tag:theconversation.com,2011:/uk/topics/homo-erectus-9204/articlesHomo erectus – The Conversation2023-01-25T11:39:11Ztag:theconversation.com,2011:article/1963982023-01-25T11:39:11Z2023-01-25T11:39:11ZLarge mammals shaped the evolution of humans: here’s why it happened in Africa<p>That humans originated in Africa is <a href="https://www.sciencedaily.com/releases/2007/05/070509161829.htm">widely accepted</a>. But it’s not generally recognised how unique features of Africa’s ecology were responsible for the crucial evolutionary transitions from forest-inhabiting fruit-eater to savanna-dwelling hunter. These were founded on earth movements and aided physically by Africa’s seasonal aridity, bedrock-derived soils and absence of barriers to movements between north and south. </p>
<p>These features promoted extensive savanna grasslands marked by erratic rainfall, regular fires and abundant numbers of diverse grazing and browsing animals. </p>
<p>My lifelong studies have focused on the ecology of Africa’s large herbivores and their effects on savanna vegetation. In my <a href="https://www.cambridge.org/za/academic/subjects/life-sciences/evolutionary-biology/only-africa-ecology-human-evolution">recent book</a>, by linking pre-existing threads together for the first time, I explain how distinctive features of these animals’ ecology, founded on Africa’s physical geography, enabled the adaptive changes that led ultimately to modern humans.</p>
<p>What emerges is the realisation that this amazing evolutionary transformation could only have occurred in Africa. This recognition emphasises the deep cultural legacy formed by Africa’s large mammal heritage for all of humankind.</p>
<h2>Ape-men</h2>
<p>Starting during the late Miocene, around 10 million years ago, a plume of molten magma, hot liquid material from deep inside the Earth, pushed eastern parts of Africa upward. This led to rifting of the Earth’s crust, volcanic eruptions and soils enriched in mineral nutrients from the lava and ash. Grassy savannas spread and animals adapted increasingly to graze this vegetation component. Apes from that time were forced to spend less time up in trees and more time walking upright on two legs. </p>
<p>Progressive reductions in rainfall, restricting plant growth and worsening dry season aridity, forced the early ape-men, (<a href="https://www.nature.com/scitable/knowledge/library/australopithecus-and-kin-145077614/"><em>Australopithecines</em></a>), to change their diet. They went from eating mainly fruits from forest trees to consuming underground bulbs and tubers found between the widely spaced trees. These were tough to extract and chew. </p>
<p>This led to the emergence through evolution of the genus <a href="https://www.maropeng.co.za/content/page/paranthropus"><em>Paranthropus</em></a> (colloquially “nutcracker man”), characterised by huge jaws and teeth. By about a million years ago they were gone. Apparently, the effort of extracting and processing these well-defended plant parts became too formidable. </p>
<h2><em>Homo habilis</em></h2>
<p>Around 2.8 million years ago, another lineage split off from the australopithecines, reversing the trend towards robust dentition. This lineage used stones chipped to serve as tools. These were used to scrape flesh from carcasses of animals killed by carnivores, and crack open long bones for their marrow content. This transition in ecology was sufficiently momentous to warrant a new generic name: <em>Homo</em>, specifically <em>habilis</em> (“handy-man”). </p>
<p>These first humans thus became scavengers on animal left-overs. They most probably exploited a time window around midday when the killers – mainly sabre-tooth cats – were resting, before hyenas arrived nocturnally to devour the leftovers. Walking upright freed their arms to carry bones away to be processed in safe sites to augment the plant-based dietary staples. </p>
<p>To facilitate such midday movements, <em>Homo habilis</em> lost its body hair; this made it possible for them <a href="https://www.nature.com/articles/nature03052">to be active</a> under conditions when fur-covered animals would soon over-heat. </p>
<h2><em>Homo erectus</em></h2>
<p>Several hundred thousand years of progressive advancements in upright walking and brain capacity led to the next major adaptive shift, exemplified by improvements in the design of stone tools. Stone cores became shaped on both sides to aid the processing of animal carcasses.</p>
<p>This led to the emergence of <a href="https://humanorigins.si.edu/evidence/human-fossils/species/homo-erectus"><em>Homo erectus</em></a> around 1.8 million years ago. These early humans had become efficient hunters. Consequently, meat and bones became reliable food resources year-round. </p>
<p>A division of labour came about. Men hunted; women gathered plant parts. This required a home base and more elaborate forms of communication about planned excursions, laying the foundations for language. </p>
<h2><em>Homo sapiens</em></h2>
<p>After 800,000 years ago, fluctuations in heat and aridity became more extreme in Africa. Finely crafted stone tools defined the transition into the Middle Stone Age, coupled with the emergence of modern <em>Homo sapiens</em> in Africa around 300 thousand years ago.</p>
<p>But despite its hunting prowess <em>Homo sapiens</em> had declined to precarious numbers in Africa by around 130,000 years ago, following an especially severe ice age. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2945812/">Genetic evidence indicates</a> that the entire human population across the continent shrank to fewer than 40,000 individuals, spread thinly from Morocco in the north to the Cape in the far south. </p>
<p>One remnant survived by inhabiting caves along the southern Cape coast, exploiting marine resources. This reliable food source fostered further advances in tool technology, and even the earliest art. </p>
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<p>The use of bows and arrows as weapons, along with spears, probably contributed crucially to the expansion of humans beyond Africa around 60,000 years ago. They spread onward through Asia and into Europe, displacing the Neanderthals. </p>
<h2>Only in Africa</h2>
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<img alt="A herd of large brown wildebeest is spread out across a grassy landscape, chewing the grass" src="https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505536/original/file-20230120-24-vwc5k1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Wildebeest grazing on the Serengeti Plains in Tanzania.</span>
<span class="attribution"><span class="source">Norman Owen-Smith</span></span>
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<p>As outlined in my book, it was the abundance specifically of medium and large grazers in fertile savannas, concentrated near water in the dry season, that enabled the evolutionary transformation of a relatively puny ape into a feared hunter in Africa.</p>
<p>Africa’s high-lying interior plateau generated the seasonal dryness that restricted plant growth through its eastern and southern regions. Widespread volcanically derived soils were sufficiently fertile to foster the spread of medium-large grazers adapted to digest dry grass efficiently.</p>
<p>These especially abundant herbivores crowded around remaining waterholes, providing sufficient remnants of flesh and marrow to make scavenging a reliable means to overcome shortages of edible plant parts during the dry season. The increased dependence on meat to supplement a plant-based diet led to social coordination between male hunters and female gatherers, which in turn promoted advances in communication and tool technology supported by expanding cranial capacity. </p>
<p>If Africa had remained largely low-lying and leached of nutrients like most of South America and Australia, this would not have been possible.</p>
<p>Africa’s mobile grazers, such as wildebeest, are currently <a href="https://www.science.org/doi/10.1126/science.aay3049">being squeezed out of their sanctuaries</a> by expanding human settlements. These animals represent a global cultural heritage, having being pivotal to our evolutionary origins. We must ensure that sufficient space remains in Africa to enable their persistence despite burgeoning human populations.</p><img src="https://counter.theconversation.com/content/196398/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Norman Owen-Smith previously received funding from Sough Africa's National Research Foundation</span></em></p>Africa’s large mammal heritage has formed a deep cultural legacy for all of humankind.Norman Owen-Smith, Emeritus Research Professor of African Ecology, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1696472021-11-02T14:41:05Z2021-11-02T14:41:05ZOur North African ancestors were making handaxes earlier than previously thought<figure><img src="https://images.theconversation.com/files/428189/original/file-20211025-23-1jka6de.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Handaxes, as seen in the top row, were common to this period; the tools seen in the bottom row appear to be unique to this site.</span> <span class="attribution"><span class="source">Rosalia Gallotti</span></span></figcaption></figure><p>More than 1.5 million years ago, a new era dawned for our human ancestors, <em>Homo erectus</em>: the <a href="https://www.britannica.com/topic/Acheulean-industry">Acheulean culture</a>. This period was marked by the ability to produce large cutting tools, mainly <a href="https://www.thoughtco.com/acheulean-handaxe-first-tool-171238">handaxes</a>, manufactured using different kinds of rocks and used for a variety of activities.</p>
<p>These tools were all longer or wider than 10 cm and clearly shaped for different purposes. The previous “culture” – referring here to an archaeological industry – was the <a href="https://link.springer.com/referenceworkentry/10.1007%2F978-1-4419-0465-2_652">Oldowan</a>, which dated from 2.6 million years ago up until at least 1.7 million years ago. Oldowan tools were small and medium-sized <a href="https://www.britannica.com/technology/flake-tool">flakes</a>, detached from a cobble or a block of raw material.</p>
<p>The Acheulean is considered a turning point in human evolution. That’s because it marked a new level of technological complexity linked to the appearance of <em>Homo erectus</em>, who become able to sculpt a block of stone to shape large objects with one or more standardised characteristics, such as a pointed form. This innovative skill first emerged on the African continent between 1.8 million and 1.6 million years ago, in <a href="https://www.theguardian.com/science/2011/aug/31/hand-axes-oldest-advanced-stone-tools">East Africa</a>. It appears to have reached South Africa somewhere between 1.6 million and 1 million years ago.</p>
<p>Until now, it’s not been clear when the Acheulean appeared in North Africa; estimates have suggested it was around 1 million years ago. <a href="https://www.nature.com/articles/s41598-021-94695-3">Our research</a>, conducted at an archaeological site called Thomas Quarry I in Casablanca, Morocco, changes this. We used the latest technologies in geology and dating methods to establish that the Acheulean likely first appeared in North Africa around 1.3 million years ago.</p>
<p>This is important information. It adds to scientists’ understanding of when <em>Homo erectus</em> spread across the African continent from its homeland (East Africa) and which cognitive and technological level allowed the species to disperse.</p>
<h2>Technological advances</h2>
<p>Two main Acheulean sites have been discovered in North Africa. One is <a href="https://www.britannica.com/place/Ternifine">Tighennif</a>, near Mascara in Algeria. Thomas Quarry I (and specifically its unit L in the lower part of the stratigraphic sequence) is the other. Stone artefacts at both sites had been dated back to about 1 million years ago before our research.</p>
<p>Thomas Quarry I was one of several quarries opened in Casablanca at the dawn of the 20th century. They were to be used as construction sites, but it soon became apparent that Thomas Quarry I represented an exceptional geological, palaeontological and archaeological heritage. It became globally famous in 1969 thanks to <a href="https://www.researchgate.net/publication/40754310_Hominid_Cave_at_Thomas_Quarry_I_Casablanca_Morocco_recent_findings_and_their_context">the discovery</a> of a human fossil dating to the Middle Pleistocene, about 500 000 years ago.</p>
<p>Since 1978, a joint Morocco-France research programme, “Préhistoire de Casablanca” has led to many more discoveries. In 1985, the first evidence of early Acheulean industry was found in two archaeological layers of Unit L. </p>
<p>First analyses suggested an age for this evidence of around 1 million years old. Since then, technology has advanced a great deal and our interdisciplinary team composed of Moroccan, French, and Italian scientists was able to use various approaches to pinpoint the site’s age.</p>
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<img alt="" src="https://images.theconversation.com/files/425675/original/file-20211011-25-m2zhv9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/425675/original/file-20211011-25-m2zhv9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/425675/original/file-20211011-25-m2zhv9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/425675/original/file-20211011-25-m2zhv9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/425675/original/file-20211011-25-m2zhv9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/425675/original/file-20211011-25-m2zhv9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/425675/original/file-20211011-25-m2zhv9.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">
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<span class="caption">The Thomas Quarry I site in Casablanca, Morocco.</span>
<span class="attribution"><span class="source">Jean-Paul Raynal</span></span>
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<p>We used two main kinds of technology in our work. One was <a href="http://quaternary.stratigraphy.org/stratigraphic-guide/magnetostratigraphy/">magnetostratigraphy</a>, which registers the polarity of the Earth’s magnetic field at the time a stratum was deposited. This process dated our research area, Unit L, at more than 1 million years ago. We also geochemically analysed the sediments to see when they were first deposited, which is a good way to refine the age model. This approach generated two sets of dates: either between 1.3 and 1.35 million years ago, or between 1.29 and 1.23 million years ago.</p>
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Read more:
<a href="https://theconversation.com/finds-in-tanzanias-olduvai-gorge-reveal-how-ancient-humans-adapted-to-change-150755">Finds in Tanzania's Olduvai Gorge reveal how ancient humans adapted to change</a>
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<p>By combining and analysing all our data, we were able to propose an average age of 1.3 million years ago for the site. This, we believe, is when the Acheulean had already appeared in North Africa.</p>
<h2>Technical know-how</h2>
<p>Another exciting element of our work was ascertaining how <em>Homo erectus</em> diversified their tool-making practices in different parts of Africa. Around 5,000 artefacts have been found in Thomas Quarry I’s Unit L, among the largest collections from the epoch. </p>
<p>Most of the tools are of quartzite, a rock largely abundant in the Casablanca cobble beaches; there are large handaxes and picks, as well as cleavers (though these are rare). These share several technological traits with their East African counterparts and are rather typical of the early stages of the Acheulean.</p>
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Read more:
<a href="https://theconversation.com/archaeology-in-west-africa-could-rewrite-the-textbooks-on-human-evolution-157610">Archaeology in West Africa could rewrite the textbooks on human evolution</a>
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<p>But there’s a technical process that is, as far as we can tell, unique to the North African site. In parallel with large cutting tools, knapping (the process of breaking or chipping flint and other kinds of stone) produced micro tools of flint such as <a href="https://www.nature.com/articles/s41598-020-65903-3">very small elongated flakes using the bipolar-on-anvil technique</a> – using a hammer to strike a cobble, which is positioned on a stationary anvil. </p>
<p><a href="https://texasbeyondhistory.net/varga/images/use.html">Use-wear analysis</a> to understand their use is underway. Our hypothesis is that these micro tools with a very sharp cutting edge like that of flint were used for extreme precision works. However, such technology is unexpected for these ancient periods, especially in an Acheulean context typically characterised by the production of large cutting tools rather than by micro-tools like this one. </p>
<p>It demonstrates that <em>Homo erectus</em> had the technical know-how to create new solutions when the need arose. They weren’t just making tools: they knew how to diversify their tools as necessary.</p><img src="https://counter.theconversation.com/content/169647/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The study of ThI-L is part of the Préhistoire de Casablanca joint program led and supported by the Institut National des Sciences de l’Archéologie et du Patrimoine (INSAP) of the Ministère de la Jeunesse, de la Culture et de la Communication/Département de la Culture of the Kingdom of Morocco, the Ministère de l’Europe et des Affaires Étrangères of France within the framework of the Mission archéologique Littoral-Maroc and the Laboratoire d’Excellence Archimède - Programme Investir l’Avenir ANR-11-LABX-0032-01 – through the Origines project. It is also financially supported by the Department of Human Evolution of the Max Planck Institute for Evolutionary Anthropology in Leipzig (Germany) and the Région Aquitaine through the Origines projects. Magnetostratigraphic analyses are supported by the Ministero dell’Istruzione, dell’Università e della Ricerca of Italy, through the project ‘Dipartimenti di Eccellenza 2018–2022’ awarded to the Dipartimento di Scienze della Terra “A. Desio” of the Università di Milano.
