tag:theconversation.com,2011:/id/topics/modern-humans-20083/articles
Modern humans – The Conversation
2024-02-06T18:06:12Z
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>
<figure class="align-center ">
<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">
<figcaption>
<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>
</figcaption>
</figure>
<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/175436
2022-02-23T16:03:13Z
2022-02-23T16:03:13Z
Ancient DNA helps reveal social changes in Africa 50,000 years ago that shaped the human story
<figure><img src="https://images.theconversation.com/files/446822/original/file-20220216-3870-1o2qb6l.jpg?ixlib=rb-1.1.0&rect=186%2C0%2C3661%2C2475&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Together with artifacts from the past, ancient DNA can fill in details about our ancient ancestors.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Kondoa_Irangi_Rock_Paintings_(51507918388).jpg">Nina R/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Every person alive on the planet today is descended from people who lived as hunter-gatherers in Africa. </p>
<p>The continent is the cradle of <a href="https://theconversation.com/how-a-handful-of-prehistoric-geniuses-launched-humanitys-technological-revolution-171511">human origins and ingenuity</a>, and <a href="https://theconversation.com/archaeological-discoveries-are-happening-faster-than-ever-before-helping-refine-the-human-story-128743">with each new fossil and archaeological discovery</a>, we learn more about our shared African past. Such research tends to focus on when our species, <em>Homo sapiens</em>, <a href="https://www.scientificamerican.com/article/how-homo-sapiens-became-the-ultimate-invasive-species/">spread out to other landmasses 80,000-60,000 years ago</a>. But what happened in Africa after that, and why don’t we know more about the people who remained?</p>
<p>Our 2022 study, conducted by an interdisciplinary team of 44 researchers based in 12 countries, <a href="https://www.nature.com/articles/s41586-022-04430-9">helps answer these questions</a>. By sequencing and analyzing ancient DNA (aDNA) from people who lived as long ago as 18,000 years, we roughly doubled the age of sequenced aDNA from sub-Saharan Africa. And this genetic information helps <a href="https://scholar.google.com/citations?user=GlrnQDgAAAAJ&hl=en&oi=ao">anthropologists</a> <a href="https://scholar.google.com/citations?user=MQkcYDYAAAAJ&hl=en&oi=ao">like</a> <a href="https://scholar.google.com/citations?user=3QKcZMoAAAAJ&hl=en&oi=ao">us</a> understand more about how modern humans were moving and mingling in Africa long ago.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441914/original/file-20220121-8326-sxvlib.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="View from above of archaeological excavation" src="https://images.theconversation.com/files/441914/original/file-20220121-8326-sxvlib.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441914/original/file-20220121-8326-sxvlib.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441914/original/file-20220121-8326-sxvlib.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441914/original/file-20220121-8326-sxvlib.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441914/original/file-20220121-8326-sxvlib.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441914/original/file-20220121-8326-sxvlib.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441914/original/file-20220121-8326-sxvlib.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">People took shelter in natural rock overhangs, leaving behind an archaeological record of their daily activities – and sometimes their graves. By digging carefully, archaeologists can connect information from aDNA to information about the social lives of these people.</span>
<span class="attribution"><span class="source">Jacob Davis</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Tracing our human past in Africa</h2>
<p><a href="https://theconversation.com/new-moroccan-fossils-suggest-humans-lived-and-evolved-across-africa-100-000-years-earlier-than-we-thought-78826">Beginning about 300,000 years ago</a>, people in Africa who looked like us – the earliest anatomically modern humans – also started behaving in ways that seem very human. They made <a href="https://www.smithsonianmag.com/science-nature/how-drastic-ecological-change-led-leap-forward-behavior-weapons-and-tools-180976101/">new kinds of stone tools and began transporting raw materials</a> up to 250 miles (400 kilometers), likely through trade networks. By 140,000-120,000 years ago, people made <a href="https://scitechdaily.com/early-humans-used-bone-tools-to-produce-clothing-in-morocco-120000-years-ago/">clothing from animal skins</a> and began to <a href="https://www.smithsonianmag.com/smart-news/worlds-oldest-jewelry-discovered-in-moroccan-cave-180978766/">decorate themselves with pierced marine shell beads</a>. </p>
<p>While early innovations appeared in a patchwork fashion, a more widespread shift happened around 50,000 years ago – around the same time that people started <a href="https://www.nationalgeographic.com/history/article/australia-aboriginal-early-human-evolution-spd">moving into places as distant as Australia</a>. New types of stone and bone tools became common, and people began <a href="https://theconversation.com/the-tiny-ostrich-eggshell-beads-that-tell-the-story-of-africas-past-128577">fashioning and exchanging ostrich eggshell beads</a>. And while most <a href="https://theconversation.com/an-ancient-san-rock-art-mural-in-south-africa-reveals-new-meaning-157177">rock art in Africa</a> is undated and badly weathered, an increase in <a href="https://theconversation.com/what-the-use-of-ochre-tells-us-about-the-capabilities-of-our-african-ancestry-47081">ochre pigment at archaeological sites</a> hints at an explosion of art. </p>
<p>What caused this shift, known as the <a href="https://en.wikipedia.org/wiki/Late_Stone_Age">Later Stone Age</a> transition, has been a longstanding archaeological mystery. Why would certain tools and behaviors, which up until that point had appeared in a piecemeal way across Africa, suddenly become widespread? Did it have something to do with changes in the number of people, or how they interacted? </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441913/original/file-20220121-9541-bx79fs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Nine disc-shaped beads" src="https://images.theconversation.com/files/441913/original/file-20220121-9541-bx79fs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441913/original/file-20220121-9541-bx79fs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=474&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441913/original/file-20220121-9541-bx79fs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=474&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441913/original/file-20220121-9541-bx79fs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=474&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441913/original/file-20220121-9541-bx79fs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=596&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441913/original/file-20220121-9541-bx79fs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=596&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441913/original/file-20220121-9541-bx79fs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=596&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Beads made from ostrich eggshell were hot trade items and can show the extent of ancient social networks.</span>
<span class="attribution"><span class="source">Jennifer Miller</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>The challenge of accessing the deep past</h2>
<p>Archaeologists reconstruct human behavior in the past mainly through things people left behind – remains of their meals, tools, ornaments and <a href="https://theconversation.com/how-we-discovered-the-oldest-human-burial-in-africa-and-what-it-tells-us-about-our-ancestors-160122">sometimes even their bodies</a>. These records may accumulate over thousands of years, creating views of daily livelihoods that are really averages over long periods of time. However, it’s hard to study ancient demography, or how populations changed, from the archaeological record alone. </p>
<p>This is where DNA can help. When combined with evidence from archaeology, linguistics and oral and written history, scientists can piece together how people moved and interacted based on which groups share genetic similarities.</p>
<p>But DNA from living people can’t tell the whole story. African populations have been transformed over the past 5,000 years by the <a href="https://theconversation.com/ancient-dna-is-revealing-the-origins-of-livestock-herding-in-africa-114387">spread of herding and farming</a>, the <a href="https://theconversation.com/how-we-recreated-a-lost-african-city-with-laser-technology-92852">development of cities</a>, <a href="https://theconversation.com/archaeology-shows-how-ancient-african-societies-managed-pandemics-138217">ancient pandemics</a> and the ravages of <a href="https://theconversation.com/a-digital-archive-of-slave-voyages-details-the-largest-forced-migration-in-history-74902">colonialism and slavery</a>. These processes caused <a href="https://www.nytimes.com/2020/02/12/science/west-africa-ancient-humans.html">some lineages to vanish</a> and <a href="https://theconversation.com/mitochondrial-dna-reveals-unexpected-ancestral-connections-122053">brought others together</a>, forming new populations. </p>
<p>Using present-day DNA to reconstruct ancient genetic landscapes is like reading a letter that was left out in the rain: some words are there but blurred, and some are gone completely. Researchers need ancient DNA from archaeological human remains to explore human diversity in different places and times and to understand what factors shaped it.</p>
<p>Unfortunately, aDNA from Africa is particularly hard to recover because the continent straddles the equator and heat and humidity degrade DNA. While the <a href="https://www.scientificamerican.com/article/oldest-ancient-human-dna-details-dawn-of-neandertals/">oldest aDNA from Eurasia is roughly 400,000 years old</a>, all sequences from sub-Saharan Africa to date have been younger than around 9,000 years. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/444879/original/file-20220207-47158-11n9ym1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map with markers showing distribution of ancient DNA data in Africa, and the world." src="https://images.theconversation.com/files/444879/original/file-20220207-47158-11n9ym1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/444879/original/file-20220207-47158-11n9ym1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=625&fit=crop&dpr=1 600w, https://images.theconversation.com/files/444879/original/file-20220207-47158-11n9ym1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=625&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/444879/original/file-20220207-47158-11n9ym1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=625&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/444879/original/file-20220207-47158-11n9ym1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=785&fit=crop&dpr=1 754w, https://images.theconversation.com/files/444879/original/file-20220207-47158-11n9ym1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=785&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/444879/original/file-20220207-47158-11n9ym1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=785&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 all published ancient genomes, with black dots scaled to the number of individuals’ genomes. Blue dots indicate Later Stone Age foragers comparable to those in our study. Red stars indicate individuals reported for the first time in our study. Inset map underscores the gap between Africa and other parts of the world in terms of published ancient genomes. Ancient DNA preserved between the Tropics of Cancer and Capricorn is rare.</span>
<span class="attribution"><span class="source">Mary Prendergast; basemaps by Natural Earth</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Breaking the ‘tropical ceiling’</h2>
<p>Because each person carries genetic legacies inherited from generations of their ancestors, our team was able to use DNA from individuals who lived between 18,000-400 years ago to explore how people interacted as far back as the last 80,000-50,000 years. This allowed us, for the first time, to test whether demographic change played a role in the Later Stone Age transition. </p>
<p><a href="https://www.nature.com/articles/s41586-022-04430-9">Our team sequenced aDNA</a> from six individuals buried in what are now Tanzania, Malawi and Zambia. We compared these sequences to previously studied aDNA from 28 individuals buried at sites stretching from Cameroon to Ethiopia and down to South Africa. We also generated new and improved DNA data for 15 of these people, trying to extract as much information as possible from the small handful of ancient African individuals whose DNA is preserved well enough to study.</p>
<p>This created the largest genetic dataset so far for studying the population history of ancient African foragers – people who hunted, gathered or fished. We used it to explore population structures that existed prior to the sweeping changes of the past few thousand years.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/444614/original/file-20220205-23-d1055k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Museum building, palm trees" src="https://images.theconversation.com/files/444614/original/file-20220205-23-d1055k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/444614/original/file-20220205-23-d1055k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/444614/original/file-20220205-23-d1055k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/444614/original/file-20220205-23-d1055k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/444614/original/file-20220205-23-d1055k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/444614/original/file-20220205-23-d1055k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/444614/original/file-20220205-23-d1055k.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">National Museum of Tanzania in Dar es Salaam. Ancient DNA studies in Africa are made possible by the efforts of curators to protect and preserve remains in tropical conditions.</span>
