>Several of the anthropoid primates from the site may represent either the direct ancestors of all (or some) living anthropoids. Or they were close relatives of this common ancestor. </p>
<p>Fossils of these early anthropoids are relatively abundant in the Fayum, with some species known from dozens of partial skulls and jaws. Because of this, the Fayum offers a fascinating glimpse into the behaviour and life of our early ancestors.</p>
<h2>Dietary interpretations</h2>
<p>Dental evidence is a powerful tool in palaeontology. Our new study examined dental wear and disease in fossilised teeth from five Fayum anthropoid primates: <em>Aegyptopithecus</em>, <em>Parapithecus</em>, <em>Propliopithecus, Apidium</em> and <em>Catopithecus</em>. </p>
<p>We focused on tooth chipping patterns and dental caries (also known as cavities), key indicators in fossils of dietary habits.</p>
<p>Our findings indicate a predominantly soft fruit diet in early anthropoids, different to some earlier research suggesting a more varied diet, including hard foods. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/human-ancestors-had-the-same-dental-problems-as-us-even-without-fizzy-drinks-and-sweets-92546">Human ancestors had the same dental problems as us – even without fizzy drinks and sweets</a>
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<p>A mere 5% of teeth show chipping (minor enamel fractures). This is substantially lower than the frequency observed in most modern anthropoids, where chipping frequencies range from 4% to 40% of teeth. </p>
<p>Additionally, the presence of dental caries, notably in Propliopithecidae (the extinct primate family that includes <em>Aegyptopithecus</em> and <em>Propliopithecus</em>), is consistent with the regular consumption of soft, sugary fruits. </p>
<p>This research also lends support to previous studies suggesting an arboreal (tree-living) lifestyle for early anthropoids. Terrestrial primates often exhibit higher chipping prevalence due to more varied diets and accidental grit consumption when feeding on the ground, none of which was evident in our findings. </p>
<h2>Adaptation and evolution</h2>
<p>The preference for soft fruits likely had significant impacts on exploration of ecological niches, and even in the development of eyesight in anthropoid primates. This includes colour vision that likely evolved as a need for <a href="https://www.jstor.org/stable/3066998">finding ripe fruit among the foliage</a>. </p>
<p>It would have also influenced the shape of their teeth, social behaviours and foraging strategies, setting the stage for an adaptive radiation, leading to the global spread and diversification of monkeys and apes. </p>
<p>This rapid evolution of diverse species from humble anthropoid beginnings was likely in response to new ecological opportunities opening up.</p>
<p>Other primates more distantly related to us, in the primate suborder Strepsirrhini, which includes lemurs and lorises, split off from the ancestors of anthropoids millions of years earlier. </p>
<p>Unlike anthropoids, Strepsirrhini show a large variation in diet during the same time interval. The diets of fossil lemurs and lorises likely consisted of hard and tough foods, insects, gum, leaves and fruits. </p>
<p>In contrast, our own ancestors took a long time to move away from a diet based on soft fruits. Our journey into the past to unravel the lives of our ancestors continues, with each fossil adding a new piece to the puzzle of early primate evolution.</p><img src="https://counter.theconversation.com/content/220218/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matthew Robert Borths receives funding from the United States National Science Foundation and the Institute for Museum and Library Services. </span></em></p><p class="fine-print"><em><span>Carolina Loch and Ian Towle do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
New fossil studies tell us our ancient ancestors enjoyed a diet of soft, sweet fruits. This would have influenced where they lived and spread to – and even the evolution of colour vision.
Carolina Loch, Senior Lecturer in Oral Biology, University of Otago
Ian Towle, Postdoctoral researcher, Centro Nacional de Investigación sobre la Evolución Humana (CENIEH)
Matthew Robert Borths, Curator of the Duke Lemur Center Museum of Natural History, Duke University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/216148
2023-12-11T13:12:05Z
2023-12-11T13:12:05Z
Why do people have wisdom teeth?
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption"></span>
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</figure>
<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
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<blockquote>
<p><strong>Why do people have wisdom teeth? – Jack J., age 17, Dedham, Massachusetts</strong></p>
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<p>Wisdom teeth are the third set of molars located at the very back of the mouth. They look just like the first and second molars, but can sometimes be a little smaller. </p>
<p>They are commonly called wisdom teeth because they are the last of the 32 permanent teeth to appear, emerging <a href="https://doi.org/10.1159/000151214">between 17 and 25 years of age</a>, when you are older and wiser.</p>
<p>You might know that <a href="https://doi.org/10.7717/peerj.10367">not everyone grows</a> all four wisdom teeth. You might also know many people get them pulled. So it’s fair to wonder – why do humans even have them? </p>
<p><a href="https://scholar.google.com/citations?hl=en&user=0lZq0kYAAAAJ">We</a> <a href="https://scholar.google.com/citations?hl=en&user=GYMrNdIAAAAJ">study</a> teeth and can tell you the answer has a lot to do with the distant past – and a bit about the present day, too. </p>
<h2>More powerful jaws</h2>
<p>Just like you have many features in common with the people you’re related to, humans share features with their extended family – the primates. <a href="https://doi.org/10.3389/fdmed.2023.1158482">Monkeys, gorillas and chimpanzees</a> all have wisdom teeth. </p>
<p>A few million years ago, early human ancestors had larger jaws and teeth than humans do today. For example, a species called <em>Australopithecus afarensis</em>, <a href="https://humanorigins.si.edu/evidence/human-fossils/species/australopithecus-afarensis">nicknamed Lucy’s species</a> after a <a href="https://www.nature.com/scitable/knowledge/library/lucy-a-marvelous-specimen-135716086/">famous fossil specimen called Lucy</a>, lived roughly 3 million to 4 million years ago. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/560510/original/file-20231120-21-9261y5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A fossilized jaw showing powerful molars and some broken and missing front teeth." src="https://images.theconversation.com/files/560510/original/file-20231120-21-9261y5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/560510/original/file-20231120-21-9261y5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/560510/original/file-20231120-21-9261y5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/560510/original/file-20231120-21-9261y5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/560510/original/file-20231120-21-9261y5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/560510/original/file-20231120-21-9261y5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/560510/original/file-20231120-21-9261y5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A fossilized jaw from the extinct human ancestor, <em>Australopithecus afarensis</em>, also known as Lucy’s species.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Australopithecus_afarensis_jaw_-_Fossils_in_the_Arppeanum_-_DSC05509.JPG">Daderot/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The jaw and teeth of an <em>Australopithecus afarensis</em> individual were quite a bit <a href="https://doi.org/10.1002/ajpa.21183">larger and thicker</a> than your own. They had three <a href="https://doi.org/10.1007/s12052-010-0249-6">big molar teeth with thick enamel</a>. The fossil skulls of some of these very early humans also show evidence of <a href="https://doi.org/10.1002/ajpa.21183">powerful chewing muscles</a>.</p>
<h2>Changes in diet</h2>
<p>Scientists think more robust jaws and teeth were needed because the foods early human ancestors ate, like raw meat and <a href="https://doi.org/10.1016/j.jhevol.2017.10.013">plants</a>, were much more difficult to chew than food is today. Researchers look at things like <a href="https://doi.org/10.1038/sj.bdj.2014.353">marks and microscopic wear patterns</a> <a href="https://theconversation.com/tooth-be-told-millions-of-years-of-evolutionary-history-mark-those-molars-71428">on fossilized teeth</a> to figure out <a href="https://press.princeton.edu/books/hardcover/9780691160535/evolutions-bite">what extinct ancestors may have eaten</a>. </p>
<p>Today’s food is much softer than it was in the past due to many factors, including <a href="https://doi.org/10.1111/joim.13011">agriculture</a>, <a href="https://doi.org/10.1007/s12110-009-9075-3">cooking</a> and <a href="https://doi.org/10.1038/nplants.2016.194">food storage</a>. Softer, easier-to-chew food means teeth have a less challenging job. As a result, modern human jaws have evolved to be <a href="https://doi.org/10.1038/s41559-019-0865-7">smaller and faces to be flatter</a> than our extinct ancestors’ were, because our meals don’t require the same big, sharp teeth that theirs did. </p>
<p>Given these changes, which took place very slowly over millions of years, the third molars – wisdom teeth – might not be as important now as they once were.</p>
<h2>Missing wisdom teeth</h2>
<p>About <a href="https://www.ncbi.nlm.nih.gov/books/NBK572295/">25% of people today are missing at least</a> one wisdom tooth completely, meaning it never formed at all. While people occasionally don’t grow other teeth, it’s <a href="https://pubmed.ncbi.nlm.nih.gov/34292692/">much more common for wisdom teeth</a>. </p>
<p>Scientists are not sure why this is the case, but it <a href="https://doi.org/10.1007/s11914-022-00761-8">may have to do with the genes</a> <a href="https://doi.org/10.3390/genes9050255">you inherit from your parents</a>. Some scientists have argued that the <a href="https://doi.org/10.1093/ejo/cjad057">lack of wisdom teeth is an advantage</a> for modern, smaller-jawed humans. It’s certainly easier to fit fewer teeth into a smaller jaw.</p>
<p>Sometimes, due to lack of space, wisdom teeth can get stuck inside the jawbone and never fully come up – or they only partially emerge. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/560516/original/file-20231120-18-71m6oo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A radiograph showing a back molar growing sideways into its neighbor." src="https://images.theconversation.com/files/560516/original/file-20231120-18-71m6oo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/560516/original/file-20231120-18-71m6oo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/560516/original/file-20231120-18-71m6oo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/560516/original/file-20231120-18-71m6oo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/560516/original/file-20231120-18-71m6oo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/560516/original/file-20231120-18-71m6oo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/560516/original/file-20231120-18-71m6oo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An impacted wisdom tooth will never come up properly.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Impacted_Wisdom_Tooth_aka_Lower_Right_Third_Molar_48_RVG_IOPA_Xray.jpg">Nizil Shah/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>A so-called impacted wisdom tooth happens <a href="https://pubmed.ncbi.nlm.nih.gov/2205795/">more often in the lower jaw</a> than in the upper jaw. In cases where wisdom teeth are only partially up, people can sometimes experience pain, tooth decay or gum inflammation, which is why they have them pulled by a dentist.</p>
<p>But wisdom teeth don’t usually need to be removed if they are fully erupted in the mouth, positioned correctly and healthy.</p>
<p>Dentists can examine your mouth to see if your wisdom teeth are present, or look at X-ray pictures of your jaw if these last molars haven’t yet emerged and you suspect they may be impacted.</p>
<p>Dentists can also advise you if any treatment – or removal – is recommended for your wisdom teeth. In the meantime, <a href="https://www.mouthhealthy.org/all-topics-a-z/brushing-your-teeth">brushing</a> at least twice a day and <a href="https://www.mouthhealthy.org/all-topics-a-z/flossing">flossing</a> daily will help keep all your teeth healthy. </p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/216148/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ariadne Letra receives funding from the National Institute for Dental and Craniofacial Research.</span></em></p><p class="fine-print"><em><span>Seth M. Weinberg receives funding from the National Institutes of Health. </span></em></p>
Two dental experts explain that these furthest-back molars may be a not-so-necessary leftover from early human evolution.
Ariadne Letra, Professor of Dental Medicine, University of Pittsburgh
Seth M. Weinberg, Professor of Oral and Craniofacial Sciences and Human Genetics, University of Pittsburgh
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/216642
2023-11-30T19:03:33Z
2023-11-30T19:03:33Z
Controversial claims about extinct humans are stirring up evolution research. Here’s how the mess could have been avoided
<p>In June, researchers led by palaeoanthropologist Lee Berger published <a href="https://www.nytimes.com/2023/06/05/science/ancient-humans-homo-naledi-buried-dead.html">sensational claims</a> about an extinct human species called <em>Homo naledi</em> online and in the Netflix documentary <a href="https://www.imdb.com/title/tt27837467/">Unknown: Cave of Bones</a>. They argued the small-brained <em>H. naledi</em> <a href="https://www.biorxiv.org/content/10.1101/2023.06.01.543127v1.article-metrics">buried their dead</a> in Rising Star Cave in South Africa more than 240,000 years ago, and may also have decorated the cave walls with engravings. </p>
<p>If true, this would be an astonishing new entry in the annals of human evolution. But <a href="https://theconversation.com/major-new-research-claims-smaller-brained-homo-naledi-made-rock-art-and-buried-the-dead-but-the-evidence-is-lacking-207000">many scientists</a> – including ourselves (the authors of this article, along with Ian Moffat at Flinders University in Australia, Andrea Zerboni at the University of Milan in Italy, and Kira Westaway at Macquarie University in Australia) – are not convinced by the evidence in the three online articles.</p>
<p>The peer reviewers of these articles and the journal editor found that the evidence was “inadequate” and <a href="https://elifesciences.org/reviewed-preprints/89106/reviews#tab-content">suggested a comprehensive list of changes</a> that would be needed to make the articles’ argument convincing. More recently, a <a href="https://www.sciencedirect.com/science/article/abs/pii/S0047248423001434?dgcid=coauthor">strongly worded, peer-reviewed critique</a> by one of us (Herries) concluded there was not enough evidence to support the hypothesis that <em>H. naledi</em> carried out intentional burials.</p>
<h2>The need for an analytical revolution</h2>
<p>What would “enough evidence” for such claims look like? As we argue in a new comment piece in <a href="https://www.nature.com/articles/s41559-023-02215-5">Nature Ecology and Evolution</a>, there are modern scientific techniques that could provide it. </p>
<p>There are many kinds of evidence for human evolution, such as fossils and artefacts, and the sediment (or dirt) from which they are recovered. There are also many new and creative ways we can use to study this evidence. </p>
<p>We argue that the routine use of these techniques to generate supporting data will help avoid future controversies and increase public confidence in such claims. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/559804/original/file-20231116-18-u8tdzn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A woman in a lab coat examining a dish full of rock or soil." src="https://images.theconversation.com/files/559804/original/file-20231116-18-u8tdzn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/559804/original/file-20231116-18-u8tdzn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1057&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559804/original/file-20231116-18-u8tdzn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1057&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559804/original/file-20231116-18-u8tdzn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1057&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559804/original/file-20231116-18-u8tdzn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1328&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559804/original/file-20231116-18-u8tdzn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1328&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559804/original/file-20231116-18-u8tdzn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1328&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Archaeological scientist Kelsey Hamilton at work, Flinders University, Adelaide.</span>
<span class="attribution"><span class="source">Mike Morley</span></span>
</figcaption>
</figure>
<h2>Scientific collaborations</h2>
<p>Human evolution researchers deal with very long timescales, often measured in hundreds of thousands – or even millions – of years. Because of this, we often work with geologists and other Earth scientists, and use their ideas and tools to analyse traces of ancient humans.</p>
<p>The analytical techniques of the Earth sciences can provide extremely useful information about the context of fossils and archaeological material. </p>
<p>These techniques are commonly used to study the sediments that the archaeology and fossils are recovered from. These kinds of analyses can be carried out at the microscopic level, which means we can find information about the collected remains that would otherwise be impossible to obtain.</p>
<h2>Answers in the dirt</h2>
<p>Better instruments and ways to study dirt means that archaeological science can be used to understand the processes that form archaeological sites and preserve fossils and artefacts in incredibly detailed ways. We can even study evidence at the scale of <a href="https://theconversation.com/digging-deep-dna-molecules-in-ancient-dirt-offer-a-treasure-trove-of-clues-to-our-past-172489">molecules and elements</a>.</p>
<p>One way of studying dirt that is gaining traction in the field is known as micromorphology. This method involves the microscopic analysis of sediment that surrounds fossils or archaeology.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/dishing-the-dirt-sediments-reveal-a-famous-early-human-cave-site-was-also-home-to-hyenas-and-wolves-122458">Dishing the dirt: sediments reveal a famous early human cave site was also home to hyenas and wolves</a>
</strong>
</em>
</p>
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<p>By studying intact blocks of sediment removed from archaeological trenches, microscopic clues can be pieced together to reconstruct the past environments present at the site and in the local environment.</p>
<figure class="align-center ">
<img alt="A close up view of a slice of brown-and-white rock." src="https://images.theconversation.com/files/561786/original/file-20231127-27-h0u61t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/561786/original/file-20231127-27-h0u61t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/561786/original/file-20231127-27-h0u61t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/561786/original/file-20231127-27-h0u61t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/561786/original/file-20231127-27-h0u61t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/561786/original/file-20231127-27-h0u61t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/561786/original/file-20231127-27-h0u61t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A microscopic view of hyena coprolite (fossilised excrement) including pieces of bone.</span>
<span class="attribution"><span class="source">Mike Morley</span></span>
</figcaption>
</figure>
<p>What’s more, the same blocks of sediment can be used for other analyses, such as refining the ages of the dirt and to better understand how archaeological sites form and preserve up until the point of discovery.</p>
<h2>What’s in the dirt? Science can tell us</h2>
<p>Micromorphology has proven to be a powerful tool for analysing ancient human remains and burial practices. In 2021, scientists who studied the oldest known human burial (78,000 years ago) used micromorphology to help identify the burial and publish the work in <a href="https://www.nature.com/articles/s41586-021-03457-8">Nature</a>.</p>
<p>Earlier, in 2017, the technique was used to identify <a href="https://www.sciencedirect.com/science/article/pii/S0305440316300838?casa_token=wf5YCUeuqCoAAAAA:PM8L5sZsNrsur2Jvvt49y2nVK2Q-d8VX5tIwBRpeL42Pjqp1Gp-q0B3dgoJdHV4ai9qHCkM-WQ">hearth features at Liang Bua cave (Indonesia)</a>. These small fireplaces were not obvious to the naked eye but under the microscope showed all of the characteristics of burning, including micro-traces of charcoal and ash. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/562032/original/file-20231128-29-qinibd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo of a thin slice of rock showing a dark band and traces of soot on a paler background." src="https://images.theconversation.com/files/562032/original/file-20231128-29-qinibd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/562032/original/file-20231128-29-qinibd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=896&fit=crop&dpr=1 600w, https://images.theconversation.com/files/562032/original/file-20231128-29-qinibd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=896&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/562032/original/file-20231128-29-qinibd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=896&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/562032/original/file-20231128-29-qinibd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1126&fit=crop&dpr=1 754w, https://images.theconversation.com/files/562032/original/file-20231128-29-qinibd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1126&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/562032/original/file-20231128-29-qinibd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1126&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A microscope slide showing traces of an ancient fireplace at Liang Bua cave.</span>
<span class="attribution"><span class="source">Mike Morley</span></span>
</figcaption>
</figure>
<p>Fossils of <em>H. floresiensis</em> (dubbed “hobbits”) were also found in this cave. However, it turned out the hearths were made by <em>H. sapiens</em> 46,000 years ago, after the last appearance of the hobbits (around 60,000–50,000 years ago).</p>
<p>In the case of <em>H. naledi</em>, micromorphology could have provided evidence for, or against, the idea that the remains were deliberately buried. It might have found traces of a grave cut or subtle differences in the sediment used to cover the body that might not have been obvious during excavation. </p>
<p>In fact, three of the four peer reviewers of the original burial paper suggested micromorphology could have been used to interpret the sediments of the possible grave fill.</p>
<h2>What next?</h2>
<p>As scientists working in the field of human evolution, we are thrilled about the Rising Star Cave fossils and the recognition of <em>H. naledi</em> as a new member of our genus, <em>Homo</em>. We trust the team working at the site will soon present new data that convinces us all one way or the other about the question of intentional burial.</p>
<p>On the weight of the currently available evidence we agree with others that there is no compelling case for that particular mortuary practice at the site. However, there are a raft of scientific techniques that could help end the controversy.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/major-new-research-claims-smaller-brained-homo-naledi-made-rock-art-and-buried-the-dead-but-the-evidence-is-lacking-207000">Major new research claims smaller-brained _Homo naledi_ made rock art and buried the dead. But the evidence is lacking</a>
</strong>
</em>
</p>
<hr>
<p>It can be incredibly difficult for the public to disentangle facts from fiction. We believe scientists need to be extremely careful about how they communicate their findings to avoid an increase in scepticism towards scientists that can have a major impact across all aspects of modern life.</p>
<p>Aside from the <em>H. naledi</em> burial debate, we would like to see a future where all investigations into human evolution use these scientific techniques from the outset. This might avoid future controversy and find clues that strongly support hypotheses. This would also allow for greater confidence in findings presented to the scientific community and public alike.</p><img src="https://counter.theconversation.com/content/216642/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mike W Morley receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Andy I.R. Herries receives funding from the Australian Research Council</span></em></p><p class="fine-print"><em><span>Anna M. Kotarba-Morley receives funding from Australian Research Council, National Centre for Science in Poland, Queensland Department of Environment, and Science and Rock Art Australia. </span></em></p><p class="fine-print"><em><span>Renaud Joannes-Boyau receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Vito C. Hernandez receives funding from the College of Humanities, Arts and Social Sciences of Flinders University, and the Australian Research Council Future Fellowship grant of Associate Professor Mike Morley.</span></em></p>
How, when and where did modern humans evolve? Nobody has all the answers, but studying rock and dirt can put the debate on firmer footing.