</span></em></p>Knowing that our North African ancestors were making handaxes helps scientists to understand how our human ancestors spread across the African continent.Rosalia Gallotti, Researcher of Prehistoric Archaeology, Université Paul Valéry – Montpellier IIILicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1655162021-11-01T12:25:40Z2021-11-01T12:25:40ZWhen and how was walking invented?<figure><img src="https://images.theconversation.com/files/425087/original/file-20211006-27-14gw1jh.jpeg?ixlib=rb-1.1.0&rect=9%2C9%2C2113%2C1712&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Three upright walkers, including Lucy (center) and two specimens of *Australopithecus sediba*, a human ancestor from South Africa dating back nearly 2 million years.</span> <span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/6/6e/Australopithecus_sediba_and_Lucy.jpg">Image compiled by Peter Schmid and courtesy of Lee R. Berger/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><figure class="align-left ">
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<p><em>Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>.</em></p>
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<p><strong>When and how was walking invented? — Rayssa, 11, Newark, New Jersey</strong></p>
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<p>This is an important question because many anthropologists see bipedalism – which means walking on two legs – as one of the defining characteristics of “hominins,” or modern humans, and their ancestors. It is difficult to give a simple answer, though, because bipedalism did not just appear one day. It went through a gradual evolution that began <a href="https://www.smithsonianmag.com/science-nature/becoming-human-the-evolution-of-walking-upright-13837658/">many millions of years ago</a>. </p>
<p>Of course there are no video clips of the first person ever walking upright. So how do scientists try to answer questions about how people moved in the very ancient past? Luckily, the shape of a creature’s bones and the way they fit together can tell the story of how that body moved when it was alive. And anthropologists can find other evidence in the landscape that indicates how ancient people walked.</p>
<p>In 1994, the first fossils of an unknown hominin were found in Ethiopia. The anthropologists who found the remains called the new discovery, an adult female individual, <em>Ardipithecus ramidus</em>, nicknamed “Ardi.” Over the next 10 years, more than 100 fossils from Ardi’s species were found and dated to between <a href="https://humanorigins.si.edu/evidence/human-fossils/species/ardipithecus-ramidus">4.2 million and 4.4 million years old</a>.</p>
<p>When scientists examined this collection of bones, they identified certain characteristics that indicated bipedalism. The foot, for example, had a structure that allowed the kind of toe push-off that we have today, which four-legged apes do not have. The shape of the pelvic bones, how the legs were positioned under the pelvis and how the leg bones fit together all suggested upright walking too. It may be that Ardi did not walk exactly as we do today, but bipedalism as the normal way of movement does seem to be characteristic of these fossils from <a href="https://doi.org/10.1073/pnas.1403659111">as early as 4.4 million years ago</a>. </p>
<p>Anthropologists had already found the nearly 40%-complete skeleton of a hominin species that lived about <a href="https://www.nationalgeographic.org/thisday/nov24/lucy-discovered-africa/">a million years after Ardi</a>, also in Ethiopia. Because of its similarity to other fossils found in southern and eastern Africa, they called it <em>Australopithecus afarensis</em>, which in Latin means “southern ape from the afar region.” This individual was female, so they nicknamed it “Lucy” after a song by the Beatles that was popular at the time. </p>
<p>Many more fossils from this species – more than 300 individuals – have been added to the group, and today researchers know quite a lot about Lucy and her relatives. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/425079/original/file-20211006-13-cagg43.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up image of face of a model based on Lucy and other _A. afarensis_ fossils" src="https://images.theconversation.com/files/425079/original/file-20211006-13-cagg43.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/425079/original/file-20211006-13-cagg43.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=655&fit=crop&dpr=1 600w, https://images.theconversation.com/files/425079/original/file-20211006-13-cagg43.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=655&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/425079/original/file-20211006-13-cagg43.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=655&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/425079/original/file-20211006-13-cagg43.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=823&fit=crop&dpr=1 754w, https://images.theconversation.com/files/425079/original/file-20211006-13-cagg43.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=823&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/425079/original/file-20211006-13-cagg43.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=823&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An image of a model based on Lucy and other <em>Australopithecus afarensis</em> skeleton fossils found in East Africa in 1974.</span>
<span class="attribution"><a class="source" href="https://media.nationalgeographic.org/assets/photos/000/346/34648_r646x705.jpg?3b599dbcd9a917b42bcb750283a52c57221d8012">Smithsonian</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Lucy had a partial but well-preserved pelvis, which was how anthropologists knew she was female. The pelvis and upper leg bones fit together in a way that showed <a href="https://www.nhm.ac.uk/discover/australopithecus-afarensis-lucy-species.html">she walked upright on two legs</a>. No feet bones were preserved, but later discoveries of <em>A. afarensis</em> do include feet and indicate bipedal walking as well.</p>
<p>In addition to fossil remains, scientists found <a href="https://doi.org/10.7554/eLife.19568">other remarkable evidence</a> for how Lucy’s species moved at the Laetoli site in Tanzania. Beneath a layer of volcanic ash dating to 3.6 million years ago, anthropologists found fossilized footprints in what had once been a wet surface of volcanic ash. The tracks go along for almost 100 feet, and 70 individual prints indicate the presence of at least three individuals walking upright on two feet. Given the presumed age, the makers were likely <em>Australopithecus afarensis</em>. </p>
<p>The tracks prove that these hominins walked on two legs, but the gait seems to be a bit different from ours today. Still, Laetoli provides <a href="https://humanorigins.si.edu/evidence/behavior/footprints/laetoli-footprint-trails">solid evidence for bipedalism</a> 3.5 million years ago.</p>
<p>A hominin whose anatomy was so like our own that we can say it walked as we do did not appear in Africa until 1.8 million years ago. <em>Homo erectus</em> was the first to have the long legs and shorter arms that would have made it possible to walk, run and <a href="https://humanorigins.si.edu/evidence/human-fossils/species/homo-erectus">move about Earth’s landscapes as we do today</a>. <em>Homo erectus</em> also had a much larger brain than did earlier bipedal hominins and made and used stone tools <a href="https://www.thoughtco.com/acheulean-tradition-169924">called Acheulean implements</a>. Anthropologists consider <em>Homo erectus</em> our close relative and an early member of our own genus, <em>Homo</em>.</p>
<p>So, as you can see, human walking took a very long time to develop. It appeared in Africa more than 4.4 million years ago, long before tool-making appeared.</p>
<p>Why did hominins walk upright? Perhaps it allowed them to see predators more easily, or to run faster, or maybe the environment changed and there were fewer trees to climb as earlier hominins did. </p>
<p>In any case, humans and their ancestors began to walk very early in their evolutionary history. Even though bipedalism came before tool-making, an upright posture freed the hands to make and use tools, which ultimately became one of the hallmarks of humans like us.</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/165516/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jan Simek has received funding from the LSB Leakey Foundation, the NSF, the Wenner-Gren Foundation and the National Geographic Society.</span></em></p>Walking has taken a very long time to develop, with evidence of bipedalism among early humans in Africa roughly 4.4 million years ago.Jan Simek, Professor of Anthropology, University of TennesseeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1350682020-04-03T04:52:43Z2020-04-03T04:52:43ZFossil find suggests ‘Homo erectus’ emerged 200,000 years earlier than thought<figure><img src="https://images.theconversation.com/files/323928/original/file-20200330-146712-1hwtgkd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The ~2 Ma Homo erectus cranium, DNH 134, from the Drimolen Fossil Hominin site.</span> <span class="attribution"><span class="source">Matthew V. Caruana</span></span></figcaption></figure><p>The <a href="https://www.britannica.com/science/human-evolution">human evolutionary path</a> is complicated. It’s almost impossible to say exactly when we modern humans became “us”. This quandary is best articulated by the famous naturalist Charles Darwin in his book <a href="https://www.bl.uk/collection-items/the-descent-of-man-by-darwin#">The Descent of Man</a>:</p>
<blockquote>
<p>In a series of forms graduating insensibly from some apelike creature to man as he now exists, it would be impossible to fix on any definite point where the term ‘man’ ought to be used.</p>
</blockquote>
<p>The understanding of modern humans’ own genus, <em>Homo</em>, has taken many turns over the last century. <em>Homo erectus</em>, one of our purported ancestors, was first discovered in Indonesia in 1891 by geologist and anatomist <a href="https://www.britannica.com/biography/Eugene-Dubois">Eugene Dubois</a>. Since then, representatives of both this species, and other <em>Homo</em>, have been found across the world; for instance, in 2015, a new species of <em>Homo</em>, <em>Homo naledi</em>, <a href="https://elifesciences.org/articles/09560">was discovered</a> in South Africa. Another new <em>Homo</em> species, <em>Homo luzonensis</em>, <a href="https://www.nature.com/articles/s41586-019-1067-9?fbclid=IwAR2oxCjrx06YGwYx8B7JjfvlAzES9Y28ZOMCUL-4JxS6zKAmryu6qNti4Ds">was found</a> more recently in the Philippines in 2019.</p>
<p>These discoveries, combined, have led scientists to set <em>Homo erectus</em>‘ emergence at about 1.8 million years ago – with the oldest known record coming from <a href="https://www.pnas.org/content/108/26/10432.short">Dmanisi, Georgia</a> and an important slightly later record from the <a href="https://advances.sciencemag.org/content/6/10/eaaw4694?utm_source=TrendMD&utm_medium=cpc&utm_campaign=TrendMD_1">East African Rift valley</a>. </p>
<p>But our new discovery in South Africa’s Cradle of Humankind, which has just been <a href="https://science.sciencemag.org/content/368/6486/eaaw7293">published in Science</a>, suggests that <em>Homo erectus</em> actually emerged 200 000 years earlier than we thought. We were part of a team from South Africa, Australia, Italy and the US that discovered a <em>Homo erectus</em> cranium which has since been dated to almost 2 million years ago. </p>
<p>This is a hugely important find. It reasserts that <em>Homo erectus’</em> origins are in Africa, not Asia. Our discovery suggests, though, that <em>Homo erectus</em> likely did not evolve in eastern Africa as so often thought but perhaps somewhere else in Africa, or potentially in South Africa itself. </p>
<p>More evidence is needed before firm conclusions can be reached, of course. But the South African find means that the <a href="http://www.kigelia.org/sitowebdrimolen/en/drimolen.html">Drimolen fossil site</a> – where we made the discovery – could represent an important shift in the simple narrative that all early species of human ancestry are East African.</p>
<h2>A critical discovery</h2>
<p>The Drimolen Fossil Hominin site in the Cradle of Humankind, northwest of Johannesburg, has been excavated since its discovery in 1992. The site is best known for its <em><a href="https://www.semanticscholar.org/paper/The-Drimolen-skull%3A-the-most-complete-cranium-and-Keyser/412396a186415423acd258989bedd33e58bb59a7/figure/0">Paranthropus robustus</a></em>, another ancient hominin species with massive teeth, as well as some early <em>Homo</em> fossils. The most famous specimen from Drimolen is the most complete skull of <em>Paranthropus robustus</em> ever discovered, <a href="http://humanorigins.si.edu/evidence/human-fossils/fossils/uw-dnh-7">DNH 7</a>.</p>
<p>It was here that members of our team found the fossil cranium that has been named DNH 134. Its nickname is Simon, named for the site technician whose contribution to the team was immeasurable. Simon Mokobane sadly passed away in 2018, but his expertise, unwavering support and fossil knowledge will forever be remembered. </p>
<p>In 2015, during the Drimolen Field School, a student named Richard Curtis began excavating an intriguing, but highly fragmented specimen. At first, no one was sure what it was from but in-field reconstructions quickly revealed that it was a hominin cranium.</p>
<p>We used a battery of dating methods, including Uranium-lead dating on the flowstones, Uranium-Series Electron Spin Resonance on fossil teeth and Palaeomagnetism on sediments. Each of these complimentary techniques helped to establish a very narrow age of 2.04-1.95 million years for the whole Drimolen Main Quarry and the fossils found in it, including DNH 134. </p>
<p>DNH 134 is extremely significant. Its discovery and dating means that the story of <em>Homo erectus</em> and its journey out of Africa is more complicated than previously thought. Also, we know too that South Africa played a seminal role in this key species that ultimately led to us. </p>
<h2>Next steps</h2>
<p>Work will continue at the Drimolen site. We aim to continue excavating using a new method where our efforts are focused along the breccia (fossilised rock with fossils in it). This has proved fruitful with not only the discovery of DNH 134, but also a male <em>Paranthropus robustus</em> skull (DNH 152; also discussed in the Science article) as well as a number of other hominin remains we are still studying. </p>
<p>The site also has a wide variety of animal fossils from both extinct and living species, all of whom add to the overall story that we aim to build about how our ancient ancestors lived. </p>
<p>We will also continue to encourage young palaeoanthropologists from across the African continent to get involved in excavations. The site hosts an <a href="https://sa.wustl.edu/index.cfm?FuseAction=Programs.ViewProgramAngular&id=10455">annual field school</a> with international partner institutes and offers full scholarships exclusively to students from African countries (South Africans have first preference). </p>
<p>The idea behind this is to ensure that researchers from the continent and country are at the forefront of future discoveries that add to the human story.</p><img src="https://counter.theconversation.com/content/135068/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Prof. Andy I.R. Herries receives funding from The Australian Research Council</span></em></p><p class="fine-print"><em><span>Renaud Joannes-Boyau receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Angeline Leece, Jesse Martin, Matthew Caruana, and Stephanie Baker do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>This is a hugely important find. It means that one of our earlier ancestors possibly originated in southern Africa.Stephanie Baker, Researcher in Palaeoanthropology, University of JohannesburgAndy I.R. Herries, Head of Department of Archaeology and History, La Trobe UniversityAngeline Leece, PalaeoanthropologistJesse Martin, PhD Researcher, La Trobe UniversityMatthew Caruana, Lecturer in Archaeology, University of JohannesburgRenaud Joannes-Boyau, Senior research fellow, Southern Cross UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1261812019-12-18T18:56:25Z2019-12-18T18:56:25ZWhen did ‘Homo erectus’ die out? A fresh look at the demise of an ancient human species over 100,000 years ago<figure><img src="https://images.theconversation.com/files/307373/original/file-20191217-164454-1tqvdww.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3615%2C1787&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The site at Ngandong held the remains of the last known members of the ancient human species Homo erectus.</span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>Imagine your child asked you “When did grandma die?” and you could only respond “It was probably a while ago, but it could have been quite recently.” Most likely your child would be unsatisfied with the reply.</p>
<p>This has been our situation regarding the ancient human species <em>Homo erectus</em>. We know these distant cousins of modern humans were alive almost 2 million years ago, but when did they die out? Probably a while ago, but perhaps quite recently. </p>
<p>A key site in our understanding of <em>Homo erectus</em>, at Ngandong, in Java, Indonesia, has until now defeated all attempts at reliable dating since it was first excavated more than 90 years ago. </p>
<p>With the aid of new techniques, <a href="https://www.nature.com/articles/s41586-019-1863-2">we have now found</a> that the Ngandong <em>Homo erectus</em> fossils are the most recent known specimens, dating from between 117,000 and 108,000 years ago. </p>
<p>This discovery will help us understand where they sit in the evolutionary tree, who they interacted with and why they became extinct. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-snapshot-of-our-mysterious-ancestor-homo-erectus-101122">A snapshot of our mysterious ancestor Homo erectus</a>
</strong>
</em>
</p>
<hr>
<h2>The discovery at Ngandong</h2>
<p>In 1931, a team of Dutch archaeologists made an unbelievable discovery at Ngandong when they unearthed 12 skulls and two leg bones of <em>Homo erectus</em>. Finding even one fossil human skull is remarkable, but finding 12 together is almost miraculous. </p>
<p>Other <em>Homo erectus</em> skulls have been found in Java and elsewhere, but the ones at Ngandong have the largest brain size and highest forehead of any of them. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/307621/original/file-20191218-11900-11gcqvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307621/original/file-20191218-11900-11gcqvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307621/original/file-20191218-11900-11gcqvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=268&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307621/original/file-20191218-11900-11gcqvx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=268&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307621/original/file-20191218-11900-11gcqvx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=268&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307621/original/file-20191218-11900-11gcqvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=336&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307621/original/file-20191218-11900-11gcqvx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=336&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307621/original/file-20191218-11900-11gcqvx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=336&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Detailed casts of the 12 skulls found at Ngandong.</span>
<span class="attribution"><span class="source">Russell L Ciochon / University of Iowa</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This indicates an important evolutionary change, and knowing when it happened is crucial to our interpretation and understanding of these ancient cousins. </p>
<p>However, the nature of the site – where the fossils were buried in a deposit of sediment close to the Solo River – makes it difficult to determine how old the fossils are. Many attempts have been made to establish a timeline for the site, but until now none have been very successful.</p>
<h2>Difficulties of dating</h2>
<p>In 1931, when Ngandong was excavated, archaeologists relied heavily on the estimated age of the associated fossil fauna to date the <em>Homo erectus</em> remains. </p>
<p>By 1996, better dating techniques such as electron spin resonance and uranium-series dating were available. A team led by American geochronologist Carl Swisher <a href="https://science.sciencemag.org/content/274/5294/1870.abstract">applied these techniques to ancient buffalo teeth</a> found at the Ngandong site.</p>
<p>Using the buffalo teeth dating, Swisher claimed that <em>Homo erectus</em> survived as recently as 27,000 years ago. This would overlap with the arrival of our own species, <em>Homo sapiens</em>, in the region. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/307578/original/file-20191218-11909-1u6r7nd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307578/original/file-20191218-11909-1u6r7nd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/307578/original/file-20191218-11909-1u6r7nd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=749&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307578/original/file-20191218-11909-1u6r7nd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=749&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307578/original/file-20191218-11909-1u6r7nd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=749&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307578/original/file-20191218-11909-1u6r7nd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=941&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307578/original/file-20191218-11909-1u6r7nd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=941&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307578/original/file-20191218-11909-1u6r7nd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=941&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 excavations at Ngandong.</span>