<span class="attribution"><span class="source">Mary Prendergast</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>DNA weighs in on a longstanding debate</h2>
<p>We found that people did in fact change how they moved and interacted around the Later Stone Age transition.</p>
<p>Despite being separated by thousands of miles and years, all the ancient individuals in this study were descended from the same three populations related to ancient and present-day eastern, southern and central Africans. The presence of eastern African ancestry as far south as Zambia, and southern African ancestry as far north as Kenya, indicates that people were moving long distances and having children with people located far away from where they were born. The only way this population structure could have emerged is if people were moving long distances over many millennia. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/446008/original/file-20220211-21-gafkub.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Lush African landscape" src="https://images.theconversation.com/files/446008/original/file-20220211-21-gafkub.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/446008/original/file-20220211-21-gafkub.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/446008/original/file-20220211-21-gafkub.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/446008/original/file-20220211-21-gafkub.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/446008/original/file-20220211-21-gafkub.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/446008/original/file-20220211-21-gafkub.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/446008/original/file-20220211-21-gafkub.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">Genetic data now suggests that people moved and mingled across the eastern African Rift Valley during the Ice Ages.</span>
<span class="attribution"><span class="source">Elizabeth Sawchuk</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Additionally, our research showed that almost all ancient eastern Africans shared an unexpectedly high number of genetic variations with hunter-gatherers who today live in central African rainforests, making ancient eastern Africa truly a genetic melting pot. We could tell that this mixing and moving happened after about 50,000 years ago, when there was a major split in central African forager populations.</p>
<p>We also noted that the individuals in our study were genetically most like only their closest geographic neighbors. This tells us that after around 20,000 years ago, the foragers in some African regions were almost exclusively finding their partners locally. This practice must have been extremely strong and persisted for a very long time, as our results show that some groups remained genetically independent of their neighbors over several thousand years. It was especially clear in Malawi and Zambia, where the only close relationships we detected were between people buried around the same time at the same sites. </p>
<p>We don’t know why people began “living locally” again. Changing environments as the last Ice Age peaked and waned between about 26,000-11,500 years ago may have made it more economical to forage closer to home, or perhaps elaborate exchange networks reduced the need for people to travel with objects.</p>
<p>Alternatively, new group identities may have emerged, restructuring marriage rules. If so, we would expect to see artifacts and other traditions like rock art diversify, with specific types clumped into different regions. Indeed, <a href="https://www.theguardian.com/science/2022/jan/16/trail-of-african-bling-reveals-50000-year-old-social-network">this is exactly what archaeologists find</a> – a trend known as regionalization. Now we know that this phenomenon not only affected cultural traditions, but also the flow of genes. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/446872/original/file-20220216-20-cuzc12.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="workers at a table sort tiny items by hand" src="https://images.theconversation.com/files/446872/original/file-20220216-20-cuzc12.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/446872/original/file-20220216-20-cuzc12.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/446872/original/file-20220216-20-cuzc12.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/446872/original/file-20220216-20-cuzc12.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/446872/original/file-20220216-20-cuzc12.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/446872/original/file-20220216-20-cuzc12.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/446872/original/file-20220216-20-cuzc12.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">Recovering and sorting archaeological remains is a slow and laborious process, where even small fragments can tell big stories.</span>
<span class="attribution"><span class="source">Chelsea Smith</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>New data, new questions</h2>
<p>As always, <a href="https://theconversation.com/ancient-dna-is-a-powerful-tool-for-studying-the-past-when-archaeologists-and-geneticists-work-together-111127">aDNA research raises as many questions as answers</a>. Finding central African ancestry throughout eastern and southern Africa prompts anthropologists to reconsider how interconnected these regions were in the distant past. This is important because central Africa has remained archaeologically understudied, in part because of political, economic and logistical challenges that make research there difficult. </p>
<p>Additionally, while genetic evidence supports a major demographic transition in Africa after 50,000 years ago, we still don’t know the key drivers. Determining what triggered the Later Stone Age transition will require closer examination of regional environmental, archaeological and genetic records to understand how this process unfolded across sub-Saharan Africa.</p>
<p>Finally, this study is a stark reminder that researchers still have <a href="https://theconversation.com/lesson-from-brazil-museums-are-not-forever-102692">much to learn from ancient individuals and artifacts</a> held in African museums, and highlights the <a href="https://theconversation.com/what-its-like-curating-ancient-fossils-a-palaeontologist-shares-her-story-96555">critical role of the curators</a> who steward these collections. While some human remains in this study were recovered within the past decade, others have been in museums for a half-century.</p>
<p>Even though technological advances are pushing back the time limits for aDNA, it is important to remember that scientists have only just begun to understand human diversity in Africa, past and present.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/GUau26szdzA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure><img src="https://counter.theconversation.com/content/175436/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elizabeth Sawchuk receives funding from the Social Sciences and Humanities Research Council of Canada. </span></em></p><p class="fine-print"><em><span>Jessica Thompson has received funding from the Leakey Foundation, National Geographic Society, Wenner-Gren Foundation, Australian Research Council, National Science Foundation, and Hyde Family Foundation. </span></em></p><p class="fine-print"><em><span>Mary Prendergast does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
A new study doubles the age of ancient DNA in sub-Saharan Africa, revealing how people moved, mingled and had children together over the last 50,000 years.
Elizabeth Sawchuk, Banting Postdoctoral Fellow and Adjunct Professor of Anthropology, University of Alberta
Jessica Thompson, Assistant Professor of Anthropology, Yale University
Mary Prendergast, Associate Professor of Anthropology, Rice University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/161585
2021-06-23T20:04:12Z
2021-06-23T20:04:12Z
Dirty secrets: sediment DNA reveals a 300,000-year timeline of ancient and modern humans living in Siberia
<figure><img src="https://images.theconversation.com/files/407374/original/file-20210621-35447-1spt3ea.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Collection of sediment DNA samples in the Main Chamber of Denisova Cave.</span> <span class="attribution"><span class="source">Bert Roberts</span>, <span class="license">Author provided</span></span></figcaption></figure><p>In the foothills of the Altai Mountains in southern Siberia lies Denisova Cave. It is the only site in the world known to have been inhabited by the eponymous Denisovans and their close relatives the Neanderthals (<em>Homo neanderthalensis</em>) — which <a href="https://www.nature.com/articles/d41586-018-06004-0">overlapped at times</a> — as well as by some of the earliest modern humans (<em>Homo sapiens</em>) to have dispersed into northern Asia.</p>
<p>Our <a href="https://www.nature.com/articles/s41586-021-03675-0">new study</a> pieces together the history of this site over the past 300,000 years from fragments of ancient DNA that survived in the cave sediments. Our findings reveal multiple turnovers of archaic and modern humans during this period, as well as major changes in the diversity of other animals.</p>
<p>We discovered Denisovans were the earliest toolmakers at the site, while Neanderthals were the sole human occupants between about 130,000 and 80,000 years ago. The first modern humans arrived much later, just as the last Denisovans and Neanderthals were leaving the scene.</p>
<p>We also detected marked changes in the types of human and animal DNA around 200,000 and 100,000 years ago, coincident with major shifts in climate and environmental conditions.</p>
<h2>Genetic ghosts</h2>
<p>Excavations in the cave by our Russian colleagues have unearthed about a dozen fossils of Denisovans and Neanderthals over the past 40 years, but none of modern humans. </p>
<p>Rather, the presence of modern humans at the cave has been surmised based on the recovery of artefacts made from stone, animal bones and teeth, mammoth ivory, ostrich eggshells, marble and gemstones.</p>
<p>The rarity of fossils at the site has also meant that questions persist about when different groups of humans occupied the cave, and which of them was responsible for making specific artefacts.</p>
<p>We managed to put flesh on the missing bones by using genetic traces of ancient humans and various other mammals preserved in the cave sediments. And we did so without having to find more fossils.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/403446/original/file-20210530-23-xbvsni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403446/original/file-20210530-23-xbvsni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403446/original/file-20210530-23-xbvsni.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403446/original/file-20210530-23-xbvsni.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403446/original/file-20210530-23-xbvsni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403446/original/file-20210530-23-xbvsni.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403446/original/file-20210530-23-xbvsni.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Project leader, Matthias Meyer, in the ancient DNA clean lab at the Max Planck Institute for Evolutionary Anthropology.</span>
<span class="attribution"><span class="source">Max Planck Institute for Evolutionary Anthropology</span></span>
</figcaption>
</figure>
<p>Our latest work is the most comprehensive study yet of ancient DNA extracted from sediment at any single site in the world. It builds on our <a href="https://science.sciencemag.org/content/356/6338/605">trailblazing research</a> published in 2017.</p>
<p>We extracted mitochondrial DNA from more than 700 samples and anchored them to a <a href="https://www.nature.com/articles/s41586-018-0843-2">timeline</a> for Denisova Cave, generating a detailed picture of which humans and animals were present at this famous site at various times in the past.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/fresh-clues-to-the-life-and-times-of-the-denisovans-a-little-known-ancient-group-of-humans-110504">Fresh clues to the life and times of the Denisovans, a little-known ancient group of humans</a>
</strong>
</em>
</p>
<hr>
<h2>Turbulent times</h2>
<p>We retrieved ancient human DNA from 175 sediment samples — more than ten times the number of human fossils found at the site. Several interesting findings emerged from our genetic analyses.</p>
<p>We found Denisovans were present at the cave, on and off, from 250,000 years ago until 60,000 years ago. And they were the only humans at the site between 250,000 and 200,000 years ago, so we can now say with more confidence they likely produced the stone tools recovered from these layers. </p>
<p>Denisovan fossils and ancient DNA have been found at only one <a href="https://theconversation.com/how-midnight-digs-at-a-holy-tibetan-cave-opened-a-window-to-prehistoric-humans-living-on-the-roof-of-the-world-148927">other site</a>, on the edge of the Tibetan Plateau.</p>
<p>Meanwhile, Neanderthals first appeared at Denisova Cave about 200,000 years ago, with a variety of DNA that was previously unknown. They vanished from the site about 40,000 years ago, around the same time Neanderthals disappeared in other parts of Eurasia.</p>