Mike W. Morley, Associate Professor and Director, Flinders Microarchaeology Laboratory, Flinders University
Andy I.R. Herries, Professor of Palaeoanthropology, La Trobe University
Anna M. Kotarba-Morley, Lecturer in Museum and Curatorial Studies, University of Adelaide
Renaud Joannes-Boyau, Associate Professor, Southern Cross University
Vito C. Hernandez, Geoarchaeologist and Postgraduate Research Scholar, Flinders University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/214347
2023-11-17T13:29:56Z
2023-11-17T13:29:56Z
Forget ‘Man the Hunter’ – physiological and archaeological evidence rewrites assumptions about a gendered division of labor in prehistoric times
<figure><img src="https://images.theconversation.com/files/560041/original/file-20231116-21-sqjk8p.jpg?ixlib=rb-1.1.0&rect=544%2C53%2C4368%2C2812&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In small-group, subsistence living, it makes sense for everyone to do lots of jobs.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/tribe-of-hunter-gatherers-wearing-animal-skin-live-royalty-free-image/1194512903">gorodenkoff/iStock via Getty Images Plus</a></span></figcaption></figure><p>Prehistoric men hunted; prehistoric women gathered. At least this is the standard narrative written by and about men to the exclusion of women.</p>
<p>The idea of “Man the Hunter” runs deep within anthropology, convincing people that hunting made us human, only men did the hunting, and therefore evolutionary forces must only have acted upon men. Such depictions are found not only in media, <a href="https://www.atlasobscura.com/places/museum-of-human-evolution">but in museums</a> and introductory anthropology textbooks, too. </p>
<p>A common argument is that a sexual division of labor and unequal division of power exists today; therefore, it <a href="https://doi.org/10.1111/0591-2385.00226">must have existed in our evolutionary past</a> as well. But this is a just-so story without sufficient evidentiary support, despite its pervasiveness in disciplines like <a href="https://doi.org/10.1080/1047840X.2013.804899">evolutionary psychology</a>.</p>
<p>There is a growing body of physiological, anatomical, ethnographic and archaeological evidence to suggest that <a href="https://www.scientificamerican.com/article/the-theory-that-men-evolved-to-hunt-and-women-evolved-to-gather-is-wrong1/">not only did women hunt</a> in our evolutionary past, but they may well have been better suited for such an endurance-dependent activity.</p>
<p><a href="https://scholar.google.com/citations?user=YE6ZrpwAAAAJ&hl=en&oi=ao">We are both</a> <a href="https://scholar.google.com/citations?user=u3iE81oAAAAJ&hl=en&oi=ao">biological anthropologists</a>. Cara specializes in the physiology of humans living in extreme conditions, using her research to reconstruct how our ancestors may have adapted to different climates. Sarah studies Neanderthal and early modern human health, and excavates at their archaeological sites.</p>
<p>It’s not uncommon for scientists like us – who attempt to include the contributions of all individuals, regardless of sex and gender, in reconstructions of our evolutionary past – to be accused of rewriting the past to fulfill a politically correct, woke agenda. The actual evidence speaks for itself, though: Gendered labor roles did not exist in the Paleolithic era, which lasted from 3.3 million years ago until 12,000 years ago. The story is written in human bodies, now and in the past.</p>
<p>We recognize that biological sex can be defined using multiple characteristics, including chromosomes, genitalia and hormones, each of which <a href="https://doi.org/10.1002/ajhb.23623">exists on a spectrum</a>. Social gender, too, is not a binary category. We use the terms female and male when discussing the physiological and anatomical evidence, as this is what the research literature tends to use.</p>
<h2>Female bodies: Adapted for endurance</h2>
<p>One of the key arguments put forth by “Man the Hunter” proponents is that <a href="https://search.worldcat.org/title/444294299">females would not have been physically capable</a> of taking part in the long, arduous hunts of our evolutionary past. But a number of female-associated features, which provide an endurance advantage, tell a different story.</p>
<p>All human bodies, regardless of sex, have and need both the hormones <a href="https://www.britannica.com/science/estrogen">estrogen</a> and <a href="https://www.britannica.com/science/testosterone">testosterone</a>. On average, females have more estrogen and males more testosterone, though there is a <a href="https://www.mountsinai.org/health-library/tests/testosterone#:%7E:text=Normal%20Results,0.5%20to%202.4%20nmol%2FL">great deal of variation</a> <a href="https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=167&ContentID=estradiol#:%7E:text=30%20to%20400%20pg%2FmL,50%20pg%2FmL%20for%20men">and overlap</a>.</p>
<p>Testosterone often gets all the credit when it comes to athletic success. But estrogen – technically the estrogen receptor – <a href="https://doi.org/10.1126/science.1086185">is deeply ancient</a>, originating somewhere between 1.2 billion and 600 million years ago. It <a href="https://www.nbcnews.com/id/wbna38268611">predates the existence of sexual reproduction</a> involving egg and sperm. The testosterone receptor originated as a <a href="https://doi.org/10.1126/science.1086185">duplicate of the estrogen receptor</a> and is only about half as old. As such, estrogen, in its many forms and pervasive functions, seems necessary for life among both females and males.</p>
<p>Estrogen influences athletic performance, <a href="https://doi.org/10.1007/s40279-022-01651-w">particularly endurance performance</a>. The greater concentrations of estrogen that females tend to have in their bodies likely confer an endurance advantage – an ability to exercise for a longer period of time without becoming exhausted.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/559161/original/file-20231113-27-iz9t0v.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="sihoutte of a woman's body with cartoon systems highlighted" src="https://images.theconversation.com/files/559161/original/file-20231113-27-iz9t0v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559161/original/file-20231113-27-iz9t0v.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=391&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559161/original/file-20231113-27-iz9t0v.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=391&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559161/original/file-20231113-27-iz9t0v.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=391&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559161/original/file-20231113-27-iz9t0v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=491&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559161/original/file-20231113-27-iz9t0v.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=491&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559161/original/file-20231113-27-iz9t0v.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=491&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The hormone estrogen has multiple effects throughout the body and plays a role in people regardless of sex.</span>
<span class="attribution"><span class="source">Cara Ocobock</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p><a href="https://doi.org/10.1139/H00-024">Estrogen signals the body to burn more fat</a> – beneficial during endurance activity for two key reasons. First, fat has more than twice the calories per gram as carbohydrates do. And it takes <a href="https://www.ncbi.nlm.nih.gov/books/NBK556002">longer to metabolize fats than carbs</a>. So, fat provides more bang for the buck overall, and the slow burn provides sustained energy over longer periods of time, which <a href="https://doi.org/10.1111/apha.12234">can delay fatigue during endurance activities</a> like running.</p>
<p>In addition to their estrogen advantage, females have a greater proportion of <a href="https://blog.nasm.org/fitness/fast-twitch-vs-slow-twitch">type I muscle fibers</a> relative to males.</p>
<p>These are slow oxidative muscle fibers that prefer to metabolize fats. They’re not particularly powerful, but they take awhile to fatigue – unlike the powerful type II fibers that males have more of but that tire rapidly. Doing the same intense exercise, <a href="https://doi.org/10.1152/JAPPL.1998.85.3.1175">females burn 70% more fats</a> than males do, and unsurprisingly, are <a href="https://doi.org/10.1007/BF00422739">less likely to fatigue</a>. </p>
<p>Estrogen also appears to be important for post-exercise recovery. Intense exercise or heat exposure can be stressful for the body, eliciting an inflammatory response via the release of heat shock proteins. Estrogen limits this response, which would otherwise inhibit recovery. Estrogen also stabilizes cell membranes that might otherwise be damaged or rupture due to the stress of exercise. Thanks to this hormone, <a href="https://doi.org/10.2165/11319760-000000000-00000">females incur less damage during exercise</a> and are therefore capable of faster recovery.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/559162/original/file-20231113-25-uu4rie.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Silhouette of woman running with cartoon systems highlighted" src="https://images.theconversation.com/files/559162/original/file-20231113-25-uu4rie.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559162/original/file-20231113-25-uu4rie.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=354&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559162/original/file-20231113-25-uu4rie.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=354&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559162/original/file-20231113-25-uu4rie.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=354&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559162/original/file-20231113-25-uu4rie.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=445&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559162/original/file-20231113-25-uu4rie.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=445&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559162/original/file-20231113-25-uu4rie.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=445&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A variety of physiological differences add up to an advantage for women in endurance activities.</span>
<span class="attribution"><span class="source">Cara Ocobock</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Women in the past likely did everything men did</h2>
<p>Forget the Flintstones’ nuclear family with a stay-at-home wife. There’s no evidence of this social structure or gendered labor roles during the 2 million years of evolution for the genus <em>Homo</em> until the last 12,000 years, with the advent of agriculture. </p>
<p><a href="https://en.wikipedia.org/wiki/Neanderthal">Our Neanderthal cousins</a>, a group of humans who lived across Western and Central Eurasia approximately 250,000 to 40,000 years ago, formed small, highly-nomadic bands. Fossil evidence shows <a href="https://doi.org/10.1016/j.jas.2012.05.039">females and males experienced the same bony traumas</a> across their bodies – a signature of a hard life hunting deer, <a href="https://www.britannica.com/animal/aurochs">aurochs</a> and wooly mammoths. <a href="https://doi.org/10.1002/(SICI)1099-1212(199703)7:2%3C133::AID-OA326%3E3.0.CO;2-4">Tooth wear that results from using the front teeth as a third hand</a>, likely in tasks like tanning hides, is equally evident across females and males.</p>
<p>This nongendered picture should not be surprising when you imagine small-group living. Everyone needs to contribute to the tasks necessary for group survival – chiefly, producing food and shelter and raising children. Individual mothers are not solely responsible for their children; in foragers, the <a href="https://dx.doi.org/10.1037/dev0001601">whole group contributes to child care</a>.</p>
<p>You might imagine this unified labor strategy then changed in early modern humans, but archaeological and anatomical evidence shows it did not. Upper Paleolithic modern humans leaving Africa and entering Europe and Asia show very few sexed differences <a href="https://doi.org/10.1002/ajpa.20950">in trauma and repetitive motion wear</a>. One difference is more evidence of <a href="https://doi.org/10.1016/j.crpv.2016.09.001">“thrower’s elbow” in males than females</a>, though some females shared these pathologies.</p>
<p>And this was also the time when <a href="https://doi.org/10.1006/jhev.2000.0435">people were innovating with hunting technologies</a> like <a href="https://www.britannica.com/technology/spear-thrower">atlatls</a>, fishing hooks and nets, and bow and arrows – alleviating some of the wear and tear hunting would take on their bodies. A recent archaeological experiment found that using <a href="https://doi.org/10.1038/s41598-023-40451-8">atlatls decreased sex differences</a> in the speed of spears thrown by contemporary men and women.</p>
<p>Even in death, there are no sexed differences in how Neanderthals or modern humans <a href="https://doi.org/10.1093/oxfordhb/9780199569069.013.0017">buried their dead, or the goods affiliated with their graves</a>. These indicators of differential gendered social status do not arrive until agriculture, with its stratified economic system and monopolizable resources.</p>
<p>All this evidence suggests paleolithic women and men did not occupy differing roles or social realms.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/560074/original/file-20231116-22-l4g97u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="young women adorned with toucan and macaw feathers holding wooden sticks" src="https://images.theconversation.com/files/560074/original/file-20231116-22-l4g97u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/560074/original/file-20231116-22-l4g97u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/560074/original/file-20231116-22-l4g97u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/560074/original/file-20231116-22-l4g97u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/560074/original/file-20231116-22-l4g97u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/560074/original/file-20231116-22-l4g97u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/560074/original/file-20231116-22-l4g97u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Young women from the Awa Indigenous group in Brazil return from a hunt with their bows and arrows.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/portrait-of-a-group-of-young-awa-women-adorned-with-toucan-news-photo/1258052224">Scott Wallace/Hulton Archive via Getty Images</a></span>
</figcaption>
</figure>
<p>Critics might point to recent forager populations and suggest that since they are using subsistence strategies similar to our ancient ancestors, their gendered roles are inherent to the hunter-gatherer lifestyle.</p>
<p>However, there are <a href="https://doi.org/10.1002/evan.20046">many flaws in this approach</a>. Foragers are not living fossils, and their social structures and cultural norms have evolved over time and in response to patriarchal agricultural neighbors and colonial administrators. Additionally, ethnographers of the last two centuries brought their sexism with them into the field, and <a href="https://kernsverlag.com/en/book/distorting-the-past/">it biased how they understood forager societies</a>. For instance, a recent reanalysis showed that 79% of cultures described in ethnographic data <a href="https://doi.org/10.1371/journal.pone.0287101">included descriptions of women hunting</a>; however, previous interpretations frequently left them out. </p>
<h2>Time to shake these caveman myths</h2>
<p>The myth that female reproductive capabilities somehow render them incapable of gathering any food products beyond those that cannot run away does more than just underestimate Paleolithic women. It feeds into narratives that the contemporary social roles of women and men are inherent and define our evolution. Our Paleolithic ancestors lived in a world where everyone in the band pulled their own weight, performing multiple tasks. It was not a utopia, but it was not a patriarchy. </p>
<p>Certainly <a href="https://doi.org/10.1080/00438243.2018.1433060">accommodations must have been made for group members</a> who were sick, recovering from childbirth or otherwise temporarily incapacitated. But pregnancy, lactation, child-rearing and menstruation are not permanently disabling events, as researchers found among the living Agta of the Philippines who <a href="https://doi.org/10.1007/BF00287829">continue to hunt during these life periods</a>.</p>
<p>Suggesting that the female body is only designed to gather plants ignores female physiology and the archaeological record. To ignore the evidence perpetuates a myth that only serves to bolster existing power structures.</p>
<ul>
<li><em>Read more on this topic in <a href="https://www.scientificamerican.com/article/the-theory-that-men-evolved-to-hunt-and-women-evolved-to-gather-is-wrong1/">Scientific American</a></em></li>
</ul><img src="https://counter.theconversation.com/content/214347/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Female bodies have an advantage in endurance ability that means Paleolithic women likely hunted game, not just gathered plants. The story is written in living and ancient human bodies.
Sarah Lacy, Assistant Professor of Anthropology, University of Delaware
Cara Ocobock, Assistant Professor of Anthropology, University of Notre Dame
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/214788
2023-10-18T13:48:08Z
2023-10-18T13:48:08Z
Evolution revolution: how a Cape Town museum exhibit is rewriting the story of humankind
<p>Picture your typical human evolution museum display. You walk into a dimly lit space with glass boxes on white plinths or roped off areas. There are lots and lots of bones. Maybe a bit of history on how those bones were collected, and pictures of the famous people – usually men – who collected them. Often there are reconstructions of what these human ancestors might have looked like: dark-skinned and hairless ape-people, walking, mostly naked, holding stone tools, or even being hunted. </p>
<p>But where are <em>you</em>? How does such an exhibit show you who you are and how you came to be? We don’t think it does. So, in 2018 we were among a group of human evolution researchers who decided it was time to do things differently. The result is Humanity, a new human evolution exhibit that opened in September 2023 at <a href="https://www.iziko.org.za/museums/south-african-museum/">Iziko South African Museum</a> in Cape Town.</p>
<p>The exhibit offers a close look at the problematic history of palaeoanthropology; it also attempts to decolonise the story of human origins. To do so, it looks at how human evolution has been <a href="https://theconversation.com/science-and-race-in-south-africa-lessons-from-old-bones-in-boxes-179774">portrayed in the past</a>, in ways that reinforce western biases and alienate and dehumanise living Africans. Then it works to remove those biases and make our understanding of human evolution scientifically accurate, broadly relevant and inclusive. </p>
<p>This is part of a broader reckoning happening in <a href="https://theconversation.com/to-accurately-portray-histories-museums-need-to-do-more-than-reimagine-galleries-189109">museum practice globally</a>. Many institutions are reconsidering their collections and their roles as participants in colonial practice, including theft of artefacts and bodies. It is essential to consider how museums continue to alienate precisely the people who are owed reparations.</p>
<p>We learned an enormous amount while developing this exhibit, which is now a permanent fixture at the museum. Our hope is that these four central lessons could help other institutions locally and internationally to reconsider how they portray human evolution – and to understand why it matters.</p>
<h2>A learning process</h2>
<p><strong>1. Make the co-creation process as inclusive as possible:</strong></p>
<p>The Humanity exhibit was created through a collaborative process involving curators, researchers, collections managers, designers, conservators, educators, artists, heritage practitioners, community members, public participants, procurement specialists, service providers and administrators. </p>
<p>In this process, our plans changed often, when a diversity of lenses showed us where content and design missed the mark. The product is radically different from what we thought we would create. It is richer for that. </p>
<p><strong>2. Lose the “great white explorer” narrative:</strong> </p>
<p>The history of human evolution is traditionally told as a story of white male exploration and discovery. South Africans learn in school and through the media about <a href="https://www.sahistory.org.za/people/raymond-arthur-dart">Raymond Dart</a>, <a href="https://www.sahistory.org.za/people/robert-broom">Robert Broom</a>, <a href="https://www.sahistory.org.za/people/professor-emeritus-phillip-tobias">Phillip Tobias</a>, <a href="https://www.britannica.com/biography/Lee-Berger">Lee Berger</a> and other mostly foreign, English-speaking white men who are associated with important fossil discoveries in the country. </p>
<p>In contrast, we centred the exhibit’s story on the diversity of people in South Africa and how that diversity came to be. </p>
<p>This was done through portraiture, genetic testing and interviews about cultural identity to explore, through individuals, what makes them “them”. Interviewees spoke in the South African languages of their choice. This exploration of our collective humanity was used as an inroad for understanding how evolution has worked to shape us into what we are today.</p>
<p><strong>3. Own the problematic past:</strong></p>
<p>Early South African palaeoanthropologists didn’t only find fossils: they also <a href="https://theconversation.com/archaeology-is-changing-slowly-but-its-still-too-tied-up-in-colonial-practices-133243">often engaged in colonial, racist science</a>, studying and measuring living people as models for our “primitive” ancestors. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/archaeology-is-changing-slowly-but-its-still-too-tied-up-in-colonial-practices-133243">Archaeology is changing, slowly. But it's still too tied up in colonial practices</a>
</strong>
</em>
</p>
<hr>
<p>Even the iconography of human evolution has racist, colonial overtones. A Google Image search for “human evolution” will turn up a trove of images depicting evolution as a line of hominins transitioning from more ape-like to more human-like. Often the earlier ones are more hunched, hairier, and darker, suggesting <a href="https://theconversation.com/comparing-black-people-to-monkeys-has-a-long-dark-simian-history-55102">a link between black bodies and primitiveness</a>, while the end product is a striding white man. </p>
<p>We put in place a number of interventions to deal with this legacy. The exhibit openly discusses race and racism, as well as the history of palaeoanthropology and institutions like Iziko Museum in propping up racist science. This is crucial because, although <a href="https://bioanth.org/about/position-statements/aapa-statement-race-and-racism-2019/">racial categories are meaningless biologically</a>, they have had adverse social effects.</p>
<p>The theme of human connection is threaded through the whole exhibit. This shows how human evolution is not linear, but rather a braided stream – a view <a href="https://www.youtube.com/watch?si=nztLth2ZCZpvVf2J&v=5Iy5mt7F_N4&feature=youtu.be">consistent with cutting-edge science</a>. It also shows how the origin of our species is pan-African, and includes <a href="https://www.scientificamerican.com/article/why-is-homo-sapiens-the-sole-surviving-member-of-the-human-family/">contributions from beyond Africa</a>, and how this has made humanity more variable and more resilient.</p>
<p><strong>4. Break the glass boxes:</strong></p>
<p>Probably the biggest surprise as we developed this exhibit, at least for those of us raised going to museums, was how alienating museums actually are to most people. </p>
<p><a href="https://www.britannica.com/topic/museum-cultural-institution">Museums are a western notion</a>. Putting heritage objects behind glass and on pedestals in sterile spaces is not only alienating, it can be downright offensive. The Humanity exhibit does not fit traditional museum aesthetics. </p>
<p>Instead, visitors are drawn into a welcoming space enveloped in a reed structure that resembles a giant basket, or a hut, staring up at the African sky. A wall of 100 handaxes is there to be touched, as are some important fossil casts. Gone are the scientific illustrations and realistically painted past landscapes. Instead, stories are communicated using art that is familiar to everyone – photographs, videos, animations, comic strips and graffiti. </p>
<h2>Everyone’s story</h2>
<p>The story of humanity is everyone’s story. A story of migration and mixing, and adapting to new contexts. It is a story of the connection of people along the long braided stream of our shared origins. It is important that we tell it that way.</p><img src="https://counter.theconversation.com/content/214788/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>We are grateful for the many voices and helping hands in the development of this exhibition. HUMANITY received funding from: Department of Sports, Art & Culture (DSAC); National Research Foundation (NRF) Human & Social Dynamics platform; University of Cape Town, #AdvancingWomen Grant; GENUS Centre of Excellence in Palaeosciences (CoE-Palaeo); Palaeontological Scientific Trust (PAST). European Society for Evolutionary Biology (ESEB), and Globe Institute, University of Copenhagen.
</span></em></p><p class="fine-print"><em><span>Rebecca Ackermann does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The exhibit offers a close look at the problematic history of palaeoanthropology.
Rebecca Ackermann, Professor, Department of Archaeology and Human Evolution Research Institute, University of Cape Town
Wendy Black, Chief Curator of Art & Social History, Iziko Museums of South Africa
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/214732
2023-10-06T15:15:48Z
2023-10-06T15:15:48Z
Discovery of half-a-million-year-old wooden structure shows we’re wrong to underestimate our ancient relatives
<figure><img src="https://images.theconversation.com/files/551508/original/file-20231002-21-vds0x3.jpg?ixlib=rb-1.1.0&rect=4%2C1%2C1014%2C614&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Excavators found part of a structure formed by two overlapping logs.</span> <span class="attribution"><span class="source">Barham et al. Nature (2023)</span>, <span class="license">Author provided</span></span></figcaption></figure><p>To most people, complex technologies separate modern humans from their ancestors who lived in the Stone Age, thousands or hundreds of thousands of years ago. In today’s fast changing world, older technologies, even those from a few years ago, are often described dismissively as “Stone Age”.</p>
<p>Such terms serve to disconnect us from our ancient relatives, who were much more sophisticated than we sometimes think they were.</p>
<p>A team led by archaeologist Larry Barham at the University of Liverpool recently published robust and well dated evidence <a href="https://www.nature.com/articles/s41586-023-06557-9">for the earliest known use of wood technology</a>. The wooden structure, along with artefacts, date to 476,000 years ago and have been excavated from waterlogged deposits at <a href="https://link.springer.com/article/10.1007/BF01963510">Kalambo Falls, Zambia</a>. </p>
<p>This archaeological site is famous for producing traces of human cultural development dating to <a href="https://w%20%20%C2%A71ww.sciencedirect.com/science/article/pii/S0047248415001104">hundreds of thousands of years ago</a>. </p>
<p>The remarkably well preserved evidence found by Barham and colleagues include, among other things, a wedge (a type of wooden tool), a digging stick, a log cut with the help of tools and a branch with a notch cut into it. </p>
<p>But why, in the age of AI and robotics, should wood technology from nearly half a million years ago generate so much interest from both scientists and the public? </p>
<p>The evidence from Kalambo Falls demonstrates a remarkable ability by early hominins (ancient human relatives) to source wood and shape it with tools.
They were able to produce, not only an assortment of other tools, but also sophisticated wooden structures. We don’t know exactly what species made the structure, but <em>Homo heidelbergensis</em> or a species similar to <em>Homo naledi</em> might be candidates, among others.</p>
<p>These results have far reaching implications for our understanding of how sustainable materials were used in the Early Stone Age. It also sheds light on the capabilities of early hominins.</p>
<h2>From speculation to fact</h2>
<p>Archaeology is the study of deep and recent history using the remains of things left by people who came before us. However, these histories are biased in favour of things that have either survived the passage of time or decayed but left traces.</p>
<p>Humans lived in the era known as the Stone Age for nearly 99% of human history. <a href="https://en.wikipedia.org/wiki/African_archaeology">The Early Stone Age</a> is considered the earliest and perhaps longest “technological age”, stretching from nearly four million years ago to 300,000 years ago. </p>
<p>We know more about stone tools during this early phase of human development, in part because inorganic materials such as rocks are nearly indestructible compared to those made of perishable materials like wood. </p>
<p>Indeed, wood is very scarce in deposits belonging to the Early Stone Age, requiring <a href="https://www.sciencedirect.com/science/article/abs/pii/S0964830500000779">exceptional conditions of preservation</a> to avoid decaying. It survives only in extremely dry environments such as deserts, or extremely wet conditions – as was the case at Kalambo Falls.</p>
<p>Given the scarcity of evidence, direct proof of the intentional use of wood from more than 400,000 years ago sharply transforms our understanding of the antiquity of wood as a technology – and <a href="https://www.sciencedirect.com/science/article/abs/pii/004724849190015N?via%3Dihub">how long hominins have been interacting</a> with this versatile material. They used it to make tools, to build shelters, to obtain food and perhaps even for fuel as they went about their daily lives.</p>
<p>Although researchers had suspected that wood technology <a href="https://archaeo.peercommunityin.org/articles/rec?id=229">was widely used by early hominins</a>, without hard, direct evidence, we could not accept that as fact. Archaeology is a discovery and evidence-based field of study –- seeing is believing. The Kalambo Falls discovery transformed speculation into fact, changing our understanding of the history of technology. </p>
<h2>Benefiting the environment</h2>
<p>However, part of the challenge comes from concepts of human history which could be described as <a href="https://oxfordre.com/education/display/10.1093/acrefore/9780190264093.001.0001/acrefore-9780190264093-e-111">progressivist or linear</a> – that envisage history as an inevitable advance towards modernity through scientific and technological achievement. </p>
<p>In the past, some scientists considered the minds of early hominins to have been more limited <a href="https://www.britannica.com/science/human-evolution/Increasing-brain-size">compared to those of modern humans</a>. They believed technology and culture improved in sophistication as human brain size increased, moving from a “simple” state to the complex, algorithm-dominated world we live in today.</p>
<p>Despite the fact that brain sizes have increased over time, and that technology has changed, it is possible that those who came before us had an impressive understanding of the materials around them and cared for their surroundings. </p>
<p>The intentionally-shaped wood construction from Kalambo Falls is an illustration of design, technology and creativity – using what in today’s world we would call a green technology. </p>
<p>Notions of “progress” are quite deeply embedded in culture. This can also be a proxy for the exceptionalism of modern humans (<em>Homo sapiens</em>) – the belief that there is something unique or exemplary about our species compared with earlier hominins. If we put these notions aside, we can recognise that so called “backward technologies” can greatly benefit the environment and the planet. </p>
<p>The fact that wood is perishable makes it a more sustainable material, unlike some modern construction materials that are nearly indestructible, and leave conspicuous ruins. Manufacturing these modern materials also <a href="https://www.nature.com/articles/d41586-021-02612-5">emits greenhouse gases</a> that contribute to climate change. </p>
<p>Of course, there are risks associated with using wood as a construction material, such as fire and decay. But in appropriate situations, we should continue our long tradition of building in wood. Perhaps the ancients were not so backward, but more progressive than us when it came to looking after the planet through sound decision making.</p>
<p>In summary, the Kalambo Falls evidence suggests that, at least sometimes, early hominins were able to take advantage of materials other than stone for their everyday needs, including tool-making and shelter. They might also have been able to use the resources in their environment for fuel and medicine. </p>
<p>However, we need more direct evidence, going back to the beginnings of the Stone Age to demonstrate how those who came before us used and worked with wood. More discoveries like this might even lead us to rename the mighty Stone Age as the Wood Age.</p><img src="https://counter.theconversation.com/content/214732/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Shadreck Chirikure receives funding from the British Academy, the University of Oxford, National Research Foundation of South Africa, and the University of Cape Town. </span></em></p>
Experts speculated that very early humans worked wood, but previously didn’t have the evidence.