<span class="attribution"><span class="source">Russell Ciochon / University of Iowa</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>However, examining the plans from the original excavation revealed the Dutch team had dug up and reburied an enormous area of ground. It turned out the buffalo teeth Swisher dated came from an area that had <a href="https://science.sciencemag.org/content/276/5318/1575">already been excavated and buried again</a>.</p>
<p>This meant they could not have come from the same layer as the 12 <em>Homo erectus</em> skulls, so their ages were not related. </p>
<p>Despite the issues with Swisher’s dating, the theory that <em>Homo erectus</em> survived so recently has persisted in the literature and our understanding of Ngandong since 1996.</p>
<p>In 2011, at team led by Indonesian researcher Etty Indriati re-dated the site and obtained ages <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0021562">between 130 and 500,000 years</a>. But again they focused mainly on dating the non-human fossil evidence and ignored the sedimentary context. </p>
<p>Consequently, the age range is too wide to provide much help in reconstructing the evolutionary significance of Ngandong. </p>
<h2>Reading the river</h2>
<p>Recently, we were part of a team of Indonesian, American, and Australian researchers led by Yan Rizal who tried a different approach. We worked on an understanding that the site is in a river deposit that is part of a sequence of floodplain steps called terraces. </p>
<p>Our study was based on how the Solo River system was created (landscape context), how the terraces were formed (terrace context), and how the fossils were deposited (fossil context). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/307579/original/file-20191218-11929-tc26zo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307579/original/file-20191218-11929-tc26zo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307579/original/file-20191218-11929-tc26zo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307579/original/file-20191218-11929-tc26zo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307579/original/file-20191218-11929-tc26zo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307579/original/file-20191218-11929-tc26zo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307579/original/file-20191218-11929-tc26zo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307579/original/file-20191218-11929-tc26zo.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">The Solo River at Ngandong, showing river terraces on the far bank.</span>
<span class="attribution"><span class="source">Kira Westaway</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>To do this we first dated when the Southern Mountains in Java were formed – to define when the Solo River was diverted to the north to form the terraces. We then dated the sequence of river terrace sediments using a technique called optically stimulated luminescence dating, which provided the first ever sedimentary age for the site. </p>
<p>Finally, we conducted extensive excavations at Ngandong in carefully selected areas using maps from previous excavations. These new excavations revealed the same bone bed found by the Dutch in 1931 and provided evidence directly associated with the human fossils that could also be dated. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/old-teeth-from-a-rediscovered-cave-show-humans-were-in-indonesia-more-than-63-000-years-ago-82075">Old teeth from a rediscovered cave show humans were in Indonesia more than 63,000 years ago</a>
</strong>
</em>
</p>
<hr>
<h2>A new age</h2>
<p>The analysis resulted in 52 new ages that were modelled to precisely define the age of the original bone layer to 117–108,000 years ago. This is the youngest reliable age for <em>Homo erectus</em> in Indonesia, and the last appearance of <em>Homo erectus</em> anywhere in the world. </p>
<p>At this age, <em>Homo erectus</em> would not have encountered <em>Homo sapiens</em>, but they may have met other now-extinct human species such as the enigmatic Denisovans. First discovered in the cold caves of Russia, the Denisovans are mostly known from traces of their DNA in modern humans rather than actual fossils. The Denisovans might have been distributed as far as Southeast Asia. </p>
<figure>
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<p>The new age range now raises important questions about the interactions between the Denisovans and the Ngandong <em>Homo erectus</em>. Could interbreeding with Denisovans be the source of the evolutionary change and larger skulls in this late <em>Homo erectus</em> population? </p>
<p>This possibility is yet to be proven. But it is clear that this improved age for the Ngandong <em>Homo erectus</em> has opened new lines of investigation that can provide a window into understanding the complex world of human evolution. </p>
<p>We are finally ready to get to know our extended family.</p><img src="https://counter.theconversation.com/content/126181/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kira Westaway receives funding from the Australian Research Council and from Macquarie University internal funding schemes. She works for Macquarie University, Australia. </span></em></p><p class="fine-print"><em><span>Michael Westaway is an Australian Research Council Future Fellow and receives funding from the ARC and University of Queensland. </span></em></p><p class="fine-print"><em><span><a href="mailto:russell-ciochon@uiowa.edu">russell-ciochon@uiowa.edu</a> receives funding from Wenner-Gren Foundation for Anthropological Research (ICRG-92), University of Iowa (UI) Center for Global and Regional Environmental Research (CGRER), UI Office of the President, UI Dean of the College of Liberal Arts and Sciences, and the UI Office of the Vice-President for Research. He works for the University of Iowa. </span></em></p>Our extinct, distant cousins still lived in Indonesia 110,000 years ago.Kira Westaway, Senior Lecturer, Macquarie UniversityMichael Westaway, Australian Research Council Future Fellow, Archaeology, School of Social Science, The University of QueenslandRussell Ciochon, Professor, University of IowaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1266382019-11-21T15:33:10Z2019-11-21T15:33:10ZWere other humans the first victims of the sixth mass extinction?<figure><img src="https://images.theconversation.com/files/302005/original/file-20191115-66945-1ccxz9v.jpg?ixlib=rb-1.1.0&rect=5%2C291%2C830%2C485&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A Neanderthal skull shows head trauma, evidence of ancient violence</span> <span class="attribution"><a class="source" href="http://humanorigins.si.edu/evidence/human-fossils/fossils/saint-c%C3%A9saire">Smithsonian National Museum of Natural History</a></span></figcaption></figure><p>Nine human species walked the Earth 300,000 years ago. Now there is just one. The Neanderthals, <em>Homo neanderthalensis</em>, were <a href="https://theconversation.com/why-the-neanderthals-may-have-been-more-sophisticated-hunters-than-we-thought-new-study-98870">stocky hunters</a> adapted to Europe’s cold steppes. The related <a href="https://theconversation.com/fresh-clues-to-the-life-and-times-of-the-denisovans-a-little-known-ancient-group-of-humans-110504">Denisovans</a> inhabited Asia, while the more primitive <a href="https://theconversation.com/a-snapshot-of-our-mysterious-ancestor-homo-erectus-101122"><em>Homo erectus</em></a> lived in Indonesia, and <a href="https://www.nature.com/articles/108371a0.pdf"><em>Homo rhodesiensis</em></a> in central Africa. </p>
<p>Several short, small-brained species survived alongside them: <a href="https://theconversation.com/homo-naledi-fossil-discovery-a-triumph-for-open-access-and-education-47726"><em>Homo naledi</em></a> in South Africa, <a href="https://theconversation.com/how-much-evidence-is-enough-to-declare-a-new-species-of-human-from-a-philippines-cave-site-115139"><em>Homo luzonensis</em></a> in the Philippines, <a href="https://theconversation.com/fast-evolution-explains-the-tiny-stature-of-extinct-hobbit-from-flores-island-124747"><em>Homo floresiensis</em></a> (“hobbits”) in Indonesia, and the mysterious <a href="https://theconversation.com/bone-suggests-red-deer-cave-people-a-mysterious-species-of-human-52437">Red Deer Cave People</a> in China. Given how quickly we’re discovering new species, more are likely waiting to be found.</p>
<p>By 10,000 years ago, they were all gone. The disappearance of these other species resembles a mass extinction. But there’s no obvious environmental catastrophe – volcanic eruptions, climate change, asteroid impact – driving it. Instead, the extinctions’ timing suggests they were caused by the spread of a new species, evolving <a href="https://science.sciencemag.org/content/358/6363/652.abstract">260,000-350,000 years ago</a> in <a href="https://www.nature.com/articles/s41586-019-1714-1">Southern Africa</a>: <em>Homo sapiens</em>. </p>
<p>The spread of modern humans out of Africa has caused a <a href="https://www.theguardian.com/environment/2017/jul/10/earths-sixth-mass-extinction-event-already-underway-scientists-warn">sixth mass extinction</a>, a greater than 40,000-year event extending from the disappearance of Ice Age mammals to the destruction of rainforests by civilisation today. But were other humans the first casualties? </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/302000/original/file-20191115-66925-p0qco1.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/302000/original/file-20191115-66925-p0qco1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/302000/original/file-20191115-66925-p0qco1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/302000/original/file-20191115-66925-p0qco1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/302000/original/file-20191115-66925-p0qco1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/302000/original/file-20191115-66925-p0qco1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/302000/original/file-20191115-66925-p0qco1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/302000/original/file-20191115-66925-p0qco1.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Human evolution.</span>
<span class="attribution"><span class="source">Nick Longrich</span></span>
</figcaption>
</figure>
<p>We are a uniquely dangerous species. We hunted <a href="https://www.amazon.com/Quaternary-Extinctions-Prehistoric-Paul-Martin/dp/0816511004/ref=sr_1_3?keywords=prehistoric+extinctions+martin&qid=1573645985&sr=8-3">wooly mammoths, ground sloths</a> and <a href="https://science.sciencemag.org/content/287/5461/2250.full?_ga=2.156387641.382776719.1573642705-28080894.1573476299">moas</a> to extinction. We destroyed plains and forests for farming, modifying over <a href="https://www.geosociety.org/gsatoday/archive/22/12/article/i1052-5173-22-12-4.htm">half the planet’s land area</a>. We altered the planet’s climate. But we are most dangerous to other human populations, because we compete for resources and land.</p>
<p>History is full of examples of people warring, displacing and wiping out other groups over territory, from Rome’s destruction of Carthage, to the American conquest of the West and the British colonisation of Australia. There have also been recent genocides and ethnic cleansing in <a href="https://theconversation.com/remembering-srebrenica-more-than-20-years-on-99122">Bosnia</a>, Rwanda, <a href="https://theconversation.com/islamic-states-genocidal-crimes-demand-justice-how-can-it-be-done-97646">Iraq</a>, Darfur and <a href="https://theconversation.com/rohingya-crisis-this-is-what-genocide-looks-like-83924">Myanmar</a>. Like language or tool use, a capacity for and tendency to engage in genocide is arguably an intrinsic, <a href="https://www.amazon.com/Third-Chimpanzee-Evolution-Future-Animal/dp/0060845503/ref=sr_1_1?keywords=the+third+chimpanzee&qid=1573645399&sr=8-1">instinctive part of human nature</a>. There’s little reason to think that early <em>Homo sapiens</em> were less territorial, less violent, less intolerant – less human.</p>
<p>Optimists have painted early hunter-gatherers as peaceful, <a href="https://theconversation.com/explainer-the-myth-of-the-noble-savage-55316">noble savages</a>, and have argued that our culture, not our nature, creates violence. But field studies, historical accounts, and archaeology <a href="https://www.amazon.com/Constant-Battles-Why-We-Fight/dp/0312310900/ref=sr_1_1?keywords=constant+battles&qid=1573829278&sr=8-1">all show</a> that war in <a href="https://www.amazon.com/War-Before-Civilization-Peaceful-Savage/dp/0195119126">primitive cultures was intense, pervasive and lethal</a>. Neolithic weapons such as clubs, spears, axes and bows, combined with guerrilla tactics like raids and ambushes, were devastatingly effective. Violence was the leading cause of death among men in these societies, and wars saw higher casualty levels per person than World Wars I and II. </p>
<p>Old bones and artefacts show this violence is ancient. The 9,000-year-old Kennewick Man, from North America, has a spear point embedded in his pelvis. The 10,000-year-old <a href="https://www.nature.com/articles/nature16477">Nataruk site</a> in Kenya documents the brutal massacre of at least 27 men, women, and children. </p>
<p>It’s unlikely that the other human species were much more peaceful. The existence of <a href="https://www.nature.com/articles/nature13727">cooperative violence in male chimps</a> suggests that war predates the evolution of humans. Neanderthal skeletons show <a href="https://www.nature.com/articles/s41586-018-0696-8">patterns</a> of <a href="https://www.pnas.org/content/99/9/6444.short">trauma</a> consistent with warfare. But sophisticated weapons likely gave <em>Homo sapiens</em> a military <a href="http://www.paleoanthro.org/media/journal/content/PA20100100.pdf">advantage</a>. The arsenal of early <em>Homo sapiens</em> probably included <a href="https://www.sciencedirect.com/science/article/pii/S030544030500230X">projectile weapons</a> like javelins and <a href="http://digitallibrary.amnh.org/bitstream/handle/2246/2613/N2403.pdf?sequence=1">spear-throwers</a>, throwing sticks and <a href="https://www.nature.com/articles/nature16477">clubs</a>.</p>
<p>Complex tools and culture would also have helped us efficiently harvest a wider range of animals and plants, feeding larger tribes, and giving our species a strategic advantage in numbers.</p>
<h2>The ultimate weapon</h2>
<p>But cave <a href="https://theconversation.com/borneo-cave-discovery-is-the-worlds-oldest-rock-art-in-southeast-asia-106252?fbclid=IwAR38kVzZ5Pa1zSZH7ZGWz1jFwJBRt_m035lvW-H6coqc8evaHWD1Ba6HisI">paintings</a>, <a href="https://www.nature.com/articles/nature07995">carvings</a>, and <a href="https://www.nature.com/articles/nature08169">musical instruments</a> hint at something far more dangerous: a sophisticated capacity for abstract thought and communication. The ability to cooperate, plan, <a href="https://www.amazon.com/War-Carl-von-Clausewitz-ebook/dp/B005R9EB68/ref=sr_1_1?keywords=clausewitz+on+war&qid=1573644303&s=digital-text&sr=1-1">strategise</a>, <a href="http://www.gutenberg.org/ebooks/1232">manipulate</a> and <a href="https://www.amazon.com/Art-War-Sun-Tzu-ebook/dp/B07YRX3MBM/ref=sr_1_2?keywords=sun+tzu+giles&qid=1573644250&s=digital-text&sr=1-2">deceive</a> may have been our ultimate weapon.</p>
<p>The incompleteness of the fossil record makes it hard to test these ideas. But in Europe, the only place with a relatively complete archaeological record, fossils show that within <a href="https://www.nature.com/articles/nature13621">a few thousand years</a> of our arrival , Neanderthals vanished. Traces of <a href="https://science.sciencemag.org/content/328/5979/710/tab-pdf">Neanderthal DNA in some Eurasian people</a> prove we didn’t just replace them after they went extinct. We met, and we mated.</p>
<p>Elsewhere, DNA tells of other encounters with archaic humans. East Asian, Polynesian and Australian groups have <a href="https://www.nature.com/articles/nature09710">DNA</a> from <a href="https://www.cell.com/cell/fulltext/S0092-8674(19)30218-1">Denisovans</a>. DNA from <a href="https://www.nature.com/articles/ng.3621#ref23">another species</a>, possibly <em>Homo erectus</em>, occurs in many Asian people. African genomes <a href="https://www.pnas.org/content/108/37/15123">show traces of DNA</a> from yet another <a href="https://www.sciencedirect.com/science/article/pii/S0092867412008318">archaic species</a>. The fact that we interbred with these other species proves that they disappeared only after encountering us. </p>
<p>But why would our ancestors wipe out their relatives, causing a mass extinction – or, perhaps more accurately, a mass genocide?</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/301300/original/file-20191112-178506-5fhhk2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/301300/original/file-20191112-178506-5fhhk2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=639&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301300/original/file-20191112-178506-5fhhk2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=639&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301300/original/file-20191112-178506-5fhhk2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=639&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301300/original/file-20191112-178506-5fhhk2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=803&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301300/original/file-20191112-178506-5fhhk2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=803&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301300/original/file-20191112-178506-5fhhk2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=803&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">13,000-year-old spear points from Colorado.</span>
<span class="attribution"><span class="source">Chip Clark, Smithsonian Institution</span></span>
</figcaption>
</figure>
<p>The answer lies in <a href="https://www.amazon.com/Constant-Battles-Why-We-Fight/dp/0312310900/ref=sr_1_1?keywords=constant+battles&qid=1573829278&sr=8-1">population growth</a>. Humans reproduce exponentially, like all species. Unchecked, we historically <a href="http://www.gutenberg.org/ebooks/4239">doubled our numbers every 25 years</a>. And once humans became cooperative hunters, we had no predators. Without predation controlling our numbers, and little family planning beyond <a href="http://www.gutenberg.org/ebooks/4239">delayed marriage</a> and <a href="https://www.annualreviews.org/doi/pdf/10.1146/annurev.es.06.110175.000543">infanticide</a>, populations grew to exploit the available resources.</p>
<p>Further growth, or food shortages caused by drought, harsh winters or overharvesting resources <a href="https://www.amazon.com/Constant-Battles-Why-We-Fight/dp/0312310900/ref=sr_1_1?keywords=constant+battles&qid=1573829278&sr=8-1">would inevitably lead tribes into conflict</a> over food and foraging territory. Warfare became a check on population growth, perhaps the most important one.</p>
<p>Our elimination of other species probably wasn’t a planned, coordinated effort of the sort practised by civilisations, but a war of attrition. The end result, however, was just as final. Raid by raid, ambush by ambush, valley by valley, modern humans would have worn down their enemies and taken their land. </p>
<p>Yet the extinction of Neanderthals, at least, took a long time – thousands of years. This was partly because early <em>Homo sapiens</em> lacked the advantages of later conquering civilisations: <a href="https://www.amazon.com/Third-Chimpanzee-Evolution-Future-Animal/dp/0060845503/ref=sr_1_1?keywords=the+third+chimpanzee&qid=1573645399&sr=8-1">large numbers, supported by farming</a>, and <a href="https://www.amazon.com/Plagues-Peoples-William-McNeill-ebook/dp/B0047747QK/ref=sr_1_1?keywords=plagues+and+peoples&qid=1573645434&sr=8-1">epidemic diseases like smallpox, flu, and measles</a> that <a href="https://theconversation.com/european-colonisation-of-the-americas-killed-10-of-world-population-and-caused-global-cooling-110549">devastated their opponents</a>. But while Neanderthals lost the war, to hold on so long they must have fought and won many battles against us, suggesting a level of intelligence close to our own.</p>
<p>Today we look up at the stars and wonder if we’re <a href="https://theconversation.com/evolution-tells-us-we-might-be-the-only-intelligent-life-in-the-universe-124706">alone in the universe</a>. In <a href="https://www.amazon.com/Hobbit-Lord-Rings-Fellowship-Towers/dp/0345538374/ref=sr_1_2?keywords=the+lord+of+the+rings&qid=1573645527&sr=8-2">fantasy</a> and <a href="https://www.imdb.com/title/tt0060028/">science fiction</a>, we wonder what it might be like to meet other intelligent species, like us, but not us. It’s profoundly sad to think that we once did, and now, because of it, they’re gone.</p><img src="https://counter.theconversation.com/content/126638/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicholas R. Longrich 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>300,000 years ago, there were lots of different species of human. Now it’s only us – and we’re probably the reason why.Nicholas R. Longrich, Senior Lecturer, Paleontology and Evolutionary Biology, University of BathLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1247472019-10-08T23:09:58Z2019-10-08T23:09:58ZFast evolution explains the tiny stature of extinct ‘Hobbit’ from Flores Island<figure><img src="https://images.theconversation.com/files/296079/original/file-20191008-128665-1ubc795.jpg?ixlib=rb-1.1.0&rect=245%2C131%2C4685%2C3506&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An Indonesian island was home to _H. Floresiensis_ – but how did the dwarfed human species evolve?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/koka-beach-one-beaches-sikka-regency-1243898557">areza taqwim/Shutterstock.com</a></span></figcaption></figure><p>It’s not every day that scientists discover a new human species. </p>