<p>Importantly, we could only find traces of Neanderthal DNA in sediments dated to between 130,000 and 80,000 years ago at Denisova Cave — and none of Denisovans.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/404606/original/file-20210605-27-1ye28kn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/404606/original/file-20210605-27-1ye28kn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=699&fit=crop&dpr=1 600w, https://images.theconversation.com/files/404606/original/file-20210605-27-1ye28kn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=699&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/404606/original/file-20210605-27-1ye28kn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=699&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/404606/original/file-20210605-27-1ye28kn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=878&fit=crop&dpr=1 754w, https://images.theconversation.com/files/404606/original/file-20210605-27-1ye28kn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=878&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/404606/original/file-20210605-27-1ye28kn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=878&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Summary timeline of the different types of human, bear and hyaena DNA in sediments at Denisova Cave. White gaps indicate missing parts of the sedimentary sequence. The graph on the left shows the changes in climate between relatively cold and warm conditions recorded in drill cores from Lake Baikal, also in southern Siberia.</span>
<span class="attribution"><span class="source">Bert Roberts</span></span>
</figcaption>
</figure>
<p>This time interval coincides with a major change in Earth’s climate: the start of the last interglacial. This was a relatively warm period similar to the present. It marked a switch from one type of Denisovan DNA before 130,000 years ago to another after 80,000 years ago.</p>
<p>This matches previous findings from genetic analysis of Denisovan fossils, which indicated a possible turnover in Denisovan populations. It also coincides with a population replacement of <a href="https://science.sciencemag.org/content/372/6542/eabf1667.full">Neanderthals in Spain</a> about 100,000 years ago — again identified from ancient DNA in cave sediments.</p>
<p>We also recovered the ancient DNA of modern humans from sediments deposited at Denisova Cave within the last 60,000 years. No modern human fossils have been found at the site, so these traces of DNA — from the same layers as the jewellery and pendants made from stone, bone, tooth and ivory — are the first direct evidence of <em>Homo sapiens</em>’ presence at the cave.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/403456/original/file-20210530-15-1thvbk4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403456/original/file-20210530-15-1thvbk4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=346&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403456/original/file-20210530-15-1thvbk4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=346&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403456/original/file-20210530-15-1thvbk4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=346&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403456/original/file-20210530-15-1thvbk4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=435&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403456/original/file-20210530-15-1thvbk4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=435&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403456/original/file-20210530-15-1thvbk4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=435&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Selection of stone tools and personal ornaments made from bone, tooth and ivory recovered from the same sediment layers as modern human ancient DNA.</span>
<span class="attribution"><span class="source">Institute of Archaeology and Ethnography of the Siberian Branch of the Russian Academy of Sciences.</span></span>
</figcaption>
</figure>
<h2>Denisova zoo</h2>
<p>We recovered other ancient animal DNA from 94% of the sediment samples. This is providing new vistas into cave use by more than 12 taxonomic families of mammals, including species such as bear, hyena, wolf and woolly mammoth.</p>
<p><a href="https://www.nature.com/articles/s41598-019-49930-3">Previous studies</a> have shown the cave was occupied at times by hyenas and bears. Our findings take this further, revealing cave bears dominated between 300,000 and 200,000 years ago, after which brown bears became more abundant.</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>
<hr>
<p>We also identified two major shifts in the types of hyena present at different times, with turnovers occurring when climatic conditions changed from relatively warm to cold 200,000 years ago, and from relatively cold to warm 100,000 years ago.</p>
<p>The timing of these turnovers, coupled with the patterns we discovered for Denisovans and Neanderthals, suggests these events were likely connected to environmental changes.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/aqdu2vjuCUY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A guided tour of our key findings, presented by the lead author of the study, Elena Zavala from the Max Planck Institute for Evolutionary Anthropology.</span></figcaption>
</figure>
<h2>Sediment diaries</h2>
<p>The power of sediment DNA lies in the fact that sediments are ubiquitous at archaeological and palaeontological sites. Even tiny samples can contain genetic traces of a variety of animals — including humans — in the absence of fossils.</p>
<p>Sediments also often contain plant remains and other materials that can be used to reconstruct ancient environments, with timelines obtained by <a href="https://www.nature.com/articles/520438a">directly dating</a> sediment grains.</p>
<p>By sampling sites with high densities of sediment DNA, the ebb and flow of humans and other animals can be compared to records of past environmental change. Making these crucial connections can help illuminate the dark corners of our planet’s history.</p><img src="https://counter.theconversation.com/content/161585/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elena Zavala receives funding from the Max Planck Society. </span></em></p><p class="fine-print"><em><span>Matthias Meyer receives funding from the Max Planck Society. </span></em></p><p class="fine-print"><em><span>Richard 'Bert' Roberts receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Zenobia Jacobs receives funding from the Australian Research Council. </span></em></p>
Our research has also uncovered major long-term changes in ancient animal populations at Denisova Cave, and has provided the first direct evidence of Homo sapiens having lived there.
Elena Zavala, PhD Student, Max Planck Institute for Evolutionary Anthropology
Matthias Meyer, Group Leader, Advanced DNA Sequencing Techniques Group, Max Planck Institute for Evolutionary Anthropology
Richard 'Bert' Roberts, Director, ARC Centre of Excellence for Australian Biodiversity and Heritage (CABAH), University of Wollongong
Zenobia Jacobs, Professor, University of Wollongong
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/156715
2021-04-05T12:34:50Z
2021-04-05T12:34:50Z
How did humans evolve, and will we evolve more?
<figure><img src="https://images.theconversation.com/files/389682/original/file-20210315-13-16jufk3.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3100%2C2408&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">This skull, found in France, was among the first fossils to be recognized as belonging to our own species.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/homo-sapien-skull-found-in-abri-de-cro-magnon-france-news-photo/541321135">DEA /G. Cigolini via Getty Images</a></span></figcaption></figure><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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<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>
<hr>
<blockquote>
<p><strong>How did humans evolve, and will they evolve more? – Anya T., 13, Brookline, Massachusetts</strong></p>
</blockquote>
<hr>
<p>Everything that is alive today has evolved, <a href="https://www.sciencemag.org/news/2018/06/momentous-transition-multicellular-life-may-not-have-been-so-hard-after-all">including human beings</a>. </p>
<p>Our ancestors evolved many traits that helped them survive in their environments, and we still have many of those traits today. Two of the most important and consequential traits are walking on two legs and having a large brain.</p>
<p>I’m a <a href="https://scholar.google.com/citations?user=TZ5HyRMAAAAJ&hl=en&oi=ao">scholar of human evolution</a>. I study how evolution works, including how it has changed the shape of the bones in the skull and ankle of humans and other primates.</p>
<p>So how did humans evolve, and where will evolution take us in the future?</p>
<h2>What evolution is</h2>
<p>People pass traits to their children through genes. We can have <a href="https://www.genome.gov/genetics-glossary/Allele">different versions of the same genes</a> – called alleles – and evolution occurs when the proportion of these alleles in the population <a href="https://www.nature.com/scitable/definition/evolution-78/">changes over multiple generations</a>.</p>
<p>Alleles in a population often help certain individuals survive in their own environment. This means that evolution isn’t about becoming the fastest, or the strongest, or the smartest, because it all depends on the environment.</p>
<p>Early ancestors of humans evolved to walk upright on two legs around <a href="https://humanorigins.si.edu/human-characteristics/walking-upright">6 million years ago</a>.</p>
<p>Scientists are still trying to figure out <a href="https://www.smithsonianmag.com/science-nature/becoming-human-the-evolution-of-walking-upright-13837658/">why our ancestors started walking on two legs</a>. Today, the most common hypothesis is that walking on two legs probably helped our ancestors to move between forest patches that were shrinking due to a changing climate.</p>
<p>What about our brains?</p>
<p>Relative to the size of our bodies, humans have the largest brains on the planet. Elephants have bigger brains, but their bodies are even bigger than ours.</p>
<p>Without big brains we wouldn’t be able to innovate, such as by creating an alphabet, sending machines to Mars or creating vaccines that protect us against measles and other dangerous diseases. Our big brains make it possible to share information culturally through books, storytelling or even movies, rather than only passing our genes to the next generation.</p>
<p>Our ancestors’ brains got bigger over the course of human evolution until about 200,000 to 300,000 years ago when modern humans, known as <em><a href="https://www.britannica.com/topic/Homo-sapiens/Origin">Homo sapiens</a></em>, showed up.</p>
<p>After that, human brains actually <a href="https://www.scientificamerican.com/article/why-have-our-brains-started-to-shrink/">started to get a bit smaller</a>, possibly because our bodies have gotten smaller or perhaps because a slightly smaller brain may not use as much energy.</p>
<p><a href="https://www.sciencemag.org/news/2016/05/humans-are-still-evolving-and-we-can-watch-it-happen">Humans are still evolving</a>. For example, because they have a largely vegetarian diet like their ancestors did, many people who live in the city of <a href="https://www.sciencedaily.com/releases/2016/03/160329184939.htm">Pune, India, have a mutation</a> that helps them more efficiently process omega-3 and omega-6 fatty acids. Vegetarians can have trouble getting enough of those nutrients, which are important for having a healthy brain.</p>
<h2>Humans in the future</h2>
<p>Nobody knows where human evolution will lead.</p>
<p>All organisms, including humans, adapt to their environments. And those environments can change – sometimes in entirely unpredictable ways. </p>
<p>It may disappoint you to hear that people aren’t likely to evolve superpowers like those in the <a href="https://www.imdb.com/title/tt0120903/">“X-Men” movies</a> or characters in the <a href="https://www.marvel.com/movies">Marvel Cinematic Universe</a>, at least for the most part.</p>
<p>However, there is one Marvel character humans have evolved to be like: <a href="https://www.cbr.com/iron-man-tony-stark-inventions-that-completely-changed-the-marvel-universe/">Iron Man</a>.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/y0brSA1cyzw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The inventions of Tony Stark, who turns into Iron Man, can both save the day and wreak havoc in the Marvel Universe.</span></figcaption>
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<p>Like Iron Man, humans are smart enough to invent things that can make some of us live longer or have more fun, whether it’s a device that keeps an ailing heart beating or an airplane that makes it possible to fly without wings.</p>
<p>It’s unlikely that humans will ever evolve laser beam eyes or wings out of our backs like the X-Men characters <a href="https://marvel.fandom.com/wiki/Scott_Summers_(Earth-616)">Cyclops</a> and <a href="https://marvel.fandom.com/wiki/Warren_Worthington_III_(Earth-616)">Archangel</a>. But other abilities that humans have evolved over millions of years of evolution allow us to do many of those same things, through innovation.</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/156715/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Evan Simons receives funding from the National Science Foundation.</span></em></p>
Our biggest evolutionary advantages are an ability to walk on two legs and our big brains.