Shadreck Chirikure, Prof of Archaeological Science & British Academy Global Professor, University of Oxford
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/214719
2023-10-04T19:05:09Z
2023-10-04T19:05:09Z
New path for early human migrations through a once-lush Arabia contradicts a single ‘out of Africa’ origin
<figure><img src="https://images.theconversation.com/files/551581/original/file-20231002-21-9nvrqz.JPG?ixlib=rb-1.1.0&rect=0%2C10%2C3456%2C2286&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A general view of Wadi Gharandal riverine wetland, along the Jordan Rift Valley, showing palm trees concentrated at the centre of the wadi near the active spring.</span> <span class="attribution"><span class="source">Mahmoud Abbas</span></span></figcaption></figure><p>Our species, <em>Homo sapiens</em>, migrated out of Africa multiple times – reaching the Levant and Arabia between 130,000 and 70,000 years ago, as exemplified by human fossils and archaeological sites found at various locations. </p>
<p>Little is known, however, about the pathways of these migrations. In a <a href="https://doi.org/10.1126/sciadv.adi6838">study</a> published today in Science Advances, we find the now inhospitable and hyper-arid zone of the southern Jordan Rift Valley was frequently lush and well-watered in the past. </p>
<p>Our evidence suggests this valley had a riverine and wetland zone that would have provided ideal passage for hunter-gatherers as they moved out of Africa and deep into the Levant and Arabia.</p>
<h2>Wandering out of Africa</h2>
<p>Researchers hypothesise humans migrating <a href="https://www.sciencedirect.com/science/article/pii/S0277379116301494">out of Africa</a> would have used platforms in the eastern Sahara, the Nile River Valley, or the margins of the western Red Sea. </p>
<p>From there, these small bands of hunter-gatherers would have passed into the Sinai – a land bridge connecting Africa with the rest of Asia – following migrating animals and hunting a variety of them for sustenance. </p>
<p>For many of these hunter-gatherers, the next stop on the journey would have been the southern portion of the Jordan Rift Valley. This valley is situated in a strategic zone, with the Dead Sea to the north and the Gulf of Aqaba in the south. </p>
<p>Our field work was concentrated on three sites. The first two were <a href="https://www.researchgate.net/publication/344122987_A_wetland_oasis_at_Wadi_Gharandal_spanning_125-70_ka_on_the_human_migration_trail_in_southern_Jordan">Wadi Gharandal</a> and an area near the village of Gregra – both in the valley itself. The third site, <a href="https://livinginjordanasexpat.com/2019/08/21/hiking-wadi-al-hasa-%D9%88%D8%A7%D8%AF%D9%8A-%D8%A7%D9%84%D8%AD%D8%B3%D8%A7/">Wadi Hasa</a>, is located in the more elevated areas of the Jordan plateau. </p>
<p>“Wadi” is an Arabic word describing a temporary riverbed that only contains water during heavy rains.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/551922/original/file-20231003-21-di5gym.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/551922/original/file-20231003-21-di5gym.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551922/original/file-20231003-21-di5gym.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=550&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551922/original/file-20231003-21-di5gym.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=550&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551922/original/file-20231003-21-di5gym.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=550&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551922/original/file-20231003-21-di5gym.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=691&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551922/original/file-20231003-21-di5gym.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=691&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551922/original/file-20231003-21-di5gym.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=691&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">We researched three sites, including two wadis and an area near a village called Gregra.</span>
<span class="attribution"><span class="source">Mahmoud Abbas</span></span>
</figcaption>
</figure>
<h2>When Arabia was a verdant land</h2>
<p>Our goal was to reconstruct the region’s past environmental settings by accurately dating various sections of sediment. We used a technique called luminescence dating to estimate how long sediment grains had been shielded from sunlight, thereby allowing us to calculate how old they were.</p>
<p>Our findings from sedimentary sections ranging 5 to 12 metres in thickness showed ecosystem fluctuations over time, including cycles of dry and humid environments. We also found evidence for the presence of ancient rivers and wetlands.</p>
<p>Luminescence dating showed the sedimentary environments formed between 125,000 and 43,000 years ago, suggesting there had been multiple wet intervals.</p>
<p>At Wadi Gharandal, our team recovered three stone tools associated with a wetland environment. Two of these were made using the <a href="https://link.springer.com/referenceworkentry/10.1007/978-3-319-47829-6_391-1">Levallois method</a> – a characteristic manufacturing technique known to have been used by both Neanderthals and <em>Homo sapiens</em>. We dated the tools to 84,000 years ago. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/551928/original/file-20231004-29-i2gfqe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/551928/original/file-20231004-29-i2gfqe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551928/original/file-20231004-29-i2gfqe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551928/original/file-20231004-29-i2gfqe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551928/original/file-20231004-29-i2gfqe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551928/original/file-20231004-29-i2gfqe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551928/original/file-20231004-29-i2gfqe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551928/original/file-20231004-29-i2gfqe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">We collected samples for luminescence dating from the Wadi Hasa area in West Jordan. Pictured are Mahmoud Abbas, Mohammed Alqudah and Yuansen Lai.</span>
<span class="attribution"><span class="source">Zhongping Lai/Shantou University</span></span>
</figcaption>
</figure>
<p>Collectively, our fieldwork in the Jordan Rift Valley demonstrates the valley once functioned as a 360-kilometre-long freshwater corridor that helped funnel humans northward into Western Asia and southward into the Arabian Peninsula. </p>
<p>Further evidence for a northward expansion comes from the famous <a href="https://en.wikipedia.org/wiki/Skhul_and_Qafzeh_hominins">Skhul and Qafzeh</a> cave sites in Israel. Fossils of <em>Homo sapiens</em> and Levallois stone tools have been found here. </p>
<p>Towards the south, <a href="https://www.nature.com/articles/s41586-021-03863-;y">fieldwork</a> in northern Saudi Arabia has also demonstrated a network of rivers and lakes was once present in the region. This allowed humans to penetrate a green Nefud Desert replete with savannahs and grassland.</p>
<p>In the heart of the Nefud, the lakeside site of Al Wusta has produced a <a href="https://theconversation.com/our-fossil-finger-discovery-points-to-earlier-human-migration-in-arabia-94670">human fossil and Levallois stone tools</a> dating to 85,000 years ago. These dates coincide with the 84,000-year-old Levallois stone tools found at Wadi Gharandal. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/major-new-research-claims-smaller-brained-homo-naledi-made-rock-art-and-buried-the-dead-but-the-evidence-is-lacking-207000">Major new research claims smaller-brained _Homo naledi_ made rock art and buried the dead. But the evidence is lacking</a>
</strong>
</em>
</p>
<hr>
<h2>Multiple migrations into South-West Asia</h2>
<p>Our findings from the Jordan Rift Valley indicate there were multiple early human migrations from Africa, and into Asia, during favourable conditions. This opposes the <a href="https://www.science.org/content/article/almost-all-living-people-outside-africa-trace-back-single-migration-more-50000-years">theory of a single</a>, rapid wave of human movement out of Africa <a href="https://education.nationalgeographic.org/resource/global-human-journey/">60,000 years ago</a>. </p>
<p>Our results also suggest, together with the Levantine and Arabian evidence, that hunter-gatherers used inland river and wetland systems as they crossed South-West Asia. This contradicts a popular model <a href="https://www.newscientist.com/article/mg18625005-200-humans-took-the-scenic-route-out-of-africa/">suggesting they mainly used</a> coastal routes as super-highways.</p>
<p>Although ancient DNA evidence indicates <em>Homo sapiens</em> interbred with Neanderthals and Denisovans multiple times as they spread into Asia, on-the-ground evidence for these encounters has generally been lacking. Our findings provide further evidence this area served as the ground for these encounters.</p>
<p>Yet numerous questions remain unanswered. Large swathes of territory in South-West Asia have not yet been surveyed or dated – and few fossils of our <a href="https://www.science.org/doi/abs/10.1126/science.aai9067">ancestors have been found</a> to shore up arguments about how early humans really dispersed.</p>
<p>We’ll need to closely investigate more long-neglected areas such as the Jordan Rift Valley to accurately portray how humankind’s voyage out of Africa unfolded. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/research-reveals-humans-ventured-out-of-africa-repeatedly-as-early-as-400-000-years-ago-to-visit-the-rolling-grasslands-of-arabia-167050">Research reveals humans ventured out of Africa repeatedly as early as 400,000 years ago, to visit the rolling grasslands of Arabia</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/214719/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Zhongping Lai receives funding from the China Natural Science Foundation.</span></em></p><p class="fine-print"><em><span>Mahmoud Abbas and Michael Petraglia do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The findings reveal a close association between climatic conditions and early human migrations out of Africa.
Michael Petraglia, Director, Australian Research Centre for Human Evolution, Griffith University
Mahmoud Abbas, Postdoctoral Research Fellow, Institute of Marine Sciences, Shantou University
Zhongping Lai, Professor, Institute of Marine Sciences, Shantou University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/213818
2023-09-22T13:11:26Z
2023-09-22T13:11:26Z
South African hominin fossils were sent into space and scientists are enraged
<p><em>When a Virgin Galactic commercial flight soared into space on 8 September 2023, there were two Virgin Galactic pilots, an instructor and three passengers on board – as well as two fossils of ancient prehuman relatives from South Africa. Timothy Nash, a businessman, carried a clavicle belonging to Australopithecus sediba and the thumb bone of a Homo naledi specimen. The fossils’ brief journey – the VSS Unity’s flight lasted just an hour – was organised by palaeontologist Lee Berger, who led the team that discovered and described Homo naledi in 2015. Berger was granted an export permit in July by the South African Heritage Resources Agency (SAHRA) to take the fossils from the country to the US launch site for VSS Unity. <a href="https://www.sahra.org.za/about/">SAHRA is a</a> “national administrative body responsible for the protection of South Africa’s cultural heritage”.</em></p>
<p><em>The event has <a href="https://www.nature.com/articles/d41586-023-02882-1">drawn the ire</a> of scores of human evolution researchers from South Africa and beyond. Some have <a href="https://www.researchprofessionalnews.com/rr-news-africa-south-2023-9-scientists-slam-pr-stunt-that-sent-hominin-fossils-into-space/">labelled it</a> “unethical” and a “publicity stunt”. Berger issued <a href="https://twitter.com/LeeRberger/status/1706277191762231582">a brief statement</a> on X (formerly Twitter) on 25 September addressing the situation. And SAHRA, in <a href="https://www.nature.com/articles/d41586-023-02882-1">a statement</a> quoted by Nature, said it was “satisfied that the promotional benefit derived was appropriately weighted against the inherent risk of travel of this nature”.</em></p>
<p><em>The Conversation Africa asked Dipuo Winnie Kgotleng, <a href="https://www.uj.ac.za/faculties/humanities/research/research-centres/palaeo-research-institute/">director of the Palaeo-Research Institute</a> at the University of Johannesburg, and Robyn Pickering, co-director of the <a href="https://www.heriuct.co.za/">Human Evolution Research Institute</a> at the University of Cape Town, why the space flight created such unhappiness.</em></p>
<h2>Why are scientists so angry about the fossils being sent to space?</h2>
<p>There are a number of reasons. </p>
<p>One is the threat to South African heritage. According to the <a href="https://sahris.sahra.org.za/sites/default/files/website/articledocs/Archaeology%20Permit%20Policy_April2016_Approved.pdf">SAHRA permitting policy</a>, fossils of this nature are only allowed to travel for scientific purposes and should be securely packed to prevent damage. The fossils travelled in space in a sealed tube – and were then kept in an individual’s pocket as he floated freely.</p>
<p>There is no scientific reason for allowing these fossils to travel to space. No new knowledge has been generated and no community, either local or international, has been engaged on this science. </p>
<p>Also, doses of radiation which these specimens were exposed to during this trip could have potentially permanently altered the fossil microstructure, affecting any data which might be required in the future. </p>
<p>A second issue is that the <em>A. sediba</em> clavicle is a type specimen: it is the original physical example of the species and, if such a specimen is lost or destroyed, it is gone forever.</p>
<p>Finally, this event demonstrated the unequal power relations at play in accessing this invaluable heritage. Some local communities – like the people of Taung, where a 2.8 million year old child’s skull <a href="https://humanorigins.si.edu/evidence/human-fossils/fossils/taung-child">nicknamed the Taung Child</a> was discovered in 1924 – have <a href="https://sundayworld.co.za/news/locals-want-taung-skull-returned-home/">requested access</a> to fossil specimens that originated from their areas. In the case of the Taung Child, there have <a href="https://sundayworld.co.za/news/locals-want-taung-skull-returned-home/">reportedly been discussions</a> “over a long time” to have the skull returned by the university where it is stored.</p>
<p>So, is it only wealthy, famous rich white men who can have access to fossils? Poor communities do not have access to the same privileges?</p>
<h2>Professor Berger’s SAHRA application <a href="https://sahris.sahra.org.za/node/620113">called</a> the fossils’ space flight a ‘once in a lifetime opportunity to bring awareness to science, exploration, human origins and South Africa and its role in understanding Humankind’s shared African ancestry’.</h2>
<p>We completely disagree. Which community has been engaged in science awareness? Surely no South African or any African community has been engaged through this act?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/science-and-race-in-south-africa-lessons-from-old-bones-in-boxes-179774">Science and race in South Africa: lessons from 'old bones in boxes'</a>
</strong>
</em>
</p>
<hr>
<h2>Some have argued that the space flight echoes colonial attitudes to human remains. How so?</h2>
<p>This is an example of what we <a href="https://www.nature.com/articles/s41561-022-01010-4">call</a> <a href="https://link.springer.com/article/10.1023/A:1022374703178">neo-colonialism</a>. The <a href="https://jacana.co.za/product/darwins-hunch-science-race-and-the-search-for-human-origins/">science of human evolution has a long</a>, dark past of exploitation and extraction. The main perpetrators of this past were privileged white men, so this latest event feels familiar but is really not OK in 2023. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/archaeology-is-changing-slowly-but-its-still-too-tied-up-in-colonial-practices-133243">Archaeology is changing, slowly. But it's still too tied up in colonial practices</a>
</strong>
</em>
</p>
<hr>
<p>Our field is just beginning to grapple with its past, and we’ve made <a href="https://www.heriuct.co.za/news-content/celebrating-5-years-of-advancing-womxn">some progress</a> in the last decade. Something like this puts us right back into the olden days.</p>
<h2>So what happens next?</h2>
<p>Several professional bodies in various African regions have <a href="https://eaappinfo.wordpress.com/">issued statements</a> <a href="https://twitter.com/SASQUA1/status/1702245012472205761/photo/1">expressing</a> their unhappiness about the treatment of the fossils. </p>
<p>Various arms of the palaeoscience community, such as the <a href="https://www.facebook.com/photo?fbid=301773955808321&set=a.159433826709002">Association of Southern African Professional Archaeologists</a>, have directly asked SAHRA and the Cradle of Humankind Management Authority (which is responsible for preserving the world heritage site where the fossils were found) and the government to address us and the South African public more broadly. </p>
<p>We are also pushing for these organisations to reflect on this issue and to discuss changes to their permitting policy. We’re confident that the outrage we’ve demonstrated will guard against something like this happening again in the future.</p>
<p>September is Heritage Month in South Africa, a time when we are asked to come together as a country, to celebrate, learn about and explore our heritage as a way to build unity in a diverse society. Our common heritage, represented by the fossils, is a great tool for bringing us together as a country. Treating the same fossils in this way goes against this noble aim.</p>
<p><em>This article was updated on 27 September to add Professor Lee Berger’s <a href="https://twitter.com/LeeRberger/status/1706277191762231582">statement</a>.</em></p><img src="https://counter.theconversation.com/content/213818/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dipuo Winnie Kgotleng has received funding from the Wenner-Gren foundation, National Heritage Council and National Research Foundation. </span></em></p><p class="fine-print"><em><span>Robyn Pickering receives funding from The University of Cape Town, the National Research Foundation (NRF) and the DSI Centre of Excellence in Palaeosciences/GENUS</span></em></p>
Experts insist there is no scientific reason for allowing these fossils to travel to space.
Dipuo Winnie Kgotleng, Director, University of Johannesburg
Robyn Pickering, Senior lecturer, University of Cape Town
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/208541
2023-07-16T11:56:52Z
2023-07-16T11:56:52Z
Sleep deprivation benefited our ancestors, yet harms us now — but staying fit may help us cope
<figure><img src="https://images.theconversation.com/files/537551/original/file-20230714-30-roooha.jpg?ixlib=rb-1.1.0&rect=975%2C0%2C6021%2C4196&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Research shows that sleep deprivation impairs communication between brain regions and brain blood flow, damages brain wiring and makes a young brain look like an aged brain.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/sleep-deprivation-benefited-our-ancestors-yet-harms-us-now-but-staying-fit-may-help-us-cope" width="100%" height="400"></iframe>
<p>Humans <a href="https://www.discovermagazine.com/planet-earth/how-our-sleeping-habits-helped-to-make-us-human">need less sleep</a> than our closest evolutionary relatives. However, we often sleep less than we need.</p>
<p>Needing less sleep is a consequence of our ancestors’ choices to remain awake longer — a behaviour that led to evolutionary benefits. Sleeping less than we need is the result of our modern-day choices to remain awake longer, but in this case the behaviour is detrimental to our health and well-being. Our research, however, finds that fitness may be a helpful tool for coping with sleep deprivation.</p>
<h2>Less sleep needed: An ancestral gift</h2>
<p>Our ancestors traded sleep for productive nightly activities like exchanging cultural information to gain social and individual learning, watching for predators and strengthening bonds with peers. This learning had evolutionary benefits and led natural selection to <a href="https://doi.org/10.1146/annurev-anthro-010220-075523">favour shorter sleep durations</a>. <a href="https://doi.org/10.1002/evan.21464">Humans are outliers</a>, however, <a href="https://doi.org/10.1093/emph/eow035">needing sleep for only seven hours</a>, far less than the <a href="https://doi.org/10.1146/annurev-anthro-010220-075523">predicted 9.55 hours of sleep</a> for a primate with similar traits to ours. </p>
<figure class="align-right ">
<img alt="A sleeping chimpanzee" src="https://images.theconversation.com/files/537403/original/file-20230713-27-udsbw2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/537403/original/file-20230713-27-udsbw2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537403/original/file-20230713-27-udsbw2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537403/original/file-20230713-27-udsbw2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537403/original/file-20230713-27-udsbw2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537403/original/file-20230713-27-udsbw2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537403/original/file-20230713-27-udsbw2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Humans need less sleep than our closest evolutionary relatives.</span>
<span class="attribution"><span class="source">(Margo Tanenbaum/Pixabay)</span></span>
</figcaption>
</figure>
<p>Our ability to thrive with longer waking hours is thought to be possibly due to our <a href="https://doi.org/10.1002/evan.21464">highest proportion of efficient, dreamy REM sleep</a> amongst all studied primates and <a href="https://doi.org/10.1098/rspb.2015.1853">brain anatomy changes</a> that facilitate essential housekeeping functions of sleep (like removal of toxins) in a shorter span. This ancestral choice to sleep less was worthwhile (although some speculate that <a href="https://doi.org/10.1093/emph/eow035">it may also have had drawbacks</a>). </p>
<h2>Less sleep available: A modern misery</h2>
<p>In an extreme example of sleep deprivation, in 1964 Randy Gardner broke the world record by staying awake for 11 days. His wake-a-thon bit him back years later in the form of unbearable insomnia that changed his personality. He referred to it as a “karmic payback” in a <a href="https://hiddenbrain.org/podcast/eyes-wide-open/">2018 interview</a> with NPR’s <em>Hidden Brain</em> podcast.</p>
<p>The year 1964 was a time when the <a href="https://www.scientificamerican.com/article/beyond-memory-the-benefits-of-sleep/">necessity of sleep</a> may not have been preached enough as the role of sleep in processing emotions and memories, preserving the body’s immune and hormonal functions, and wringing out its toxins was less well understood.</p>
<figure class="align-center ">
<img alt="A tired woman with her chin in her hand, looking at a laptop" src="https://images.theconversation.com/files/537544/original/file-20230714-23-j0atp3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537544/original/file-20230714-23-j0atp3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537544/original/file-20230714-23-j0atp3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537544/original/file-20230714-23-j0atp3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537544/original/file-20230714-23-j0atp3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537544/original/file-20230714-23-j0atp3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537544/original/file-20230714-23-j0atp3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We forgo sleep to pull an all-nighter in preparation for an exam or a meeting, binge-watch TV shows or scroll through social media.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Today, despite knowing its benefits, humans still willingly sacrifice sleep. We forgo sleep to pull an all-nighter in preparation for an exam or a meeting, binge-watch TV shows, conform to the <a href="https://www.psychologytoday.com/ca/blog/happiness-is-state-mind/202012/the-dangers-sleep-machismo-culture">sleeplessness trend of the modern culture</a> or scroll through social media. </p>
<p>Sleep is not a luxury for people who must face <a href="https://www.sleepfoundation.org/sleep-disorders">sleep disorders</a>, <a href="https://www.theatlantic.com/health/archive/2015/10/the-sleep-gap-and-racial-inequality/412405/">socioeconomic sleep disparity</a>, new parenthood or work obligations of pilots, health-care workers and others with irregular hours. One-third of Americans and Canadians are <a href="https://www.sleepfoundation.org/how-sleep-works/sleep-facts-statistics#references-184386">short of sleep</a>.</p>
<p>Considerable research shows that sleep deprivation impairs <a href="https://doi.org/10.1038%2Fnrn.2017.55">communication between brain regions</a> and <a href="https://doi.org/10.1097%2FMD.0000000000014008">brain blood flow</a>, <a href="https://doi.org/10.1371/journal.pone.0127351">damages brain wiring</a> and makes a young brain <a href="https://doi.org/10.1089/brain.2016.0452">look like an aged brain</a>. For humans, compromising sleep to be productive is counterproductive. It compromises our best performance, attention, decision-making abilities and memory. We risk road and industrial accidents, psychiatric illnesses, dementia and cardiovascular diseases, <a href="https://www.rand.org/randeurope/research/projects/the-value-of-the-sleep-economy.html">costing governments</a> billions of dollars annually.</p>
<p>For our evolutionary ancestors, sleep was costly because it risked being vulnerable to predators and limited the time to engage in productive activities. Today it is the lack of sleep that is costly because sleep is essential. </p>
<p>Sleep research pioneer Allan Rechtschaffen noted: “<a href="https://news.uchicago.edu/story/allan-rechtschaffen-sleep-research-pioneer-1927-2021">If sleep doesn’t serve an absolutely vital function, it is the biggest mistake the evolutionary process has ever made</a>.”</p>
<h2>Countermeasures against sleep deprivation</h2>
<p>An easy fix is to sleep more. But it is a far-fetched goal. Today, getting even an hour or two of extra sleep is challenging. </p>
<p>Policies must intervene to address sleep-related issues. For example: <a href="https://doi.org/10.1126/sciadv.aau6200">pushing the school start time later</a> to match <a href="https://doi.org/10.1093/sleep/21.8.871">teens’ circadian rhythm</a> (teens are not night owls by choice) or <a href="https://knowingneurons.com/blog/2021/11/06/why-are-legislators-trying-to-get-rid-of-daylight-saving-time/">abolishing daylight savings</a>, reducing work hours for essential professions, implementing evidence-based regulations for <a href="https://doi.org/10.1177/1745691615598509">nightshift work</a>, <a href="https://doi.org/10.5665%2Fsleep.3298">defining and normalizing sleep health</a>. </p>
<p>But until policies change, how can we better cope with sleep loss? </p>
<h2>Protective power of fitness</h2>
<p><a href="https://doi.org/10.1249/MSS.0000000000003200">A recent study</a> by our team of researchers at McGill University’s <a href="https://memorylab.ca/">MEMORY lab</a>, led by master’s student Beatrice Ayotte, may have identified a protective factor. The research team — ironically while getting sleep-deprived — showed that people who were more physically fit performed better at a memory task compared to people with lower fitness levels after a night of sleep loss.</p>
<p>Fitness was measured as the ability of the participants’ heart and lungs to supply oxygen and their muscles’ ability to use it while exercising. This is referred to as cardiorespiratory fitness, as opposed to muscular fitness. For this, in the gym-like laboratory, healthy 18-to-35-year-olds biked with increasing resistance until exhaustion. They wore masks with tubes hooked to a computer that measured VO₂peak — the volume of peak oxygen consumption. A higher VO₂peak indicates better fitness.</p>
<figure class="align-center ">
<img alt="A fitness class at a gym" src="https://images.theconversation.com/files/537406/original/file-20230713-19-a3kuf7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537406/original/file-20230713-19-a3kuf7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537406/original/file-20230713-19-a3kuf7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537406/original/file-20230713-19-a3kuf7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537406/original/file-20230713-19-a3kuf7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537406/original/file-20230713-19-a3kuf7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537406/original/file-20230713-19-a3kuf7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">People who were more physically fit performed better at a memory task compared to people with lower fitness levels after a night of sleep loss.</span>
<span class="attribution"><span class="source">(Pixabay)</span></span>
</figcaption>
</figure>
<p>The fun part was when one group of participants spent one night in the lab staying awake, without caffeine, doing mild activities and a lot of talking with the researchers who supervised them. Participants were asked to stay awake for 30 hours, which is brutal but distressingly common among essential workers.</p>
<p>After their wakeful period, participants viewed some images. Four days later, they were given a surprise memory test. Participants who remembered more images scored higher on this memory task.</p>
<p>Sleep deprivation, as expected, had significantly decimated participants’ memory, as reflected in their poorer memory scores compared to the well-rested group. But what’s interesting is that, in the sleep-deprived group, most of the high memory scorers were also highly fit. This indicates that fitter people had some leverage in the sleep-deprived situation.</p>
<figure class="align-center ">
<img alt="A health-care worker sitting on the floor of a corridor looking tired" src="https://images.theconversation.com/files/537549/original/file-20230714-27836-e17pa4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537549/original/file-20230714-27836-e17pa4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537549/original/file-20230714-27836-e17pa4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537549/original/file-20230714-27836-e17pa4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537549/original/file-20230714-27836-e17pa4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537549/original/file-20230714-27836-e17pa4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537549/original/file-20230714-27836-e17pa4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Essential workers often have schedules that are challenging for sleep.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>One interesting finding is that the association between VO₂peak and memory scores was not explained by the participants’ levels of fatigue and attention. So it was not that fitter people could endure more fatigue during sleep deprivation and therefore performed well. Fitness was working in their favour in a different way. </p>
<p>Research has shown that people with <a href="https://doi.org/10.1002%2Fhipo.22827">higher cardiorespiratory fitness</a> tend to have better brain connectivity and cognition. These brain changes could be one of the many mediators of the association found in this study.</p>
<h2>Exercise caution</h2>
<p>We cannot conclude that higher fitness is a cause of memory protection during sleep deprivation. Other healthy habits of fitter participants such as <a href="https://sleeponitcanada.ca/10-simple-tips-for-better-sleep/">good sleep hygiene</a>, higher <a href="https://www.health.harvard.edu/mind-and-mood/what-is-cognitive-reserve">cognitive reserve</a> and healthy diet may have contributed to their better memory performance despite sleep loss.</p>
<figure class="align-center ">
<img alt="A man sleeping in a darkened room" src="https://images.theconversation.com/files/537546/original/file-20230714-23-qivw5u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537546/original/file-20230714-23-qivw5u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537546/original/file-20230714-23-qivw5u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537546/original/file-20230714-23-qivw5u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537546/original/file-20230714-23-qivw5u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537546/original/file-20230714-23-qivw5u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537546/original/file-20230714-23-qivw5u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Other healthy habits of fitter participants such as good sleep hygiene, higher cognitive reserve, healthy diet may have contributed to their better memory performance despite sleep loss.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>However, <a href="https://doi.org/10.1249/jes.0000000000000273">animal research</a> has shown that aerobic exercise training — which increases cardiorespiratory fitness — can protect against the detriments of sleep deprivation. These findings synergize with our own and suggest possible forward steps in dealing with the epidemic. </p>
<p>Compromising sleep has not served our ancestors and us equally. Nature’s incessant drive to choose sleep underscores its irreplaceability. But today, if you decide to run a wake-a-thon, it is advisable to stay fit!</p><img src="https://counter.theconversation.com/content/208541/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Madhura Lotlikar is funded by Fonds de Recherche du Québec - Santé for her Ph.D. study.</span></em></p>
Ancient humans chose to sleep less, which had evolutionary benefits. For modern humans, sleeping less is futile and detrimental, but fitness may be a powerful ally in today’s epidemic of sleep loss.