<p>But that’s just what happened back in 2004, when archaeologists uncovered some very well-preserved fossil remains in the Liang Bua cave on Flores Island, Indonesia. The diminutive size of this new human species, <a href="https://www.nature.com/news/the-discovery-of-homo-floresiensis-tales-of-the-hobbit-1.16197"><em>Homo floresiensis</em></a>, earned it the nickname “Hobbit.” </p>
<p>Shockingly, researchers believed it had survived until the end of the last Ice Age, some 18,000 years ago. That was much later than Neanderthals lived, later than any human species other than our own.</p>
<p>Almost immediately, interpretations of this Hobbit skeleton met with fierce criticism from both anthropologists and evolutionary biologists. The poor Hobbit was accused of being an example not of a small new human species, but an abnormal <em>Homo sapiens</em>, bearing any of a variety <a href="https://doi.org/10.1002/ajpa.20655">of growth and</a> <a href="https://doi.org/10.1098/rspb.2007.1488">hormonal conditions</a>. The Hobbit, many scientists decided, had no place among the giants of the human evolutionary record.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/295885/original/file-20191007-52202-lzkp34.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/295885/original/file-20191007-52202-lzkp34.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/295885/original/file-20191007-52202-lzkp34.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/295885/original/file-20191007-52202-lzkp34.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/295885/original/file-20191007-52202-lzkp34.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/295885/original/file-20191007-52202-lzkp34.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/295885/original/file-20191007-52202-lzkp34.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/295885/original/file-20191007-52202-lzkp34.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">An artist’s interpretation of how <em>H. floresiensis</em> looked in life.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/timevanson/7283199410">Tim Evanson/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Yet she – yes, the Hobbit was later found to be a female – had her revenge. This tiny, small-brained creature stood just a bit more than three feet tall and had a brain as big as a chimp. But her place in the human ancestral line was cemented when researchers uncovered another tiny individual in Flores. This second, much older discovery debunked the idea that the Hobbit was a unique, abnormal <em>Homo sapiens</em>.</p>
<p>After 15 years of <a href="https://theconversation.com/the-hobbit-took-our-breath-away-now-its-the-new-normal-60784">intense research</a>, anthropologists now confidently date the Liang Bua individual to have lived between 60,000 and 90,000 years ago. Her much older cousins in Flores lived 700,000 years ago. This long reign testifies to the success of this tiny human species, no matter how small-statured and small-brained they were. </p>
<p>And this year anthropologists found a new dwarfed human species, christened <a href="https://doi.org/10.1038/s41586-019-1067-9"><em>Homo luzonensis</em></a>, in the Philippines.</p>
<p>So why did tiny humans wind up living on these islands? For us biogeographers and <a href="https://scholar.google.com/citations?user=gE-4C2cAAAAJ&hl=en&oi=ao">evolutionary</a> <a href="https://scholar.google.com/citations?user=scYHGuQAAAAJ&hl=en&oi=ao">biologists</a>, the answer was right in front of us: <a href="https://www.pbs.org/wgbh/nova/article/gigantism-and-dwarfism-islands/">the island rule</a>.</p>
<h2>Island life and body size</h2>
<p>Zoologist J. Bristol Foster <a href="https://doi.org/10.1038/202234a0">originally proposed</a> the island rule in 1964. </p>
<p>He’d noted that when a large-bodied species settles onto an island, it will tend to evolve to shrink in size – all the way to the point of leaving dwarf descendants. At the same time, the opposite will happen. Small-bodied species will evolve to be larger, producing gigantic daughter species.</p>
<p>There are spectacular cases of this island rule in action across the world. Think of pygmy elephants and mammoths from <a href="https://doi.org/10.1023/A:1025577414005">Mediterranean</a> and Baja California islands, hippos that would barely outweigh a donkey in Cyprus, deer as tall as a pet dog in Crete, rats as big as a cow in the Caribbean and insects as long as a human hand in New Zealand.</p>
<p>Biologists have proposed various mechanisms that could be responsible for this evolutionary trend. A good motive might be the absence of natural predators on islands. A number of species, most notably elephants and hippos, fend predators off by virtue of their size, an expensive strategy when no killer is lurking in the dark. Also, on islands the scarce resource supply might favor smaller body size because smaller individuals can live with less.</p>
<p>Or it could be that smaller individuals with no predators just produce more offspring, which implies females start delivering earlier and at smaller size, investing less in growth and more in reproduction. This possibility is a likely explanation for <a href="https://doi.org/10.1073/pnas.0708024105">how contemporary human pygmies evolved</a>. </p>
<p>All of these options will eventually lead to changes in the genetic architecture that underlies body-size variation.</p>
<p>So, we asked, could the island rule be an explanation for small size of <em>Homo floresiensis</em> and <em>Homo luzonensis</em>? We thought probably yes.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/296081/original/file-20191008-128681-801yeu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/296081/original/file-20191008-128681-801yeu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/296081/original/file-20191008-128681-801yeu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=420&fit=crop&dpr=1 600w, https://images.theconversation.com/files/296081/original/file-20191008-128681-801yeu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=420&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/296081/original/file-20191008-128681-801yeu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=420&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/296081/original/file-20191008-128681-801yeu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=528&fit=crop&dpr=1 754w, https://images.theconversation.com/files/296081/original/file-20191008-128681-801yeu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=528&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/296081/original/file-20191008-128681-801yeu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=528&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Excavations in 2009 at Liang Bua cave, where <em>Homo floresiensis</em> was found.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Indonesia-Hobbit/2a6835d986064cf095696d86e3e700e6/1/0">AP Photo/Achmad Ibrahim</a></span>
</figcaption>
</figure>
<h2>Modeling generations on the island</h2>
<p>The Hobbit’s most likely ancestor is <em>Homo erectus</em>, a species more than twice its size in terms of its brain and overall bulk. Based on the geological history of Flores and the oldest known fossils of <em>Homo floresiensis</em>, it seems the evolution of the new species must have occurred in less than about 300,000 years.</p>
<p>As evolutionary biologists, we are acquainted with the idea that Darwinian evolution is a slow and gradual process that takes place over very long timescales. Could such drastic change in body size happen this fast?</p>
<p>So our interdisciplinary research team developed a <a href="https://theconversation.com/simulating-evolution-how-close-do-computer-models-come-to-reality-57538">computer model</a> to try to answer this basic question. It’s like a computer game that simulates body size evolution under biologically and ecologically realistic scenarios.</p>
<p>In our model, individuals colonize the island, grow to their adult body size according to how much food is available, give birth to a number of young and die. The basic rule of the game is that individuals that are closer to the “optimum” body size for the island in that moment will leave more descendants. Offspring inherit genes for large or small body size.</p>
<p>Generation after generation, new mutations may appear in the population and shift body size toward either higher or lower values. Occasionally, new individuals might even invade the island and mix with the residents. Another basic rule is that the initial small population cannot grow above the number the island’s resources might sustain.</p>
<p>Our colleagues, Earth systems scientists <a href="https://scholar.google.com/citations?user=kSDahsoAAAAJ&hl=en&oi=ao">Neil Edwards</a> and <a href="https://scholar.google.com/citations?user=1gais1MAAAAJ&hl=en">Phil Holden</a>, used paleoclimatic data to tweak our model. Hotter and wetter times can support more people on the island, and would influence optimum body size at any given moment.</p>
<p>We started our simulations assuming that large-bodied <em>Homo erectus</em> arrived at the island and then evolved into a smaller species there. Since we just don’t know the exact numbers our model should crank through, we based them on estimates obtained from current human populations.</p>
<p>Because of this uncertainty, we ran our model thousands of times, each time using a random combination of all the parameters. Ultimately we were able to build a statistical distribution of how long it took for <em>Homo erectus</em> to become as small as <em>Homo floresiensis</em>.</p>
<p><iframe id="bx726" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/bx726/3/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<h2>A new species, in the blink of an evolutionary eye</h2>
<p>After running 10,000 simulations, we were surprised to discover that <a href="http://dx.doi.org/10.1098/rsbl.2019.0481">in less than 350 generations, the process was complete</a>. Thinking in terms of years, assuming a young female delivers a first baby at the average age of 15, that translates to about 10,000 years.</p>
<p>That may seem long for you and me. But from an evolutionary perspective, that’s the blink of an eye – a little more than a thousandth of <em>Homo</em> evolutionary history.</p>
<p>Of course we do not expect that all the features that make <em>Homo floresiensis</em> as unique as it is evolved that fast and at the same time. Yet, our simulation still shows, 300,000 years is far more than enough time for a new human species to arise.</p>
<p>Our work supports the idea that fast evolution is quite plausible under a realistic set of ecological parameters, and that natural selection may be a powerful force influencing body size on islands. And if <em>Homo floresiensis</em> is indeed a product of the island rule, she shows – yet again – that we humans tend to obey the same overall rules driving evolution in many other mammals.</p>
<p>[ <em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=youresmart">You can read us daily by subscribing to our newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/124747/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>José Alexandre Felizola Diniz-Filho receives funding from CNPq and CAPES. </span></em></p><p class="fine-print"><em><span>Pasquale Raia 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>New research models how the Homo floresiensis species could have evolved its small size remarkably quickly while living on an isolated island.José Alexandre Felizola Diniz-Filho, Professor of Ecology and Evolution, Universidade Federal de Goias (UFG)Pasquale Raia, Associate Professor of Paleontology and Paleoecology, University of Naples Federico IILicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1198182019-07-15T05:23:35Z2019-07-15T05:23:35ZSoutheast Asia was crowded with archaic human groups long before we turned up<figure><img src="https://images.theconversation.com/files/283013/original/file-20190708-51273-o0si3h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The ancestral population of modern humans appears to have split as it moved across Asia.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/thursday-island-australia-february-20-2019-1377625862?src=MW-IovWrGzMMMZVGn77kKw-1-15&studio=1">Shutterstock</a></span></figcaption></figure><p>Around 55,000-50,000 years ago, a population of modern humans left Africa and started on the long trek that would lead them around the world. After rapidly crossing Eurasia and Southeast Asia, they travelled through the islands of Indonesia, and eventually as far as <a href="https://theconversation.com/when-did-aboriginal-people-first-arrive-in-australia-100830">the continent of Sahul</a> – modern-day Australia and New Guinea. </p>
<p>Their descendants are the modern human populations found right across this enormous region today.</p>
<p>In new research <a href="https://www.pnas.org/content/early/2019/07/11/1904824116">published in Proceedings of the National Academy of Sciences</a>, we detail how during this remarkable journey the ancestors of modern humans met and genetically mixed with a number of archaic human groups, including Neandertals and Denisovans, and several others for which we currently have no name. The traces of these interactions are still preserved in our genomes. </p>
<p>For example, all modern non-African populations contain about 2% Neandertal ancestry. This strong universal signal shows that the original Neandertal mixing event must have happened just after the small founding population left Africa. </p>
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Read more:
<a href="https://theconversation.com/when-did-aboriginal-people-first-arrive-in-australia-100830">When did Aboriginal people first arrive in Australia?</a>
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<p>We can even use the Neandertal genetic signal to date when they left Africa. The large size of Neandertal DNA fragments in the genome of an ancient skeleton from southern Russia, which is 45,000 years old, shows that at most 230-430 generations could have passed since the initial mixing event (dating it around 50-55,000 years ago).</p>
<p>By analysing where the archaic genetic traces are found today (from previous genetic studies) and using paleovegetation maps that identify favourable savannah-like habitat along the route 55,000 years ago, we have reconstructed the likely geographic locations and number of the archaic hominin mixing events. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/282999/original/file-20190708-51312-1e8uawy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/282999/original/file-20190708-51312-1e8uawy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/282999/original/file-20190708-51312-1e8uawy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=386&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282999/original/file-20190708-51312-1e8uawy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=386&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282999/original/file-20190708-51312-1e8uawy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=386&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282999/original/file-20190708-51312-1e8uawy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=485&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282999/original/file-20190708-51312-1e8uawy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=485&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282999/original/file-20190708-51312-1e8uawy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=485&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A map showing where the ancestors of modern humans appear to have met and mixed with archaic hominins.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Leaving Africa</h2>
<p>One of the first mixing events after the Neandertals appears to have taken place during the movement across southern Asia. The archaic human group involved was neither the Neandertals or Denisovans, but something similar – which currently has no name. </p>
<p>The genetic traces of this archaic group can be found from modern Punjabi and Bengal populations all the way through to New Guinea and Australia. As a result, we think this mixing event (marked 1 on the map) likely took place somewhere around northern India, which is the most “upstream” or westerly position it is first observed.</p>
<p>The ancestral population of modern humans then appears to have split as it moved across Asia with one pulse dispersing north into mainland Asia, where it met and mixed with a Denisovan group (marked 2 on the map). These Denisovans were genetically close to those we already know about from the Altai mountains. The traces of this event can be seen in East Asia today, and also in North and South America populations, who stem from northeastern Asia.</p>
<h2>Island Southeast Asia was already crowded</h2>
<p>The other pulse of modern humans headed south down the Malaysian Peninsula and into Island Southeast Asia (ISEA) where a big surprise awaited. They found the area was already crowded with different archaic human groups, including completely different species. </p>
<p>Recent fossil finds of small skeletons have shown that apparent relatives of <em>Homo erectus</em> (whose early fossils are common on Java) had survived on the Philippines and Flores (where they are known as “hobbits”) until around <a href="https://www.nature.com/articles/d41586-019-01019-7">52,000 years ago</a>. Effectively right up until the modern humans arrived.</p>
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Read more:
<a href="https://theconversation.com/an-incredible-journey-the-first-people-to-arrive-in-australia-came-in-large-numbers-and-on-purpose-114074">An incredible journey: the first people to arrive in Australia came in large numbers, and on purpose</a>
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</em>
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<hr>
<p>The incoming modern human population apparently first met and mixed with a distant relative of the Denisovans in the area, leaving a signal in the genomes of Australo-Papuans and several ISEA populations. These signals are very different from the above East Asian mixing event, and instead come from a Denisovan relative that had separated genetically from the Altai/East Asian Denisovans around 280,000 years ago. This mixing event appears to have been somewhere around southern Malaysia/Borneo (marked 3 on the map).</p>
<h2>Landfall in Australia</h2>
<p>The wave of modern humans does not appear to have waited long to cross Wallace’s Line – the famous biogeographic barrier that effectively marks the edge of the ISEA landmasses joined together during past glacial periods, when sea levels were up to 120 metres lower. </p>
<p>We know this because a sudden appearance of archaeological sites right across Australia around 50,000 years ago indicates that modern humans had <a href="https://theconversation.com/an-incredible-journey-the-first-people-to-arrive-in-australia-came-in-large-numbers-and-on-purpose-114074">quickly crossed the marine gaps</a> through ISEA. </p>
<p>While there is one much earlier Australian site, the 65-80,000 year old Madjedbebe rock shelter in Arnhem Land, it is a complete outlier to <a href="https://theconversation.com/australias-epic-story-a-tale-of-amazing-people-amazing-creatures-and-rising-seas-115701">the rest of the Australian record</a> and the age of the site has <a href="https://theconversation.com/when-did-aboriginal-people-first-arrive-in-australia-100830">been queried</a>.</p>
<p>While moving through ISEA, the modern human population appears to have met – and mixed with – two more archaic human groups. Hunter-gatherer populations in the Philippines preserve signals of yet another Denisovan-mixing event (marked 4 on the map), after they had diverged from the main wave of modern humans moving through ISEA. </p>
<p>Similarly, a genetic study of the short-statured modern day population that lives around the Flores cave where the tiny skeletons of the “hobbits” were found identified signals of DNA not from <em>Homo erectus</em>, the target of the study, but an enigmatic signal from something else. The source was neither Neandertal nor Denisovan but something of similar age – yet another currently unknown archaic group (marked 5 on the map).</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/australias-epic-story-a-tale-of-amazing-people-amazing-creatures-and-rising-seas-115701">Australia’s epic story: a tale of amazing people, amazing creatures and rising seas</a>
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<h2>The last survivors</h2>
<p>What the different genetic studies across this region tell us is that the ancestors of modern humans appear to have met and mixed with four different archaic hominins, in at least six events. And this all happened in the very short window of time between leaving Africa 50-55,000 years ago, and arriving in Australia and New Guinea at most 5,000 years later. </p>
<p>Remarkably, none of these genetic mixing events appears to have involved fossil species in ISEA that we know were still around when modern humans arrived, such as <em>Homo luzonensis</em> (Philippines) and the Flores hobbits. </p>
<p>ISEA was clearly a very crowded place around 50,000 years ago, occupied by many different archaic human groups on many different islands. But shortly thereafter there was only one survivor: us.</p><img src="https://counter.theconversation.com/content/119818/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>João Teixeira receives funding from the Australian Research Council.</span></em></p>New research outlines how the ancestors of modern humans interbred with several archaic human groups on the passage from Africa to Australia.João Teixeira, Research associate, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1011222019-01-20T18:50:54Z2019-01-20T18:50:54ZA snapshot of our mysterious ancestor Homo erectus<figure><img src="https://images.theconversation.com/files/248350/original/file-20181203-194928-1spcrr2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Homo erectus had many features in common with Homo sapiens – but we still don't have a genetic profile for this species. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/silhouette-woman-standing-on-hill-dramatic-501150766">from www.shutterstock.com </a></span></figcaption></figure><p>If you bumped into a <em>Homo erectus</em> in the street you might not recognise them as being very different from you. You’d see a certain “human-ness” in the stance, and his or her size and shape might be similar to yours.</p>