Evan Simons, Postdoctoral Research Associate in Anthropology, University at Buffalo
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/144145
2020-08-20T12:52:44Z
2020-08-20T12:52:44Z
Humans aren’t inherently selfish – we’re actually hardwired to work together
<figure><img src="https://images.theconversation.com/files/353854/original/file-20200820-16-640roy.jpg?ixlib=rb-1.1.0&rect=0%2C53%2C5991%2C2937&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/diverse-crowd-people-seamless-banner-100-1168257583">Franzi/Shutterstock</a></span></figcaption></figure><p>There has long been a general assumption that human beings are <a href="https://digest.bps.org.uk/2018/10/12/what-are-we-like-10-psychology-findings-that-reveal-the-worst-of-human-nature/">essentially selfish</a>. We’re apparently ruthless, with strong impulses to compete against each other for resources and to accumulate power and possessions. </p>
<p>If we are kind to one another, it’s usually because we have ulterior motives. If we are good, it’s only because we have managed to control and transcend our innate selfishness and brutality.</p>
<p>This bleak view of human nature is closely associated with the science writer Richard Dawkins, whose book <a href="https://global.oup.com/academic/product/the-selfish-gene-9780198788607?cc=gb&lang=en&">The Selfish Gene</a> became popular because it fitted so well with (and helped to justify) the competitive and individualistic ethos of late 20th-century societies. </p>
<p>Like many others, Dawkins justifies his views with reference to the field of <a href="https://www.youtube.com/watch?v=fRpfPyIM5lc">evolutionary psychology</a>. Evolutionary psychology theorises that present-day human traits developed in prehistoric times, during what is <a href="https://link.springer.com/referenceworkentry/10.1007%2F978-3-319-28099-8_1627-1#:%7E:text=Definition,pressures%20that%20shaped%20an%20adaptation.">termed</a> the “environment of evolutionary adaptedness”. </p>
<p>This is usually seen as a period of intense competition, when life was a kind of Roman gladiatorial battle in which only the traits that gave people a survival advantage were selected and all others fell by the wayside. And because people’s survival depended on access to resources – think rivers, forests and animals – there was bound to be competition and conflict between rival groups, which led to the development of traits like <a href="https://www.researchgate.net/publication/320005754_The_Evolutionary_Anthropology_of_War">racism and warfare</a>.</p>
<p>This seems logical. But in fact the assumption it’s based on — that prehistoric life was a desperate struggle for survival — is false.</p>
<h2>Prehistoric abundance</h2>
<p>It’s important to remember that in the prehistoric era, the world was very sparsely populated. So it’s likely there was an abundance of resources for hunter-gatherer groups. </p>
<p>According to <a href="https://www.academia.edu/2968441/The_Prehistory_of_Warfare_Misled_by_Ethnography">some estimates</a>, around 15,000 years ago, the population of Europe was only 29,000, and the population of the whole world was less than half a million. With such small population densities, it seems unlikely that prehistoric hunter-gatherer groups had to compete against each other or had any need to develop ruthlessness and competitiveness, or to go to war. </p>
<p>Indeed, <a href="https://blogs.scientificamerican.com/cross-check/new-study-of-prehistoric-skeletons-undermines-claim-that-war-has-deep-evolutionary-roots/">many anthropologists</a> now agree that war is a late development in human history, arising with the first <a href="https://www.academia.edu/2968441/The_Prehistory_of_Warfare_Misled_by_Ethnography">agricultural settlements</a>. </p>
<h2>Contemporary evidence</h2>
<p>There’s also significant evidence from contemporary hunter-gatherer groups who live in the same way as prehistoric humans. One of the striking things about such groups is their egalitarianism. </p>
<p>As the anthropologist <a href="https://www.journals.uchicago.edu/doi/abs/10.1086/203975?journalCode=ca">Bruce Knauft</a> has remarked, hunter-gatherers are characterised by “extreme political and sexual egalitarianism”. Individuals in such groups don’t accumulate their own property and possessions. They have a moral obligation to share everything. They also have methods of preserving egalitarianism by ensuring that status differences don’t arise. </p>
<p><a href="https://en.wikipedia.org/wiki/%C7%83Kung_people">The !Kung</a> of southern Africa, for example, swap arrows before going hunting and when an animal is killed, the credit does not go to the person who fired the arrow, but to the person who the arrow belongs to. And if a person becomes too domineering or arrogant, the other members of the group ostracise them.</p>
<figure class="align-center ">
<img alt="ǃKung woman making jewellery next to a child." src="https://images.theconversation.com/files/353834/original/file-20200820-16-rfz0u8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/353834/original/file-20200820-16-rfz0u8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/353834/original/file-20200820-16-rfz0u8.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/353834/original/file-20200820-16-rfz0u8.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/353834/original/file-20200820-16-rfz0u8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/353834/original/file-20200820-16-rfz0u8.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/353834/original/file-20200820-16-rfz0u8.jpeg?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">ǃKung woman making jewellery next to a child.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:San_Schmuck.JPG">Staehler/wikimediacommons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Typically in such groups, men have <a href="https://science.sciencemag.org/content/348/6236/796.abstract">no authority</a> over women. Women usually choose their own marriage partners, decide what work they want to do and work whenever they choose to. And if a marriage breaks down, they have custody rights over their children. </p>
<p>Many anthropologists agree that such egalitarian societies were normal until a few thousand years ago, when population growth led to the development of farming and a <a href="https://www.newscientist.com/article/dn22071-inequality-why-egalitarian-societies-died-out/">settled lifestyle</a>.</p>
<h2>Altruism and egalitarianism</h2>
<p>In view of the above, there seems little reason to assume that traits such as racism, warfare and male domination should have been selected by evolution – as they would have been of little benefit to us. Individuals who behaved selfishly and ruthlessly would be less likely to survive, since they would have been ostracised from their groups.</p>
<p>It makes more sense then to see traits such as cooperation, egalitarianism, altruism and peacefulness as natural to human beings. These were the traits that have been prevalent in human life for tens of thousands of years. So presumably these traits are still strong in us now. </p>
<p>Of course, you might argue that if this is case, why do present day humans often behave so selfishly and ruthlessly? Why are these negative traits so normal in many cultures? Perhaps though these traits should be seen as the result of environmental and psychological factors. </p>
<figure class="align-center ">
<img alt="People protesting." src="https://images.theconversation.com/files/353846/original/file-20200820-16-1x0buvh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/353846/original/file-20200820-16-1x0buvh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/353846/original/file-20200820-16-1x0buvh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/353846/original/file-20200820-16-1x0buvh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/353846/original/file-20200820-16-1x0buvh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/353846/original/file-20200820-16-1x0buvh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/353846/original/file-20200820-16-1x0buvh.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">There are lots of examples of humans working together for the greater good.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/rear-view-people-placards-posters-on-1513189949">Halfpoint/Shutterstock</a></span>
</figcaption>
</figure>
<p><a href="http://nonkilling.org/pdf/wp1.pdf">Research</a> has shown repeatedly that when the natural habitats of primates are disrupted, they tend to become more violent and hierarchical. So it could well be that the same thing has has happened to us, since we gave up the hunter-gatherer lifestyle. </p>
<p>In my book <a href="https://www.stevenmtaylor.com/books/the-fall/">The Fall</a>, I suggest that the end of the hunter-gatherer lifestyle and the advent of farming was connected to a psychological change that occurred in some groups of people. There was a new sense of individuality and separateness, which led a new selfishness, and ultimately to hierarchical societies, patriarchy and warfare.</p>
<p>At any rate, these negative traits appear to have developed so recently that it doesn’t seem feasible to explain them in adaptive or evolutionary terms. Meaning that the “good” side of our nature is much more deep-rooted than the “evil” side.</p><img src="https://counter.theconversation.com/content/144145/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Steve Taylor 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 ‘good’ side of our nature is much more deep-rooted than the ‘evil’ side.
Steve Taylor, Senior Lecturer in Psychology, Leeds Beckett University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/103858
2018-09-26T18:01:01Z
2018-09-26T18:01:01Z
Neanderthals were no brutes – research reveals they may have been precision workers
<figure><img src="https://images.theconversation.com/files/238070/original/file-20180926-48650-130bahw.jpg?ixlib=rb-1.1.0&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/pahudson/13809176994">Paul Hudson/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Neanderthals were until quite recently often seen as simple-minded savages – powerful hunters with a short attention span. But in the last few years, scientists have realised that they were a lot more refined than previously thought – capable of <a href="https://theconversation.com/neanderthals-cared-for-each-other-and-survived-into-old-age-new-research-93110">caring for the vulnerable</a>, <a href="https://theconversation.com/neanderthal-dispute-laid-to-rest-they-buried-their-dead-21593">burying their dead</a> and even <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0021545">adorning themselves</a> with feathers and beads.</p>
<p>Now new evidence, <a href="http://advances.sciencemag.org/content/4/9/eaat2369">published in Science Advances</a>, reveals that the Neanderthals were also more similar to modern humans in their physical expression than previously thought. The study, which analysed Neanderthal hand and arm bones, reveals that these individuals didn’t actually rely primarily on force in their daily activities – they used precision grips just like we do. </p>
<p>The remarkable findings were possible thanks to a new approach to investigating and decoding the tiny marks left on skeletal remains by the muscle attachments of individual fingers and thumbs. It has been well known for many decades that one’s skeleton responds to the forces resulting from habitual muscle use through life, with bones becoming more robust at points of increased strain. </p>
<figure> <img src="https://i.giphy.com/media/8cALU2xQWsVdYlXzCW/giphy.gif"><figcaption>Hand bones with the muscle attachment for both grips shown. Blue: precision, Red: Power. Credit: Copyright Katerina Harvati, University of Tübingen.</figcaption></figure>
<p>And therefore you can compare Neanderthal injuries and areas of distinctive skeletal robustness with modern data. One such previous study found that the skeletal injuries of Neanderthals <a href="https://www.sciencedirect.com/science/article/pii/0305440395900136">were similar</a> to those of professional rodeo riders. The authors suggested this could have been because Neanderthal hunting involved close-quarters spearing – forcing them to cling on to their weapon as an injured animal thrashed around.</p>
<h2>Bricklayers versus writers</h2>
<p>In the new study, researchers investigated modern comparative skeletal data from 50 (one hopes and presumes) willing modern human posthumous donors of their bodies to scientific research. They all had well documented life histories, although the precise origins of the sample were not presented. One group had an occupational history interpreted as involving power grips – bricklayers, stone masons and carpenters. The other group had been involved in less intensive manual work with greater requirement for precision – including tailors, shoemakers, joiners, a writer and a painter. </p>
<p>The resulting statistical analysis was exemplary, providing a framework that related certain combinations of skeletal marks to heavy work and lighter work, respectively. The assumptions underpinning the selection of the groups, however, could be questioned – it may be the case that stone masons and carpenters rely on manual precision in their work, too. </p>
<p>Still, the results were intriguing and the researchers compared them with archaeological data from six Neanderthal remains and six early modern human specimens. The results were very clear for the Neanderthal sample. All the skeletons showed strong and consistent similarities with the modern precision-grip group. Surprisingly, the results were less clear for the early modern human sample. Only three specimens matched this group. Two were instead consistently related to the heavy work group and the results were ambiguous for the other. </p>
<p>The surprise here is not that Neanderthals have been shown to have an adaptation involving manual dexterity and a precision grip, but rather that this should ever have been a matter of doubt. </p>
<h2>Clues about societies</h2>
<p>The <a href="https://www.cambridge.org/core/journals/cambridge-archaeological-journal/article/understanding-levallois-lithic-technology-and-cognitive-archaeology/607650D8257922747A273F138F07BBB6">Levalloisian lithic technology</a> often used by Neanderthals to produce a range of flake end products of predetermined form would require both an essentially modern human cognitive capability to conceive it and great manual dexterity to achieve it. </p>
<p>This work therefore continues the trend over recent decades of bringing Neanderthals into the human family as complex beings. Clearly, these individuals negotiated their social and cultural worlds though brain power and technological sophistication.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/238064/original/file-20180926-48659-xeh2tt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/238064/original/file-20180926-48659-xeh2tt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=373&fit=crop&dpr=1 600w, https://images.theconversation.com/files/238064/original/file-20180926-48659-xeh2tt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=373&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/238064/original/file-20180926-48659-xeh2tt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=373&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/238064/original/file-20180926-48659-xeh2tt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=469&fit=crop&dpr=1 754w, https://images.theconversation.com/files/238064/original/file-20180926-48659-xeh2tt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=469&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/238064/original/file-20180926-48659-xeh2tt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=469&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Levalloisian lithic technology.</span>
<span class="attribution"><span class="source">Didier Descouens/wikipedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Perhaps the mixed results for the early modern human sample is of even greater importance. Here we have undoubted members of the human family failing to demonstrate evidence of habitual use of precision-gripping through their lifetime. How can we explain that? It does suggest that these ancestors may have been more specialised in terms of labour than the Neandertals. There could have been social stratification in early modern human Upper Palaeolithic society, in which people had different occupations and perhaps status.</p>
<p>However, the sample was quite small so more research would be needed to settle this question. The next step will be to apply these techniques to new material in greater quantities, and perhaps with a more refined basis of comparative material.</p>
<p>Overall, however, this is a valuable and robust piece of research that reinforces what should now be the wide acceptance of Neanderthals as complex and sentient beings equivalent to ourselves.</p><img src="https://counter.theconversation.com/content/103858/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Francis Wenban-Smith 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>
Nimble-fingered Neanderthals went about their daily business in a similar way to modern humans.