Madhura Lotlikar, Ph.D. student, Neuroscience, McGill University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/208653
2023-07-03T03:05:31Z
2023-07-03T03:05:31Z
4 reasons not teaching evolution in schools is immoral
<figure><img src="https://images.theconversation.com/files/535184/original/file-20230703-182282-gjldng.jpeg?ixlib=rb-1.1.0&rect=0%2C35%2C3000%2C1958&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Educators involved in curriculum design know one hard truth: you can’t fit in everything. Whatever the finished product, there will always be someone who thinks something important has been missed or something unnecessary has been included. </p>
<p>This is what happened in the recent redesign of the Australian Curriculum, for example, where the emphasis on Western civilisation <a href="https://theconversation.com/the-national-history-curriculum-should-not-be-used-and-abused-as-an-election-issue-176783">became politicised</a>.</p>
<p>When it comes to science curriculums, the amount of potential content that can be included is staggering. </p>
<p>In the case of physics in primary or middle schools, we may or may not see the inclusion of topics such as wave theory, acoustics, electronics or relativity. Some may lament these exclusions, but most agree physics at this level can be taught without them. </p>
<p>Similarly, there are areas of biology that may be considered optional at this level, such as botany, entomology or marine ecosystems. Evolution, however, is a concept that underpins and integrates all facets of biological study.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-exactly-is-the-scientific-method-and-why-do-so-many-people-get-it-wrong-65117">What exactly is the scientific method and why do so many people get it wrong?</a>
</strong>
</em>
</p>
<hr>
<h2>The central role of evolution in biology</h2>
<p>As evolutionary biologist Theodosius Zobzansky noted in the title of his <a href="https://www.pbs.org/wgbh/evolution/library/10/2/text_pop/l_102_01.html">seminal essay</a>, Nothing in Biology Makes Sense Except in the Light of Evolution. </p>
<p>Without evolution, the living world is a kaleidoscope of disconnected form and colour. With evolution, it is breathtakingly coherent. In terms of its simplicity and explanatory power, the theory of evolution by natural selection is arguably one of our most successful scientific achievements.</p>
<p>Because of evolution’s centrality to biology, its omission in any substantive course seems a matter of serious neglect. </p>
<p>Today many countries in the world, predominantly Islamic ones, do not teach evolution, as it is <a href="https://www.nature.com/articles/s41562-019-0771-7#">said to contradict</a> religious teachings.</p>
<p>Recently, <a href="https://www.science.org/content/article/scientists-india-protest-move-drop-darwinian-evolution-textbooks">India</a> also removed evolution from the formal education of students up to Year 10. This decision was supposedly related to its right-wing government’s commitment to <a href="https://www.aljazeera.com/news/2023/4/14/mughals-rss-evolution-outrage-as-india-edits-school-textbooks">promoting Hindu-nationalist</a> perspectives.</p>
<p>These examples do not represent simple oversight. They are serious attempts to restrict people thinking about evolution and, ultimately, to delegitimise science for ideological gain. </p>
<h2>Excluding evolution is a moral concern</h2>
<p>Omitting evolution from educational curriculums isn’t just educationally fraught, it’s also a serious moral issue.</p>
<p>Morally speaking, at least four related points present themselves in favour of the inclusion of evolution in any biology curriculum.</p>
<p><strong>1. Equality of opportunity</strong></p>
<p><a href="https://plato.stanford.edu/entries/rawls/">John Rawls</a>, one of the most influential political philosophers of the 20th century, set <a href="https://edeq.stanford.edu/sections/section-2-conceptions-equality-opportunity/fair-equality-opportunity">equality of opportunity</a> as a key social justice principle. </p>
<p>Many scientists have been inspired towards their work by understanding the grand narrative of evolution, which provides a coherent and effective framework to understand biological systems and their relationships. </p>
<p>Depriving students of this educational experience means they could be disadvantaged in further study or work. Or, worse, they might be dissuaded from it. </p>
<p><strong>2. Free inquiry</strong></p>
<p>Deliberate attempts to exclude serious rational inquiry are anathema to most philosophical schools of thought. Philosopher and scientist <a href="https://digitalcommons.montclair.edu/cgi/viewcontent.cgi?article=1120&context=educ-fdns-facpubs#:%7E:text=Peirce%20argued%20that%20even%20though,is%20%27self%2Dcorrective%27.">C.S. Peirce</a> expressed this powerfully:</p>
<blockquote>
<p>Upon this first, and in one sense this sole, rule of reason, that in order to learn you must desire to learn, and in so desiring not be satisfied with what you already incline to think, there follows one corollary which itself deserves to be inscribed upon every wall of the city of philosophy: do not block the way of inquiry.</p>
</blockquote>
<p>To stifle inquiry is also to inhibit the development of important traits in students – especially curiosity, one of our most powerful tools for knowledge creation. </p>
<p><strong>3. Fairness and public reasoning</strong></p>
<p>Philosopher Immanuel Kant, expressing the essence of the <a href="https://www.nypl.org/sites/default/files/kant_whatisenlightenment.pdf">Enlightenment</a> as he saw it, set public reasoning through an individual commitment to rational inquiry as its cornerstone. </p>
<p>If we value the freedom to inquire and freedom of religious belief, it follows that no particular ideology should have unquestioned authority over others. </p>
<p>It’s naive to think science is a value-free arena. Yet it represents the most effective means of rational inquiry into the world we currently possess. </p>
<p>We can certainly allow for (and indeed need) explanations that the methodologies of science can’t provide. But rational inquiry needs to be accommodated, rather than usurped, by religious or political ideologies.</p>
<p>As the late author and journalist <a href="https://www.nytimes.com/2011/12/16/arts/christopher-hitchens-is-dead-at-62-obituary.html">Christopher Hitchens</a> elegantly stated:</p>
<blockquote>
<p>We do not rely solely upon science and reason, because these are necessary rather than sufficient factors, but we distrust anything that contradicts science or outrages reason.</p>
</blockquote>
<p><strong>4. Intellectual honesty, integrity and a commitment to scientific truths</strong></p>
<p>An extended biology course that doesn’t contain evolution represents a promise made and broken. </p>
<p>To present something as scientific means it should embrace the methodologies and dispositions of scientific inquiry, including open-mindedness, scepticism and fallibility. </p>
<p>Ideologically driven censorship is therefore intellectually dishonest and, in these cases, results in a misrepresentation of science.</p>
<h2>The bottom line</h2>
<p>A moral stance is not something simply held dogmatically. It is one that can be reasoned in a way that’s rationally accessible to others. </p>
<p>Education in a cosmopolitan world – in as much as it is social, collaborative and cooperative – should be characterised by morality and rationality. Excising our best ideas from curriculums is both immoral and irrational.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/guide-to-the-classics-darwins-on-the-origin-of-species-96533">Guide to the classics: Darwin's On the Origin of Species</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/208653/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Ellerton is affiliated with the Rationalist Society of Australia.</span></em></p>
There are areas of biology that may be considered optional at younger year levels, such as botany, entomology and marine ecosystems. Evolution is not one of these.
Peter Ellerton, Senior Lecturer in Philosophy and Education; Curriculum Director, UQ Critical Thinking Project, The University of Queensland
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/207000
2023-06-06T02:42:34Z
2023-06-06T02:42:34Z
Major new research claims smaller-brained ‘Homo naledi’ made rock art and buried the dead. But the evidence is lacking
<figure><img src="https://images.theconversation.com/files/530232/original/file-20230606-23-klb0fr.jpeg?ixlib=rb-1.1.0&rect=48%2C24%2C5306%2C2183&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Wikimedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>On September 13 2013, speleologists Rick Hunter and Steven Tucker descended deep into South Africa’s Rising Star cave system and discovered the first evidence of an extraordinary assemblage of <a href="https://australian.museum/learn/science/human-evolution/hominid-and-hominin-whats-the-difference/">hominin</a> fossils. </p>
<p>To date, the remains of more than 15 individuals belonging to a previously unknown species of extinct human, dubbed <em>Homo naledi</em>, have been found in the cave. These short-statured, small-brained ancient cousins are thought to have lived in Southern Africa between 335,000 and 241,000 years ago.</p>
<p>Rising Star Cave is an exceptional resource for exploring the origins of our species. However, archaeological work at the site has been some of the <a href="https://www.sciencenews.org/article/pieces-homo-naledi-story-continue-puzzle">most</a> <a href="https://www.newyorker.com/magazine/2016/06/27/lee-berger-digs-for-bones-and-glory">controversial</a> in the discipline.</p>
<p><a href="https://www.biorxiv.org/content/10.1101/2023.06.01.543127v1">Three</a> <a href="https://www.biorxiv.org/content/10.1101/2023.06.01.543133v1">new</a> <a href="https://www.biorxiv.org/content/10.1101/2023.06.01.543135v1">studies</a> made available today (as pre-prints awaiting peer review) claim to have found evidence <em>Homo naledi</em> intentionally buried their dead (a sophisticated practice we usually associate with <em>Homo sapiens</em>) and made rock art, which suggests advanced cognitive abilities. </p>
<p>However, as archaeologists who investigate early humans in Africa, we’re not convinced the new research stacks up.</p>
<h2>Did <em>Homo naledi</em> bury their dead?</h2>
<p>The research purports to have evidence <em>Homo naledi</em> undertook deliberate burial of their dead – a major claim. </p>
<p>So far, the <a href="https://www.nature.com/articles/s41586-021-03457-8">earliest secure evidence</a> for burial in Africa comes from the Panga ya Saidi cave site in eastern Kenya, excavated by our team and dated to 78,000 years ago. This burial of a <em>Homo sapiens</em> child meets rigorous criteria agreed upon by the scientific community for identifying <a href="https://www.sciencedirect.com/science/article/pii/S004724841100090X?casa_token=Ij7IJcdPIaoAAAAA:-oP3zX8NHW18oJetZcL9X494dJ4EkFBIoGdi8md-th8lFlFbcCDMwCt_pWFIXrcrxYZOIYsD">intentional human burial</a>.</p>
<p>The aim of the criteria is to help differentiate burial from other practices and phenomena that could lead to the depositing of human remains. These include, for example, the natural accumulation of skeletal parts in a predator’s cavern, or the kind of <a href="https://www.bbc.com/future/article/20120919-respect-the-dead">carrying and protecting</a> of dead bodies observed among cognitively advanced non-human species such as gorillas and chimpanzees.</p>
<p>The claimed <em>Homo naledi</em> burials precede the Panga ya Saidi burial evidence by as much as 160,000 years. If the claim is correct, it significantly pushes back evidence for advanced mortuary behaviour in Africa. It also implies intentional burial wasn’t limited to our species or other big-brained hominins.</p>
<p>Such a finding would force us to rethink the role of brain size in advanced “meaning-making” cognition, as well as what distinguishes our species from our ancestors.</p>
<p>But is there actually evidence for funerary behaviour at Rising Star Cave? According to standards set by the palaeoanthropology community, the evidence presented so far indicates no.</p>
<h2>Insufficient evidence</h2>
<p>The site’s researchers <a href="https://www.biorxiv.org/content/10.1101/2023.06.01.543127v1">claim to have evidence</a> for three intentional burials. </p>
<p>However, not one of the burials provides compelling evidence of a deliberately excavated pit. Indeed, the shallow cavities may not be dug pits at all, but natural depressions where the bodies accumulated and were later disturbed by trampling, or partial cave collapse. </p>
<p>The alleged burials also fail to meet another fundamental criteria for deliberate burials: anatomical alignment of the body and articulation of skeletal remains. </p>
<p>In a deliberate burial, the body is generally intact and any minimal displacement can be explained by decomposition. That’s because burial involves immediately covering the body with soil, which protects the anatomical integrity of the skeleton.</p>
<p>Rising Star Cave so far hasn’t produced evidence for anything other than the general spatial association of some skeletal elements. At most, it provides evidence for the in-situ decomposition of particular body parts, such as an ankle, and partial hand and foot articulations.</p>
<p>Moreover, confirming intentional burial in the past has required the presentation of human remains in an arrangement that can’t have been achieved by chance. However, the scattered distribution of the remains at Rising Star prevents reconstruction of their original positions.</p>
<p>Other claimed evidence for funerary behaviour is equally uncompelling. A stone artefact supposedly included in the burial as a “grave good” is said to have scratches and edge serrations from use. But this so-called artefact’s shape suggests it may be natural. It’s still encased in sediment and has only been studied through <a href="https://en.wikipedia.org/wiki/Synchrotron_light_source">synchrotron X-ray</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/530237/original/file-20230606-17-cso4oh.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/530237/original/file-20230606-17-cso4oh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530237/original/file-20230606-17-cso4oh.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=432&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530237/original/file-20230606-17-cso4oh.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=432&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530237/original/file-20230606-17-cso4oh.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=432&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530237/original/file-20230606-17-cso4oh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=543&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530237/original/file-20230606-17-cso4oh.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=543&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530237/original/file-20230606-17-cso4oh.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=543&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The purported stone artefact (from synchrotron X-ray) showing so-called scratches and edge serrations may actually be a natural rock and not culturally modified.</span>
<span class="attribution"><span class="source">Lee Berger et al</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>But perhaps the biggest barrier to confirming the status of the findings is that so far none of the alleged burials have been fully excavated. It’s therefore impossible to assess the completeness of the bodies, their original position, and the limits of the purported pits.</p>
<h2>Did <em>Homo naledi</em> make rock art?</h2>
<p>An equally splashy claim made in one of the publications is that <em>Homo naledi</em> left rock art on the walls of Rising Star Cave.</p>
<p>The <a href="https://www.biorxiv.org/content/10.1101/2023.06.01.543133v1">report</a> describes engravings in the form of deeply impressed cross-hatchings and geometric shapes such as squares, triangles, crosses and X’s. Further claims are made about the preparation of and potential repeated handling or rubbing of the associated rock surface, and the use of a similar “tool” to the one they claim was found with the alleged burial.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/530224/original/file-20230606-27-9qrejq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/530224/original/file-20230606-27-9qrejq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530224/original/file-20230606-27-9qrejq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=906&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530224/original/file-20230606-27-9qrejq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=906&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530224/original/file-20230606-27-9qrejq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=906&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530224/original/file-20230606-27-9qrejq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1139&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530224/original/file-20230606-27-9qrejq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1139&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530224/original/file-20230606-27-9qrejq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1139&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The researchers point to engravings in the wall as evidence of <em>Homo naledi’s</em> capability to create art and symbols. But these etchings haven’t been dated, and some of the lines look relatively recently etched.</span>
<span class="attribution"><a class="source" href="https://www.biorxiv.org/content/10.1101/2023.06.01.543133v1">Lee Berger et al</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>This claim has major implications. To date, rock art has only reliably been linked to <em>Homo sapiens</em> and, in rarer cases, some of our large-brained ancestors. Similar to deliberate burial, producing rock art has major implications for the cognitive abilities of a species. It denotes a capacity for representation, and the creation and communication of meaning via abstract symbols. </p>
<p>The problem with the rock art at Rising Star Cave is that it’s undated. To imply any link with <em>Homo naledi</em> requires firm dates. This could be achieved through using dating techniques on associated residues or <a href="https://www.science.org/doi/abs/10.1126/sciadv.abd4648">natural deposits</a> covering the art, or by studying materials from excavated and dated archaeological layers that can be linked to the art (for instance, if they contain engraving tools or engraved rock fall fragments).</p>
<p>In the absence of dating, it’s simply spurious to claim the engravings were made by <em>Homo naledi</em>, rather than by another species (and potentially at a much later date).</p>
<h2>Did <em>Homo naledi</em> light up Rising Star Cave?</h2>
<p>The researchers also claim the mortuary and engraving activities in Rising Star Cave involved strategic use of fire for illumination. </p>
<p>In <a href="https://www.youtube.com/watch?v=kOtX_Bcs_F4&ab_channel=CarnegieScience">public lectures</a> and on social media they clarify they have found new evidence for hearths, including charcoal, ash, discoloured clay and burned animal bones. Yet none of the scientific research needed to confirm the use of fire has been carried out. Or if it has, it hasn’t been published.</p>
<p>Previously acquired radiocarbon dates obtained by the site investigators on the apparent hearth material provided <a href="https://www.youtube.com/watch?v=kOtX_Bcs_F4&ab_channel=CarnegieScience">very late dates</a> that distanced the hearths from the remains of <em>Homo naledi</em> by several hundred thousand years.</p>
<p>We’re not opposed to the idea that the Rising Star Cave witnessed precocious mortuary behaviour involving the intentional disposal of bodies by <em>Homo naledi</em>. But it’s clear the latest inferences require further investigation before they’re accepted by the broader scientific community.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/i-was-part-of-the-team-that-found-the-homo-naledi-childs-skull-how-we-did-it-171153">I was part of the team that found the Homo naledi child's skull: how we did it</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/207000/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Homo naledi had a brain less than half the size of our own. Yet the new research claims it had cognitive abilities far beyond what we might expect.
Michael Petraglia, Director, Australian Research Centre for Human Evolution, Griffith University
Emmanuel K. Ndiema, Senior Research Scientist, National Museums of Kenya
María Martinón-Torres, CENIEH Director, Atapuerca Research Team and author of "Homo imperfectus" (Ed. Destino), Centro Nacional de Investigación sobre la Evolución Humana (CENIEH)
Nicole Boivin, Professor, Max Planck Institute of Geoanthropology
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/206200
2023-05-24T03:15:20Z
2023-05-24T03:15:20Z
Ancient humans may have paused in Arabia for 30,000 years on their way out of Africa
<figure><img src="https://images.theconversation.com/files/527894/original/file-20230524-20-w6g0dp.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6000%2C3997&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Most scientists agree modern humans developed in Africa, more than 200,000 years ago, and that a great human diaspora across much of the rest of the world occurred between perhaps 60,000 and 50,000 years ago. </p>
<p>In new research <a href="https://www.pnas.org/doi/10.1073/pnas.2213061120">published</a> in Proceedings of the National Academies of Sciences, we have uncovered dozens of distinctive historical changes in the human genome to reveal a new chapter in this story. </p>
<p>Our work suggests there may have been a previously unknown phase of humanity’s great migration: an “Arabian standstill” of up to 30,000 years in which humans settled in and around the Arabian Peninsula. These humans slowly adapted to life in the region’s colder climate before venturing to Eurasia and beyond. </p>
<p>The legacy of these adaptations still lingers. Under modern conditions, many genetic changes from this period are linked to diseases including obesity, diabetes, and cardiovascular disorders. </p>
<h2>History in our genomes</h2>
<p>Since the first human genome was published in 2000, the amount of human genomic data available has grown exponentially. These rapidly growing datasets contain traces of key events in human history. Researchers have been actively developing new techniques to find those traces.</p>
<p>When ancient humans left Africa and moved around the globe, they likely met new environments and challenges. New pressures would have led to adaptation and genetic changes. These changes would subsequently have been inherited by modern humans.</p>
<p><a href="https://www.nature.com/articles/s41586-021-03244-5">Previous research</a> on genomic data shows ancient humans most likely left Africa and spread across the planet between 60,000 and 50,000 years ago. </p>
<p>However, we still don’t know much about genetic adaptations during this crucial time period. </p>
<h2>Ancient adaptation events</h2>
<p>Our team of evolutionary and medical researchers has shed new light on this period. By studying both ancient and modern genomes, we have shown genetic selection was probably an important facilitator of this ancient human diaspora.</p>
<p>Using ancient human genomes makes it possible to recover <a href="https://theconversation.com/ancient-dna-reveals-a-hidden-history-of-human-adaptation-193251">evidence of past events</a> in which specific genetic variants were strongly favoured over others and swept through a population. These “hard sweep” events are surprisingly rare in modern human genomes, most likely because their traces have been erased or distorted by subsequent mixing between populations.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-dna-reveals-a-hidden-history-of-human-adaptation-193251">Ancient DNA reveals a hidden history of human adaptation</a>
</strong>
</em>
</p>
<hr>
<p>However, in <a href="https://www.nature.com/articles/s41559-022-01914-9">earlier work</a> we identified 57 regions in the human genome where an initially rare beneficial genetic variant effectively replaced an older variant in ancient Eurasian groups. </p>
<p>In our <a href="https://www.pnas.org/doi/10.1073/pnas.2213061120">new study</a>, we reconstructed the historical spread of these genetic variants. We also estimated the temporal and geographical origins of the underlying selection pressures. </p>
<p>Further, we identified the gene in each hard sweep region most likely to have been selected for. Knowing these genes helped us understand the ancient pressures that may have led to their selection.</p>
<h2>Coping with cold</h2>
<p>Our findings suggest early humans went through a period of extensive adaptation, lasting up to 30,000 years, before the big diaspora between 60,000 and 50,000 years ago. This period of adaptation was followed by rapid dispersal across Eurasia and as far as Australia. </p>
<p>We call this period the “Arabian standstill”. Genetic, archaeological and climatic evidence all suggest these ancient humans were most likely living in and around the Arabian Peninsula.</p>
<p><iframe id="8yMnX" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/8yMnX/1/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>The genetic adaptations involved parts of the genome related to fat storage, nerve development, skin physiology, and tiny hair-like fibres in our airways called cilia. These adaptations share striking functional similarities with those found in humans and other mammals living in the Arctic today. </p>
<p>We also detected similar functional similarities with previously identified human adaptive genes derived from historical mixing events with Neanderthals and Denisovans. These distant relatives of humans are also thought to have adapted to cold Eurasian climates. </p>
<p>Overall, these changes seem likely to have been driven by adaptation to the cool and dry climates in and around prehistoric Arabia between 80,000 and 50,000 years ago. The changes would also have prepared the ancient humans for the cold Eurasian climates they would eventually encounter.</p>
<h2>Old adaptations, modern diseases</h2>
<p>Many of these adaptive genes have links to modern diseases, including obesity, diabetes, and cardiovascular disorders. The adaptations around the human expansion from Africa may have established genetic variations that, under modern conditions, are associated with common diseases. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-found-traces-of-humanitys-age-old-arms-race-with-coronaviruses-written-in-our-dna-163254">We found traces of humanity's age-old arms race with coronaviruses written in our DNA</a>
</strong>
</em>
</p>
<hr>
<p>As we have suggested in <a href="https://theconversation.com/we-found-traces-of-humanitys-age-old-arms-race-with-coronaviruses-written-in-our-dna-163254">another study</a>, genes that were adaptive in the past might contribute to modern human susceptibility to various diseases. Identifying the genetic targets of historical adaptation events could help the development of therapeutic approaches and preventive measures for contemporary populations.</p>
<p>Our findings contribute to a new but growing literature highlighting the importance of adaptation in shaping human history. They also show the growing potential of evolutionary genetics for medical research.</p><img src="https://counter.theconversation.com/content/206200/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ray Tobler receives funding from Australian Research Council.</span></em></p><p class="fine-print"><em><span>Shane T Grey receives funding from NHMRC, ARC, MRFF, JDRF and NIH. </span></em></p><p class="fine-print"><em><span>Yassine Souilmi is supported by funding from the ARC and NHMRC.</span></em></p>
Genetic evidence reveals a long, previously unknown period of adaptation to cold climates in the history of ancient human migrations across the globe.