<p>But their face would be flatter, with a more obvious brow. And having a conversation would be hard – his or her language skills would be poor (although they could certainly craft a stone tool or light a fire). </p>
<p>Of course this is entirely hypothetical, as <em>Homo erectus</em> is now extinct. This enigmatic human ancestor probably evolved in Africa more than <a href="https://www.nature.com/scitable/knowledge/library/homo-erectus-a-bigger-smarter-97879043">2 million years ago</a>, although the timing of their disappearance is less clear. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/stone-tools-date-early-humans-in-north-africa-to-2-4-million-years-ago-107617">Stone tools date early humans in North Africa to 2.4 million years ago</a>
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<p><em>Homo erectus</em> was in the news over 2018 thanks to new discoveries in the <a href="http://nature.com/articles/doi:10.1038/s41586-018-0072-8">Philippines</a> and <a href="https://www.nature.com/articles/s41586-018-0299-4">China</a>, which have transformed our understanding of this not too distant family member. </p>
<p>So who was <em>Homo erectus</em>? And could 2019 be the year we learn more about our mysterious ancestor? </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/248357/original/file-20181203-194922-1vhw7gz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/248357/original/file-20181203-194922-1vhw7gz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=544&fit=crop&dpr=1 600w, https://images.theconversation.com/files/248357/original/file-20181203-194922-1vhw7gz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=544&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/248357/original/file-20181203-194922-1vhw7gz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=544&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/248357/original/file-20181203-194922-1vhw7gz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=683&fit=crop&dpr=1 754w, https://images.theconversation.com/files/248357/original/file-20181203-194922-1vhw7gz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=683&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/248357/original/file-20181203-194922-1vhw7gz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=683&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Homo erectus skull discovered in 1969 in Sangiran, Indonesia.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/set-homo-erectus-skull-discovered-1969-726532813?src=mJCWresHNM93-ZxIqH3vKQ-1-0">from www.shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Where and when did they live?</h2>
<p><em>Homo erectus</em> was first discovered in Java, Indonesia and then <a href="http://whc.unesco.org/en/list/449:PekingManSiteatZhoukoudian">China</a> – these are the famous “Java Man” and “Peking Man” fossils. Eugène Dubois’ 1891 <a href="https://archive.org/details/Pithecanthropus00Dubo">discovery</a> on Java (originally called <em>Pithecanthropus erectus</em>) was a key piece of evidence in supporting Darwin’s ideas of human evolution. </p>
<p>The recent <a href="https://www.nature.com/articles/s41586-018-0299-4">discovery</a> of stone artefacts in the Loess Plateau of China suggests that a hominin, probably <em>Homo erectus</em>, was living in the region by 2.1 million years ago. This evidence pushes back their presence in Asia back by at least 400,000 years. </p>
<p>Other ancient <em>Homo erectus</em> sites are present in <a href="http://www.pnas.org/content/108/26/10432">the Caucasus region</a> of Georgia (1.8 million years ago), on Java and in Africa.</p>
<p><em>Homo erectus</em> is thought to have become mostly extinct following the emergence of modern humans – yet some <a href="https://www.sciencedirect.com/science/article/pii/S004724840800047X">specimens from Java</a> have been dated (with some controversy) to as recently as 40,000 years ago. If this dating is correct, it suggests that they coexisted with <em>Homo sapiens</em>, although probably only in very small pockets in Indonesia. </p>
<p>The expansion of <em>Homo erectus</em> throughout the globe was the first time that a hominin species had ventured beyond Africa, and occurred 2 million years before modern humans replicated this great feat of exploration. They may have been encouraged to spread so rapidly by the expansion of grassland during this period, driven by climate change. This created more habitats for plant-eating animals and so increased the amount of available prey.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/rhino-fossil-rewrites-the-earliest-human-history-of-the-philippines-95879">Rhino fossil rewrites the earliest human history of the Philippines</a>
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<h2>What did they look like?</h2>
<p><em>Homo erectus</em> was the first of our ancestors to physically resemble modern humans. They were taller and their brain was larger than previous hominin species such as <em>Australopithecus sp.</em> or <em>Homo habilis</em>. </p>
<p>They had a slightly different <a href="http://humanorigins.si.edu/sites/default/files/styles/full_width/public/images/square/erectus_JC_Recon_Head_CC_f_sq.jpg?itok=5yDjSzJx">face</a> to us: it was flatter with more prominent brow ridges. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/248352/original/file-20181203-194932-142btpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/248352/original/file-20181203-194932-142btpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/248352/original/file-20181203-194932-142btpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=204&fit=crop&dpr=1 600w, https://images.theconversation.com/files/248352/original/file-20181203-194932-142btpd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=204&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/248352/original/file-20181203-194932-142btpd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=204&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/248352/original/file-20181203-194932-142btpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=256&fit=crop&dpr=1 754w, https://images.theconversation.com/files/248352/original/file-20181203-194932-142btpd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=256&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/248352/original/file-20181203-194932-142btpd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=256&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">There are clear differences in the size and shape of the skull in <em>Homo sapiens</em> compared to other human-like species including <em>Homo erectus</em> (schematic).</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/evolution-skull-1097845550?src=jKcI7rWJmUj2mGN0cfa4uA-2-1">from www.shutterstock.com</a></span>
</figcaption>
</figure>
<p>The long legs and the fact that they were fully upright meant <em>Homo erectus</em> individuals were <a href="https://www.sciencedirect.com/science/article/pii/S0047248410000564">efficient walkers and could cover larger ranges than their ancestors</a>. </p>
<p>Their body shape also meant that they could <a href="https://www.sciencedirect.com/science/article/pii/004724849290071G">control their temperature and water balance well and so were well suited for living in open forests</a>.</p>
<h2>What did they eat?</h2>
<p><em>Homo erectus</em> were probably advanced <a href="https://link.springer.com/article/10.1023%2FA%3A1014507129795">scavengers who augmented their diet with some predation</a> rather than sophisticated hunters. In fact, they probably occupied a similar ecological niche to hyenas today. </p>
<p>The importance of meat in their diets is still contested, with some researchers considering they were primarily <a href="https://www.sciencedirect.com/science/article/pii/0047248489900377">meat eaters</a> and others believing that they had a much <a href="https://www.pnas.org/content/113/51/14674">broader diet</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-where-did-the-first-person-come-from-85891">Curious Kids: Where did the first person come from?</a>
</strong>
</em>
</p>
<hr>
<h2>How smart where they?</h2>
<p><em>Homo erectus</em> was much smarter than previous hominins, being the first species to use <a href="https://core.ac.uk/reader/80779283">fire</a> and may have been the first to live in hunter-gather groups. They made stone tools in a style called the <a href="http://discovery.ucl.ac.uk/1498590/1/Torre%20The%20origins%20of%20the%20Acheulean%20%E2%80%93%20past%20and%20present%20perspectives%20on%20a%20major%20transition%20in%20human%20evolution%20AAM.pdf">Acheulian</a>, characterised by distinctive hand axes.</p>
<p>Despite this, their cognitive ability fell a long way short of modern humans. There is currently no evidence that <em>Homo erectus</em> was capable of undertaking modern behaviours such as using language or making art.</p>
<p>The importance of the recent discovery of archaeological material attributed to <em>Homo erectus</em> in the Philippines helps us learn more details about what this species may have been capable of. </p>
<p>Previously, it was widely accepted that <em>Homo erectus</em> was not able to undertake water crossings. This theory fitted with their presence as far as Java, but not across deeper water represented by the <a href="http://discovermagazine.com/1997/aug/mrwallacesline1198">Wallace line</a> to travel further east. </p>
<p>A discovery in the <a href="https://theconversation.com/rhino-fossil-rewrites-the-earliest-human-history-of-the-philippines-95879">Philippines</a> (and possibly in <a href="https://theconversation.com/ancient-stone-tools-found-on-sulawesi-but-who-made-them-remains-a-mystery-92277">Sulawesi</a>) overturns this, and opens the exciting possibility that <em>Homo erectus</em> may have been more capable sailors than we previously thought.</p>
<h2>How are they related to us?</h2>
<p>One of the most contentious aspects of <em>Homo erectus</em> is who to include in the <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/ajpa.10399">species</a>. While many researchers include a wide range of specimens from around the world as <em>Homo erectus</em>, some classify the African and Eurasian specimens as <em>Homo ergaster</em>. Others use the terms <em>Homo erectus</em> senso stricto (ie. in the narrow sense) for the Asian specimens and <em>Homo erectus</em> senso lato (ie. in the broad sense) for all specimens. </p>
<p>This somewhat confusing situation is actually far clearer than the early history of <em>Homo erectus</em> where a wide range of names including <em>Anthropopithecus</em>, <em>Homo leakeyi</em>, <em>Pithecanthropus</em>, <em>Sinanthropus</em>, <em>Meganthropus</em>, and <em>Telanthropus</em> were used. The reason for this complexity is that <em>Homo erectus</em> (whatever you choose to call them) have a comparatively wide range of morphological characteristics making it difficult to decide how much diversity to include within the definition of the species.</p>
<p>What is clear is that <em>Homo erectus</em> sits somewhere on the human lineage as an ancestor to modern humans, serving as a transition from early hominins such as <em>Australopithecus</em> to <em>Homo heidelbergensis</em>, <em>Homo neanderthalensis</em> and <em>Homo sapiens</em>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-know-why-short-statured-people-of-flores-became-small-but-for-the-extinct-hobbit-its-not-so-clear-100752">We know why short-statured people of Flores became small – but for the extinct 'Hobbit' it's not so clear</a>
</strong>
</em>
</p>
<hr>
<h2>What next for <em>Homo erectus</em>?</h2>
<p>No area of archaeology has seen such vibrant change in recent years than how we understand our family tree. New species have been discovered (and debated) and the ages of the earliest examples of various species are constantly being revised. Unfortunately we only have limited fossils to work with and so new specimens and sites can quickly change our understanding of human evolution.</p>
<p>There is no doubt that ancient DNA studies will contribute to resolving this uncertainty – however DNA sequences have not yet been recovered from <em>Homo erectus</em>. We await this eventual discovery with bated breath!</p>
<hr>
<p><em>This article has been updated to correct the spelling of Homo habilis.</em></p><img src="https://counter.theconversation.com/content/101122/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Moffat receives funding from the Australian Research Council, the Commonwealth Scholarships Commission and the Australian Nuclear Science and Technology Organisation. </span></em></p>No area of archaeology has seen such vibrant change in recent times than how we understand our family tree. Could 2019 be the year we learn more about our mysterious ancestor Homo erectus?Ian Moffat, ARC DECRA Research Fellow in Archaeological Science, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1078342018-11-29T19:09:19Z2018-11-29T19:09:19ZHuman ancestors may have spread to north Africa earlier than thought, stone tool discovery suggests<figure><img src="https://images.theconversation.com/files/247783/original/file-20181128-32226-1i5mteg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An Oldowan core freshly excavated at Ain Boucherit from which sharp-edged cutting flakes were removed.
</span> <span class="attribution"><span class="source"> M. Sahnouni</span></span></figcaption></figure><p>East Africa is famously the birthplace of humankind and the location where our ancient hominin ancestors first invented sophisticated stone tools. This technology, dating back to 2.6m years ago, is then thought to have spread around Africa and the rest of the Old World later on. </p>
<p>But new research, <a href="http://science.sciencemag.org/cgi/doi/10.1126/science.aau0008">published in Science</a>, has uncovered an archaeological site in Algeria containing similar tools that may be as old as 2.44m years. The team, led by the archaeologist <a href="http://www.stoneageinstitute.org/pdfs/Sahnouni%20profile.pdf">Mohamed Sahnouni</a>, excavated stone tools at the site Ain Boucherit that they estimate are between 1.92m and 2.44m years old. This suggests that human ancestors spread to the region much earlier than previously thought or that the stone tool technology was simultaneously invented by earlier hominin species living outside east Africa.</p>
<p>The artefacts belong to the “<a href="https://anthromuseum.missouri.edu/exhibit/oldowan-and-acheulean-stone-tools">Oldowan</a>” – the oldest known stone tool industry. Rounded river cobbles, used as hammer stones, were used to flake other cobbles, turning them into simple cores. The flakes were then transformed into scrapers and various knives by resharpening their edges. Essentially this was a tool kit for processing animal tissue, such as marrow, bone and brain tissue, but also plant material. However, it is not known for sure which hominin species first created Oldowan tools – potentially <em>Australopithecus</em> or <em>Homo habilis</em>. </p>
<p>The stone tools are very similar to those of early <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0147352">Oldowan sites in East Africa</a>. Bones at the site even have cut marks, where a stone tool has gouged into the bone during butchery. The cut marks may mean these hominins were actively hunting. </p>
<p>But we have only ever found early Oldowan tools in the east African rift valley before, more than 4,000km away. We have always assumed that it started there some 2.6m years ago, so we shouldn’t find it so far from its original home at that age unless we have missed something. </p>
<p>Many archaeologists do indeed suspect there is an unseen ghost somewhere in the machine. There have been discoveries of early hominin sites to the south, <a href="https://www2.palomar.edu/anthro/hominid/australo_2.htm">in Chad</a>, that suggest that some of our earliest ancestors lived well beyond East Africa. Oldowan-like sites <a href="https://www.researchgate.net/figure/Dmanissi-Georgia-181-million-years-Pre-Oldowan-or-Archaic-Oldowan-Lithic-industry-in_fig8_268521102">have also been found</a> outside of Africa, in Georgia, beginning at 1.8m years ago – which seems surprisingly early. </p>
<h2>Game changer</h2>
<p>The new discovery is telling us that our focus on East Africa as the birthplace of early humans is too narrow – we should be doing what Sahnouni and others have done all along and looking elsewhere. The same team <a href="http://www.stoneageinstitute.org/ain-hanech.html#.W__dAtv7S70">recently published findings</a> about another Oldowan site in Algeria that is about 1.75m years old, but to find early Oldowan tools well over half a million years earlier is a bit of a game changer.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/247787/original/file-20181128-32197-uty58a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/247787/original/file-20181128-32197-uty58a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/247787/original/file-20181128-32197-uty58a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/247787/original/file-20181128-32197-uty58a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/247787/original/file-20181128-32197-uty58a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/247787/original/file-20181128-32197-uty58a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/247787/original/file-20181128-32197-uty58a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sahnouni excavating at the site.</span>
<span class="attribution"><span class="source">M. Sahnouni</span></span>
</figcaption>
</figure>
<p>It all hinges on how reliable that 2.44m-year-old date really is. Dating specialists will be scrutinising the details very carefully. According to the paper, four different techniques were used. <a href="http://www.anth.ucsb.edu/faculty/stsmith/classes/anth3/courseware/Chronology/11_Paleomag_Archaeomag.html">Palaeomagnetic dating</a> measures the direction and intensity of the Earth’s magnetic field in sediments – this is locked into rocks when they form, helping to tell us how old they are.</p>
<p>The team found that the upper level mapped onto a short period of normal polarity taking place between 1.77m and 1.94m years ago. The lower level’s sediments fitted into a long period of reversed direction at between 1.94m and 2.58m years ago. </p>
<p>To get more precise dates, the team turned to a dating technique called <a href="https://en.wikipedia.org/wiki/Electron_spin_resonance_dating">electron spin resonance dating</a>, which measures radioactive decay in quartz sand grains. However, they used a less common version of the technique that was operating close to its upper limit of reliability at this age range. The measurement delivered an age of 1.92m years old, younger than suggested by paleomagnetism.</p>
<p>There are some concerns about how suitable this last method is but the team has been honest about that. They also compared the dates with extinction times of animals present at the site, which suggested the date wasn’t impossible. </p>
<p>To get a better idea of the maximum age of the tools, they used a technique for estimating the rates of sedimentation – basically how long the different layers at the site took to build up. You have to throw in some fancy statistical work though, and map it onto the palaeomagnetic results. Extrapolating backwards in time, the team calculated that the actual age of the lower level is 2.44m years old. I suspect dating specialists will be looking at this carefully.</p>
<h2>Mystery hominin?</h2>
<p>Now to our ghost. The oldest tools ever found outside of Africa are the ones from Georgia dated to 1.8m years ago. There is a small Oldowan-like site in Pakistan from around the same time and more <a href="https://www.researchgate.net/publication/8258761_New_evidence_on_the_earliest_human_presence_at_high_northern_latitudes_in_northeast_Asia">core-and-flake sites in east China</a> at 1.66m years ago. If the Georgian site represents the first move out of Africa, then these early African migrants got to Pakistan and China extremely quickly. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/247788/original/file-20181128-32221-ag3ivr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/247788/original/file-20181128-32221-ag3ivr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=750&fit=crop&dpr=1 600w, https://images.theconversation.com/files/247788/original/file-20181128-32221-ag3ivr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=750&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/247788/original/file-20181128-32221-ag3ivr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=750&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/247788/original/file-20181128-32221-ag3ivr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=943&fit=crop&dpr=1 754w, https://images.theconversation.com/files/247788/original/file-20181128-32221-ag3ivr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=943&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/247788/original/file-20181128-32221-ag3ivr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=943&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Stone tool cut marks on animal skeleton.</span>
<span class="attribution"><span class="source">I. Caceres</span></span>
</figcaption>
</figure>
<p>In Georgia, the tools may have been made by early <a href="http://humanorigins.si.edu/evidence/human-fossils/species/homo-erectus"><em>Homo erectus</em></a>, which dates back to about 1.8m years ago. As there is a <em>Homo erectus</em> specimen from China dated to 1.6m years old, it is easy to assume that <em>Homo erectus</em> must have been the species that spread the tool technology around the world – and much quicker than we had thought. </p>
<p>But we cannot be sure of that. What if our ghost was an earlier hominin species from Africa predating <em>Homo erectus</em> – such as <em>Homo habilis</em>? Perhaps the Oldowan actually began earlier than 2.6m years ago, and was already widespread throughout Africa by 2.4m years ago. </p>