Francis Wenban-Smith, Principal Research Fellow of Archaeology, University of Southampton
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/54385
2018-01-07T19:09:16Z
2018-01-07T19:09:16Z
The origin of ‘us’: what we know so far about where we humans come from
<figure><img src="https://images.theconversation.com/files/199881/original/file-20171219-27557-sri3mm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The story of where we come from evolves almost every year.</span> <span class="attribution"><span class="source">Shutterstock/Eugenio Marongiu </span></span></figcaption></figure><p>The question of where we humans come from is one many people ask, and the answer is getting more complicated as <a href="https://theconversation.com/worlds-scientists-turn-to-asia-and-australia-to-rewrite-human-history-88697">new evidence</a> is emerging all the time.</p>
<p>For most of recorded history humankind has been placed on a metaphorical, and sometimes literal, pedestal. Sure, modern humans were flesh and blood like other animals. </p>
<p>But they were regarded as being so special that in the <a href="https://www.britannica.com/science/taxonomy/The-Linnaean-system">Linnaean taxonomy</a> that prevailed well into the second half of the 20th century they were given their own family, the <a href="https://www.britannica.com/animal/Hominidae">Hominidae</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-dna-sheds-light-on-the-origin-of-europeans-33907">Ancient DNA sheds light on the origin of Europeans</a>
</strong>
</em>
</p>
<hr>
<p>This distinguished them from the Pongidae, the separate family used for the three African great apes – the common chimpanzee, bonobo and gorilla – plus the orangutan from Southeast Asia. </p>
<p>We now realise that modern humans are just one of the African great apes.</p>
<p>So when and how did this radically changed perception come about?</p>
<h2>Early observations</h2>
<p>In the 19th century the only evidence available for determining the closeness of the relationship between any two living animals was how similar they were in terms of what the naked eye could tell from their bones, teeth, muscles and organs.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/198739/original/file-20171212-9410-rl1ai7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/198739/original/file-20171212-9410-rl1ai7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/198739/original/file-20171212-9410-rl1ai7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=929&fit=crop&dpr=1 600w, https://images.theconversation.com/files/198739/original/file-20171212-9410-rl1ai7.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=929&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/198739/original/file-20171212-9410-rl1ai7.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=929&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/198739/original/file-20171212-9410-rl1ai7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1167&fit=crop&dpr=1 754w, https://images.theconversation.com/files/198739/original/file-20171212-9410-rl1ai7.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1167&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/198739/original/file-20171212-9410-rl1ai7.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1167&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Biologist Thomas Henry Huxley (1825-1895).</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Thomas_Henry_Huxley_1874.JPG">Wikimedia/Carte de Visite Fotografie</a></span>
</figcaption>
</figure>
<p>The first person to undertake a systematic comparative review of these differences between modern humans and the apes was English biologist <a href="https://www.britannica.com/biography/Thomas-Henry-Huxley">Thomas Henry Huxley</a>.</p>
<p>In the central section of a small book he published in 1863, called <a href="https://archive.org/details/evidenceastomans00huxl">Evidence as to Man’s Place in Nature</a>, Huxley concluded that the differences between modern humans and African apes were less than those between African apes and orangutans.</p>
<p>This was the evidence the English naturalist <a href="https://www.britannica.com/biography/Charles-Darwin">Charles Darwin</a> referred to in <a href="http://darwin-online.org.uk/EditorialIntroductions/Freeman_TheDescentofMan.html">The Descent of Man</a> in 1871.</p>
<p>He speculated that because African apes were morphologically closer to modern humans than the apes from Asia, then the ancestors of modern humans were more likely to be found in Africa than elsewhere.</p>
<h2>A closer inspection</h2>
<p>Developments in biochemistry and immunology during the first half of the 20th century enabled the search for evidence of the relationships between modern humans and the apes to shift from macroscopic morphology to the morphology of molecules.</p>
<p>The results of applying a new generation of analytical methods to proteins were reported by the Austrian-born French biologist Emile Zuckerkandl and American biologist Morris Goodman in the early 1960s.</p>
<p><a href="https://babel.hathitrust.org/cgi/pt?id=mdp.39015002245846;view=1up;seq=259">Zuckerkandl used enzymes</a> to break up the protein component of haemoglobin into its peptide components. He showed that the patterns of the peptides from modern humans, gorilla and chimpanzee were indistinguishable.</p>
<p><a href="https://babel.hathitrust.org/cgi/pt?id=mdp.39015002245846;view=1up;seq=220">Goodman used a different method</a>, immunodiffusion, to study albumin, a serum protein. He showed that the patterns produced by the albumins of modern humans and the chimpanzee were identical. He concluded that this was because the albumin molecules were, to all intents and purposes, identical. </p>
<h2>Apes and humans: related</h2>
<p>Proteins are made up of a string of amino acids and in many instances one amino acid can be substituted for another without changing the function of the protein.</p>
<p>In the late 1960s, the American anthropologist Vince Sarich and New Zealand biologist <a href="http://www.allanwilsoncentre.ac.nz/massey/learning/departments/centres-research/allan-wilson-centre/about-us/allan-wilson.cfm">Allan Wilson</a> exploited these minor differences in protein structure and <a href="https://www.ncbi.nlm.nih.gov/pubmed/4964406">concluded</a> that modern humans and the African apes were very closely related.</p>
<p>They also provided the first molecular clock estimate of modern human-African ape divergence, dating the split to only around five million years ago. This date was less than half of contemporary estimates based on fossil evidence.</p>
<p>In 1975 the American human geneticist <a href="https://www.jax.org/news-and-insights/jax-blog/2017/february/mary-claire-king">Mary-Claire King</a> and Allan Wilson <a href="http://science.sciencemag.org/content/188/4184/107">showed</a> that 99% of the amino-acid sequences of chimpanzee and modern human blood proteins were identical.</p>
<h2>Enter DNA</h2>
<p>The discovery by James Watson and Francis Crick, with unwitting help from Rosalind Franklin, of the <a href="http://www.nature.com/nature/dna50/archive.html">basic structure of DNA</a>, and the subsequent discovery by Crick and others of the nature of the genetic code, meant that the relationships among organisms could be pursued at the level of the genome.</p>
<p>Nowadays technological advances mean that whole genomes can be sequenced. Over the past decade researchers have published good draft sequences of the nuclear genomes of the <a href="https://www.nature.com/articles/nature04072">chimpanzee</a>, <a href="https://www.nature.com/articles/nature09687">orangutan</a>, <a href="https://www.nature.com/articles/nature10842">gorilla</a> and the <a href="https://www.nature.com/articles/nature11128">bonobo</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/198955/original/file-20171213-27597-9fynou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/198955/original/file-20171213-27597-9fynou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/198955/original/file-20171213-27597-9fynou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/198955/original/file-20171213-27597-9fynou.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/198955/original/file-20171213-27597-9fynou.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/198955/original/file-20171213-27597-9fynou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/198955/original/file-20171213-27597-9fynou.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/198955/original/file-20171213-27597-9fynou.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">How close? A chimpanzee (top left), an orangutan (top right), a gorilla (bottom left) and a bonobo (bottom right).</span>
<span class="attribution"><span class="source">Shutterstock/Sergey Uryadnikov/Petr Masek/Sergey Uryadnikov/Eric Gevaert</span></span>
</figcaption>
</figure>
<p>More and better data are steadily being accumulated, and in 2013 a review of ape DNA based on the genomes of 79 great apes was <a href="https://www.nature.com/articles/nature12228">published</a>.</p>
<p>These new ape genome sequences support the results of earlier analyses of both nuclear and mitochondrial DNA that suggested modern humans and chimpanzees are more closely related to each other than either is to the gorilla.</p>
<p>When DNA differences among modern humans and the great apes are calibrated using the best palaeontological evidence for the split between the apes and the old world monkeys, those differences predict that the hypothetical common ancestor of modern humans, chimpanzees and bonobos lived about 8 million years ago. </p>
<h2>The rise of the hominins</h2>
<p>Most researchers now recognise the modern human as <a href="https://www.britannica.com/animal/hominin">hominins</a>.</p>
<p>Still, the question “where do we come from” can from a scientific perspective be difficult for someone outside of the discipline to come to grips with. In part this is because the fossil record for human evolution seems to grow exponentially, with the author of each new discovery often claiming that the textbooks need to be rewritten. </p>
<p>The interdisciplinary nature of palaeoanthropology also means that new evidence that helps us make sense of our ancestry does not always come in the form of new fossils.</p>