Ray Tobler, Postdoctoral fellow, Australian National University
Shane T Grey, Chair professor, Garvan Institute
Yassine Souilmi, Group Leader, Genomics and Bioinformatics, Australian Centre for Ancient DNA, University of Adelaide
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/205807
2023-05-19T09:16:22Z
2023-05-19T09:16:22Z
Humans were using fire in Europe 50,000 years earlier than we thought – new research
<figure><img src="https://images.theconversation.com/files/526868/original/file-20230517-17-lmjl05.jpg?ixlib=rb-1.1.0&rect=33%2C0%2C5493%2C3692&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The control of fire by humans probably developed gradually over thousands of years.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/burning-red-hot-sparks-fly-big-1454468750">matsiukpavel / Shutterstock</a></span></figcaption></figure><p>Human history is intimately entwined with the use and control of fire. However, working out when our relationship with fire began and how it subsequently evolved has been notoriously difficult.</p>
<p>This is partly due to the incomplete nature of archaeological records, and also because fire use was fleeting, making burnt remains difficult to detect.</p>
<p>But our team has found evidence of the controlled use of fire by direct human ancestors – or hominins – at a site in Spain dating to 250,000 years ago. This pushes the earliest evidence of fire control in Europe back by 50,000 years. The findings have been published in <a href="https://www.nature.com/articles/s41598-023-32673-7">Nature Scientific Reports</a>. It is truly special to find the remains of human ancestors and fire at the same location. </p>
<p>There is much earlier evidence of hominins exploiting fire, but this could have taken the form of hominins taking advantage of the burning embers from a natural wildfire to cook their food. The controlled use of fire is where humans intentionally start it and then manage, say, its extent or temperature. This is what we have evidence for at the site in Spain.</p>
<p>Much older evidence from outside Europe, which could be from humans making use of natural blazes, comes from <a href="https://www.nature.com/articles/336464a0">Swartkrans cave in South Africa</a>, where hominin remains were found with hundreds of burnt animal bones dating to between 1 and 1.5 million years ago. Burnt animal bone fragments were also identified at the 1.5 million-year-old site known as <a href="https://www.sciencedirect.com/science/article/abs/pii/S0047248484710414">FxJj 20AB at Koobi Fora, Kenya</a>.</p>
<p>Yet finding hominin artefacts and burnt bones at the same site does not in itself indicate that they coincided in time, let alone that humans were controlling fire. The path to its controlled use, is likely to have been gradual.</p>
<h2>Intentional use?</h2>
<p>Fast forward almost a million years to the earliest-known clear evidence of fire made by humans: an open-air site called Gesher Benot Ya’aqov in Israel, <a href="https://www.science.org/doi/10.1126/science.1095443">dated to about 790,000 years ago</a>. The evidence found at this location includes charred plants and burnt stone tools lying alongside one another. </p>
<p>Other sites in Israel, such as Quesem Cave, with finds dating to between <a href="https://www.journals.uchicago.edu/doi/10.1086/691211#:%7E:text=Fire%20was%20used%20throughout%20the,intake%20of%20the%20cave%27s%20inhabitants.">420,000 and 200,000 years ago</a> and Tabun Cave, where the archaeological discoveries <a href="https://www.sciencedirect.com/science/article/abs/pii/S0047248414001778?via%3Dihub">are around 340,000 years old</a>, feature similar fire evidence. </p>
<figure class="align-center ">
<img alt="An Acheulean hand-axe from Africa held by the Regional Archaeological Museum of Madrid." src="https://images.theconversation.com/files/527048/original/file-20230518-21022-kiwno2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527048/original/file-20230518-21022-kiwno2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=926&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527048/original/file-20230518-21022-kiwno2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=926&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527048/original/file-20230518-21022-kiwno2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=926&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527048/original/file-20230518-21022-kiwno2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1164&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527048/original/file-20230518-21022-kiwno2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1164&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527048/original/file-20230518-21022-kiwno2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1164&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The spread of a stone tool technology called the Acheulean may be linked to the exploitation of fire in Europe.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/large-olivine-basalt-biface-early-african-1899031012">WH_Pics / Shutterstock</a></span>
</figcaption>
</figure>
<p>While early evidence such as this is suggestive of fire control, a direct link between resources such as wood fuel, activities, such as the preparation of fire, and intention –- arguably a prerequisite for controlled fire –- can be difficult to establish. In Europe, it is generally accepted that fire was routinely exploited by hominins at least 350,000 years ago, with some suggestion of fire control being linked to the <a href="https://www.sciencedirect.com/science/article/abs/pii/S0003552116300309?via%3Dihub">expansion of a particular stone tool technology</a> known as <a href="https://royalsocietypublishing.org/doi/10.1098/rstb.2015.0245">the Acheulean</a>.</p>
<p>Indeed, there is a concurrent rise in apparent prehistoric “fireplaces”, or hearths, and burnt Acheulean artefacts, such as hand-axes made from flint and a sedimentary rock called chert, at lots of European sites dated between 450,000 and 250,000. Many of these also contain charred plant materials and bones. </p>
<p>Yet there is some reason to believe that these associations are of natural origin – for example, from wildfires or lightning strikes. Before the new evidence, the oldest clear evidence of fire control in Europe came from Menez-Dregan in France and Bolomor Cave in Spain, which are both dated to about 200,000 years ago. Another early site with clear evidence of domestic fire use is Abrigo de la Quebrada in Spain, dated to around 100,000 years ago.</p>
<h2>New benchmark</h2>
<p>The new evidence from the Valdocarros II site in Spain, dated to about 250,000 years ago, serves as a new benchmark for understanding our ancient relationship with fire. </p>
<p>Lipid biomarkers are the remains of molecules that have come from specific sources, such as particular types of wood, and have been left by processes such as fire. Recently published data on lipid biomarkers from various archaeological sites reveals details of the unique resources – for example, the types of wood – used to create isolated campfires associated with Acheulean artefacts.</p>
<p>Lipid biomarker evidence from Valdocarros shows diagnostic signatures indicating that decaying pine was used as fuel. Intriguingly, records of pollen and of the relationship between water and climate from the surrounding region suggest that decaying pine would have been an uncommon resource.</p>
<p>Corroborative evidence comes in the form of molecules called polyaromatic hydrocarbons, or PAHs, which are products of incomplete combustion. Analysis of these reveals that decaying pine at Valdocarros II was burned at low temperatures of around 350°C for relatively short periods. </p>
<p>Fires that are too hot tend to char and burn foods on the outside before the inside of the item has reached a useful temperature. Lower temperatures are needed to break down biological tissue, so that it’s easier to digest – <a href="https://www.sciencedirect.com/science/article/abs/pii/S1095643307015632?casa_token=MRKnhAdnhFIAAAAA:psRH29RagpJdMw4gQfHS5hOQmVgfo0LYFwtzhUT55Ij3xAu51CDK8oZsSHLEY73gHHdjxpe-NSg">one of the key reasons for cooking food</a>. Conversely, it’s unlikely that low-temperature fires would have been used purely for warmth, given much more commonplace wood burns at hotter temperatures. Another perk of using decaying pine is that it’s easy to ignite.</p>
<h2>Choice of fuel</h2>
<p>Thus the fires at Valdocarros II look to have been used for activities such as cooking. The intriguing record of fire use at this Spanish site begins to emerge upon combining all of the available evidence. For instance, there is a rich fossil record of mammals at Valdocarros II that includes abundant butchered <a href="https://en.wikipedia.org/wiki/Red_deer">red deer (<em>Cervus elaphus</em>)</a> and the wild ancestors of domestic cattle, known as <a href="https://en.wikipedia.org/wiki/Aurochs">aurochs (<em>Bos primigenius</em>)</a>. The aurochs could each have weighed up to 1,500kg or more. </p>
<p>Therefore, hominins at this site show all the necessary prerequisites for controlling fire: the use of specific resources such as decaying pine wood; specific activities, such as the low-temperature fires used for cooking; and intention, which can be implied by the need to transport large carcasses to a single location where fire was being used.</p>
<p>By any standard, hominins at Valdocarros II were controlling fire. The site is not the oldest, nor the first instance of controlled fire. Rather, it is a significant benchmark in the course of human evolution because it sets a clear time limit on the emergence of a defining human characteristic. </p>
<p>The work at Valdocarros II also creates the opportunity for a wider discussion about how to establish intention and foresight from archaeological evidence, as well as from the wider breadth of human evolution and prehistory.</p><img src="https://counter.theconversation.com/content/205807/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Clayton Magill receives funding from UK Research & Innovation, the European Regional Development Fund, and Agencia Estatal de Investigacíon. </span></em></p>
Signs of controlled fire use from Spain are at least 50,000 years older than previous evidence.
Clayton Magill, Assistant Professor, School of Energy, Geoscience, Infrastructure and Society, The Lyell Centre, Heriot-Watt University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/205010
2023-05-16T16:36:26Z
2023-05-16T16:36:26Z
Evolution is making us treat AI like a human, and we need to kick the habit
<figure><img src="https://images.theconversation.com/files/525686/original/file-20230511-23-et0anf.jpg?ixlib=rb-1.1.0&rect=0%2C39%2C8875%2C4237&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">shutterstock</span> </figcaption></figure><p>The artificial intelligence (AI) pioneer Geoffrey Hinton recently <a href="https://www.bbc.co.uk/news/world-us-canada-65452940">resigned</a> from Google, warning of the dangers of the technology “becoming more intelligent than us”. His fear is that AI will one day succeed in “manipulating people to do what it wants”. </p>
<p>There are reasons we should be concerned about AI. But we frequently treat or talk about AIs as if they are human. Stopping this, and realising what they actually are, could help us maintain a fruitful relationship with the technology.</p>
<p>In a recent essay, the US psychologist Gary Marcus advised us to <a href="https://garymarcus.substack.com/p/stop-treating-ai-models-like-people">stop treating AI models like people</a>. By AI models, he means large language models (LLMs) like ChatGPT and Bard, which are now being used by millions of people on a daily basis.</p>
<p>He cites egregious examples of people “over-attributing” human-like cognitive capabilities to AI that have had a range of consequences. The most amusing was the US senator who claimed that <a href="https://twitter.com/ChrisMurphyCT/status/1640186536825061376?lang=en">ChatGPT “taught itself chemistry”</a>. The most harrowing was the report of a young Belgian man <a href="https://nypost.com/2023/03/30/married-father-commits-suicide-after-encouragement-by-ai-chatbot-widow/">who was said to have taken his own life</a> after prolonged conversations with an AI chatbot.</p>
<p>Marcus is correct to say we should stop treating AI like people - conscious moral agents with interests, hopes and desires. However, many will find this difficult to near-impossible. This is because LLMs are designed – by people – to interact with us as though they are human, and we’re designed – by biological evolution – to interact with them likewise.</p>
<h2>Good mimics</h2>
<p>The reason LLMs can mimic human conversation so convincingly stems from a
profound insight by computing pioneer Alan Turing, who realised that it is not necessary for a computer to understand an algorithm in order to run it. This means that while ChatGPT can produce paragraphs filled with emotive language, it doesn’t understand any word in any sentence it generates.</p>
<p>The LLM designers successfully turned the problem of semantics – the arrangement of words to create meaning – into statistics, matching words based on their frequency of prior use. Turing’s insight echos Darwin’s theory of evolution, which explains how species adapt to their surroundings, becoming ever-more complex, without needing to understand a thing about their environment or themselves.</p>
<p>The cognitive scientist and philosopher <a href="https://sites.tufts.edu/cogstud/daniel-dennett/">Daniel Dennett</a> coined the phrase “competence without comprehension”, which perfectly captures the insights of Darwin and Turing.<br>
Another important contribution of Dennett’s is his <a href="https://en.wikipedia.org/wiki/Intentional_stance#:%7E:text=The%20intentional%20stance%20is%20a,in%20terms%20of%20mental%20properties">“intentional stance”</a>. This essentially states that in order to fully explain the behaviour of an object (human or non-human), we must treat it like a rational agent. This most often manifests in our tendency to anthropomorphise non-human species and other non-living entities. </p>
<p>But it is useful. For example, if we want to beat a computer at chess, the best strategy is to treat it as a rational agent that “wants” to beat us. We can explain that the reason why the computer castled, for instance, was because “it wanted to protect its king from our attack”, without any contradiction in terms.</p>
<p>We may speak of a tree in a forest as “wanting to grow” towards the light. But neither the tree, nor the chess computer represents those “wants” or reasons to themselves; only that the best way to explain their behaviour is by treating them as though they did.</p>
<h2>Intentions and agency</h2>
<p>Our evolutionary history has furnished us with mechanisms that predispose us to find intentions and agency everywhere. In prehistory, these mechanisms helped our ancestors avoid predators and develop altruism towards their nearest kin. These mechanisms are the same ones that cause us to see faces in clouds and anthropomorphise inanimate objects. No harm comes to us when we mistake a tree for a bear, but plenty does the other way around.</p>
<p>Evolutionary psychology shows us how we are always trying to interpret any object that might be human as a human. We unconsciously adopt the intentional stance and attribute all our cognitive capacities and emotions to this object.</p>
<p>With the potential disruption that LLMs can cause, we must realise they are simply probabilistic machines with no intentions, or concerns for humans. We must be extra-vigilant around our use of language when describing the human-like feats of LLMs and AI more generally. Here are two examples. </p>
<p>The first was a <a href="https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2804309">recent study</a> that found ChatGPT is more empathetic and gave “higher quality” responses to questions from patients compared with those of doctors. Using emotive words like “empathy” for an AI predisposes us to grant it the capabilities of thinking, reflecting and of genuine concern for others – which it doesn’t have.</p>
<p>The second was when GPT-4 (the latest version of ChatGPT technology) was launched last month, capabilities of greater skills in creativity and reasoning were ascribed to it. However, we are simply seeing a scaling up of “competence”, but still no “comprehension” (in the sense of Dennett) and definitely no intentions – just pattern matching.</p>
<h2>Safe and secure</h2>
<p>In his recent comments, Hinton raised a near-term threat of “bad actors” using AI for subversion. We could easily envisage an unscrupulous regime or multinational deploying an AI, trained on fake news and falsehoods, to flood public discourse with misinformation and deep fakes. Fraudsters could also use an AI to prey on vulnerable people in financial scams.</p>
<p>Last month, Gary Marcus and others, including Elon Musk, signed an <a href="https://futureoflife.org/open-letter/pause-giant-ai-experiments/">open letter</a> calling for an immediate pause on the further development of LLMs. Marcus has also called for a an international agency to promote safe, secure and peaceful AI technologies" - dubbing it a “Cern for AI”. </p>
<p>Furthermore, many have suggested that anything generated by an AI should <a href="https://theconversation.com/watermarking-chatgpt-dall-e-and-other-generative-ais-could-help-protect-against-fraud-and-misinformation-202293">carry a watermark</a> so that there can be no doubt about whether we are interacting with a human or a chatbot.</p>
<p>Regulation in AI trails innovation, as it so often does in other fields of life. There are more problems than solutions, and the gap is likely to widen before it narrows. But in the meantime, repeating Dennett’s phrase “competence without comprehension” might be the best antidote to our innate compulsion to treat AI like humans.</p><img src="https://counter.theconversation.com/content/205010/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Neil Saunders does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
When you stop treating AI as another human, you’ll get on with it better.
Neil Saunders, Senior Lecturer in Mathematics, University of Greenwich
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/205339
2023-05-11T14:45:11Z
2023-05-11T14:45:11Z
Some Neanderthals hunted bigger animals, across a larger range, than modern humans
<figure><img src="https://images.theconversation.com/files/525479/original/file-20230510-13046-3wl703.jpg?ixlib=rb-1.1.0&rect=20%2C0%2C4580%2C3449&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Neanderthals were evolutionary cousins to our species, Homo sapiens.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/male-neanderthal-replicate-exhibited-museum-13feb2019-1314340712">Chettaprin.P / Shutterstock</a></span></figcaption></figure><p>The region of Estremadura in Portugal was home to a band of <a href="https://www.nhm.ac.uk/discover/who-were-the-neanderthals.html">Neanderthals</a> – an ancient evolutionary relative of modern humans – about 95,000 years ago. They made use of the patchwork of limestone caves, crags and river valleys, leaving traces of their activities in the form of stone tools, butchered animal bones and the remnants of fireplaces.</p>
<p>Now their teeth are providing new insights on how they hunted and interacted with their landscape. I was one of an international team of researchers that compared the levels of different forms of the chemical element strontium that had been preserved within the tooth enamel of two Neanderthals from the Almonda cave system in central Portugal, dating back about 95,000 years. The results have been <a href="https://www.pnas.org/doi/10.1073/pnas.2204501120">published in the journal PNAS</a>.</p>
<p>We also analysed the tooth enamel of a human who lived about 13,000 years ago during what’s <a href="https://www.britannica.com/topic/Magdalenian-culture">known as the Magdalenian period</a>, between about 17,000 and 12,000 years ago. Coupled with data recovered from the tooth enamel of a variety of local animals –- including horse, wild goat, red deer and an extinct form of rhinoceros –- our findings show that Neanderthals in the region were hunting fairly large animals across wide tracts of land. Humans living in the same location tens of thousands of years later survived on smaller creatures in an area half the size. </p>
<p>Some researchers have wondered whether differences between the subsistence strategies of modern humans and Neanderthals contributed to the disappearance of the latter around 40,000 years ago. Our study was conducted over a limited area, but wider evidence suggests that range size and prey type may well have varied between different regions.</p>
<h2>From rocks to enamel</h2>
<p><a href="https://www.rsc.org/periodic-table/element/38/strontium">Isotopes of the element strontium</a> in rocks gradually change over millions of years because of radioactive processes. This means they vary from place to place depending on the age of the underlying geology. As rocks weather, these <a href="https://cais.uga.edu/service/strontium-isotope-analysis/">isotopic “fingerprints” are passed into plants via sediments</a> and make their way along the food chain –- eventually passing into tooth enamel.</p>
<p>Because tooth enamel forms incrementally, it preserves a times series of those strontium isotope signals, which in turn reflect the geological origin of the food a person or animal ate over time. Using a technique <a href="https://www.cranfield.ac.uk/facilities/laser-ablation">for analysing elements</a> in archaeological samples, we were able to take thousands of strontium isotope measurements along the length of the tooth enamel, measuring variation over the two or three years it takes for the enamel to form. </p>
<figure class="align-center ">
<img alt="A Neanderthal premolar tooth from the Almonda cave system, Portugal (seen from different angles)." src="https://images.theconversation.com/files/525484/original/file-20230510-29-8nzgtz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525484/original/file-20230510-29-8nzgtz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=451&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525484/original/file-20230510-29-8nzgtz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=451&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525484/original/file-20230510-29-8nzgtz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=451&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525484/original/file-20230510-29-8nzgtz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525484/original/file-20230510-29-8nzgtz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525484/original/file-20230510-29-8nzgtz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A Neanderthal premolar tooth from the Almonda cave system, Portugal (seen from different angles).</span>
<span class="attribution"><span class="source">Credit: João Zilhão</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>By comparing the strontium isotopes in the teeth with sediments collected at different locations in the region, we were able to reconstruct the movements of Neanderthals and the Magdalenian human across the landscape. The geology around the Almonda caves is highly variable, making it possible to spot mobility of just a few kilometres.</p>
<p>We also looked at isotopes in the tooth enamel of animals found in the cave system. Alongside strontium, we measured oxygen isotopes, which vary seasonally from summer to winter. This enabled us to establish not only where the animals ranged across the landscape, but in which seasons they were available for hunting.</p>
<h2>Seasonal patterns</h2>
<p>We showed that the Neanderthals, who were targeting large animals, could have hunted wild goat in the summer, whereas horses, red deer and an extinct form of rhinoceros were available all year round within about 30km of the cave. The Magdalenian human showed a different pattern of subsistence, with seasonal movement of about 20km from the <a href="https://en.wikipedia.org/wiki/Almonda">Almonda caves</a> to the banks of the <a href="https://en.wikipedia.org/wiki/Tagus">Tagus River</a>, and a diet that included rabbits, red deer, wild goat and freshwater fish. </p>
<p>We approximated the territory of the two different human groups, revealing contrasting results. The Neanderthals obtained their food over approximately 600 sq km, whereas the humans occupied a much smaller territory of about 300 sq km. They suggest that the reduction in territory size could be a shift in population density. </p>
<p>With a relatively low population, Neanderthals were free to roam further to target large prey species, such as horses, without encountering rival groups. By the Magdalenian period, an increase in population density reduced available territory, and human groups had moved down the food chain to occupy smaller territories, hunting mostly rabbits and catching fish on a seasonal basis.</p>
<p>The study illustrates how new analytical methods can deepen our understanding of archaeology and human evolution. Previously, our knowledge of the lives and behaviour of past individuals was limited to what we could infer from marks on their bones or the artefacts they used. Now, using the chemistry of bones and teeth, we can begin to reconstruct detailed individual life histories, even as far back as the Neanderthals.</p><img src="https://counter.theconversation.com/content/205339/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bethan Linscott previously received funding from the AHRC. She has not received funding from the AHRC since 2019.</span></em></p>
The analysis could help us understand behavioural differences between the two groups of humans.
Bethan Linscott, Postdoctoral Researcher, Archaeological Geochemistry, University of Oxford
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/196555
2023-05-02T12:14:34Z
2023-05-02T12:14:34Z
Enigmatic human fossil jawbone may be evidence of an early ‘Homo sapiens’ presence in Europe – and adds mystery about who those humans were
<figure><img src="https://images.theconversation.com/files/522664/original/file-20230424-25-snjmo4.jpg?ixlib=rb-1.1.0&rect=1041%2C1616%2C9952%2C6772&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Close examination of digital and 3D-printed models suggested the fossil needs to be reclassified.</span> <span class="attribution"><span class="source">Brian A. Keeling</span></span></figcaption></figure><p><em>Homo sapiens</em>, our own species, evolved in Africa sometime between <a href="https://doi.org/10.1038/nature22336">300,000</a> and <a href="https://doi.org/10.1038/s41586-021-04275-8">200,000</a> years ago. Anthropologists are pretty confident in that estimate, based on <a href="https://doi.org/10.1098/rstb.2015.0237">fossil</a>, <a href="https://doi.org/10.1038/325031a0">genetic</a> and <a href="https://doi.org/10.1016/j.quascirev.2008.09.010">archaeological</a> evidence.</p>
<p>Then what happened? How modern humans spread throughout the rest of the world is one of the most active areas of research in human evolutionary studies.</p>
<p>The earliest fossil evidence of our species outside of Africa is found at <a href="https://www.science.org/content/article/ancient-jawbone-suggests-our-species-left-africa-40000-years-earlier-expected">a site called Misliya cave</a>, in the Middle East, and dates to around 185,000 years ago. While additional <em>H. sapiens</em> fossils are found from around 120,000 years ago in this same region, it seems modern humans reached Europe much later.</p>
<p>Understanding when our species migrated out of Africa can reveal insights into present-day biological, behavioral and cultural diversity. While we <em>Homo sapiens</em> are the only humans alive today, <a href="https://doi.org/10.1016/j.quaint.2016.06.008">our species coexisted</a> with different human lineages in the past, including <a href="https://doi.org/10.3998/jar.0521004.0069.202">Neandertals</a> and <a href="https://doi.org/10.17746/1563-0110.2020.48.3.003-032">Denisovans</a>. Scientists are interested in when and where <em>H. sapiens</em> encountered these other kinds of humans.</p>
<p><a href="https://scholar.google.com/citations?user=EjyT0fIAAAAJ&hl=en&oi=ao">Our</a> <a href="https://scholar.google.com/citations?user=JG6YfO4AAAAJ&hl=en&oi=ao">recent</a> reanalysis of a <a href="https://doi.org/10.1016/j.jhevol.2022.103291">fossil jawbone from a Spanish site called Banyoles</a> is raising new questions about when our species may have migrated to Europe.</p>
<h2><em>Homo sapiens</em> fossils found in Europe</h2>
<p>The <a href="https://australian.museum/learn/science/human-evolution/a-timeline-of-fossil-discoveries/">first documented discoveries</a> of human fossils were in Europe, just before Darwin’s 1859 publication of “<a href="https://www.britannica.com/biography/Charles-Darwin/On-the-Origin-of-Species">The Origin of Species</a>.” Ideas of evolution were being actively debated within European universities and scientific societies.</p>
<p>Many of the earliest fossil findings were <a href="https://www.nhm.ac.uk/discover/who-were-the-neanderthals.html">Neandertals</a>, a species that evolved in Europe by 250,000 years ago and became extinct around 40,000 years ago. They <a href="https://humanorigins.si.edu/evidence/genetics/ancient-dna-and-neanderthals">are also our closest evolutionary relatives</a> and, because of ancient interbreeding, the genomes of people today include Neandertal DNA. Because of their early historical presence, Neandertal fossils had a big influence on how early researchers thought about human evolution. </p>
<p>The first <a href="https://doi.org/10.1073/pnas.192464099">fossil evidence of Neandertals was found in 1856</a> during quarrying activities from the Neander Tal (Neander Valley) in Germany. Paleontologists took the hint and started to search for human fossils in other caves and exposed areas that preserved ancient sediments.</p>
<p>More than a decade later, in 1868, paleontologists uncovered <em>H. sapiens</em> fossils at the <a href="https://humanorigins.si.edu/evidence/human-fossils/fossils/cro-magnon-1">site of Cro-Magnon in southern France</a>. For much of the 20th century, the 30,000-year-old Cro-Magnon fossils represented the earliest fossil evidence of our species in Europe.</p>
<p>More recently, evidence for an earlier <em>H. sapiens</em> presence in Europe has come from two sites in Eastern Europe, including a partial skull from <a href="https://doi.org/10.1038/s41559-021-01443-x">Zlatý kůň Cave in Czechia</a> dating to 45,000 years ago, as well as more fragmentary remains from <a href="https://doi.org/10.1038/s41586-020-2259-z">Bacho Kiro Cave in Bulgaria</a> dating to around 44,000 years ago. Ancient DNA analysis has confirmed that the fossils from these sites represent <em>H. sapiens</em>. Additional, potentially earlier, evidence is represented by a <a href="https://theconversation.com/new-research-suggests-modern-humans-lived-in-europe-10-000-years-earlier-than-previously-thought-in-neanderthal-territories-176648">single tooth dating to 54,000 years ago</a> from the <a href="https://doi.org/10.1126/sciadv.abj9496">Grotte Mandrin Cave in France</a>.</p>
<p>This is where the human fossil from Banyoles comes into the story.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/t_ZZkzCbd3U?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A new look at an old fossil find potentially pushes back the date when <em>Homo sapiens</em> lived in Europe.</span></figcaption>
</figure>
<h2>Reinvestigating a ‘Neandertal’ mandible</h2>
<p>Over a century ago in 1889, a fossil human lower jaw, or mandible, was found at a quarry near the town of Banyoles, in northeastern Spain. Pere Alsius, a prominent local pharmacist, first studied the mandible, and the fossil has been curated by his family ever since.</p>
<p>A number of anthropologists have studied the fossil over time, but it has not usually been included in discussions about <em>H. sapiens</em> in Europe. Most researchers instead argued it represented a Neandertal or showed Neandertal-like features, in part because the Banyoles fossil lacks a feature considered typical and diagnostic of our own species: a bony chin on the front of the mandible.</p>
<p>Researchers did not have a good idea of how old the Banyoles mandible was, with most believing it likely dated to the Middle Pleistocene (780,000-130,000 years ago). That age made it seem too old to represent <em>H. sapiens</em>. Thus, with the absence of a chin and the presumed early date, the designation as a Neandertal seemed to make sense.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/502873/original/file-20230103-20-qzh844.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing the green and rocky terrain of Spain with fossil discovery sites indicated." src="https://images.theconversation.com/files/502873/original/file-20230103-20-qzh844.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/502873/original/file-20230103-20-qzh844.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/502873/original/file-20230103-20-qzh844.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/502873/original/file-20230103-20-qzh844.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/502873/original/file-20230103-20-qzh844.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/502873/original/file-20230103-20-qzh844.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/502873/original/file-20230103-20-qzh844.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Map of the Iberian Peninsula indicating where the Banyoles mandible (yellow star) was found, along with Late Pleistocene Neandertal (orange triangles) and <em>H. sapiens</em> (white squares) sites.</span>
<span class="attribution"><span class="source">Brian A. Keeling</span></span>
</figcaption>
</figure>
<p>Based on recent modern <a href="https://doi.org/10.1007/978-1-4020-4409-0_50">uranium-series</a> and <a href="https://doi.org/10.1007/978-1-4757-9694-0_8">electron spin resonance</a> dating, researchers now believe the Banyoles mandible is between 45,000 and 66,000 years old. This younger estimate overlaps with the early <em>H. sapiens</em> fossils from Eastern Europe.</p>
<p>Working with Spanish paleoanthropologists and archaeologists, we took another look at what species the fossil might represent. We relied on a CT scan to virtually reconstruct damaged or missing portions of the mandible and generated a 3D model of the complete fossil. Then, we studied its overall shape and distinctive anatomical features, comparing it to <em>H. sapiens</em>, Neandertals and other earlier human species.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/502874/original/file-20230103-26-x4inu6.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three side-by-side digital reconstructions of the Banyoles mandible, from side and above." src="https://images.theconversation.com/files/502874/original/file-20230103-26-x4inu6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/502874/original/file-20230103-26-x4inu6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=200&fit=crop&dpr=1 600w, https://images.theconversation.com/files/502874/original/file-20230103-26-x4inu6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=200&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/502874/original/file-20230103-26-x4inu6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=200&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/502874/original/file-20230103-26-x4inu6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=251&fit=crop&dpr=1 754w, https://images.theconversation.com/files/502874/original/file-20230103-26-x4inu6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=251&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/502874/original/file-20230103-26-x4inu6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=251&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Virtual reconstruction of the 3D model of the Banyoles mandible. Highlighted piece in blue indicates a mirrored element that researchers used to fill out missing sections.</span>
<span class="attribution"><span class="source">Brian A. Keeling</span></span>
</figcaption>
</figure>
<p>In contrast to earlier analyses, our results revealed that the Banyoles jawbone was most similar to <em>H. sapiens</em> fossils – not Neandertals.</p>
<p>When we examined the mandible’s bony features where muscle tendons and ligaments would have attached, it most closely resembled <em>H. sapiens</em>. We also found no unique bony features shared with the Neandertals. Additionally, when we used sophisticated 3D analysis techniques, we found that Banyoles’ overall shape was a better match with <em>H. sapiens</em> than with Neandertal individuals.</p>
<p>While nearly all of our evidence suggests this prehistoric human was indeed a member of our species, the lack of a chin remains puzzling. This feature is present in all human populations today and should be present in Banyoles if it is a member of our species.</p>
<h2>Figuring out the closest match</h2>
<p>How do we reconcile our results showing that Banyoles is a modern human with the fact that it lacks one of the most distinctive modern human features? We considered several possible scenarios.</p>
<p>When the mandible was discovered, it was still encased in a hard travertine block and only partially exposed. During initial cleaning and preparation of the specimen, it was <a href="https://helvia.uco.es/bitstream/handle/10396/16390/carandell51.pdf?sequence=1&isAllowed=y">accidentally dropped</a> and the chin region was damaged. The fossil was subsequently reconstructed, with the damaged fragments aligned in their correct anatomical position, and the current state of the fossil does seem to accurately reflect an original chinless shape. Thus, the lack of a chin in Banyoles cannot be attributed to this initial incident.</p>
<p>Could the lack of a chin in the Banyoles fossil be a result of interbreeding with Neandertals, who also lacked a chin? <a href="https://doi.org/10.1371/journal.pgen.1002947">Genetic evidence</a> suggests that <em>H. sapiens</em> most likely interbred with Neandertals between 45,000 and 65,000 years ago, making this a possibility.</p>
<p>To assess this hypothesis, we compared Banyoles with an early <em>H. sapiens</em> mandible dating to about 42,000 years ago from <a href="https://doi.org/10.1073%2Fpnas.2035108100">a Romanian site called Peştera cu Oase</a>. <a href="https://doi.org/10.1038/nature14558">Ancient DNA analysis</a> has revealed that the Oase individual had a Neandertal ancestor between four and six generations back, making it close to a hybrid individual. However, unlike Banyoles, this mandible shows a full chin along with some other Neandertal features. Since Banyoles shared no distinctive features with Neandertals, we ruled out the possibility of this individual representing interbreeding between Neandertals and <em>H. sapiens</em>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/502875/original/file-20230103-24-rjv92m.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three different lower jaw bones side by side" src="https://images.theconversation.com/files/502875/original/file-20230103-24-rjv92m.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/502875/original/file-20230103-24-rjv92m.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=226&fit=crop&dpr=1 600w, https://images.theconversation.com/files/502875/original/file-20230103-24-rjv92m.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=226&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/502875/original/file-20230103-24-rjv92m.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=226&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/502875/original/file-20230103-24-rjv92m.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=284&fit=crop&dpr=1 754w, https://images.theconversation.com/files/502875/original/file-20230103-24-rjv92m.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=284&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/502875/original/file-20230103-24-rjv92m.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=284&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Comparison of mandibles between <em>H. sapiens</em>, at left; Banyoles, center; and a Neandertal, at right.</span>
<span class="attribution"><span class="source">Brian A. Keeling</span></span>
</figcaption>
</figure>
<p>We’re left with two possibilities. Banyoles may represent a hybrid individual between <em>H. sapiens</em> and a non-Neandertal archaic human lineage. This scenario might account for the absence of the chin as well as the lack of any other Neandertal features in Banyoles. However, scientists haven’t identified any such non-Neandertal archaic group in the fossil record of the European <a href="https://www.geosociety.org/GSA/Education_Careers/Geologic_Time_Scale/GSA/timescale/home.aspx">Late Pleistocene</a> (129,000-11,700 years ago), making this hypothesis less likely.</p>
<p>Alternatively, Banyoles may document a previously unknown lineage of largely chinless <em>H. sapiens</em> in Europe. Possible support for this hypothesis comes from the fact that early <em>H. sapiens</em> fossils from Africa and the Middle East show a less prominent chin than do living humans. </p>
<p>Additionally, <a href="https://doi.org/10.1038/nature17993">ancient DNA research</a> has shown that <em>H. sapiens</em> populations in Europe before 35,000 years ago did not contribute to the modern European gene pool. Thus, we believe the least unlikely hypothesis is that Banyoles represents an individual from one of these early <em>H. sapiens</em> populations.</p>
<p>Our study of Banyoles demonstrates how new discoveries about our evolutionary past do not solely rely on new fossil discoveries, but can also come about through applying new methodologies to previously discovered fossils. If Banyoles is really a member of our species, it would potentially represent the earliest <em>H. sapiens</em> lineage documented to date in Europe. Future ancient DNA analysis could confirm or refute this surprising result. In the meantime, <a href="https://www.morphosource.org/">the 3D model of Banyoles</a> is available for other researchers to study and form their own conclusions.</p><img src="https://counter.theconversation.com/content/196555/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Scientists had figured a fossil found in Spain more than a century ago was from a Neandertal. But a new analysis suggests it could be from a lost lineage of our species, Homo sapiens.