<p>Maybe our mysterious hominin began to migrate out from Africa before 1.8m years ago, and carried its core-and-flake industry eastwards. That would certainly give it more time to cover those huge distances. Perhaps <em>Homo erectus</em> only migrated eastwards out of Africa later, following in the footsteps of an earlier traveller that we know nothing about. </p>
<p>So that’s a lot of maybes, but then nobody expected there to be Oldowan tools in Georgia when they were first found. It caused <a href="https://en.wikipedia.org/wiki/Dmanisi_skull_5">a lot of controversy</a>, but now most archaeologists are comfortable with the finding. The Georgian archaeologists went back, did more work and proved their case. I don’t doubt Sahnouni and his team will be doing the same.</p><img src="https://counter.theconversation.com/content/107834/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John McNabb 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>New discovery could be a game changer for archaeology.John McNabb, Senior Lecturer in Palaeolithic Archaeology, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/958792018-05-02T20:23:30Z2018-05-02T20:23:30ZRhino fossil rewrites the earliest human history of the Philippines<figure><img src="https://images.theconversation.com/files/216997/original/file-20180501-135851-a9qsa0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Excavations at Kalinga in Luzon's Cagayan Valley (Philippines). </span> <span class="attribution"><span class="source">G.D. van den Bergh</span>, <span class="license">Author provided</span></span></figcaption></figure><p>A dig in Luzon, an island in the northern Philippines, has uncovered fossils of an “Ice Age” rhinoceros that was butchered around 700,000 years ago. It’s the first evidence demonstrating the presence of archaic humans in the Philippines.</p>
<p>This exciting new finding, published today in <a href="https://www.nature.com/articles/doi:10.1038/s41586-018-0072-8">Nature</a>, suggests that early hominins were more widespread than previously thought in <a href="https://theconversation.com/wallacea-a-living-laboratory-of-evolution-85602">Wallacea</a> – the vast network of islands located east of continental Eurasia.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/217001/original/file-20180501-135803-j4f8ud.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/217001/original/file-20180501-135803-j4f8ud.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/217001/original/file-20180501-135803-j4f8ud.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/217001/original/file-20180501-135803-j4f8ud.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/217001/original/file-20180501-135803-j4f8ud.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/217001/original/file-20180501-135803-j4f8ud.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/217001/original/file-20180501-135803-j4f8ud.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">The near-complete skeleton of an extinct rhino from Kalinga in Luzon.</span>
<span class="attribution"><span class="source">G.D. van den Bergh</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The work is published by an international research team, including French, Filipino, Australian and Dutch scientists. </p>
<p>They discovered the now-extinct rhino carcass during excavations at Kalinga in Luzon’s Cagayan Valley. Marks on the bones indicate slicing with sharp-edged stone tools, showing that hominins removed flesh and fat from this large animal which they either killed or found recently deceased. Simple stone tools were found near the rhino.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-stone-tools-found-on-sulawesi-but-who-made-them-remains-a-mystery-92277">Ancient stone tools found on Sulawesi, but who made them remains a mystery</a>
</strong>
</em>
</p>
<hr>
<p>The rhino and tools were buried in river sediments. The team, co-led by <a href="https://cas.uow.edu.au/members/UOW094227.html">Gerrit (“Gert”) van den Bergh</a> from the University of Wollongong, has proposed an age of between 777,000 to 631,000 years ago for their discovery. We can be confident in these results because they used several independent dating methods that are all in agreement. </p>
<h2>Who butchered the rhino?</h2>
<p>In archaeological sciences, the term “archaic hominin” is generally used to refer to extinct forms of humans. </p>
<p>Prior research shows that archaic hominins had reached the islands of <a href="http://www.abc.net.au/news/science/2016-01-14/stone-tools-date-earliest-occupations-of-humans-on-sulawesi/7086308">Sulawesi</a> and <a href="http://www.sciencemag.org/news/2010/03/hobbit-ancestors-arrived-flores-early">Flores</a> to the south of Luzon by at least 200,000 years ago and one million years ago, respectively. Like Luzon, Sulawesi and Flores are large Wallacean islands located relatively close to the edge of the southeastern tip of continental Asia (“Sundaland”). </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/216998/original/file-20180501-135848-1t7vdj0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/216998/original/file-20180501-135848-1t7vdj0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/216998/original/file-20180501-135848-1t7vdj0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/216998/original/file-20180501-135848-1t7vdj0.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/216998/original/file-20180501-135848-1t7vdj0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/216998/original/file-20180501-135848-1t7vdj0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/216998/original/file-20180501-135848-1t7vdj0.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">The research team in Cagayan Valley, Luzon, Phillipines.</span>
<span class="attribution"><span class="source">G.D. van den Bergh</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Given that archaic hominins were able to colonise Sulawesi and Flores, it stands to reason that they also could have made it to the Philippines – but until now conclusive evidence for this has been lacking. </p>
<p>At this stage we don’t know which species the early tool-makers in Luzon belonged to, owing to the lack of hominin fossils from the rhino site.</p>
<p>However, the most likely candidate is <a href="https://australianmuseum.net.au/homo-erectus"><em>Homo erectus</em></a>, a widespread species that inhabited Java from 1.2 million years ago, and was also in China – this would also include “<a href="https://australianmuseum.net.au/homo-floresiensis">the Hobbit</a>” (<em>Homo floresiensis</em>) from Flores, which may be a <a href="https://theconversation.com/a-700-000-year-old-fossil-find-shows-the-hobbits-ancestors-were-even-smaller-60192">dwarfed <em>Homo erectus</em></a>. </p>
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<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>
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<p>That said, it is now clear that Wallacea is a highly enigmatic region with a complex role in the human evolutionary story, so I would not rule out the possibility that an entirely unknown species inhabited Luzon.</p>
<h2>How did hominins get to Luzon?</h2>
<p>The Luzon team <a href="https://www.nature.com/articles/doi:10.1038/s41586-018-0072-8">concludes</a> that hominins of some kind had established a presence in the northern Philippines during the Middle Pleistocene epoch (between 781,000 and 126,000 years ago), that they must have come originally from Borneo to the southwest or Taiwan to the north, and that they could <em>potentially</em> have used boats. </p>
<p>I think most scientists will be reluctant to accept the idea of archaic hominins paddling beyond Eurasia in purpose-built watercraft, even very rudimentary ones. This is not to say that such a scenario is impossible, but I think if it were so then we would already have evidence that archaic hominins got to more remote parts of the region, including Australia. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/217000/original/file-20180501-135825-ce9xar.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/217000/original/file-20180501-135825-ce9xar.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/217000/original/file-20180501-135825-ce9xar.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/217000/original/file-20180501-135825-ce9xar.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/217000/original/file-20180501-135825-ce9xar.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/217000/original/file-20180501-135825-ce9xar.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/217000/original/file-20180501-135825-ce9xar.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">Excavations at the Kalinga site in the Cagayan Valley of Luzon.</span>
<span class="attribution"><span class="source">G.D. van den Bergh</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>It is more likely that rare events are the mechanism behind hominin populations taking root on oceanic islands near Asia, like Flores, Sulawesi, and Luzon: for instance, hominins may have been swept out to sea by tsunamis and survived ocean crossings by clinging to floating vegetation.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/debris-from-the-2011-tsunami-carried-hundreds-of-species-across-the-pacific-ocean-84773">Debris from the 2011 tsunami carried hundreds of species across the Pacific Ocean</a>
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<h2>What this means for the “Hobbit” story</h2>
<p>The oldest stone tools on Flores <a href="http://www.abc.net.au/radionational/programs/scienceshow/tools-show-humans-in-flores-one-million-years-ago/3115264">date back at least one million years</a>. The earliest hominin fossils from this island <a href="https://www.theguardian.com/science/2016/jun/08/new-fossils-shed-light-evolution-hobbits-flores">are 700,000 years old</a> and belong to a Hobbit-like population that may be directly ancestral to <em>Homo floresiensis</em>. </p>
<p>The Luzon find is important to the Hobbit story because it now looks like the northern part of Wallacea was the source of origin for the hominin population that first reached Flores (via Sulawesi) on the southern fringes of Wallacea. </p>
<p>The “Hobbit trail” may begin in the Philippines!</p>
<p>The Flores fossils suggest that hominins cut off on this Wallacean island survived for hundreds of millennia and underwent unexpected evolutionary changes, including shrinking dramatically in both body and brain size. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/217175/original/file-20180502-153873-1rc6eh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/217175/original/file-20180502-153873-1rc6eh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/217175/original/file-20180502-153873-1rc6eh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=433&fit=crop&dpr=1 600w, https://images.theconversation.com/files/217175/original/file-20180502-153873-1rc6eh6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=433&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/217175/original/file-20180502-153873-1rc6eh6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=433&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/217175/original/file-20180502-153873-1rc6eh6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=544&fit=crop&dpr=1 754w, https://images.theconversation.com/files/217175/original/file-20180502-153873-1rc6eh6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=544&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/217175/original/file-20180502-153873-1rc6eh6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=544&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 Southeast Asia and the wider region during the Late Pleistocene period.</span>
<span class="attribution"><span class="source">Adam Brumm</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>It is possible a similar story of hominins evolving in genetic isolation took place in Luzon; but, that said, the Luzon environments are distinct from those of Flores, so we can’t easily predict the outcome of a new evolutionary “experiment” with different parameters in this Wallacean island. </p>
<p>There may be some real surprises in store when a hominin fossil record is available in Luzon.</p>
<h2>Did “archaics” meet “moderns” in the Philippines?</h2>
<p>Finally, the biggest of big picture questions is whether archaic hominins in Flores and Luzon (and Sulawesi) persisted for long enough to come face-to-face with modern humans, who probably migrated into this area around <a href="https://www.nature.com/articles/nature23452">70,000 years ago</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/worlds-scientists-turn-to-asia-and-australia-to-rewrite-human-history-88697">World's scientists turn to Asia and Australia to rewrite human history</a>
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<p>We now know from ancient DNA studies that our species <a href="https://theconversation.com/worlds-scientists-turn-to-asia-and-australia-to-rewrite-human-history-88697">interbred</a> with at least two (but probably more) archaic hominin species encountered by modern humans outside Africa: Neanderthals and Denisovans. </p>
<p>Could there have been other gene flow events involving unique populations of archaic humans scattered throughout Wallacea? </p>
<p>We don’t yet know the answer to that question.</p><img src="https://counter.theconversation.com/content/95879/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam Brumm receives funding from the Australian Research Council.</span></em></p>Humans butchered a rhino in a remote part of the Philippines 700,000 years ago, but who were they and how did they get there?Adam Brumm, ARC Future Fellow, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/915842018-02-12T14:15:21Z2018-02-12T14:15:21ZWhat ancient footprints can tell us about what it was like to be a child in prehistoric times<figure><img src="https://images.theconversation.com/files/205918/original/file-20180212-58327-vep4i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Footprint from 700,000 years ago.</span> <span class="attribution"><span class="source">Matthew Bennett</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Western society has a rather specific view of what a good childhood should be like; protecting, sheltering and legislating to ensure compliance with it. However, perceptions of childhood <a href="https://doi.org/10.1017/9781108227629">vary greatly</a> with geography, culture and time. What was it like to be a child in prehistoric times, for example – in the absence of toys, tablets and television? </p>
<p>In our new paper, <a href="https://www.nature.com/articles/s41598-018-21158-7">published in Scientific Reports</a>, we outline the discovery of children’s footprints in Ethiopia which show how children spent their time 700,000 years ago.</p>
<p>We first came across the question of what footprints can tell us about past childhood experiences a few years back while studying some <a href="https://doi.org/10.1016/j.jafrearsci.2014.05.015">astonishingly beautiful children’s footprints</a> in Namibia, just south of Walvis Bay. In archaeological terms the tracks were young, dating only from around 1,500 years ago. They were made by a small group of children walking across a drying mud surface after a flock of sheep or goats. Some of these tracks were made by children as young as three-years-old in the company of slightly older children and perhaps young adolescents. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/205696/original/file-20180209-51731-kf5fqi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/205696/original/file-20180209-51731-kf5fqi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=228&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205696/original/file-20180209-51731-kf5fqi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=228&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205696/original/file-20180209-51731-kf5fqi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=228&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205696/original/file-20180209-51731-kf5fqi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=287&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205696/original/file-20180209-51731-kf5fqi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=287&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205696/original/file-20180209-51731-kf5fqi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=287&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Namibian footprints.</span>
<span class="attribution"><span class="source">Matthew Bennett</span>, <span class="license">Author provided</span></span>
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</figure>
<p>The detail in these tracks, preserved beneath the shifting sands of the Namibian Sand Sea, is amazing, and the pattern of footfall – with the occasional skip, hop and jump – shows they were being playful. The site also showed that children were trusted with the family flock of animals from an early age and, one assumes, they learnt from that experience how to function as adults were expected to within that culture. </p>
<h2>No helicopter parents</h2>
<p>But what about the childhood of our earlier ancestors – those that came before anatomically modern humans (<em>Homo sapiens</em>)? Children’s tracks by <a href="https://www.smithsonianmag.com/science-nature/homo-antecessor-common-ancestor-of-humans-and-neanderthals-143357767/">Homo antecessor</a> (1.2m to 800,000 years ago) <a href="https://doi.org/10.1371/journal.pone.0088329">were found at Happisburgh in East Anglia</a>, a site dating to a million years ago. Sadly though, these tracks leave no insight into what these children were doing.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/205705/original/file-20180209-51731-zvclug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/205705/original/file-20180209-51731-zvclug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=729&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205705/original/file-20180209-51731-zvclug.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=729&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205705/original/file-20180209-51731-zvclug.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=729&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205705/original/file-20180209-51731-zvclug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=916&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205705/original/file-20180209-51731-zvclug.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=916&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205705/original/file-20180209-51731-zvclug.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=916&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Reconstruction of Homo Heidelbergensis.</span>
<span class="attribution"><span class="source">Jose Luis Martinez Alvarez/wikipedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>But the footprints described in our recent study – from a remarkable site in the Upper Awash Valley of Southern Ethiopia that was excavated by researchers from the <a href="http://en.uniroma1.it/">Università di Roma “La Sapienza”</a> – reveal a bit more. The children’s tracks were probably made by the extinct species <a href="http://humanorigins.si.edu/evidence/human-fossils/species/homo-heidelbergensis"><em>Homo heidelbergensis</em></a>(600,000 to 200,000 years ago), occurring next to adult prints and an abundance of animal tracks congregated around a small, muddy pool. Stone tools and the butchered remains of a hippo were also found at the site, called Melka Kunture. </p>
<p>This assemblage of tracks is capped by an ash flow from a nearby volcano which has been dated to 700,000 years ago. The ash flow was deposited shortly after the tracks were left, although we don’t know precisely how soon after. The tracks are not as anatomically distinct as those from Namibia but they are smaller and may have been made by children as young as one or two, standing in the mud while their parents and older siblings got on with their activities. This included knapping the stone tools with which they butchered the carcass of the hippo. </p>
<p>The findings create a unique and momentary insight into the world of a child long ago. They clearly were not left at home with a babysitter when the parents were hunting. In the harsh savannah plains of the East African Rift Valley, it was natural to bring your children to such daily tasks, perhaps so they could observe and learn.</p>
<p>This is not surprising, when one considers the wealth of ethnographic <a href="https://doi.org/10.1017/9781108227629">evidence from modern, culturally distinct human societies</a>. Babies and children are most often seen as the lowliest members of their social and family groups. They are often expected to contribute to activities that support the mother, and the wider family group, according to their abilities. In many societies, small boys tend to help with herding, while young girls are preferred as babysitters. Interestingly, adult tools – like axes, knives, machetes, even guns – are often freely available to children as a way of learning.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/205714/original/file-20180209-51713-iq9e5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/205714/original/file-20180209-51713-iq9e5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=396&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205714/original/file-20180209-51713-iq9e5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=396&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205714/original/file-20180209-51713-iq9e5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=396&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205714/original/file-20180209-51713-iq9e5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=497&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205714/original/file-20180209-51713-iq9e5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=497&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205714/original/file-20180209-51713-iq9e5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=497&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Artistic impression of scene at Melka Kunture.</span>