<p>It comes from advances in a range of disciplines that include archaeology, comparative anatomy, earth sciences, evolutionary biology, genomics and primatology.</p>
<p>A further complicating factor is that the human fossil record does not just consist of the fossil evidence of our direct ancestors.</p>
<p>Many of the fossils belong to lineages that do not make it to the surface of the <a href="http://www.bbc.co.uk/nature/life/">Tree of Life</a>. They belong to extinct close relatives, and the task of sorting close relatives from ancestors is one with which we are only just now beginning to grapple.</p>
<p>There is a lineage that leads to today’s <a href="https://www.britannica.com/topic/Homo-sapiens"><em>Homo sapiens</em></a>, but there are also a host of side experiments that are equally important to understand. They represent some of the most interesting chapters in human evolution.</p>
<h2>Origins of the genus <em>Homo</em></h2>
<p>Understanding the origins of our own genus <em>Homo</em> means establishing what fossils we recognise as being the first early humans. </p>
<p>Sometime before 4 million years ago we see the first evidence of the genus <a href="http://www.columbia.edu/itc/anthropology/v1007/2002projects/web/australopithecus/austro.html"><em>Australopithecus</em></a>. These fossils sample the kind of creature that was most likely the ancestor to the genus <em>Homo</em>. </p>
<p>Around 2.5 million years ago we see the first fossil evidence of species in Africa that many argue belong to our own lineage. One of these, <a href="http://humanorigins.si.edu/evidence/human-fossils/species/homo-habilis"><em>Homo habilis</em></a>, almost certainly made stone tools, had a slightly larger brain than <em>Australopithecus</em>, stood upright and regularly walked on two legs.</p>
<p>Some recognise a second species, <a href="http://humanorigins.si.edu/evidence/human-fossils/species/homo-rudolfensis"><em>Homo rudolfensis</em></a>, about which we know even less. </p>
<p>These possible human ancestors lived alongside close relatives that were almost certainly not our ancestors. These species are called <a href="https://australianmuseum.net.au/paranthropus-species"><em>Paranthropus</em></a> or <a href="http://www.columbia.edu/itc/anthropology/v1007/2002projects/web/paranth/paranth.html">robust australopiths</a> – they had small brains, big jaw bones, large flat faces, and huge chewing teeth.</p>
<p>They lasted for at least a million years, so whatever they were eating (which is still a mystery) they were successful in the sense that they lasted as long in the fossil record as the average mammal. </p>
<p>But some <a href="http://www.nature.com/news/human-evolution-fifty-years-after-homo-habilis-1.14957">researchers</a> think that <em>Homo habilis</em> and <em>Homo rudolfensis</em> are not different enough from the australopiths that preceded them to justify being included in the genus <em>Homo</em>.</p>
<p>They claim that the size and shape of their body and the size of their teeth and jaws was little different from that of the australopiths. This means that their locomotion and diet had not shifted far enough in the direction of pre-modern <em>Homo</em> species such as <a href="https://australianmuseum.net.au/homo-erectus"><em>Homo erectus</em></a> to justify inclusion in <em>Homo</em>.</p>
<h2>Tool making is not enough</h2>
<p>Also, because it is becoming evident that australopiths may have been making tools earlier than <em>Homo habilis</em> it means that tool-making can no longer be seen as the sole prerogative of <em>Homo</em>.</p>
<p>There is a developing consensus that the relaxation of the criteria more than 50 years ago that saw the inclusion of <em>Homo habilis</em> into the genus <em>Homo</em> <a href="http://www.nature.com/news/human-evolution-fifty-years-after-homo-habilis-1.14957">needs to be reconsidered</a>. </p>
<p>Species that emerge slightly later from Africa, such as <a href="https://australianmuseum.net.au/homo-ergaster"><em>Homo ergaster</em></a>, fit much more clearly within what we understand by the genus <em>Homo</em>. That species probably left Africa around 2 million years ago and migrated ultimately as far east as China and Indonesia where it evolved, eventually, into <em>Homo erectus</em>.</p>
<p>A number of further migrations out of Africa probably occurred after the initial <em>Homo ergaster</em> migration, one of which, <a href="https://australianmuseum.net.au/homo-heidelbergensis"><em>Homo heidelbergensis</em></a>, is considered by many palaeoanthropologists to be the ancestor of both Neanderthals (<a href="https://australianmuseum.net.au/homo-neanderthalensis"><em>Homo neanderthalensis</em></a>) and modern humans (<a href="https://australianmuseum.net.au/homo-sapiens-modern-humans"><em>Homo sapiens</em></a>).</p>
<p>As far as we know, Neanderthals evolved outside of Africa, perhaps in response to the ice ages of Europe. Our ancestors remained in Africa where perhaps as early as 300,000 years ago, as revealed from <a href="https://www.nature.com/articles/nature22336">recent redating</a> of the Moroccan site of Jebel Irhoud, were well along in the process of <a href="http://dx.doi.org/10.1016/j.cub.2017.06.052">evolving into modern humans</a>. </p>
<h2>So the origins of ‘us’</h2>
<p>Once we get to the origins of our own species <em>Homo sapiens</em> we have the added advantage that we are able to now use <a href="https://www.ebi.ac.uk/training/online/course/ebi-next-generation-sequencing-practical-course/what-you-will-learn/what-next-generation-dna-">next generation sequencing methods</a> to recover ancient DNA (aDNA). </p>
<p>As geneticists recover ancient genomes from different extinct hominin species, they are generating insights that are not possible from comparing the anatomy of the fossils alone.</p>
<p>There is now fossil evidence <a href="http://www.nature.com/news/teeth-from-china-reveal-early-human-trek-out-of-africa-1.18566">from teeth</a> to suggest that <em>Homo sapiens</em> may have been in China by 120,000 years ago and in South East Asia <a href="https://www.ncbi.nlm.nih.gov/pubmed/20569967">by 67,000 years</a>. </p>
<p>The <a href="http://www.bbc.com/news/science-environment-35595661">discovery</a> of some distinctive modern human DNA within the DNA recovered from a Neanderthal fossil suggests that modest interbreeding was occurring between Neanderthals and modern humans in Central Asia by 100,000 years ago.</p>
<p>Modern humans have not shared the planet with another hominin species for several tens of thousands of years. But before that, in the past 300,000 years or so, there is fossil and DNA evidence of several hominin species, including the recently reported archaic hominin <a href="https://www.nature.com/news/small-brained-early-human-lived-more-recently-than-expected-1.21961"><em>Homo naledi</em></a> </p>
<p>First and foremost there was <em>Homo neanderthalensis</em>, whose range overlapped with modern humans in the Near East. Neanderthals most likely became extinct as a result of direct competition with the more technologically sophisticated <em>Homo sapiens</em>.</p>
<p>The <a href="http://www.nature.com/news/evidence-mounts-for-interbreeding-bonanza-in-ancient-human-species-1.19394">evidence from DNA</a> shows that there was interbreeding between our species and pre-modern humans, including the Neanderthals and the other enigmatic hominin referred to as the <a href="http://www.nature.com/news/new-dna-analysis-shows-ancient-humans-interbred-with-denisovans-1.11331">Denisovans</a>.</p>
<p>We do not yet know how and when <em>Homo erectus</em> became extinct. It would appear that another unexpected side experiment in hominin evolution, known from the island of Flores and called <a href="https://australianmuseum.net.au/homo-floresiensis"><em>Homo floresiensis</em></a> most likely became extinct sometime after 60,000 years ago.</p>
<p>Indeed this hominin may represent something far more significant than simply an interesting side experiment, with many leading palaeoanthropologists arguing that the Hobbit may represent a <a href="https://www.newscientist.com/article/2128483-mystery-human-hobbit-ancestor-may-have-been-first-out-of-africa/">pre-ergaster migration out of Africa</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-700-000-year-old-fossil-find-shows-the-hobbits-ancestors-were-even-smaller-60192">A 700,000-year-old fossil find shows the Hobbits’ ancestors were even smaller</a>
</strong>
</em>
</p>
<hr>
<h2>What next?</h2>
<p>Even though thousands of hominin fossils have now been recovered and described there is still much work to be done.</p>
<p>Was there a hominin that successfully migrated out of Africa prior to <em>Homo ergaster</em>? Did most of human evolution occur in Africa? Did some important transitions occur outside of Africa?</p>
<p>When did <em>Homo erectus</em> become extinct, and was there genetic exchange between erectus, sapiens and perhaps other hominin species?</p>
<p>As is often the case in science, with the recovery of additional data, in this case fossils and DNA extracted from fossils, we generate more questions than answers.</p>
<p>But ultimately all of this new evidence will result in a far more sophisticated appreciation of not only our evolution, but also the evolution of our extinct fossil cousins.</p><img src="https://counter.theconversation.com/content/54385/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bernard Wood receives funding from National Science Foundation. </span></em></p><p class="fine-print"><em><span>Michael Westaway receives funding from the Australian Research Council. </span></em></p>
The story of where humans come from is growing as new evidence – and new methods of analysis – emerge all the time.
Bernard Wood, University Professor of Human Origins, George Washington University
Michael Westaway, Senior Research Fellow, Australian Research Centre for Human Evolution, Griffith University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/73856
2017-03-24T02:57:13Z
2017-03-24T02:57:13Z
How our species got smarter: through a rush of blood to the head
<figure><img src="https://images.theconversation.com/files/161950/original/image-20170322-16490-uh7ozf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hominin skull casts (L-R) Australopithecus afarensis, Homo habilis, Homo ergaster, Homo erectus, Homo neanderthalensis.