Brian Anthony Keeling, Doctoral Candidate in Anthropology, Binghamton University, State University of New York
Rolf Quam, Associate Professor of Anthropology, Binghamton University, State University of New York
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/203532
2023-04-13T18:03:53Z
2023-04-13T18:03:53Z
Wooded grasslands flourished in Africa 21 million years ago – new research forces a rethink of ape evolution
<figure><img src="https://images.theconversation.com/files/520610/original/file-20230412-18-2l6ftt.png?ixlib=rb-1.1.0&rect=5%2C808%2C3552%2C3217&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An ape that lived 21 million years ago was used to a habitat that was both grassy and wooded.</span> <span class="attribution"><span class="source">Corbin Rainbolt</span></span></figcaption></figure><p>Human evolution is tightly connected to the environment and landscape of Africa, <a href="https://humanorigins.si.edu/evidence/human-fossils/species/sahelanthropus-tchadensis">where our ancestors first emerged</a>.</p>
<p>According to the traditional scientific narrative, Africa was once a verdant idyll of vast forests stretching from coast to coast. In these lush habitats, around 21 million years ago, the earliest ancestors of apes and humans first evolved traits – including upright posture – that distinguished them from their monkey cousins.</p>
<p>But then, the story went, global climates cooled and dried, and forests began to shrink. By about 10 million years ago, grasses and shrubs that were better able to tolerate the increasingly dry conditions started to take over eastern Africa, replacing forests. The earliest hominins, our distant ancestors, ventured out of the forest remnants that had been home onto the grass-covered savanna. The idea was that this new ecosystem pushed a radical change for our lineage: We became bipedal.</p>
<p>For a long time, researchers have <a href="https://doi.org/10.1038/s41598-020-69378-0">linked the expansion of grasslands in Africa</a> to the evolution of numerous human traits, including walking on two legs, using tools and hunting.</p>
<p>Despite the prominence of this theory, mounting evidence from paleontological and paleoclimatological research undermines it. <a href="https://www.science.org/doi/10.1126/science.abq2834">In two</a> <a href="https://www.science.org/doi/10.1126/science.abq2835">recent papers</a>, our multidisciplinary team of Kenyan, Ugandan, European <a href="https://scholar.google.com/citations?user=DjYvbR8AAAAJ&hl=en">and</a> <a href="https://scholar.google.com/citations?user=W7H_Y0oAAAAJ&hl=en&oi=ao">American</a> <a href="https://scholar.google.com/citations?user=gwZCXkQAAAAJ&hl=en&oi=ao">scientists</a> concluded that it is time finally to discard this version of the evolutionary story.</p>
<p>A decade ago, we began what, at the time, was a unique experiment in paleoanthropology: Several independent research teams joined together to build a regional perspective on the evolution and diversification of early apes. The project, dubbed REACHE, short for Research on Eastern African Catarrhine and Hominoid Evolution, was based on the premise that conclusions drawn from evidence across many locations would be more powerful than interpretations from individual fossil sites. We wondered whether previous researchers had missed the forest for the trees.</p>
<h2>An ape in Uganda 21 million years ago</h2>
<p>Based on the lifestyle of apes alive today, scientists have hypothesized that the very first ones evolved in dense forests, <a href="https://doi.org/10.1086/284139">where they successfully fed on fruit</a>, thanks to a few key anatomical innovations.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/QKuyv6YdBx4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Chimpanzees move with an upright posture.</span></figcaption>
</figure>
<p>Apes have stable, upright backs. <a href="https://doi.org/10.1007/978-3-319-47829-6_2001-1">Once the back is vertical</a>, an ape no longer has to walk on the top of small branches like a monkey. Instead, it can grab different branches with its arms and legs, distributing its body mass across multiple supports. Apes can even hang below branches, making them less likely to lose their balance. In this way, they are able to access fruits growing on the edges of tree crowns that otherwise might be available only to smaller species.</p>
<p>But was this scenario true for the earliest apes? A 21 million-year-old site in Moroto, Uganda, became an ideal place to investigate this question. There our REACHE team discovered teeth and other remains belonging to <em>Morotopithecus</em>, the oldest ape for which scientists have found fossils from the cranium, teeth and other parts of the skeleton.</p>
<p>Two bones in particular helped us understand how this species moved. A lower backbone found decades ago and curated by the Uganda National Museum had already been noted for its <a href="https://doi.org/10.1006/jhev.1994.1012">bony attachments for back muscles</a>, indicating that <em>Morotopithecus</em> had a stiff lower back, good for climbing upright in the trees.</p>
<p>A discovery of our own confirmed this climbing behavior in a major way. At Moroto we found a fossil ape thigh bone that is short but strong, with a very thick shaft. This kind of bone is characteristic of living apes and helps them climb up and down trees with a vertical torso.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520652/original/file-20230413-20-yvp928.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="vertebra, partial jaw and femur fossils" src="https://images.theconversation.com/files/520652/original/file-20230413-20-yvp928.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520652/original/file-20230413-20-yvp928.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=240&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520652/original/file-20230413-20-yvp928.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=240&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520652/original/file-20230413-20-yvp928.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=240&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520652/original/file-20230413-20-yvp928.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=302&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520652/original/file-20230413-20-yvp928.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=302&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520652/original/file-20230413-20-yvp928.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=302&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Three fossilized bones from <em>Morotopithecus</em>: a vertebra, part of a jaw and a femur.</span>
<span class="attribution"><span class="source">L. MacLatchy and J. Kingston</span></span>
</figcaption>
</figure>
<p>Although both skeletal fossils are consistent with the fruit-eating, forest-dwelling ape hypothesis, <a href="https://www.science.org/doi/10.1126/science.abq2835">we found something astonishing</a> when we discovered an ape lower jaw fragment in the same excavation layer. Its molars were elongated, with well-developed shearing crests running between the cusps. These ridges are ideal for slicing leaves but are unlike the low, round, crushing tooth cusps of committed fruit eaters. If ape skeletal adaptations evolved in forests to aid in fruit exploitation, why would the earliest ape showing these locomotor features instead have teeth like a leaf eater’s?</p>
<p>Such inconsistencies between our evidence and the traditional narrative of ape origins led us to question other assumptions: Did <em>Morotopithecus</em> live in a forested habitat at all? </p>
<h2>The environment at Moroto</h2>
<p>To figure out <em>Morotopithecus’</em> habitat, we studied the chemistry of fossil soils – called paleosols – and the microscopic remains of plants they contain in order to reconstruct the ancient climate and vegetation at Moroto.</p>
<p>Trees and most shrubs and nontropical grasses are classified as C₃ plants, based on the type of photosynthesis they perform. Tropical grasses, which rely on a different photosynthetic system, are known as C₄ plants. Importantly, C₃ plants and C₄ plants differ in the proportions of the various carbon <a href="https://www.britannica.com/science/isotope">isotopes</a> they take in. That means carbon isotope ratios preserved in the paleosols can tell us the composition of the ancient vegetation.</p>
<p>We measured three distinct carbon isotope signatures, each providing a different perspective on the plant community: carbon resulting from decomposition of vegetation and soil microbes; carbon resulting from plant waxes; and calcium carbonate nodules formed in soils through evaporation.</p>
<p>Although each proxy gave us slightly different values, <a href="https://www.science.org/doi/10.1126/science.abq2834">they converged on a single remarkable story</a>. Moroto was not a closed forest habitat but rather a relatively open woodland environment. What’s more, we found evidence of abundant C₄ plant biomass – tropical grasses.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520653/original/file-20230413-16-s1no2w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Traditional versus updated view of early ape habitat and evolution" src="https://images.theconversation.com/files/520653/original/file-20230413-16-s1no2w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520653/original/file-20230413-16-s1no2w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=484&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520653/original/file-20230413-16-s1no2w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=484&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520653/original/file-20230413-16-s1no2w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=484&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520653/original/file-20230413-16-s1no2w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=608&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520653/original/file-20230413-16-s1no2w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=608&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520653/original/file-20230413-16-s1no2w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=608&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">(A) Forested ecosystem traditionally believed to be the habitat of early apes, which ate fruit at the ends of tree branches, compared with (B) new perspective of grassy woodland ecosystem reconstruction, where early apes lived in open habitats and fed on leaves.</span>
<span class="attribution"><span class="source">Figure modified with permission from MacLatchy et al., Science 380, eabq2835 (2023)</span></span>
</figcaption>
</figure>
<p>This discovery was a revelation. C₄ grasses lose less water during photosynthesis than C₃ trees and shrubs do. Today, C₄ grasses dominate seasonally dry savanna ecosystems that <a href="https://unesdoc.unesco.org/ark:/48223/pf0000058054">cover more than half of Africa</a>. But scientists hadn’t thought the levels of C₄ biomass we measured at Moroto had evolved in Africa until 10 million years ago. Our data suggests it happened twice as far back in time, 21 million years ago.</p>
<p>Our colleagues <a href="https://scholar.google.com/citations?user=A5RCBfEAAAAJ&hl=en&oi=ao">Caroline Strömberg</a>, Alice Novello and <a href="https://scholar.google.com/citations?user=Sg0Q5xkAAAAJ&hl=en&oi=ao">Rahab Kinyanjui</a> used another line of evidence to corroborate the abundance of C₄ grasses at Moroto. They analyzed phytoliths, tiny silica bodies created by plant cells, preserved in the paleosols. Their results supported an open woodland and wooded grassland environment for this time and place.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520540/original/file-20230412-20-hnv0wy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Early Miocene grass phytoliths" src="https://images.theconversation.com/files/520540/original/file-20230412-20-hnv0wy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520540/original/file-20230412-20-hnv0wy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520540/original/file-20230412-20-hnv0wy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520540/original/file-20230412-20-hnv0wy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520540/original/file-20230412-20-hnv0wy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520540/original/file-20230412-20-hnv0wy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520540/original/file-20230412-20-hnv0wy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Example of typical grass phytoliths, extracted from paleosol at one of the sites, some of which indicate the presence of C₄ grass.</span>
<span class="attribution"><span class="source">Alice Novello</span></span>
</figcaption>
</figure>
<p>Taken together, this evidence dramatically contradicts the traditional view of ape origins – that apes evolved upright torsos to reach fruit in forest canopies. Instead, <em>Morotopithecus</em>, the earliest known ape with upright locomotion, consumed leaves and inhabited an open woodland with grassy areas.</p>
<h2>A new, regional view of early ape habitats</h2>
<p>Through the REACHE project, we applied the same approach to reconstruct habitats at eight other fossil sites in Kenya and Uganda, ranging in age from around 16 million to 21 million years old. After all, <em>Morotopithecus</em> is only one of several apes that lived during this time period.</p>
<p>To our surprise, we discovered that the ecological signal measured at Moroto was not unique. Instead, it was part of a broader pattern in eastern Africa during this time. </p>
<p>Our isotopic proxies at each fossil site contributed two significant revelations. First, vegetation types ranged from closed canopy forests to open wooded grasslands. And second, every site had a mixture of C₃ and C₄ vegetation, with some locations having a high proportion of C₄ grass biomass. Phytoliths from the same paleosols again corroborated that abundant C₄ grasses were present at multiple sites. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520539/original/file-20230412-20-ys57ae.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="cartoon depictions of nine paleoenvironments placed on timeline" src="https://images.theconversation.com/files/520539/original/file-20230412-20-ys57ae.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520539/original/file-20230412-20-ys57ae.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=274&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520539/original/file-20230412-20-ys57ae.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=274&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520539/original/file-20230412-20-ys57ae.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=274&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520539/original/file-20230412-20-ys57ae.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=345&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520539/original/file-20230412-20-ys57ae.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=345&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520539/original/file-20230412-20-ys57ae.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=345&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Paleoenvironments for the nine fossil sites analyzed range from closed canopy forest to more open wooded grassland environments. Inset map shows the geographic location of sites in eastern Africa.</span>
<span class="attribution"><span class="source">Dan Peppe</span></span>
</figcaption>
</figure>
<p>The realization that such a variety of environments, especially open habitats with C₄ grasses, was present at the dawn of the apes forces a reassessment not just of the evolution of apes but of humans and other African mammals. Although some studies had suggested such habitat variation was present across Africa, our project was able to confirm it, repeatedly, within the very habitats that early apes and their animal contemporaries occupied.</p>
<p>Because the timing of the assembly of Africa’s grassland habitats underlies many evolutionary hypotheses, our discovery that they existed much earlier than expected calls for a recalibration of those ideas.</p>
<p>Regarding human origins, our study adds to a growing body of evidence that our divergence from apes – in anatomy, ecology, behavior – cannot be simply explained by the appearance of grassland habitats. Nevertheless, we cautiously remind ourselves that hominin evolution unfolded over many millions of years. It is almost certain that the vast and majestic grasslands of Africa played an important role in some of the many steps along the path to becoming human.</p><img src="https://counter.theconversation.com/content/203532/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Laura M MacLatchy receives funding from the US National Science Foundation, the LSB Leakey Foundation, the Wenner-Gren Foundation and the University of Michigan. </span></em></p><p class="fine-print"><em><span>Dan Peppe receives funding from National Science Foundation, Leakey Foundation, Baylor University.</span></em></p><p class="fine-print"><em><span>Kieran McNulty has received funding from the National Science Foundation, Leakey Foundation, Wenner-Gren Foundation, Leverhulme Foundation, and the University of Minnesota. </span></em></p>
Contrary to the idea that apes evolved their upright posture to reach for fruit in the forest canopy, the earliest known ape with this stature, Morotopithecus, lived in more open grassy environments.
Laura M. MacLatchy, Professor of Anthropology, University of Michigan
Dan Peppe, Associate Professor of Geosciences, Baylor University
Kieran McNulty, Professor of Anthropology, University of Minnesota
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/201765
2023-03-22T00:10:13Z
2023-03-22T00:10:13Z
Why do animals living with humans evolve such similar features? A new theory could explain ‘domestication syndrome’
<figure><img src="https://images.theconversation.com/files/516822/original/file-20230321-22-capxez.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2840%2C1798&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/lulamy2000/9340339538/in/photolist-2h4MUQA-ECzajB-fenFwS-fgdTnU-m3Fc12-EmenP7-RMLpn9-3rga9q-k87cqH-oK1mH-ve6Y5-2bL1nDV-2jP34d7-2nCmNJG-2kFzuQc-TdCr2U-2kD2qvS-2aB5gEC-2kGDdkZ-2jjh5LD-RBYNoR-2kXsbmS-r3xRgc">Luz Rovira / Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>In the 19th century, Charles Darwin was one of the first to notice something interesting about domesticated animals: different species often developed similar changes when compared to their ancient wild ancestors.</p>
<p>But why would a host of seemingly unrelated features repeatedly occur together in different domesticated animals?</p>
<p>Scientists call this collection of shared changes “<a href="https://theconversation.com/why-so-many-domesticated-mammals-have-floppy-ears-29141">domestication syndrome</a>”, and the reason it occurs is still <a href="https://www.cell.com/trends/ecology-evolution/fulltext/S0169-5347(19)30302-7">hotly debated</a>. </p>
<p>In <a href="https://doi.org/10.1098/rspb.2022.2464">a new paper in Proceedings of the Royal Society B</a>, we argue that currently popular explanations aren’t quite right – and propose a new explanation focused on big changes in the way domesticated animals live. Along the way, our theory also offers insights into the unexpected story of how we humans domesticated ourselves.</p>
<h2>Shared changes under domestication</h2>
<p>The most commonly shared change is tamer behaviour. All domesticated animals are calmer than their wild ancestors naturally were. </p>
<p>That’s probably not very surprising. Ancient humans would’ve preferred docile animals, and likely selected breeding stock for tameness. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-so-many-domesticated-mammals-have-floppy-ears-29141">Why so many domesticated mammals have floppy ears</a>
</strong>
</em>
</p>
<hr>
<p>But other common changes don’t seem at all useful to humans – or to the animals themselves. Like shorter faces, smaller teeth, more fragile skeletons, smaller brains, and different colours in skin, fur, and feathers. </p>
<p><a href="https://royalsocietypublishing.org/doi/10.1098/rsos.160107">Not all domesticated animals</a> share all these features. For example, dogs have many, and camels only a few. </p>
<p>But each change occurs in more than one domesticated species. </p>
<h2>Wild self-domestication</h2>
<p>Surprisingly, very similar changes sometimes also appear in wild animals, leading some scientists to think they “self-domesticated” in some way. </p>
<p>The bonobo (a great ape closely related to the chimpanzee) is <a href="https://www.scientificamerican.com/article/tame-theory-did-bonobos/">one famous example</a> of an animal that has undergone these changes without human intervention. <a href="https://www.science.org/content/article/urban-foxes-may-be-self-domesticating-our-midst">Urban foxes</a> are another.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/516826/original/file-20230321-159-82f6ev.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/516826/original/file-20230321-159-82f6ev.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516826/original/file-20230321-159-82f6ev.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=345&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516826/original/file-20230321-159-82f6ev.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=345&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516826/original/file-20230321-159-82f6ev.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=345&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516826/original/file-20230321-159-82f6ev.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=434&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516826/original/file-20230321-159-82f6ev.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=434&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516826/original/file-20230321-159-82f6ev.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=434&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bonobos are a species who are believed to have ‘self-domesticated’.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Wild self-domestication is most common in isolated sub-populations, <a href="https://pubmed.ncbi.nlm.nih.gov/31119086/">like on islands</a>, and may overlap with a similar phenomenon known as the “island effect”.</p>
<p>Perhaps more surprisingly, modern humans also show features of domestication syndrome, when compared to our ancient ancestors. This suggests <a href="https://www.youtube.com/watch?v=acOZT240bTA">we also self-domesticated</a>. </p>
<p>Some scientists argue these changes made us more sociable, helping us to develop complex languages and culture.</p>
<p>So a clearer understanding of domestication syndrome in animals might improve our knowledge of human evolution too. </p>
<h2>What causes domestication syndrome?</h2>
<p>In recent years, two main possible explanations for domestication syndrome have dominated scientific discussion. </p>
<p>The first suggests it was caused when ancient humans selected animals for tamer behaviour, which somehow triggered all of the other traits too. </p>
<p>This idea is supported by a famous <a href="https://evolution-outreach.biomedcentral.com/articles/10.1186/s12052-018-0090-x">long-running Russian fox-breeding experiment</a> which began in 1959, in which caged foxes were selected only for tameness but developed the other “unselected” features as well.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/4dwjS_eI-lQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The <a href="https://theconversation.com/why-so-many-domesticated-mammals-have-floppy-ears-29141">second hypothesis</a> complements this first one. It suggests selection for tameness causes the other features because they’re all linked by genes controlling “<a href="https://www.ncbi.nlm.nih.gov/books/NBK10065/">neural crest cells</a>”. These cells, found in embryos, form many animal features – so changing them could cause several differences at once. </p>
<h2>More than selection for tameness</h2>
<p>However, our <a href="https://doi.org/10.1098/rspb.2022.2464">new research</a> suggests these two ideas oversimplify and obscure the complex evolutionary effects at play. </p>
<p>For one thing, there are problems with the famous Russian fox experiment. As other authors have noted, the experiment <a href="https://www.nytimes.com/2019/12/03/science/foxes-tame-belyaev.html">didn’t begin by taming wild foxes</a>, but used foxes from a farm in Canada. And these pre-farmed foxes already had features of domestication syndrome. </p>
<p>What’s more, the experimenters didn’t only select for tameness. They bred other foxes for aggression, but the aggressive foxes also developed domestication syndrome features. </p>
<p>And in <a href="https://babel.hathitrust.org/cgi/pt?id=coo.31924002886996&view=1up&seq=6">a similar experiment conducted in the 1930s</a>, caged rats developed the same common changes, including tamer behaviour, despite no deliberate selection for tameness, or aggression. </p>
<p>So, it seems domestication syndrome might not be caused by humans selecting animals for tameness. Instead, it might be caused by unintended shared effects from the new domestic environment. </p>
<h2>A new hypothesis for domestication syndrome</h2>
<p>Crucially, it’s not just new forces of selection, such as a human preference for tameness, that matters. The removal of pre-existing selection is just as important, because that’s what naturally shaped the wild ancestors in the first place.</p>
<p>For example, domesticated animals are often protected from predators, so wild traits for avoiding them might be lost. Competition for mating partners is also often reduced, so wild reproductive features and behaviours could decline, or disappear.</p>
<p>Domesticated animals are also usually reliably fed. This might alter certain features, but would certainly change natural metabolism and growth. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/516828/original/file-20230321-174-82f6ev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516828/original/file-20230321-174-82f6ev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516828/original/file-20230321-174-82f6ev.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516828/original/file-20230321-174-82f6ev.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516828/original/file-20230321-174-82f6ev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516828/original/file-20230321-174-82f6ev.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516828/original/file-20230321-174-82f6ev.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Caged rats have also been seen to develop signs of domestication syndrome.</span>
<span class="attribution"><span class="source">Oxana Golubets / Unsplash</span></span>
</figcaption>
</figure>
<p>In effect, we argue there are multiple selective changes at work on domesticated animals, not just “selection for tameness”, and that shared shifts in evolutionary selection would often cause shared changes in features. Even across different species. </p>
<p>Our new hypothesis highlights four ways that selection shaping wild animals is often disrupted by domestication. These are: </p>
<ol>
<li>less fighting between males </li>
<li>fewer males for females to choose between</li>
<li>more reliable food and fewer predators, and </li>
<li>elevated maternal stress, which initially reduces the health and survival of offspring.</li>
</ol>
<p>Several of these might resemble “selection for tameness”, but using this one term to describe them all is misleadingly vague, and obscures other changes in selection. </p>
<h2>So how did we domesticate ourselves?</h2>
<p>Well, <a href="https://www.cambridge.org/core/journals/evolutionary-human-sciences/article/targeted-conspiratorial-killing-human-selfdomestication-and-the-evolution-of-groupishness/B70C0490CEFFFB3B5231A5426A1D1577">one current theory</a> is that sociable “beta males” began cooperating to kill alpha bullies. This changed how competition worked among males, leading to fewer big and aggressive males. </p>
<p>But our hypothesis suggests other effects also played a role. For example, our early ancestors evolved the <a href="https://www.youtube.com/watch?v=XsuuPMUIMEE">capacity for shared infant care</a>. In our chimpanzee relatives today, sharing care of an infant would likely trigger extreme stress for the mother – but our ancestors adapted to this increased stress and gained an effective survival strategy.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/516590/original/file-20230321-20-994gxo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/516590/original/file-20230321-20-994gxo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516590/original/file-20230321-20-994gxo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516590/original/file-20230321-20-994gxo.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516590/original/file-20230321-20-994gxo.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516590/original/file-20230321-20-994gxo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516590/original/file-20230321-20-994gxo.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516590/original/file-20230321-20-994gxo.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Adapting to the increased maternal stress that accompanies separation from infants (either for shared care or domestication) may be one of the drivers of ‘domestication syndrome’.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>More reliable food access due to group foraging and sharing, plus collective defence against predators, might also have made us more sociable, more cooperative, and more complex, while promoting other changes commonly seen in non-human domesticated animals.</p>
<p>Whatever the specific drivers in each species, recognising multiple selective pathways better explains the domestication syndrome, and reaffirms the complexity of evolutionary effects shaping all life on Earth.</p><img src="https://counter.theconversation.com/content/201765/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ben Thomas Gleeson receives funding from an Australian Government RTP Scholarship. </span></em></p><p class="fine-print"><em><span>Laura A. B. Wilson receives funding from the Australian Research Council. </span></em></p>
For more than a century, scientists have been puzzled by the set of shared changes that happen to many animals when they are domesticated.