<span class="attribution"><span class="source">Matthew Bennett</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>So, if we picture the scene at Melka Kunture, the children observing the butchery were probably allowed to handle stone tools and practice their skills on discarded pieces of carcass while staying out of the way of the fully-occupied adults. This was their school room, and the curriculum was the acquisition of survival skills. There was little time or space to simply be a child, in the sense that we would recognise today.</p>
<p>This was likely the case for a very long time. The <a href="http://www.tandfonline.com/doi/abs/10.1080/10420940802470748?journalCode=gich20">Monte Hermoso Human Footprint Site</a> in Argentina (roughly 7,000-years-old) contains predominantly small tracks (of children and women) preserved in coastal sediments and it has been suggested that the children <a href="http://www.tandfonline.com/doi/abs/10.1080/10420940802470748">may have played an important role</a> in gathering seafood or coastal resources. Similarly, most of the tracks in the <a href="http://www.bradshawfoundation.com/france/bison-tuc-d-audoubert/index.php">Tuc d'Audoubert Cave</a> in France (15,000-years-old) <a href="http://www.bradshawfoundation.com/france/bison-tuc-d-audoubert/bison-tuc-d-audoubert2.php">are those of children</a> and the art there is striking. Perhaps they were present when it was carved and painted? </p>
<p>However, these observations contrasts to the story that <a href="https://www.ncbi.nlm.nih.gov/pubmed/19251625">emerged last year</a> based on tracks from the older Homo <em>Homo erectus</em> (1.5m-year-old) at Ileret, located further south in the Rift Valley, just within the northern border of Kenya. Here the tracks <a href="https://dx.doi.org/10.1038%2Fsrep26374">have been interpreted</a> as the product of adult hunting groups moving along a lake shore, rather than a domestic scene such as that at Melka Kunture. However, these scenes aren’t mutually exclusive and both show the power of footprints to provide a snapshot into past hominin behaviour. </p>
<p>But it does seem like the overwhelming parenting lesson from the distant past is that children had more responsibilities, less adult supervision and certainly no indulgence from their parents. It is a picture of a childhood very different from our own, at least from the privileged perspective of life in Western society.</p><img src="https://counter.theconversation.com/content/91584/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matthew Robert Bennett receives funding from UK Natural Environment Research Council. </span></em></p><p class="fine-print"><em><span>Sally Christine Reynolds 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>Children in the distant past were put to work early, reveal footprints.Matthew Robert Bennett, Professor of Environmental and Geographical Sciences, Bournemouth UniversitySally Christine Reynolds, Senior Lecturer in Hominin Palaeoecology, Bournemouth UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/756672017-04-06T13:37:14Z2017-04-06T13:37:14ZOur ancestors were cannibals – and probably not because they needed the calories<figure><img src="https://images.theconversation.com/files/164182/original/image-20170405-14612-1a6tgyw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Homo neanderthalensis reconstruction.</span> <span class="attribution"><span class="source">Matteo De Stefano/MUSE Science ms </span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>In the recently released horror movie <a href="http://www.imdb.com/title/tt4954522/">Raw</a>, a lifelong vegetarian teenager arrives at a veterinary school and, after being forced to consume a rabbit kidney at a student initiation ritual, discovers a deep desire to eat human flesh. Most of us are fascinated with cannibalism – and there are many examples of brutal and dark dramas exploring the topic, including <a href="http://www.imdb.com/title/tt0102926/">Silence of the Lambs</a> and Hannibal. </p>
<p>But in real life, cannibalism hasn’t just been practised by bloodthirsty psychopaths. Common motivations for eating human flesh include <a href="http://www.dailymail.co.uk/news/article-4076244/Distressing-photos-1920s-Russian-famine-turned-hopeless-peasants-cannibals-five-million-people-starved-death.html">periods of starvation</a>, <a href="http://news.bbc.co.uk/1/hi/world/africa/2661365.stm">warfare</a> and <a href="http://www.smithsonianmag.com/travel/sleeping-with-cannibals-128958913/">ritualistic behaviour</a>. And it hasn’t been all that uncommon – many of our ancestors were actually cannibals. But exactly why has remained a bit of a mystery. In a new paper, <a href="http://nature.com/articles/doi:10.1038/srep44707">published in Scientific Reports</a>, I have now started to answer the question.</p>
<p>We know from archaeological evidence that cannibalism took place across prehistoric western Europe. A <a href="https://www.sparrho.com/item/archaeological-evidence-for-cannibalism-in-prehistoric-western-europe-from-homo-antecessor-to-the-bronze-age/b0bb47/">recent review</a> – covering a period from 960,000 years ago to the Bronze Age – shows that it must have been fairly common, given the number of hominin remains that show evidence of cut marks and human gnaw marks. We have also found many broken long bones – indicating an effort to get to the marrow. </p>
<h2>Nutritional value of human flesh</h2>
<p>We can’t know exactly why these societies were cannibalistic. But researchers have broadly interpreted it to be “<a href="https://www.sparrho.com/item/archaeological-evidence-for-cannibalism-in-prehistoric-western-europe-from-homo-antecessor-to-the-bronze-age/b0bb47/">nutritional cannibalism</a>”, forming a regular component of a species’ overall diet. This is because most of the marks found on the skeletal remains relate to processing the carcass for food, such as getting to the the marrow. If the bodies were cut up for ritual purposes, such as defleshing, we would expect to see more scraping marks along the bone as they were cleaned of their flesh. But despite assuming that corpses were eaten for nutrition, we still don’t have a clear idea of how nutritional (in the sense of calories) humans actually are.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/164184/original/image-20170405-14629-43rcoe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/164184/original/image-20170405-14629-43rcoe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=455&fit=crop&dpr=1 600w, https://images.theconversation.com/files/164184/original/image-20170405-14629-43rcoe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=455&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/164184/original/image-20170405-14629-43rcoe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=455&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/164184/original/image-20170405-14629-43rcoe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=572&fit=crop&dpr=1 754w, https://images.theconversation.com/files/164184/original/image-20170405-14629-43rcoe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=572&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/164184/original/image-20170405-14629-43rcoe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=572&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Gough’s Cave in Somerset (UK), 14,700 years ago. Facial remains show cutting marks where the meat has been removed, a clear sign of cannibalism. Picture from London’s Natural History Museum.</span>
<span class="attribution"><span class="source">José-Manuel Benito Alvarez</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>I attempted to find out by looking at cannibalism in the Pleistocene – a period from about 2.5m to 11,700 years ago, often broadly referred to as the Ice Age. This study includes human species such as ourselves (<em>Homo sapiens</em>), <em>Homo Neanderthalensis</em>, <em>Homo erectus</em> and <em>Homo antecessor</em>.</p>
<p>I started by creating a “nutritional template” for the human body by incorporating <a href="http://www.jbc.org/content/158/3/625.full.pdf">data on its chemical composition</a>. This data provided the protein and fat content of each body part, which I then converted into calorie values. One gram of protein is about four calories and one gram of fat is about nine. However, as these measurements come from modern humans we cannot be sure exactly how they would vary for related human species. Neanderthals, for example, had slightly greater muscle mass.</p>
<p>Nevertheless, I then compared these proxy values to those of animal species such as mammoth, bison, horse and reindeer, which we know that our ancestors often consumed. Indeed, archaeologists have found plenty of such animal remains at the same sites where there’s evidence of cannibalism. Interestingly, the calorific value of humans is not very high when compared to such animals. Indeed, when muscle masses are compared, a single horse can return approximately the same number of calories as up to six human individuals. </p>
<p>I argue that this suggests that the idea that early humans hunted and consumed groups of their own species only for nutritional purposes makes little sense – given that there were better options around. Indeed, we don’t have a huge number of remains from these species at hand, but within that small record there’s a relatively large sample of remains that appear to have been butchered. So it seems unlikely that cannibalism only occured infrequently during periods of starvation.</p>
<h2>Interpreting the data</h2>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/163654/original/image-20170403-21983-181md7i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/163654/original/image-20170403-21983-181md7i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1008&fit=crop&dpr=1 600w, https://images.theconversation.com/files/163654/original/image-20170403-21983-181md7i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1008&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/163654/original/image-20170403-21983-181md7i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1008&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/163654/original/image-20170403-21983-181md7i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1267&fit=crop&dpr=1 754w, https://images.theconversation.com/files/163654/original/image-20170403-21983-181md7i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1267&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/163654/original/image-20170403-21983-181md7i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1267&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Homo antecessor female eating a human head.</span>
<span class="attribution"><span class="source">Jose Luis Martinez Alvarez from Asturias, España/Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>So why then did prehistoric cannibalism occur? In short, there cannot have been a single reason. Each episode of prehistoric cannibalism will undoubtedly have had its own complex reason for occurring. But the poor calorific return of human flesh suggests to me that it may have been down to social or cultural reasons rather than the need to fill a gap in the diet. For example, it may be related to the social defence of resources or territory from interlopers who, having been killed, were then consumed. </p>
<p>Also, we shouldn’t underestimate the cultural and social sophistication of these species. Recent studies looking at the broader behavioural patterns for our ancestors, including the neanderthals, have started to show that they may have been <a href="https://www.ncbi.nlm.nih.gov/pubmed/23928352">more culturally complex</a> than previously thought.</p>
<p>Recent <a href="https://www.ncbi.nlm.nih.gov/pubmed/21179161">palaeo-genetic studies</a> also hint at a more explicit and active degree of social interaction and interbreeding between hominin species than was thought possible. This <a href="https://theconversation.com/jaw-bone-discovery-reveals-more-about-secret-sex-lives-of-neanderthals-and-early-humans-43656">includes interbreeding between our own species and the Neanderthals</a>. For those genetic exchanges to have taken place, I would argue that there must have been not only a recognised biological similarity between the species, but also a cultural parity in terms of ability for language communication and symbolism. Indeed, it has already been recognised that different Neanderthal groups may have had distinct <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0119802">cultural and symbolic traditions</a> and a <a href="http://www.pnas.org/content/111/1/81">varied attitude to the burial of their dead</a>. </p>
<p>Why then would these species not also have had a variety of motivations for consuming members of their own species? Yet dietary motivations cannot be discounted as a driver for prehistoric cannibalism – it could be that these species were opportunists, eating anything they came across. But we should equally not discount the possibility that social motivations could have played an important role in determining why acts of cannibalism took place.</p><img src="https://counter.theconversation.com/content/75667/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Cole 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 study estimates the nutritional value of human flesh and challenges the belief that prehistoric humans engaged in cannibalism just to fill their stomachs.James Cole, Senior Lecturer in Archaeology, University of BrightonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/649812016-09-07T19:20:33Z2016-09-07T19:20:33ZKenyan farmer’s unique rock find uncovers new prehistoric clues<figure><img src="https://images.theconversation.com/files/136892/original/image-20160907-25257-16yvp1l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A prehistoric hand-held multipurpose stone tool the size of a person's palm recovered by a farmer in Kenya. More tools were found during a search.</span> <span class="attribution"><span class="source">Stephen Thompson</span></span></figcaption></figure><p>Untold numbers of relics from our human past lie along cattle paths, on farms and in remote expanses across Africa. These include fossilised bones of ancients and the animals they preyed on as well as hearths, tools, jewellery and even footprints. </p>
<p>The most durable of these prehistoric calling cards often comprise stone tools. But it’s not easy determining what’s prehistoric and special, and what’s not.
In rare cases someone will recognise a piece of stone that stands out, or appears modified and call attention to it. This is what happened earlier this year at Eor Enkitok village in Narok, Kenya. Francis Yaipan picked up a tear-drop shaped rock on his family farm that puzzled him so much that he made contact with the Kenyan <a href="http://www.museums.or.ke/content/blogcategory/11/17/">National Museum</a>. </p>
<p>The unique piece of rock, carefully crafted on both sides, turned out to be a hand-held multipurpose stone tool the size of a person’s palm. It was crafted by a human ancestor using locally available volcanic rock tens of thousands of years ago. An initial visit by Nairobi museum scientists established that there were more prehistoric tools in eroded volcanic ash layers nearby. </p>
<p>The <a href="http://news.nationalgeographic.com/2015/04/150416-oil-fish-hearts-spill-tuna-gulf-bp-deepwater-exxon-alaska/150416-oldest-stone-tools-archaeology-kenya-human-origins-evolution/">world’s oldest tools</a> date some 3.3 million years and are from Lomweki in Turkana in northeastern Kenya. Kenyan sites boast a record of human cultural evolution that charts stone tool technological progress from 3.3 million years to 800 years ago. </p>
<p>But the evidence from Kenya and other African prehistoric sites is not sufficient to paint a clear picture of the first appearance, duration and variation of technologies found so far. Just as important is knowing which of these technologies are definitively made by our species – Homo sapiens – and which were made by <a href="http://www.livescience.com/41048-facts-about-homo-erectus.html">Homo erectus</a>. </p>
<p>The Narok finds are significant because they straddle two technological phases. These are:</p>
<ul>
<li><p>the <a href="http://www.macroevolution.net/acheulean.html">Acheuluen</a>, a technology that is traced to Homo erectus, and </p></li>
<li><p>the <a href="http://humanorigins.si.edu/evidence/behavior/stone-tools/middle-stone-age-tools">Middle Stone Age</a>, technology firmly linked to our species.</p></li>
</ul>
<h2>Early humans occupied this locality</h2>
<p>I was part of a bigger team that <a href="http://mobile.nation.co.ke/news/Early-man-tools-find-sparks-new-research-ideas/1950946-3347226-format-xhtml-t340f6/index.html">returned</a> to the Narok site in August 2016. At the top layer, the scientists found small tools in shiny obsidian. In the middle and lower layers, few obsidian tools were found and those present had carbonate impurities in them that rendered them less useful for making tools. </p>
<p>The sequential layers consisted of prehistoric soils sandwiched between layers of volcanic ash. The ash from volcanic activity would have been deposited repeatedly over extended periods of time. It was rapidly sealed and protected surfaces from erosion, preserving them for posterity. The site was also used by other generations during periods of geological respite. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/136898/original/image-20160907-25240-11oa01e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/136898/original/image-20160907-25240-11oa01e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/136898/original/image-20160907-25240-11oa01e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/136898/original/image-20160907-25240-11oa01e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/136898/original/image-20160907-25240-11oa01e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/136898/original/image-20160907-25240-11oa01e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/136898/original/image-20160907-25240-11oa01e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/136898/original/image-20160907-25240-11oa01e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A 2.5cm arrowhead made of obsidian imported from distant sources was also found at the site.</span>
<span class="attribution"><span class="source">Stephen Thompson</span></span>
</figcaption>
</figure>
<p>Tens of thousands of years later nothing hints at the tribulations, successes and ingenuity of the ancients that lived here. Along the village paths of what is today land of the Maasai, cows make their way uphill from the river, potato plants in purple bloom sway in the breeze and locals talk about the price of wheat. </p>
<p>The Narok site holds a long record of technological evidence that ranges from the Acheulean, Middle Stone Age to the later Stone Age. This helps in the understanding of technological changes and adaptations that ancients used to overcome environmental constraints and probably thrive. </p>
<p>The closest prehistoric tools that technologically approximate the Narok lower level finds are from the <a href="http://scholar.harvard.edu/catryon/kapthurin-formation-lake-baringo-kenya">Kapthurin Formation</a> in Baringo, also in Kenya. These date to over 200,000 years. Kapthurin is one of the few well-dated localities that represent a transitional Early to the Middle Stone Age phase.</p>
<h2>Yet another possible connection</h2>
<p>Further analyses will reveal the true age of the new Narok site. It will also help answer many of Francis Yaipan’s questions: What did they use the tools for? How old are they? How do we know? Did ancient Maasai make them? He also makes his own efforts to find answers. </p>
<p>Yaipan’s unceasing enquiries led to information from a community elder about a cave (enkampune) site near a river. On a cold morning in August we linked up with this elder, a retinue of his neighbours. We all trooped downhill to a wooded pathless area. We end up not at a cave but a rock shelter. </p>
<p>We decided against any excavation. Less that 35 km away is another well-studied prehistoric rock shelter site dating to 40,000 years. It is appropriately named Enkampune ya Muto or “Cave of the river”. As scientists, we are very excited about yet another possible connection. </p>
<p>There is a chance that during the some 130,000 to 5,000 years ago, that prehistoric occupants of this enkampune could have used the upper levels of the Yaipan site 1.5 kilometres away as a workshop. For now we would have to focus our energy, limited time and funds on the Yaipan site upslope.</p>
<p>To get a clearer picture of the site’s context, we collect surface artefacts, fossil remains, soil and volcanic ash samples. We walk in the areas around the site tracing out the different layers of volcanic ash. Two teenaged boys lead the way cautioning us to avoid a thicket where they had sighted leopard cubs the day before. We finally find a quarry still in use that may also have been exploited by prehistoric people at the Yaipan site.</p>
<p>At the end of the expedition, a motley crew of scientists, a US engineer, local newspaper reporter, local farmers, elders and teenage boys had worked together to put together a sketch of the picture of the prehistoric site now christened Yaipan. Preliminary analyses of the finds will be done at Nairobi Museum and Yale University. Comprehensive excavations will likely start in 2017. </p>
<p>Then perhaps we will able to tell the people of the village of Eor Enkitok how far back humans walked this land, how they lived and what the environment was like. Regardless of our future findings, it is indisputable that the cumulative inventions, decisions and choices made by the ancients at Yaipan’s site contributed to our success as human beings.</p><img src="https://counter.theconversation.com/content/64981/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Acknowledgement: This short expedition was supported by the National Museums of Kenya, and was funded by scientists from the Museum (Dr. Job Kibii, Dr. Christine Ogolla, Mr. John Mwangi) and Dr. Veronica Waweru of the McMillan Center for Area and International Studies, Yale University. Stephen Thompson assisted with the photography.