</span> <span class="attribution"><span class="source">Roger Seymour/South Australian Museum</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Anthropologists have been curious about the evolution of human intelligence for many decades. The main lines of research have involved archaeological finds concerning the use of fire, tools and so on.</p>
<p>But what about looking for evidence in fossil skulls, the place where the brain resided? </p>
<p>The volume of the human brain increased to be about three and a half times larger than our <a href="https://www.britannica.com/topic/Australopithecus">Australopithecus</a> ancestors 3 million years ago.</p>
<p>It is generally assumed that intelligence is correlated with brain size, and the reason for this is that the number of nerve cells in mammalian brains seems to be directly related to brain size.</p>
<p>Our <a href="https://doi.org/10.1098/rsos.160305">research</a> focused on the rate of blood flow to the brain, which relates closely to metabolic rate because the blood supplies the essential oxygen. If blood flow to your brain is stopped, you will pass out within seconds. </p>
<p>Normally you have about 7 millilitres of blood flowing to your brain each second. Remarkably, this rate changes little, regardless of whether you are awake, asleep or solving mathematical problems.</p>
<h2>The brain’s plumbing</h2>
<p>The blood flow to the cognitive part of the brain, the cerebrum, comes through two internal carotid arteries, one on the right and one on the left. The size of these arteries is related to the rate of blood flow through them. </p>
<p>Just as a plumber would install larger water pipes to accommodate a higher flow rate to a larger building, the blood circulatory system continually adjusts the sizes of blood vessels to match the rate of blood flow inside them. This in turn is related to the oxygen demand of the organ. </p>
<p>If we can measure the size of the large arteries that supply an organ such as the brain, we can calculate the average rate of blood flow with some accuracy.</p>
<p>This principle has been known for a century and its beauty lies in its simplicity. </p>
<h2>Size matters</h2>
<p>My eureka moment occurred when I realised that the size of an artery can be gauged by the size of the hole in a bone that it passes through.</p>
<p>This meant that the rate of blood flow to the brain could be measured by the sizes of the carotid canals in fossil skulls from human evolution.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/159694/original/image-20170307-20756-agjtj4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/159694/original/image-20170307-20756-agjtj4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/159694/original/image-20170307-20756-agjtj4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=417&fit=crop&dpr=1 600w, https://images.theconversation.com/files/159694/original/image-20170307-20756-agjtj4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=417&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/159694/original/image-20170307-20756-agjtj4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=417&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/159694/original/image-20170307-20756-agjtj4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=524&fit=crop&dpr=1 754w, https://images.theconversation.com/files/159694/original/image-20170307-20756-agjtj4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=524&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/159694/original/image-20170307-20756-agjtj4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=524&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 arrows on the human skull (right) show two internal carotid artery foramina, the size of which indicates the rate of blood flow to the cerebrum.</span>
<span class="attribution"><span class="source">Edward Snelling. Sourced from the Raymond Dart Collection of Human Skeletons, School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>It was a nice idea, but it took the enthusiasm of my student <a href="http://www.flinders.edu.au/people/vanya.bosiocic">Vanya Bosiocic</a> to turn it into a piece of research. She travelled to museums in Australia and in South Africa, gaining access to priceless fossil hominin skulls to make the measurements. </p>
<p>We found that the size of the carotid canals increased much faster than expected from brain size in 12 species of our human ancestors over a period of 3 million years.</p>
<p>While brain size was increasing 3.5 times, blood flow rate surprisingly increased sixfold, from about 1.2ml per second to 7ml per second. </p>
<p>This indicates that our brains are six times as hungry for oxygen as those of our ancestors, presumably because our cognitive ability is greater and therefore more energy-intensive.</p>
<p>Because the number of nerve cells (neurons) in human brains seems to be roughly as expected for a larger primate brain, our discovery implies that the brain’s substance is more active, probably because there are more connections between the neurons. </p>
<p>Each connection, called a synapse, operates to transmit electrical impulses from one cell to another, usually by the release of a chemical substance from one cell that stimulates or inhibits the production of impulses in another cell. </p>
<p>The cycling of the substances between impulses costs a tiny amount of energy. But considering that the brain contains 80 billion nerve cells and each one has thousands of synapses with other cells, the energy cost mounts up. </p>
<h2>The human computer</h2>
<p>The human body allocates 20-25% of its total resting metabolic rate to the brain, compared with 8-10% in other primates and a mere 3-5% in other mammals.</p>
<p>Thus we view the brain as a rather energy-hungry supercomputer. </p>
<p>This analogy with an electrical computer is a good one. The greater a computer’s capacity, the more electrical power is required to keep it running, and the larger the electrical supply cables need to be. </p>
<p>It is the same with the brain. The higher the cognitive function, the higher the metabolic rate, the greater the blood flow and the larger the arteries.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/161931/original/image-20170322-5384-bg8anr.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/161931/original/image-20170322-5384-bg8anr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/161931/original/image-20170322-5384-bg8anr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=428&fit=crop&dpr=1 600w, https://images.theconversation.com/files/161931/original/image-20170322-5384-bg8anr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=428&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/161931/original/image-20170322-5384-bg8anr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=428&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/161931/original/image-20170322-5384-bg8anr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=538&fit=crop&dpr=1 754w, https://images.theconversation.com/files/161931/original/image-20170322-5384-bg8anr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=538&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/161931/original/image-20170322-5384-bg8anr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=538&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Evolution of blood flow to the brains of human ancestors. The data reveal an increasing rate of blood flow among hominin species over 3 million years.</span>
<span class="attribution"><a class="source" href="http://rsos.royalsocietypublishing.org/content/3/8/160305">Royal Society Open Science/Roger Seymour, Vanya Bosiocic, Edward Snelling/Skull illustrations by Vivi Hu.</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The evolution of the human brain is unique among animals. We have looked at the size of the carotid arteries in 34 species of living primates that represent evolution toward the great apes and hominins. </p>
<p>Among these representatives of primate evolution, both body size and brain size increased, but body size increased faster. The blood flow to primate brains increased roughly in proportion to brain size. Only in the hominins do we see that blood flow increased faster than brain size, which indicates that the brain was not only developing in size, but in usage as well. And that shows our ancestors were getting smarter.</p><img src="https://counter.theconversation.com/content/73856/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger S. Seymour receives funding from the Australian Research Council. The results of the research, including this work, are freely available.</span></em></p>
The brains of our ancestors grew larger and smarter thanks to an increase in the flow of blood to the brain
Roger S. Seymour, Professor Emeritus of Physiology, University of Adelaide
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/56922
2016-03-30T19:09:54Z
2016-03-30T19:09:54Z
The ‘hobbits’ were extinct much earlier than first thought
<figure><img src="https://images.theconversation.com/files/116591/original/image-20160329-13698-wxmkqi.jpg?ixlib=rb-1.1.0&rect=454%2C274%2C1523%2C1015&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Excavations in Liang Bua, a limestone cave on the Indonesian island of Flores.</span> <span class="attribution"><span class="source">Smithsonian Digitization Program Office Liang Bua Team</span></span></figcaption></figure><p>New discoveries at the Indonesian cave site of Liang Bua are changing the way we look at the mysterious <em><a href="http://australianmuseum.net.au/homo-floresiensis">Homo floresiensis</a></em> – known as “hobbits” because of their short stature. </p>
<p>We originally believed these hobbits disappeared around 12,000 years ago, but it appears they may have actually died out long before this, around 40,000 years earlier. Research <a href="http://nature.com/articles/doi:10.1038/nature17179">published in Nature today</a> shows they used the cave between 190,000 and 50,000 years ago.</p>
<p>The finding, by ourselves and a team of international researchers, puts the disappearance of <em>Homo floresiensis</em> at around the same time that modern humans (<em><a href="http://australianmuseum.net.au/homo-sapiens-modern-humans">Homo sapiens</a></em>) first spread through the region and reached Australia.</p>
<p>But whether these two species of hominin (primates more closely related to modern humans than to living apes) ever interacted, and our ancestors can be blamed for the hobbits’ demise, remain open questions until direct evidence is found placing modern humans at the scene.</p>
<p>At present, the earliest evidence for modern humans on Flores is just 11,000 years old.</p>
<h2>The discovery</h2>
<p>The <a href="http://news.nationalgeographic.com/news/2004/10/1027_041027_homo_floresiensis.html">original discovery</a> of <em>Homo floresiensis</em> was made back in September 2003, in the fading light of an archaeological excavation on the Indonesian island.</p>
<p>The skeletal remains of this primitive, small-brained and diminutive hominin were found buried six metres below the ground surface at Liang Bua, an impressive limestone cave in the island’s western highlands.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/63119/original/2n4k2jn3-1414551327.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/63119/original/2n4k2jn3-1414551327.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/63119/original/2n4k2jn3-1414551327.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/63119/original/2n4k2jn3-1414551327.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/63119/original/2n4k2jn3-1414551327.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/63119/original/2n4k2jn3-1414551327.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/63119/original/2n4k2jn3-1414551327.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">Thomas Sutikna holds the skull of LB1, the specimen of the ‘Hobbit’, <em>Homo floresiensis</em>.</span>
<span class="attribution"><span class="source">Indonesian National Centre for Archaeology (ARKENAS)/University of Wollongong</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In the same deposits as the remains of this new species were stone artefacts and the remains of pygmy elephant (<em>Stegodon</em>), giant marabou stork, vulture and komodo dragon.</p>
<p>Samples of charcoal and sediment were collected for radiocarbon and luminescence dating. The resulting age estimates of just 18,000 years ago for the <a href="http://museum.wa.gov.au/explore/blogs/museumcollections/what-type-specimen">type specimen</a> – i.e. the specimen that is used to name the species – of the hobbit, known as LB1, sent shock waves through the paleoanthropological community. </p>
<p>Fragmentary remains of other individuals were found in layers then thought to be deposited as recently as 12,000 years ago.</p>
<p>The tiny hominin presented us with puzzles aplenty. It has an appearance most similar to fossil human species that lived in Africa and Asia between one and three million years ago.</p>
<p>So how and when did this species or its ancestors get to this remote island? And how did it apparently manage to survive on Flores for 40,000 years after the first Australians had already passed through this island archipelago?</p>
<p>Elsewhere in the world, first contact of a native fauna with modern humans usually ends badly for the endemic animals. Not so, it seemed, with the hardy hobbits.</p>
<h2>Further digging</h2>