Ben Thomas Gleeson, Doctoral Candidate, Australian National University
Laura A. B. Wilson, ARC Future Fellow, Australian National University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/199499
2023-02-09T19:11:02Z
2023-02-09T19:11:02Z
We found 2.9-million-year-old stone tools used to butcher ancient hippos – but likely not by our ancestors
<figure><img src="https://images.theconversation.com/files/509068/original/file-20230209-21-4zmo2b.jpeg?ixlib=rb-1.1.0&rect=209%2C8%2C5158%2C1263&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Julian Louys</span>, <span class="license">Author provided</span></span></figcaption></figure><p>On the shores of Lake Victoria in Kenya, a short valley extends south towards the looming Mount Homa. From it have emerged some of the oldest-known stone tools used to butcher large animals, as well as the oldest remains of one of our early cousins, <em><a href="https://australian.museum/learn/science/human-evolution/paranthropus-species/">Paranthropus</a></em> – a genus we think <a href="https://www.latrobe.edu.au/news/articles/2020/release/skull-shines-light-on-human-evolution#">co-existed with</a> our direct ancestors.</p>
<p>Similar tool and fossil discoveries had been made before, in different places and at different times. But to find these all together in one place, as old as they are, is truly extraordinary. </p>
<p>In research published today in <a href="https://science.org/doi/10.1126/science.abo7452">Science</a>, we explain how findings at the Nyayanga site are changing the way experts think about carnivory among hominins – a <a href="https://australian.museum/learn/science/human-evolution/hominid-and-hominin-whats-the-difference/">group that includes</a> modern humans, extinct humans, direct ancestors and close cousins.</p>
<p>It also raises doubt about who was really responsible for making the stone tools we’d previously <a href="https://anthromuseum.missouri.edu/e-exhibits/oldowan-and-acheulean-stone-tools#:%7E:text=Dating%20as%20far%20back%20as,Homo%20sapiens%2C%20manufactured%20Oldowan%20tools">attributed to <em>Homo</em></a> and <a href="https://anthromuseum.missouri.edu/e-exhibits/oldowan-and-acheulean-stone-tools#:%7E:text=Dating%20as%20far%20back%20as,Homo%20sapiens%2C%20manufactured%20Oldowan%20tools">closely related</a> species.</p>
<h2>Fossils on the Homa Peninsula</h2>
<p>Nyayanga is a typical pastoral valley situated on the Homa Peninsula in western Kenya. This peninsula has long been known to produce various fossils. In 1996, a multidisciplinary team led by one of us (Thomas) began work on a two-million-year-old site called <a href="https://qcpages.qc.cuny.edu/anthro/Web_Pages/plummer/plummer3.html">Kanjera South</a>. This work produced a wealth of fossil remains from large mammals, as well as stone tools associated with our genus, <em>Homo</em>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/508774/original/file-20230208-15-37gyqj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/508774/original/file-20230208-15-37gyqj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/508774/original/file-20230208-15-37gyqj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/508774/original/file-20230208-15-37gyqj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/508774/original/file-20230208-15-37gyqj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/508774/original/file-20230208-15-37gyqj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/508774/original/file-20230208-15-37gyqj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Excavations at Kanjera South provide evidence of two-million-year-old stone tools, and butchered antelopes.</span>
<span class="attribution"><span class="source">Julien Louys</span></span>
</figcaption>
</figure>
<p>During a field season at Kanjera South, a local man named Peter Onyango who was working with the team suggested we investigate some fossils and stone tools eroding out of a valley on the shores of Lake Victoria. This new site, named Nyayanga after the nearby beach, was situated on a donkey track leading to the lake. </p>
<p>The first stone tools and fossils we collected were eroding out from the gully walls. Beginning in 2015, a series of excavations eventually returned a trove of 330 artefacts and 1,776 animal bone fragments from a range of species characteristic of open savannah and open woodland environments.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/508775/original/file-20230208-19-pd9ktg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/508775/original/file-20230208-19-pd9ktg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/508775/original/file-20230208-19-pd9ktg.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/508775/original/file-20230208-19-pd9ktg.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/508775/original/file-20230208-19-pd9ktg.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/508775/original/file-20230208-19-pd9ktg.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/508775/original/file-20230208-19-pd9ktg.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The site of Nyayanga was primarily used as a track for donkeys and cattle, leading to the shores of Lake Victoria.</span>
<span class="attribution"><span class="source">Julien Louys</span></span>
</figcaption>
</figure>
<p>The bones included animals we’re familiar with today, such as giraffes, antelopes, elephants and hippos. But they also included extinct megafauna such as <em><a href="https://en.wikipedia.org/wiki/Eurygnathohippus">Eurygnathohippus</a></em>, an extinct horse ancestor, <a href="https://en.wikipedia.org/wiki/Pelorovis"><em>Pelorvis</em></a>, the giant buffalo, and <a href="https://en.wikipedia.org/wiki/Megantereon"><em>Megantereon</em></a>, the sabre-toothed cat. </p>
<p>Of particular interest were the remains of two teeth from the extinct hominin <em>Paranthropus</em> – nicknamed the Nutcracker Man as its large flat teeth are thought to have been used to process tough vegetable matter. These teeth, one intact and the other a fragment, were the first direct evidence of an extinct hominin on the Peninsula.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/508848/original/file-20230208-17-di5tis.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two Paranthropus teeth." src="https://images.theconversation.com/files/508848/original/file-20230208-17-di5tis.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/508848/original/file-20230208-17-di5tis.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=328&fit=crop&dpr=1 600w, https://images.theconversation.com/files/508848/original/file-20230208-17-di5tis.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=328&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/508848/original/file-20230208-17-di5tis.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=328&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/508848/original/file-20230208-17-di5tis.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=413&fit=crop&dpr=1 754w, https://images.theconversation.com/files/508848/original/file-20230208-17-di5tis.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=413&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/508848/original/file-20230208-17-di5tis.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=413&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Two <em>Paranthropus</em> teeth were recovered from Nyayanga.</span>
<span class="attribution"><span class="source">S. E. Bailey, Homa Peninsula Paleoanthropology Project</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>What made their recovery even more surprising were the tools we found associated with them. Alongside <em>Paranthropus’s</em> teeth were some stone tools belonging to a technology known as the Oldowan, characterised by three main forms: hammerstone, core, and flake. </p>
<p>Oldowan tools had long been associated with our own genus, <em>Homo</em>, and were once considered a marker for the beginnings of human modernity. While we can’t demonstrate <em>Paranthropus</em> actually made these tools, this species is so far the only suspect at the scene of the crime.</p>
<figure class="align-center ">
<img alt="Tools belonging to the Oldowan technology." src="https://images.theconversation.com/files/508846/original/file-20230208-21-v015kd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/508846/original/file-20230208-21-v015kd.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=281&fit=crop&dpr=1 600w, https://images.theconversation.com/files/508846/original/file-20230208-21-v015kd.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=281&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/508846/original/file-20230208-21-v015kd.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=281&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/508846/original/file-20230208-21-v015kd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=353&fit=crop&dpr=1 754w, https://images.theconversation.com/files/508846/original/file-20230208-21-v015kd.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=353&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/508846/original/file-20230208-21-v015kd.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=353&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We found stone tools belonging to the Oldowan technology found at Nyayanga.</span>
<span class="attribution"><span class="source">T.W. Plummer, J.S. Oliver, and E. M. Finestone, Homa Peninsula Paleoanthropology Project</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Early signs of butchery</h2>
<p>So, what was a nutcracking, plant-chomping hominin using these tools for? Well it turns out in addition to processing plants – the evidence of which we could see on the tools’ edges – these lithics were also used to make hippo tartare. </p>
<p>We found evidence of meat cutting on the edges – but the smoking gun was the cut and percussion marks found on several hippo individuals associated with these stone tools. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/508845/original/file-20230208-17-7ls67s.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Hippo skeleton excavated at Nyayanga." src="https://images.theconversation.com/files/508845/original/file-20230208-17-7ls67s.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/508845/original/file-20230208-17-7ls67s.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/508845/original/file-20230208-17-7ls67s.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/508845/original/file-20230208-17-7ls67s.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/508845/original/file-20230208-17-7ls67s.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/508845/original/file-20230208-17-7ls67s.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/508845/original/file-20230208-17-7ls67s.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hippo skeleton excavated at Nyayanga. This probably represents a single individual, and shows evidence of butchery.</span>
<span class="attribution"><span class="source">T.W. Plummer, Homa Peninsula Paleoanthropology Project</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Of course, this wasn’t the first time cut marks had been found on megafauna. In fact, some of the earliest evidence of megafauna butchery was <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0062174">reported</a> on by our team at Kanjera South back in 2013. </p>
<p>However, our comprehensive dating program at Nyayanga revealed the site’s deposits to be about 2.9 million years old. This means they’re probably the oldest stone tools found to have butchered hippos and processed plant material. </p>
<p>Not only that, but this is about two million years before the first evidence that people used fire. This suggests raw hippo was on the menu for the hungry hominins.</p>
<p>Adding to that, the tooth fossils are the oldest <em>Paranthropus</em> remains ever found, and the associated tools are the oldest-known Oldowan tools. The second-oldest were uncovered some 1,200 kilometres away in Ethiopia, and dated to about <a href="https://www.pnas.org/doi/abs/10.1073/pnas.1820177116">2.6 million years</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/research-reveals-humans-ventured-out-of-africa-repeatedly-as-early-as-400-000-years-ago-to-visit-the-rolling-grasslands-of-arabia-167050">Research reveals humans ventured out of Africa repeatedly as early as 400,000 years ago, to visit the rolling grasslands of Arabia</a>
</strong>
</em>
</p>
<hr>
<h2>A brave old world</h2>
<p>There’s no evidence <em>Paranthropus</em> was actively hunting megafauna. But it would have been competing with sabre-toothed cats, hyenas and crocodiles for access to carcasses, at the very least. </p>
<p>The Nyayanga deposits provide a glimpse into an ancestral world that’s possibly radically different from any we had pictured. In doing so, they’ve raised even more questions about hominin evolution.</p>
<p>Who were these resourceful toolmakers? How far back does carnivory go? And just how old and widespread is the innovative Oldowan toolkit? Despite more than 100 years of research on the Homa Peninsula, much remains unearthed.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-found-the-oldest-ever-vertebrate-fossil-heart-it-tells-a-380-million-year-old-story-of-how-our-bodies-evolved-190230">We found the oldest ever vertebrate fossil heart. It tells a 380 million-year-old story of how our bodies evolved</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/199499/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julien Louys receives funding from the Australian Research Council. He was formally at Liverpool John Moores University</span></em></p><p class="fine-print"><em><span>Thomas Plummer receives funding from the National Science Foundation, the LSB Leakey Foundation, the Wenner-Gren Foundation, and the PSC-CUNY Research Award Program. He is research associate in the Human Origins Program of the Smithsonian Institution.</span></em></p>
The findings suggest we weren’t the first advanced carnivore among the hominins, as has been previously assumed.
Julien Louys, Deputy Director, Australian Research Centre for Human Evolution, Griffith University
Thomas Plummer, Professor, Anthropology Department, Queens College, CUNY
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/193167
2023-01-25T13:25:51Z
2023-01-25T13:25:51Z
Fossil teeth reveal how brains developed in utero over millions of years of human evolution – new research
<figure><img src="https://images.theconversation.com/files/505255/original/file-20230118-16643-pgt4h9.jpg?ixlib=rb-1.1.0&rect=861%2C1219%2C4422%2C3038&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Any hominid fossil find with molar teeth can be plugged into a new equation that reveals its species' prenatal growth rate.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/archaeologist-yossi-zaidner-from-the-hebrew-universitys-news-photo/1233682440?phrase=human%20fossil%20skull">Gil Cohen-Magen/AFP via Getty Images</a></span></figcaption></figure><p>Fossilized bones help tell the story of what human beings and our predecessors were doing hundreds of thousands of years ago. But how can you learn about important parts of our ancestors’ life cycle – like pregnancy or gestation – that leave no obvious trace in the fossil record?</p>
<p>The large brains, relative to overall body size, that are a defining characteristic of our species make pregnancy and gestation particularly interesting to <a href="https://scholar.google.com/citations?user=UdOOsTAAAAAJ&hl=en&oi=ao">paleoanthropologists like me</a>. <em>Homo sapiens’</em> big skulls contribute to our difficult labor and delivery. But the big brains inside are what let our species really take off.</p>
<p>My colleagues and I especially wanted to know how fast our ancestors’ brains grew before birth. Was it comparable to fetal brain growth today? Investigating when prenatal growth and pregnancy became humanlike can help reveal when and how our ancestors’ brains became more like ours than like our ape relatives’.</p>
<p>To investigate the evolution of prenatal growth rates, we focused on the in-utero development of teeth – which do fossilize. <a href="https://doi.org/10.1073/pnas.2200689119">By building a mathematical model</a> using the relative lengths of molar teeth, we were able to track evolutionary changes in prenatal growth rates in the fossil record. Based on our model, it looks as if pregnancy and prenatal growth became more humanlike than chimplike almost 1 million years ago.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/505651/original/file-20230120-26-idfswj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="pregnant woman's silhouette against sunset on landscape" src="https://images.theconversation.com/files/505651/original/file-20230120-26-idfswj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505651/original/file-20230120-26-idfswj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505651/original/file-20230120-26-idfswj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505651/original/file-20230120-26-idfswj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505651/original/file-20230120-26-idfswj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505651/original/file-20230120-26-idfswj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505651/original/file-20230120-26-idfswj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pregnancy and delivery come with a lot of risks for parent and baby.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/silhouette-pregnant-woman-standing-on-field-against-royalty-free-image/1082494338">Jimy Lindner/EyeEm via Getty Images</a></span>
</figcaption>
</figure>
<h2>Gestation and the human brain</h2>
<p><a href="https://doi.org/10.1002/(SICI)1520-6505(1998)6:2%3C54::AID-EVAN3%3E3.0.CO;2-W">Pregnancy and gestation are important periods</a> – they guide future growth and development and set the biological course for life.</p>
<p>But human pregnancy, and particularly labor and delivery, <a href="https://doi.org/10.1152/physiologyonline.1996.11.4.149">cost a lot of energy</a> and are often dangerous. The large fetal brain requires a lot of nutrients during development. The rate of embryonic growth during gestation, also known as the prenatal growth rate, exacts a metabolic and physiological toll on the gestating parent. And the <a href="https://doi.org/10.1002/ajpa.1330350605">tight fit of the infant’s head and shoulders</a> through the pelvic canal during delivery can lead to death, for both the mother and child.</p>
<p>As a trade-off to those potential downsides, there must be a really good reason to have such large heads. The justification is all the abilities that <a href="https://doi.org/10.1016/j.jhevol.2009.04.009">come along with having a big human brain</a>. The <a href="https://doi.org/10.1098/rstb.2012.0115">evolution of our large brain</a> contributed to our species’ dominance and is associated with increased use of technology and tools, creation of art and the ability to survive in diverse landscapes, among other advances.</p>
<p>The timing and sequence of events that led to the evolution of our large brains is entangled with the ability to find and process more resources, through the use of tools and <a href="https://doi.org/10.1086/667623">cooperative group work</a>, for example.</p>
<p>By investigating changes in prenatal growth, we are also investigating changes in how parents gathered food resources and distributed them to their offspring. These increasing resources would have also helped drive the evolution of an even bigger brain. Understanding more about when prenatal growth and pregnancy became humanlike at the same time reveals information about when and how our brains did too.</p>
<p><a href="https://doi.org/10.1073/pnas.2200689119">Humans have the highest prenatal growth rate</a> of all primates living today, at 0.41 ounces/day (11.58 grams/day). Gorillas, for example, have a much larger adult body size than humans, but their prenatal growth rate is only 0.29 ounces/day (8.16 grams/day). Because <a href="https://carta.anthropogeny.org/moca/topics/proportion-pre-and-postnatal-brain-growth">more than a quarter of all human brain growth</a> is completed during gestation, the rate of prenatal growth directly relates to how big an adult brain grows. How and when <em>Homo sapiens</em>‘ high prenatal growth rate evolved has been a mystery, until now.</p>
<h2>What teeth can tell about prenatal growth</h2>
<p>Researchers have spent centuries investigating variation in fossilized skeletal remains. Unfortunately brains – let alone gestation and prenatal growth rate – don’t fossilize.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/505250/original/file-20230118-20-a40toc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="ultrasound of a baby in utero" src="https://images.theconversation.com/files/505250/original/file-20230118-20-a40toc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/505250/original/file-20230118-20-a40toc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=623&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505250/original/file-20230118-20-a40toc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=623&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505250/original/file-20230118-20-a40toc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=623&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505250/original/file-20230118-20-a40toc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=783&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505250/original/file-20230118-20-a40toc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=783&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505250/original/file-20230118-20-a40toc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=783&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The developing brain of a human being gestating at 26 weeks.</span>
<span class="attribution"><span class="source">Tesla Monson</span></span>
</figcaption>
</figure>
<p>But my colleagues and I started thinking about how teeth develop very, very early in utero. Your permanent adult teeth started developing long before you were born, when you were just a 20-week-old fetus.
<a href="https://doi.org/10.1016/j.crpv.2016.10.006">Tooth enamel is more than 95% inorganic</a>, and the vast majority of everything we see in the vertebrate fossil record is teeth, or has teeth.</p>
<p>Building off this realization, we decided to investigate the relationship between prenatal growth rate, brain size and the lengths of teeth.</p>
<p>We measured the teeth of 608 recently living primates from skeletal collections all around the world. We compared those measurements to rates of prenatal growth that we calculated from average gestation length and mass at birth for each species. We also looked at endocranial volume – essentially how much space is inside the skull – as a proxy for brain size.</p>
<p><a href="https://doi.org/10.1073/pnas.2200689119">We found that the rate of prenatal growth</a> is significantly correlated with both adult brain size and relative tooth lengths, across apes and monkeys.</p>
<p>Because prenatal growth is so tightly correlated with relative molar lengths, we were able to use this statistical relationship to generate a mathematical equation that predicts prenatal growth rate from teeth alone. With this equation, we can take a few molar teeth from an extinct fossil species and reconstruct exactly how fast their offspring grew during gestation.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/505479/original/file-20230119-5264-t8y9ql.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="alt" src="https://images.theconversation.com/files/505479/original/file-20230119-5264-t8y9ql.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505479/original/file-20230119-5264-t8y9ql.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=276&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505479/original/file-20230119-5264-t8y9ql.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=276&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505479/original/file-20230119-5264-t8y9ql.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=276&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505479/original/file-20230119-5264-t8y9ql.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=346&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505479/original/file-20230119-5264-t8y9ql.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=346&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505479/original/file-20230119-5264-t8y9ql.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=346&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Using the new equation, researchers found that prenatal growth rates increased over millions of years of human and hominid evolution.</span>
<span class="attribution"><span class="source">Tesla Monson</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Using our new method, we then reconstructed prenatal growth rates for 13 fossil species, building a timeline of changes over the past 6 million years of human and hominid evolution. “Hominid” describes all the species on the human side of the family tree after the split about 6 million to 8 million years ago from the common ancestor we shared with chimpanzees. From our new research, we now know that prenatal growth rates increased throughout hominid evolution, reaching a humanlike rate that exceeds what we see in all other apes less than 1 million years ago.</p>
<p>A fully human prenatal growth rate appeared with the evolution of our species <em>Homo sapiens</em> only around 200,000 years ago. But other hominid species living in the past 200,000 years, such as Neanderthals, also had “human” prenatal growth rates. Which genes were involved in these changes in growth rate remains to be investigated.</p>
<h2>Equation means teeth now reveal even more</h2>
<p><a href="https://doi.org/10.1002/1096-8644(200103)114:3%3C192::AID-AJPA1020%3E3.0.CO;2-Q">Even with only a few teeth and some of the jaw</a>, <a href="http://www.annualreviews.org/doi/full/10.1146/annurev-an-42">a trained expert can tell countless things</a> about an extinct individual – what species it was, what kind of diet it ate, whether it competed for mates through fighting, how old it was when it died, whether or not it had any serious health issues and more.</p>
<p>Now, for the first time, we can add to that list knowing what pregnancy and gestation were like for that individual and other members of its species. Teeth can even indirectly hint at the emergence of human consciousness, via evolving brain size.</p>
<p>Interestingly, our model suggests that prenatal growth rates started increasing well before the emergence of our <em>Homo sapiens</em> species. We can hypothesize that having a fast prenatal growth rate was necessary for growing that big brain and evolving human consciousness and cognitive abilities.</p>
<p>These are the sorts of big-picture questions this research lets us start to formulate now – all from just a few teeth.</p><img src="https://counter.theconversation.com/content/193167/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This research was supported through grants to Tesla Monson's collaborators by the Washington Research Foundation and the John Templeton Foundation. Much of the data collection for the extant primates was funded by National Science Foundation Division of Behavioral and Cognitive Sciences grants 0500179, 0616308, and 0130277.</span></em></p>
Using a new equation based on today’s primates, scientists can take a few molar teeth from an extinct fossil species and reconstruct exactly how fast their offspring grew during gestation.