<p>The revision in the last-appearance age for <em>Homo floresiensis</em> is the culmination of eight further years of painstaking excavation and study of the cave deposits at Liang Bua by many of the same researchers involved in the original discovery.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/116702/original/image-20160330-28443-oh4p61.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/116702/original/image-20160330-28443-oh4p61.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/116702/original/image-20160330-28443-oh4p61.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/116702/original/image-20160330-28443-oh4p61.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/116702/original/image-20160330-28443-oh4p61.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/116702/original/image-20160330-28443-oh4p61.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/116702/original/image-20160330-28443-oh4p61.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/116702/original/image-20160330-28443-oh4p61.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">Archaeological excavations of deposits at Liang Bua.</span>
<span class="attribution"><span class="source">Liang Bua Team</span></span>
</figcaption>
</figure>
<p>The key breakthrough has been the recognition of a major break in the deposit of the sedimentary layers – a “stratigraphic unconformity” – immediately above LB1 as a result of one or more erosional events in the past.</p>
<p>As the excavations were extended each year, it became increasingly clear that all of the skeletal remains of <em>Homo floresiensis</em>, and the stone tools made by the hobbits, came from a large remnant pedestal of deposit that accumulated between 190,000 and 50,000 years ago.</p>
<p>At the location of LB1, the hobbit-bearing deposits are truncated by a steeply sloping surface, which is capped by sediments that accumulated only in the last 20,000 years. It was those sediments that had been inadvertently dated in the original study.</p>
<p>We now know that the stratigraphic sequence at Liang Bua is far more complex than had originally been thought. So, can we be confident in our new interpretation of the stratigraphy and chronology for the home of the hobbit? We think so.</p>
<p>By excavating more of the cave deposits in the past decade, we have added many new pieces to the jigsaw puzzle of how the site has formed. This results in a vastly improved picture of what was deposited where, when and how in the cave.</p>
<p>We have also used a range of new dating techniques, some of which were not available in 2003. As with technical developments in other fields of science, such as ancient DNA, time has also marched on with improvements to geochronology methods.</p>
<p>For example, the bones of LB1 and two other hobbits were dated using the latest uranium-series methods, while the associated sediments were dated using infrared stimulated luminescence procedures that were developed only in 2011.</p>
<p>These and other dating techniques, including radiocarbon, thermoluminescence and argon dating, provide a new, more robust chronology for Liang Bua and the prehistoric hominins that used this cave in the past.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/116705/original/image-20160330-28443-1bc0iim.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/116705/original/image-20160330-28443-1bc0iim.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/116705/original/image-20160330-28443-1bc0iim.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=262&fit=crop&dpr=1 600w, https://images.theconversation.com/files/116705/original/image-20160330-28443-1bc0iim.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=262&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/116705/original/image-20160330-28443-1bc0iim.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=262&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/116705/original/image-20160330-28443-1bc0iim.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=330&fit=crop&dpr=1 754w, https://images.theconversation.com/files/116705/original/image-20160330-28443-1bc0iim.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=330&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/116705/original/image-20160330-28443-1bc0iim.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=330&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Liang Bua, a limestone cave on the Indonesian island of Flores.</span>
<span class="attribution"><span class="source">Liang Bua Team</span></span>
</figcaption>
</figure>
<h2>What next for the hobbit?</h2>
<p>There are still many chapters of hobbit history to be written. </p>
<p>When did the ancestors of <em>Homo floresiensis</em> first arrive on Flores and what did they look like? When did hobbits finally go extinct, and did modern humans play any role in their downfall?</p>
<p>Liang Bua still holds many secrets, but a single site can provide only a snapshot in time.</p>
<p>So the search is on for more hobbit sites, spanning a wider geographic area, both on Flores and elsewhere in the Indonesian archipelago. A decade from now, we hope to have found many more pieces of this prehistoric puzzle in human evolution.</p><img src="https://counter.theconversation.com/content/56922/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Thomas Sutikna receives funding from Waitt Foundation/National Geographic Society.</span></em></p><p class="fine-print"><em><span>Matthew Tocheri receives and/or has received funding from the Canada Research Chair Program, the Peter Buck Fund for Human Origins Research, the Smithsonian’s Human Origins Program, the Waitt Foundation/National Geographic Society, the Smithsonian Scholarly Studies Program, the Wenner-Gren Foundation, the Leakey Foundation, the National Science Foundation (USA), and the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Richard 'Bert' Roberts receives funding from the Australian Research Council.</span></em></p>
New excavations at an Indonesian cave have pushed back the time the ‘hobbits’ disappeared to about 50,000 years ago.
Thomas Sutikna, PhD candidate in archaeological science, University of Wollongong
Matthew Tocheri, Canada Research Chair in Human Origins, Lakehead University
Richard 'Bert' Roberts, ARC Australian Laureate Fellow, University of Wollongong
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/47081
2015-09-07T04:07:27Z
2015-09-07T04:07:27Z
What the use of ochre tells us about the capabilities of our African ancestry
<figure><img src="https://images.theconversation.com/files/93984/original/image-20150906-14625-19q8v1x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ochre is still used throughout parts of Africa as a form of sunscreen. Its uses go back 285,000 years. </span> <span class="attribution"><span class="source">Supplied</span></span></figcaption></figure><p>The use of <a href="https://www.academia.edu/12090780/Ochre_use_at_Sibudu_Cave_and_its_link_to_complex_cognition_in_the_Middle_Stone_Age">ochre</a> dates to the <a href="http://humanorigins.si.edu/evidence/behavior/tools/middle-tools">Middle Stone Age</a> and <a href="http://archaeology.about.com/od/mterms/qt/middle_paleolit.htm">Middle Palaeolithic</a>. The earliest evidence of its use in Africa dates 285 000 years.</p>
<p>In Africa, ochre is used for protection from the sun and as a barrier from insects such as mosquitos. It has also been scientifically proven to inhibit the effects of UV radiation. There are many other uses. </p>
<p><a href="http://archaeology.about.com/od/oterms/qt/Ochre.htm">Ochre</a> is an umbrella term for a range of earthy, iron-rich rocks composed of iron oxides or oxyhydroxides, such as shales, sandstones, mudstones and specularite. </p>
<h2>Why the fuss</h2>
<p>Ochre appears in the archaeological record around the same time as anatomically modern humans. Its use became more frequent from about 100,000 years ago at many Middle Stone Age sites. </p>
<p>At the same time, we find other significant developments in the material culture, such as new tool technologies and the use of a wide range of raw materials. Consequently, ochre is often seen as an indicator of “modern human behaviour” and cognitive development through its use as an indicator of symbolic behaviour. </p>
<p>This is reinforced by the preferential use of bright red ochre and ochre powder, as well as the deliberate engraving of ochre. Therefore, archaeological studies of the use of ochre can give fresh insights into the cognitive development of our early ancestors.</p>
<h2>Past and present uses of ochre</h2>
<p>Current and ethnographic uses of ochre have influenced interpretations of how it was used in the Middle and Later Stone Age. This must be done with caution because ochre has many different uses and we cannot assume that it was used in the same way in the past as it is today. Nevertheless, a great deal is now known about the properties of ochre. Here are some of its confirmed uses:</p>
<ul>
<li><p>Ochre is used as an adhesive. Its powder is an effective aggregate in resin adhesives to mount tools onto handles or <a href="http://www.pnas.org/content/106/24/9590.full">shafts</a>. Evidence of it being used in this way is found in the <a href="http://www.sciencedirect.com/science/article/pii/S1040618212001140">Middle Stone Age</a>. </p></li>
<li><p>It was also used to tan hide. Ochre has anti-bacterial qualities which prevent the breakdown of collagen. This helps <a href="http://www.researchgate.net/profile/Riaan_Rifkin/publication/257944765_Assessing_the_efficacy_of_red_ochre_as_a_prehistoric_hide-tanning_ingredient/links/0deec5266bd1158551000000.pdf">preserve hides</a>. There is no direct evidence of its use as a hide tanning substance in the Middle Stone Age as no hides are preserved. But <a href="http://www.sciencedirect.com/science/article/pii/S0305440310002761">traces</a> on the ochre pieces indicate that some pieces were rubbed on <a href="http://www.eva.mpg.de/evolution/pdf/Soressi%20et%20D'errico%202007%20in%20Vandermeersch%20et%20Maureille.pdf">soft materials</a>. </p></li>
<li><p>It is more commonly known for protection from the sun protection. Ochre-based pastes has been used as protection from the sun as well as a barrier from insects like <a href="http://www.researchgate.net/profile/Riaan_Rifkin/publication/264623585_Ethnographic_and_experimental_perspectives_on_the_efficacy_of_red_ochre_as_a_mosquito_repellent/links/559d2dd208ae76bed0bad645.pdf">mosquitos</a>. It has been scientifically proven to inhibit the effects of <a href="http://www.sajs.co.za/sites/default/files/publications/pdf/Rifkin_Research%20Article_0.pdf">ultra-violet radiation</a>. It is still used as a sunscreen today, for example, by the Ovahimba in Namibia. </p></li>
<li><p>Ochre pigments were, and still are, widely used in paint and artwork. Many of the red and yellow pigments in rock art panels around the world are made with ochre-based paints. There is limited evidence for the creation of ochre paint in the Middle Stone Age, but 30,000 years ago its use as a <a href="http://www.sciencemag.org/content/334/6053/219.full">paint</a> was established.</p></li>
</ul>
<h2>Connecting the dots</h2>
<p>Links between the visible uses of ochre and cognition have not been clearly defined. To reconstruct the technology and processes involved in using ochre, it is important to understand the physical and chemical qualities of this material, whether as pieces or in powdered form. It is then possible to conclude whether ochre was used in the same way in the ancient past as it was in the recent past.</p>
<p>The main ways that ochre was used in the Middle Stone Age was by grinding pieces on coarse sandstone slab to create powder, scoring (or engraving) pieces with sharp tools, or rubbing ochre on soft surfaces, such as animal hide or human skin. </p>
<p>Grinding, to create a powder, is the most common use trace on Middle Stone Age ochre pieces. Red ochre appears to be preferentially ground at many Middle Stone Age sites implying that bright red powder was desired. Additionally, ochre powder has been found on various archaeological artefacts in this period such as stone tools, grindstones, perforated shell beads and bone tools. </p>
<p>The construction of thought-and-action cognitive sequences for activities involving the use of ochre has helped to reconstruct which actions require enhanced cognitive functions.</p>
<p>To model these sequences, each activity performed with ochre <a href="http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9398689&fileId=S0959774314000663">must be considered</a> – from collection, to possible modification by heat, to use with other tools, to discard.</p>
<p>By reconstructing the series of actions we can look at the <a href="http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8589664&fileId=S095977431200025X">cognitive requirements</a> needed to perform them, such as problem solving abilities, the need to switch attention between two concurrent activities, long range planning and response inhibition.</p>
<p>The requirement for cognitively complex abilities in some of the ochre-related activities in the Middle Stone Age suggests that the people living then had the advanced mental capabilities of people today. Ochre use could be a proxy for cognitive capabilities, and can therefore shed light on the evolution of the modern mind.</p>
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<p><em>This article is based on a submission by the author to the <a href="http://journals.cambridge.org/abstract_S0959774314000663">Cambridge Archaeological Journal</a>.</em></p><img src="https://counter.theconversation.com/content/47081/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tammy Reynard receives funding from The Centre of Excellence in Palaeosciences (CoE_PAL), The National Research Foundation (NRF), The Palaeontological Scientific Trust (PAST) and The Mellon Fondation.</span></em></p>
Ochre has many uses. It can be used to shed information on the evolution of the modern mind.
Tammy Hodgskiss, Postdoctoral Fellow, Evolutionary Studies Institute, University of the Witwatersrand
Licensed as Creative Commons – attribution, no derivatives.