Tesla Monson, Assistant Professor of Anthropology, Western Washington University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/196398
2023-01-25T11:39:11Z
2023-01-25T11:39:11Z
Large mammals shaped the evolution of humans: here’s why it happened in Africa
<p>That humans originated in Africa is <a href="https://www.sciencedaily.com/releases/2007/05/070509161829.htm">widely accepted</a>. But it’s not generally recognised how unique features of Africa’s ecology were responsible for the crucial evolutionary transitions from forest-inhabiting fruit-eater to savanna-dwelling hunter. These were founded on earth movements and aided physically by Africa’s seasonal aridity, bedrock-derived soils and absence of barriers to movements between north and south. </p>
<p>These features promoted extensive savanna grasslands marked by erratic rainfall, regular fires and abundant numbers of diverse grazing and browsing animals. </p>
<p>My lifelong studies have focused on the ecology of Africa’s large herbivores and their effects on savanna vegetation. In my <a href="https://www.cambridge.org/za/academic/subjects/life-sciences/evolutionary-biology/only-africa-ecology-human-evolution">recent book</a>, by linking pre-existing threads together for the first time, I explain how distinctive features of these animals’ ecology, founded on Africa’s physical geography, enabled the adaptive changes that led ultimately to modern humans.</p>
<p>What emerges is the realisation that this amazing evolutionary transformation could only have occurred in Africa. This recognition emphasises the deep cultural legacy formed by Africa’s large mammal heritage for all of humankind.</p>
<h2>Ape-men</h2>
<p>Starting during the late Miocene, around 10 million years ago, a plume of molten magma, hot liquid material from deep inside the Earth, pushed eastern parts of Africa upward. This led to rifting of the Earth’s crust, volcanic eruptions and soils enriched in mineral nutrients from the lava and ash. Grassy savannas spread and animals adapted increasingly to graze this vegetation component. Apes from that time were forced to spend less time up in trees and more time walking upright on two legs. </p>
<p>Progressive reductions in rainfall, restricting plant growth and worsening dry season aridity, forced the early ape-men, (<a href="https://www.nature.com/scitable/knowledge/library/australopithecus-and-kin-145077614/"><em>Australopithecines</em></a>), to change their diet. They went from eating mainly fruits from forest trees to consuming underground bulbs and tubers found between the widely spaced trees. These were tough to extract and chew. </p>
<p>This led to the emergence through evolution of the genus <a href="https://www.maropeng.co.za/content/page/paranthropus"><em>Paranthropus</em></a> (colloquially “nutcracker man”), characterised by huge jaws and teeth. By about a million years ago they were gone. Apparently, the effort of extracting and processing these well-defended plant parts became too formidable. </p>
<h2><em>Homo habilis</em></h2>
<p>Around 2.8 million years ago, another lineage split off from the australopithecines, reversing the trend towards robust dentition. This lineage used stones chipped to serve as tools. These were used to scrape flesh from carcasses of animals killed by carnivores, and crack open long bones for their marrow content. This transition in ecology was sufficiently momentous to warrant a new generic name: <em>Homo</em>, specifically <em>habilis</em> (“handy-man”). </p>
<p>These first humans thus became scavengers on animal left-overs. They most probably exploited a time window around midday when the killers – mainly sabre-tooth cats – were resting, before hyenas arrived nocturnally to devour the leftovers. Walking upright freed their arms to carry bones away to be processed in safe sites to augment the plant-based dietary staples. </p>
<p>To facilitate such midday movements, <em>Homo habilis</em> lost its body hair; this made it possible for them <a href="https://www.nature.com/articles/nature03052">to be active</a> under conditions when fur-covered animals would soon over-heat. </p>
<h2><em>Homo erectus</em></h2>
<p>Several hundred thousand years of progressive advancements in upright walking and brain capacity led to the next major adaptive shift, exemplified by improvements in the design of stone tools. Stone cores became shaped on both sides to aid the processing of animal carcasses.</p>
<p>This led to the emergence of <a href="https://humanorigins.si.edu/evidence/human-fossils/species/homo-erectus"><em>Homo erectus</em></a> around 1.8 million years ago. These early humans had become efficient hunters. Consequently, meat and bones became reliable food resources year-round. </p>
<p>A division of labour came about. Men hunted; women gathered plant parts. This required a home base and more elaborate forms of communication about planned excursions, laying the foundations for language. </p>
<h2><em>Homo sapiens</em></h2>
<p>After 800,000 years ago, fluctuations in heat and aridity became more extreme in Africa. Finely crafted stone tools defined the transition into the Middle Stone Age, coupled with the emergence of modern <em>Homo sapiens</em> in Africa around 300 thousand years ago.</p>
<p>But despite its hunting prowess <em>Homo sapiens</em> had declined to precarious numbers in Africa by around 130,000 years ago, following an especially severe ice age. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2945812/">Genetic evidence indicates</a> that the entire human population across the continent shrank to fewer than 40,000 individuals, spread thinly from Morocco in the north to the Cape in the far south. </p>
<p>One remnant survived by inhabiting caves along the southern Cape coast, exploiting marine resources. This reliable food source fostered further advances in tool technology, and even the earliest art. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/south-africas-blombos-cave-is-home-to-the-earliest-drawing-by-a-human-103017">South Africa's Blombos cave is home to the earliest drawing by a human</a>
</strong>
</em>
</p>
<hr>
<p>The use of bows and arrows as weapons, along with spears, probably contributed crucially to the expansion of humans beyond Africa around 60,000 years ago. They spread onward through Asia and into Europe, displacing the Neanderthals. </p>
<h2>Only in Africa</h2>
<figure class="align-center ">
<img alt="A herd of large brown wildebeest is spread out across a grassy landscape, chewing the grass" src="https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Wildebeest grazing on the Serengeti Plains in Tanzania.</span>
<span class="attribution"><span class="source">Norman Owen-Smith</span></span>
</figcaption>
</figure>
<p>As outlined in my book, it was the abundance specifically of medium and large grazers in fertile savannas, concentrated near water in the dry season, that enabled the evolutionary transformation of a relatively puny ape into a feared hunter in Africa.</p>
<p>Africa’s high-lying interior plateau generated the seasonal dryness that restricted plant growth through its eastern and southern regions. Widespread volcanically derived soils were sufficiently fertile to foster the spread of medium-large grazers adapted to digest dry grass efficiently.</p>
<p>These especially abundant herbivores crowded around remaining waterholes, providing sufficient remnants of flesh and marrow to make scavenging a reliable means to overcome shortages of edible plant parts during the dry season. The increased dependence on meat to supplement a plant-based diet led to social coordination between male hunters and female gatherers, which in turn promoted advances in communication and tool technology supported by expanding cranial capacity. </p>
<p>If Africa had remained largely low-lying and leached of nutrients like most of South America and Australia, this would not have been possible.</p>
<p>Africa’s mobile grazers, such as wildebeest, are currently <a href="https://www.science.org/doi/10.1126/science.aay3049">being squeezed out of their sanctuaries</a> by expanding human settlements. These animals represent a global cultural heritage, having being pivotal to our evolutionary origins. We must ensure that sufficient space remains in Africa to enable their persistence despite burgeoning human populations.</p><img src="https://counter.theconversation.com/content/196398/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Norman Owen-Smith previously received funding from Sough Africa's National Research Foundation</span></em></p>
Africa’s large mammal heritage has formed a deep cultural legacy for all of humankind.
Norman Owen-Smith, Emeritus Research Professor of African Ecology, University of the Witwatersrand
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/197011
2023-01-22T19:02:35Z
2023-01-22T19:02:35Z
We can still see these 5 traces of ancestor species in all human bodies today
<figure><img src="https://images.theconversation.com/files/504835/original/file-20230117-3073-b5tm5x.jpg?ixlib=rb-1.1.0&rect=242%2C26%2C5416%2C3332&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/ufVCWjfFh5Q">Elia Pellegrini/Unsplash</a></span></figcaption></figure><p>Many of us are returning to work or school after spending time with relatives over the summer period. Sometimes we can be left wondering how on earth we are related to some of these people with whom we seemingly have nothing in common (especially with a particularly annoying relative). </p>
<p>However, in evolutionary terms, we all share ancestors if we go far enough back in time. This means many features in our bodies stretch back thousands or even millions of years in our great family tree of life. </p>
<p>In biology, the term “<a href="https://en.wikipedia.org/wiki/Homology_(biology)">homology</a>” relates to the similarity of a structure based on descent from a shared common ancestor. Think of the similarities of a human hand, a bat wing and a whale flipper. These all have specialist functions, but the underlying body plan of the bones remains the same.</p>
<figure class="align-center ">
<img alt="A graphic showing three shared bone structures across humans, dogs, birds and whales." src="https://images.theconversation.com/files/505484/original/file-20230119-26-ldvf9z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505484/original/file-20230119-26-ldvf9z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=514&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505484/original/file-20230119-26-ldvf9z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=514&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505484/original/file-20230119-26-ldvf9z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=514&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505484/original/file-20230119-26-ldvf9z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=647&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505484/original/file-20230119-26-ldvf9z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=647&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505484/original/file-20230119-26-ldvf9z.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=647&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Волков Владислав Петрович/Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>This differs from “analogous” structures, such as wings in insects and birds. Although they serve a similar function, the wings of a dragonfly and the wings of a parrot have arisen independently, and don’t share the same evolutionary origin.</p>
<p>Here are five examples of ancient traits you might be surprised to learn are still seen in humans today. </p>
<h2>One step ahead</h2>
<p>What makes us human? This question has plagued scientists and scholars for centuries. Today it seems relatively straightforward to tell who is a human and who is not, but looking through the fossil record, things very quickly become less clear. </p>
<p>Does humanity begin with the origins of our own species, <em>Homo sapiens</em>, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6736881/">from 300,000 years ago</a>? Or should we stretch things back more than three million years to ancestors such as “<a href="https://en.wikipedia.org/wiki/Lucy_(Australopithecus)">Lucy” (<em>Australopithecus afarensis</em>)</a> from eastern Africa? Or even further back to our split from the other great apes? </p>
<p>Whatever line you draw in the sand to pinpoint the birth of humanity, one thing is certain. The act of habitually walking around on two legs, known as “bipedalism”, was one of our ancestors’ greatest steps. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/504834/original/file-20230117-14-9008f2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two naked feet taking a step on a blue gait measuring plate in a laboratory" src="https://images.theconversation.com/files/504834/original/file-20230117-14-9008f2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/504834/original/file-20230117-14-9008f2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/504834/original/file-20230117-14-9008f2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/504834/original/file-20230117-14-9008f2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/504834/original/file-20230117-14-9008f2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/504834/original/file-20230117-14-9008f2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/504834/original/file-20230117-14-9008f2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It’s hard to overestimate the importance of bipedalism in human evolution.</span>
<span class="attribution"><span class="source">Microgen/Shutterstock</span></span>
</figcaption>
</figure>
<p>Almost every part of our skeleton was affected by the switch from walking on all fours to standing upright. These adaptations include the alignment and size of the foot bones, hip bones, knees, legs, and vertebral column. </p>
<p>Importantly, we know from fossil skulls that rapid increases in our brain size <a href="https://www.science.org/doi/abs/10.1126/science.809842">occurred shortly after we started walking upright</a>. This required changes to the pelvis to allow for our larger-brained babies to fit through a widened birth canal. </p>
<p>Our broadened pelvis (sometimes called iliac flaring) is a homologous feature <a href="https://royalsocietypublishing.org/doi/10.1098/rstb.2014.0063">shared with several lineages of early fossil humans</a>, as well as all those living today. </p>
<p>Those big brains of ours then fuelled an explosion of art, culture and language, important concepts when considering what makes us human. </p>
<h2>A hole in your head</h2>
<p>In addition to your eyeballs sitting in their orbits, you may be surprised to learn that you have other large holes (known as fenestrae) in your skull.</p>
<p>A single window is found on each side of the human skull, uniting us with our <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/spp2.1316">shared common ancestors from over 300 million years ago</a>. </p>
<p>Animals with this single window in their skulls are known as <a href="https://en.wikipedia.org/wiki/Synapsid">synapsids</a>. The word means “fused arch”, referring to the bony arch found underneath the opening in the skull behind each eye. </p>
<p>Today all mammals, including humans, are synapsids (but reptiles and birds are not).</p>
<p>Other famous synapsids from prehistoric times include the often misidentified <a href="https://en.wikipedia.org/wiki/Dimetrodon"><em>Dimetrodon</em></a>. The sail-backed ancient reptile is commonly mistaken for a dinosaur. However, with its sprawling limbs and single temporal fenestra it instead belongs to a lineage sometimes referred to as “mammal-like reptiles”, although we prefer the more accurate term of synapsid. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/504825/original/file-20230117-3073-lcg0m1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Colourful illustration of a green, reptile-like animal with a large semi-circular fin across its entire back" src="https://images.theconversation.com/files/504825/original/file-20230117-3073-lcg0m1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/504825/original/file-20230117-3073-lcg0m1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/504825/original/file-20230117-3073-lcg0m1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/504825/original/file-20230117-3073-lcg0m1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/504825/original/file-20230117-3073-lcg0m1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/504825/original/file-20230117-3073-lcg0m1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/504825/original/file-20230117-3073-lcg0m1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Artist’s impression of a Dimetrodon, a long-extinct animal that was not a dinosaur.</span>
<span class="attribution"><span class="source">David Roland/Shutterstock</span></span>
</figcaption>
</figure>
<h2>10 little fingers and 10 little toes</h2>
<p>I am typing this article on my computer using ten of my digits (fingers and thumbs; digits also refer to toes but mine don’t reach the keyboard).</p>
<p>This pattern of five digits in the human hand or foot, known as a “pentadactyl limb”, is found in most amphibians, reptiles, birds and mammals.</p>
<p>But fish don’t have fingers and toes, so when was it that digits first evolved? </p>
<p>A <a href="https://www.nature.com/articles/s41586-020-2100-8?from=article_link">recent study</a> by myself and colleagues actually described the first digits found preserved within a fish fin. We used powerful imaging methods to peer inside a 380-million-year-old fossil called <em>Elpistostege</em> from Quebec, Canada, to reveal the oldest fish fingers!</p>
<p>Somewhat surprisingly, the first fish to evolve digits still retained fin rays around them so these bones would not have been visible on the animal externally. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/uyUYKTBA91k?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The earliest tetrapods (four-limbed animals with a backbone that eventually moved out of water and onto land) “experimented” with the number of digits, sometimes being found with six, seven or eight of them. </p>
<p>These earliest tetrapods were likely still living in the water. It wasn’t until tetrapods became truly terrestrial that the five-digit limb arrived. This arrangement most likely arose as a practical solution <a href="http://www.prehistoric-wildlife.com/species/p/pederpes.html">to weight bearing on land</a>. </p>
<h2>Long in the tooth</h2>
<p>Does your mind wander when you brush your teeth? Well, have you ever considered how evolutionarily old your pearly whites are?</p>
<p>In 2022 a team of palaeontologists described isolated fossil fish teeth <a href="https://www.nature.com/articles/s41586-022-05166-2">from Silurian age rocks in Guizhou province, China</a>. This remarkable discovery pushed the minimum age of teeth back a further 14 million years from previous findings. This means our dentition now harks back to a whopping 439 million years ago. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/505485/original/file-20230119-19-gajnjf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up of a stone spiral with pointy edges set on a purple background" src="https://images.theconversation.com/files/505485/original/file-20230119-19-gajnjf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/505485/original/file-20230119-19-gajnjf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=455&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505485/original/file-20230119-19-gajnjf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=455&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505485/original/file-20230119-19-gajnjf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=455&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505485/original/file-20230119-19-gajnjf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=572&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505485/original/file-20230119-19-gajnjf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=572&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505485/original/file-20230119-19-gajnjf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=572&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A fossil of a <em>Helicoprion bessonowi</em> tooth whorl from the Ural Mountains, Russia.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Helicoprion#/media/File:Spirale_dentaire_d'helicoprion.jpg">Citron/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>That new fish, a very early jawed vertebrate, was named <em>Qianodus duplicis</em> and is only known from isolated specialised teeth known as “whorls”. A tooth whorl is a bizarre row of teeth that curls in on itself in a spiral pattern (most famously present in the buzz-saw shark, <a href="https://royalsocietypublishing.org/doi/full/10.1098/rsbl.2013.0057"><em>Helicoprion</em></a>). </p>
<p>Nevertheless, the teeth in the Chinese jawed fish have a number of features found in other modern jawed vertebrates, which highlight their relevance in understanding the evolution of our very own gnashers. Chomp on that! </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/hIqfRC8Nb64?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<h2>Grow a spine</h2>
<p>To “grow a spine” means to become emboldened and confident. The first animals to do just that must have surely been courageous to venture out into the perilous ancient seas 500 million years ago. </p>
<p>First, these worm-like animals evolved a “notochord” – a rod built of cartilage running along the back of the body. This enabled the attachment of segmented muscle blocks and a long tail extending beyond the anus. All animals with a notochord are called <a href="https://manoa.hawaii.edu/exploringourfluidearth/biological/invertebrates/phylum-chordata">chordates</a>, and includes everything from sea squirts to sea gulls, comprising more than 65,000 living species. </p>
<p>To get an idea of the first chordates, today we can look to animals such as the <a href="https://en.wikipedia.org/wiki/Lancelet">lancelet</a> (known as <em>Amphioxus</em> or <em>Branchiostoma</em>). Lancelets look a bit like tiny, primitive fishes without fins. They swim by undulating their body from side to side.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/504832/original/file-20230117-18-k69nqy.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A semi-transparent looking fish with no fins on a dark background" src="https://images.theconversation.com/files/504832/original/file-20230117-18-k69nqy.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/504832/original/file-20230117-18-k69nqy.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=475&fit=crop&dpr=1 600w, https://images.theconversation.com/files/504832/original/file-20230117-18-k69nqy.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=475&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/504832/original/file-20230117-18-k69nqy.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=475&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/504832/original/file-20230117-18-k69nqy.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=597&fit=crop&dpr=1 754w, https://images.theconversation.com/files/504832/original/file-20230117-18-k69nqy.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=597&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/504832/original/file-20230117-18-k69nqy.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=597&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Branchiostoma lanceolatum, a type of lancelet.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Lancelet#/media/File:Branchiostoma_lanceolatum.jpg">Hans Hillewaert/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Next come those with well organised heads (craniates), and those in which the notochord is replaced by a backbone in adults (vertebrates).</p>
<p>A backbone is built of individual segmented bones (vertebrae) which fit together in a specific interlocking pattern. We have a few tantalising fossils representing the earliest known examples of vertebrates, such as <a href="https://www.nature.com/articles/nature13414"><em>Metaspriggina</em></a> known from Canada, or <a href="https://www.nature.com/articles/nature01264"><em>Haikouichthys</em></a> from China in rocks more than 500 million years old.</p>
<p>So, whether it be your large brain and broad pelvis from walking around upright, skull with a single opening and bony arch, your fingers, toes, teeth or spinal cord, we humans share many ancient features in our bodies.</p>
<p>And so, <a href="https://allpoetry.com/Human-Family">in the words of the poet and activist Maya Angelou</a>, it may be worth remembering that we are more alike than we are unalike.</p><img src="https://counter.theconversation.com/content/197011/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alice Clement receives funding from the Australian Research Council.</span></em></p>
If we go far enough back in time, we all share an ancestor. And some of the features found in our bones and bodies today are a testament to that.
Alice Clement, Research Associate in the College of Science and Engineering, Flinders University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/191594
2023-01-05T20:37:46Z
2023-01-05T20:37:46Z
Human and Neanderthal brains have a surprising ‘youthful’ quality in common, new research finds
<figure><img src="https://images.theconversation.com/files/488715/original/file-20221007-18-5lkprh.jpg?ixlib=rb-1.1.0&rect=35%2C64%2C3847%2C2781&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Neanderthal skull</span> <span class="attribution"><span class="source">Petr Student/Shutterstock</span></span></figcaption></figure><p>Many believe our particularly large brain is what makes us human – but is there more to it? The brain’s shape, as well as the shapes of its component parts (lobes) may also be important.</p>
<p>Results of a study we <a href="https://www.nature.com/articles/s41559-022-01933-6">published today in Nature Ecology & Evolution</a> show that the way the different parts of the human brain evolved separates us from our primate relatives. In a sense, our brains never grow up. We share this “Peter Pan syndrome” with only one other primate – the Neanderthals.</p>
<p>Our findings provide insight into what makes us human, but also further narrow any distinction between ourselves and our extinct, heavy-browed cousins.</p>
<h2>Tracking the evolution of the brain</h2>
<p>Mammalian brains have four distinct regions or lobes, each with particular functions. The frontal lobe is associated with reasoning and abstract thought, the temporal lobe with preserving memory, the occipital lobe with vision, and the parietal lobe helps to integrate sensory inputs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/488712/original/file-20221007-14-wbmoxc.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A colourful diagram of the human brain, showing frontal lobes at the front and occipital lobe at the back" src="https://images.theconversation.com/files/488712/original/file-20221007-14-wbmoxc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/488712/original/file-20221007-14-wbmoxc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=577&fit=crop&dpr=1 600w, https://images.theconversation.com/files/488712/original/file-20221007-14-wbmoxc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=577&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/488712/original/file-20221007-14-wbmoxc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=577&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/488712/original/file-20221007-14-wbmoxc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=726&fit=crop&dpr=1 754w, https://images.theconversation.com/files/488712/original/file-20221007-14-wbmoxc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=726&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/488712/original/file-20221007-14-wbmoxc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=726&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The four main parts of the brain form the cerebral cortex.</span>
<span class="attribution"><span class="source">The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We investigated whether the brain’s lobes evolved independently of each other, or whether evolutionary change in any one lobe appears to be necessarily tied to changes in others – that is, evidence the evolution of the lobes is “integrated”.</p>
<p>In particular, we wanted to know how human brains might differ from other primates in this respect.</p>
<p>One way to address this question is to look at how the different lobes have changed over time among different species, measuring how much shape change in each lobe correlates with shape change in others.</p>
<p>Alternatively, we can measure the degree to which the brain’s lobes are integrated with each other as an animal grows through different stages of its life cycle.</p>
<p>Does a shape change in one part of the growing brain correlate with change in other parts? This can be informative because evolutionary steps can often be retraced through an animal’s development. A common example is the brief appearance of gill slits in early human embryos, reflecting the fact we can trace our evolution back to fish.</p>
<p>We used both methods. Our first analysis included 3D brain models of hundreds of living and fossil primates (monkeys and apes, as well as humans and our close fossil relatives). This allowed us to map brain evolution over time.</p>
<p>Our other digital brain data set consisted of living ape species and humans at different growth stages, allowing us to chart integration of the brain’s parts in different species as they mature. Our brain models were based on CT scans of skulls. By digitally filling the brain cavities, you can get a good approximation of the brain’s shape.</p>
<h2>A surprising result</h2>
<p>The results of our analyses surprised us. Tracking change over deep time across dozens of primate species, we found humans had particularly high levels of brain integration, especially between the parietal and frontal lobes.</p>
<p>But we also found we’re not unique. Integration between these lobes was similarly high in Neanderthals too.</p>
<p>Looking at changes in shape through growth revealed that in apes, such as the chimpanzee, integration between the brain’s lobes is comparable to that of humans until they reach adolescence.</p>
<p>At this point, integration rapidly falls away in the apes, but continues well into adulthood in humans.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/487918/original/file-20221003-14932-k7g16f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chart mapping brain integration in evolution" src="https://images.theconversation.com/files/487918/original/file-20221003-14932-k7g16f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/487918/original/file-20221003-14932-k7g16f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487918/original/file-20221003-14932-k7g16f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487918/original/file-20221003-14932-k7g16f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487918/original/file-20221003-14932-k7g16f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487918/original/file-20221003-14932-k7g16f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487918/original/file-20221003-14932-k7g16f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Left: a chart shows the degree of integration between the brain’s lobes, with cooler colours indicating higher integration. Right: translucent skulls of a human, Neanderthal, chimp and gorilla, showing the digitally reconstructed brains within.</span>
<span class="attribution"><span class="source">Gabriele Sansalone and Marina Melchionna</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Neanderthals were sophisticated people</h2>
<p>So what does this all mean? Our result suggest what distinguishes us from other primates is not just that our brains are <em>bigger</em>. The evolution of the different parts of our brain is more deeply integrated, and, unlike any other living primate, we retain this right through into adult life.</p>
<p>A greater capacity for learning is typically associated with juvenile life stages. We suggest this Peter Pan syndrome played a powerful role in the evolution of human intelligence.</p>
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Read more:
<a href="https://theconversation.com/when-did-humans-first-start-to-speak-how-language-evolved-in-africa-194372">When did humans first start to speak? How language evolved in Africa</a>
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<p>There’s another important implication. It’s increasingly clear that Neanderthals, long characterised as brutish dullards, were adaptable, capable and sophisticated people.</p>
<p>Archaeological findings continue to mount support for their development of sophisticated technologies, from the earliest known evidence of <a href="https://www.nature.com/articles/s41598-020-61839-w">string, to the manufacture of tar</a>. Neanderthal cave art shows they indulged in <a href="https://www.science.org/doi/10.1126/science.aap7778">complex symbolic thought</a>.</p>
<h2>Us and them</h2>
<p>Our results further blur any dividing line between us and them. This said, many remain convinced some innately superior intellectual quality gave us humans a competitive advantage, allowing us to drive our “inferior” cousins to extinction.</p>
<p>There are many reasons why one group of people may dominate, or even eradicate others. Early Western scientists sought to identify cranial features linked to their own “greater intelligence” to explain world domination by Europeans. Of course, we now know skull shape had nothing to do with it. </p>
<p>We humans may ourselves have come perilously close to extinction <a href="https://www.sciencedirect.com/science/article/pii/S0002929707606454">70,000 years ago</a>.</p>
<p>If so, it’s not because we weren’t smart. If we had gone extinct, perhaps the descendants of Neanderthals would today be scratching their heads, trying to figure out just how their “superior” brains gave them the edge.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/first-ever-genetic-analysis-of-a-neanderthal-family-paints-a-fascinating-picture-of-a-close-knit-community-192595">First-ever genetic analysis of a Neanderthal family paints a fascinating picture of a close-knit community</a>
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<img src="https://counter.theconversation.com/content/191594/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephen Wroe receives funding from the Australian Research Council and the University of New England.</span></em></p><p class="fine-print"><em><span>Pasquale Raia receives funding from the University of Naples Federico II. </span></em></p><p class="fine-print"><em><span>Gabriele Sansalone does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The way human brains develop is special – but not quite as special as you’d like to think, if we consider Neanderthals as well.
Stephen Wroe, Professor, University of New England
Gabriele Sansalone, PostDoc fellow, Institute of Marine Sciences
Pasquale Raia, Professor of Paleontology and Paleoecology, University of Naples Federico II
Licensed as Creative Commons – attribution, no derivatives.