</span></em></p>Scientists are hoping that ancient stone tools found on a family farm in Kenya will add to a clearer picture of the first appearance, duration and variation of prehistoric technologies found so far.Veronica Waweru, Lecturer in African Studies, Yale UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/595292016-06-08T20:06:29Z2016-06-08T20:06:29ZHow the Hobbits kept their tools as they shrank into island life<figure><img src="https://images.theconversation.com/files/125086/original/image-20160603-11593-ub4l6j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A 700,000 year-old stone tool excavated by an Indonesian field worker at Mata Menge, Flores. </span> <span class="attribution"><span class="source">Yinika Perston</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The scientific debate continues over the bones of the mysterious human-like creature <a href="http://australianmuseum.net.au/homo-floresiensis"><em>Homo floresiensis</em></a> – nicknamed “Hobbits” – with the discovery of new fossils in the So'a Basin on the island of Flores, Indonesia, dating to <a href="http://nature.com/articles/doi:10.1038/nature17663">700,000 years ago</a>.</p>
<p>But one often-overlooked aspect is that <em>Homo floresiensis</em> used technology —- in this case stone toolkits —- to adapt to the exotic Flores environment. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/124411/original/image-20160530-874-1e3vnbm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/124411/original/image-20160530-874-1e3vnbm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/124411/original/image-20160530-874-1e3vnbm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=344&fit=crop&dpr=1 600w, https://images.theconversation.com/files/124411/original/image-20160530-874-1e3vnbm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=344&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/124411/original/image-20160530-874-1e3vnbm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=344&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/124411/original/image-20160530-874-1e3vnbm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=432&fit=crop&dpr=1 754w, https://images.theconversation.com/files/124411/original/image-20160530-874-1e3vnbm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=432&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/124411/original/image-20160530-874-1e3vnbm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=432&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Field site of Mata Menge in the So’a Basin, Flores, Indonesia, with the active volcano, Ebulobo, on the horizon. The hominin fossils were uncovered in the area shaded by the silver tarp.</span>
<span class="attribution"><span class="source">Yinika Perston</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Island life</h2>
<p><em>Homo floresiensis</em> and its ancestors lived on Flores from about 1 million to 50,000 years ago, camping in limestone caves and on the banks of streams and lakes amid active volcanoes. It was a tropical landscape populated by miniature elephants, giant rats and Komodo dragons.</p>
<p>Analysis of these <a href="http://nature.com/articles/doi:10.1038/nature17999">new fossils</a> supports the <a href="http://www.nature.com/nature/journal/v431/n7012/full/nature02999.html">hypothesis</a> that <em>Homo floresiensis</em> evolved from a population of large-bodied <a href="http://australianmuseum.net.au/homo-erectus"><em>Homo erectus</em></a> that were stranded on the island and subjected to the “island rule”. This is where selective pressures unique to islands cause large-bodied animal species to become smaller over time. </p>
<p>Surprisingly, we now have evidence that the founding population of <em>Homo erectus</em> shrunk to Hobbit size and evolved into the new species, <em>Homo floresiensis</em>, within 300,000 years of arriving there.</p>
<p>This is a dramatically short period in evolutionary terms. Yet this hominin used tools they made to adapt to the Flores environment, which in turn raises interesting questions about the technological niche characteristic of the genus <em>Homo</em>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/124412/original/image-20160530-894-1rnuxoj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/124412/original/image-20160530-894-1rnuxoj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/124412/original/image-20160530-894-1rnuxoj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=284&fit=crop&dpr=1 600w, https://images.theconversation.com/files/124412/original/image-20160530-894-1rnuxoj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=284&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/124412/original/image-20160530-894-1rnuxoj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=284&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/124412/original/image-20160530-894-1rnuxoj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=356&fit=crop&dpr=1 754w, https://images.theconversation.com/files/124412/original/image-20160530-894-1rnuxoj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=356&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/124412/original/image-20160530-894-1rnuxoj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=356&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A flaked cobble of silicified volcanic ash found in association with the hominin fossils at Maga Menge. Flakes were struck to two faces of the cobble, creating a sharp edge. Scale bar 50 mm.</span>
<span class="attribution"><span class="source">Mark Moore</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>The stone tools</h2>
<p>Making stone tools might seem like a simple process. After all, how hard can it be to bash rocks together?</p>
<p>But, despite what you might assume, controlling the process is not easy. It requires complex mental evaluations of geometrical configurations on the stone, and blows that are simultaneously <a href="https://www.academia.edu/466217/The_toolmakers_of_Flores">controlled and forceful</a> </p>
<p>I taught myself ancient stoneworking to better understand these tools. As such, I have found that the coarse-grained volcanic river cobbles used by the So'a Basin hominins are very resistant to stone-flaking techniques.</p>
<p>You have to hit a volcanic rock exceptionally hard to initiate a fracture.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/CuVWSfd7jLU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The author shows how flakes are struck from basalt using a hammerstone. The simple method is similar to that used by <em>Homo floresiensis</em> on Flores, but the hominin’s hand and body size was much smaller.</span></figcaption>
</figure>
<p>Even though <em>Homo floresiensis</em> adults were the size of a modern human five-year-old, they were capable of removing volcanic flakes up to 12cm long.</p>
<p>These hominins were small but powerful. They nevertheless had an eye for easier material, and frequently collected small, high-quality flint-like pebbles during their stone forays. </p>
<p>The toolkits themselves were simple, comprising knife-like flakes for various cutting tasks, and the stout-edged <a href="https://sketchfab.com/models/db859323f80b448a9991e5cdcba3d3ff/embed">cobble cores</a> they were struck from which were suitable as heavy chopping tools. The edges of the flakes were sometimes trimmed, perhaps to resharpen them or modify their shape.</p>
<p>You can see it here in three dimensions, thanks to <a href="https://sketchfab.com/mcurry">Michael Curry</a> from <a href="https://sketchfab.com/">Sketchfab</a>.</p>
<iframe width="100%" height="480" src="https://sketchfab.com/models/db859323f80b448a9991e5cdcba3d3ff/embed" frameborder="0" allowfullscreen="" mozallowfullscreen="true" webkitallowfullscreen="true" onmousewheel=""></iframe>
<h2>Stone tool sites</h2>
<p>Although hominin skeletal remains have only been found at two Flores sites – Mata Menge and Liang Bua – this simple stone toolkit has been found at multiple sites in the So'a Basin dating up to <a href="http://www.nature.com/nature/journal/v464/n7289/full/nature08844.html">1 million years ago</a> </p>
<p>The genesis of the hominin tool-making tradition is in Africa, with stone-flaking origins some <a href="https://theconversation.com/our-stone-tool-discovery-pushes-back-the-archaeological-record-by-700-000-years-42103">3.3 million years ago</a>. </p>
<p>Stone toolkits allowed our ancestors to hack meat from tough animal carcasses and cut it into small pieces that were <a href="http://www.sciencemag.org/news/2016/03/how-sliced-meat-drove-human-evolution">more easily chewed and digested</a> Greater access to meat was a key factor in the evolution of a bigger body size and, crucially, a larger brain. </p>
<p>Equipped with toolkits similar to those on Flores, populations of <em>Homo erectus</em> left Africa by 1.8 million years ago and quickly fanned out across Asia. They arrived in Indonesia by <a href="http://onlinelibrary.wiley.com/enhanced/doi/10.1002/ajpa.10399">1.5 million years ago</a> </p>
<h2>Stranded</h2>
<p>The <em>Homo floresiensis</em> story began when one population of <em>Homo erectus</em> became stranded on Flores about 1 million years ago. There are two reasons why this was among the most significant challenges ever faced by a <em>Homo erectus</em> population.</p>
<p>First, landing on Flores from a jumping-off point on Java or <a href="http://news.nationalgeographic.com/2016/01/160113-stone-tool-sulawesi-hobbit-flores-archaeology/">Sulawesi</a> meant that <em>Homo erectus</em> was leaving behind familiar mainland Asian plants and animals to confront on Flores an exotic and unfamiliar mix of Australian and Asian species.</p>
<p>And second, unlike <em>Homo erectus</em> elsewhere in Asia, the Flores colonisers were tightly constrained by the boundaries of this small (13,500 sq km) island. The environmental resources available to them were strictly limited, and moving elsewhere during times of stress was not an option.</p>
<p>You might think that that their stone technology was an “ace in the hole” in confronting these challenges. After all, the global history of <a href="http://australianmuseum.net.au/homo-sapiens-modern-humans"><em>Homo sapiens</em></a> shows that technology is a fabulous means for squeezing the maximum amount of energy possible from the environment. </p>
<p>But our analyses to date show that the Flores hominins continued making simple stone tools in much the same way over their entire million-year long occupation of the island.</p>
<h2>Shrinking</h2>
<p>While this was sufficient for the population’s survival, it was not sufficient to buffer it from the extremes of the selective pressures encountered on Flores. </p>
<p>Hence their skeletal anatomy and body shapes <a href="http://www.isita-org.com/jass/Contents/2016vol94/Baab/26829572.pdf">morphed</a> and their cranial capacity <a href="http://rspb.royalsocietypublishing.org/content/280/1760/20130338.short">dramatically decreased</a> </p>
<p>Yet, paradoxically, <em>Homo floresiensis</em> didn’t lose the capability to make stone tools. Their brains reorganised to retain the complex cognitive abilities necessary to make and use their toolkit, and the dramatic changes in body shape must have accommodated the physical requirements of forceful stone-flaking.</p>
<p>The hominin’s technological abilities had entered an evolutionary cul-de-sac: crucial to the survival of these enigmatic creatures, yet unable to be enhanced to break free from the island rule.</p>
<p>The <em>Homo floresiensis _story may be a lesson for all of us. There was nothing inevitable about the genus _Homo</em> using technology to conquer the planet, and technology may not always serve as a firewall between us and the powerful forces of natural selection.</p><img src="https://counter.theconversation.com/content/59529/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Moore's research was partly funded by the Australian Research Council (DP1096558)</span></em></p>New fossil finds show the first large-bodied inhabitants of an isolated Indonesian island evolved to Hobbit-size, but they always remembered how to make and use stone tools.Mark Moore, Senior Lecturer in Archaeology, University of New EnglandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/504162015-11-25T12:33:43Z2015-11-25T12:33:43ZHomo naledi may be two million years old (give or take)<figure><img src="https://images.theconversation.com/files/101607/original/image-20151111-9400-17a11sc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Professor Lee Berger from the University of the Witwatersrand holding the skull of Homo Naledi.</span> <span class="attribution"><span class="source">EPA/Shiraaz Mohamed</span></span></figcaption></figure><p>There has been global interest in the announcement of new fossils from a cave called Rising Star in the <a href="http://www.maropeng.co.za/videos/entry/sterkfontein-caves-unesco-world-heritage-site">Cradle of Humankind World Heritage Site</a> in South Africa.</p>
<p>These fossils were recently reported by <a href="http://dx.doi.org/10.7554/eLife.09560">Lee Berger</a> and his team, who described the discovery of more than 1500 fossils as representing a new species of the genus Homo. It has been called Homo naledi, associated with a name for star in the Sesotho language.</p>
<p>But the age of Homo naledi is not yet known with certainty. The new species has not yet been dated. Unsuccessful attempts had been made by <a href="http://dx.doi.org/10.7554/eLife.09561">Paul Dirks</a> and members of the Rising Star team to obtain an age. They used techniques applied previously to date a range of fossils. These included Australopithecus africanus, such as the famous <a href="http://www.encounter.co.za/article/58.html">“Mrs Ples”</a> skull, as more than two million years old, and fossils of <a href="http://humanorigins.si.edu/evidence/human-fossils/species/paranthropus-robustus">Paranthropus</a> robustus and <a href="http://www.livescience.com/41048-facts-about-homo-erectus.html">Homo erectus</a>.</p>
<p>In a new <a href="http://www.sajs.co.za/sites/default/files/publications/pdf/SAJS%20111_11-12_Thackeray_Sci%20Cor.pdf">paper</a> in the South African Journal of Science I suggest that Homo naledi lived two million years ago (plus or minus 500,000 years). If shown to be correct, this will help to place Homo naledi in the family tree of human relatives.</p>
<p>The variance is based on the fact that the earliest date for Homo rudolfensis is about 2.5 million years, and the date for certain African Homo erectus samples is about 1.5 million years.</p>
<p>Although different, Homo naledi is most similar to fossils attributed to Homo habilis (about 1.8 million years old), and to a lesser extent to fossils of Homo rudolfensis and Homo erectus.</p>
<p>Taken together I am suggesting that Homo naledi is in the order of two million years old, with upper and lower limits of about 1.5 and 2.5 million years respectively. </p>
<h2>Why is dating so important</h2>
<p>Estimating the age of <a href="http://antiquity.ac.uk/projgall/thackeray335/">fossils</a> is important because it allows palaeoanthropologists the opportunity to try to draw up a family tree. It shows the evolutionary relationships of distant relatives.</p>
<p>Some of the fossil species can be considered to represent possible ancestors of our own species, Homo sapiens, while other species such as <a href="http://humanorigins.si.edu/evidence/human-fossils/species/paranthropus-robustus">Paranthropus</a> robustus can be considered to be evolutionary “dead ends”.</p>
<p>The big question being asked is: where does Homo naledi fit in the evolutionary tree?</p>
<p>It had a small brain of about 500 cubic centimetres in volume. This makes it similar to fossils of Australopithecus. On the other hand, bones of parts of the skeleton, especially the foot, indicate that this species was in some respect remarkably like Homo. </p>
<p>Dating such enigmatic fossils is crucial for an understanding of evolutionary relationships of Homo naledi, compared to more than ten other species which are recognised by palaeontologists.</p>
<p>My approach has been to assess the degree of similarity or dissimilarity between skulls. This can help to assess the age and affinities of fossils.</p>
<h2>Quantifying degrees of similarity between fossils</h2>
<p>Recognising that the new fossils have features of both Australopithecus and Homo, we need to know how old they are. One way of addressing this is to use a technique that I have previously described, based on measurements of <a href="https://theconversation.com/species-without-boundaries-a-new-way-to-map-our-origins-42646">skulls</a>.</p>
<p>Statistics are calculated by taking one set of measurements for specimen A, plotted against the corresponding measurements of specimen B. When A and B are the same species, the values for the two specimens are typically distributed along a straight line, with little scatter around that linear pattern. </p>
<p>When measurements of two specimens (C and D) of different species are plotted against each other, there is a high degree of scatter. The degree of scatter around the line can be quantified using a statistic that I have called log sem, based on a standard mathematical technique that is known as least squares linear regression. </p>
<p>Remarkably, a pattern has been found for comparisons of modern skulls of the same species, whether these are of mammals, birds or reptiles. The mean log sem value for comparisons of pairs of modern species has central tendency around a particular number with a value of -1.61 (plus or minus 0.1), which I have regarded as an approximation of a biological species constant called <a href="http://www.scielo.org.za/pdf/sajs/v103n11-12/a0210312.pdf">T</a>.</p>
<h2>How does this help to date Homo naledi</h2>
<p>Comparisons have been made between the skull measurements of Homo naledi and those of more than ten other recognised species. </p>
<p>It is possible to say that Homo naledi is indeed different because in all cases the log sem statistics for such comparisons is significantly greater than -1.61. </p>
<p>But what is exciting is the fact that of all such comparisons, Homo naledi is most similar to skulls attributed to Homo habilis known to date to about 1.8 million years, and to some extent to other fossils attributed to Homo rudolfensis between about two and 2.5 million years ago.</p>
<p>To a smaller extent Homo naledi is similar to fossil skulls of Homo erectus between about 1.5 and 1.8 million years ago. Using these results, based on comparisons of skulls, I suggest that Homo naledi is two million years old, plus or minus 500,000 years.</p><img src="https://counter.theconversation.com/content/50416/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Francis Thackeray received funding for this study from the National Research Foundation and the A.W. Mellon Foundation</span></em></p>The big question being asked is: where does Homo naledi fit in the evolutionary tree? Assessing the similarity or dissimilarity between fossil skulls has provided a possible clue to the answer.Francis Thackeray, Phillip Tobias Chair in Palaeoanthropology, Evolutionary Studies Institute, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/506292015-11-20T04:36:01Z2015-11-20T04:36:01ZHow science has been abused through the ages to promote racism<figure><img src="https://images.theconversation.com/files/102325/original/image-20151118-14189-1mpkamn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientific evidence shows overwhelmingly that people across the world are genetic refugees from Africa.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Race in <a href="https://www.cbd.int/gti/taxonomy.shtml">human taxonomy</a> – the science of classifying organisms – has a long, disgraceful history. </p>
<p>Individuals have used race to divide and denigrate certain people while promoting their claims of superiority. Some of these individuals were, and are, respected in their time and their fields. They include philosopher and scientist <a href="http://global.britannica.com/biography/Robert-Boyle">Robert Boyle</a> and sociologists like <a href="https://books.google.co.za/books?id=IWDyVPi6pHgC&pg=PA35&lpg=PA35&dq=Hans+G%C3%BCnther+1891+%E2%80%93+1968&source=bl&ots=-UUgXQRqQO&sig=XAyokkxiY_wknDBWZyJ2GEvzsSU&hl=en&sa=X&ved=0CC0Q6AEwBGoVChMI5KapqZGcyQIVRlkUCh3E1AbV#v=onepage&q=Hans%20G%C3%BCnther%201891%20%E2%80%93%201968&f=false">Hans Günther</a>. Others who’ve been guilty include biologists like <a href="http://www.ucmp.berkeley.edu/history/haeckel.html">Ernst Haeckel</a> and historians such as <a href="http://global.britannica.com/biography/Henri-de-Boulainvilliers-comte-de-Saint-Saire">Henri de Boulainvilliers</a>. </p>
<p>What is the history of racially based classifications of humans? And does it have any scientific validity?</p>
<h2>Starting with Kant</h2>
<p>The eminent philosopher <a href="https://books.google.co.za/books?id=TE021UmMiAsC&pg=PA513&lpg=PA513&dq=Immanuel+Kant,+stupid,+trifling&source=bl&ots=FcD4KcVfoq&sig=-2rG2Iqv9Keq2adOa0Wb3PMV6u8&hl=en&sa=X&ved=0CEwQ6AEwCWoVChMIhq7_xpuXyQIVAW8UCh3t5QFM#v=onepage&q=Immanuel%20Kant%2C%20stupid%2C%20trifling&f=false">Immanuel Kant</a> was arguably the first “scientific racist”. He maintained that dark-skinned Africans were “vain and stupid”. He insisted that they were only capable of trifling feelings and were resistant to any form of education other than learning how to be enslaved.</p>
<p>By contrast, Kant maintained, light-skinned Caucasians were “active, acute, and adventurous”. </p>
<p>Renowned German anthropologist <a href="https://embryo.asu.edu/pages/johann-friedrich-blumenbach-1752-1840">Johann Blumenbach</a> used skull anatomy to divide humans into five races:</p>
<ul>
<li><p>Caucasians (Europe and western Asia);</p></li>
<li><p>Mongoloids (eastern Asia);</p></li>
<li><p>Malays (south-eastern Asia);</p></li>
<li><p>Negros (sub-Saharan Africa); and</p></li>
<li><p>Americans (North and South America).</p></li>
</ul>
<p>But he disagreed with the common view that humans from sub-Saharan Africa were inferior. Blumenbach’s “benign” racial categorisation persisted well into the 20th century.</p>
<p><a href="http://global.britannica.com/biography/Samuel-Morton">Samuel Morton</a> drew on refined, quantitative assessments of skull anatomy to provide further “scientific evidence”. He claimed that interracial intellectual variation is reflected by the interior volume of the skull, and that this justified the use of Blumenbach’s groupings to determine relative racial superiority. </p>
<p>He regarded the Caucasian as:</p>
<blockquote>
<p>… distinguished by the facility with which it attains the highest intellectual endowments</p>
</blockquote>
<p>and Africans as</p>
<blockquote>
<p>… joyous, flexible, and indolent; while the many nations which compose this race present a singular diversity of intellectual character, of which the far extreme is the lowest grade of humanity. </p>
</blockquote>
<p>“Scientific racism”“ was used to justify the ownership of <a href="http://abolition.e2bn.org/slavery_40.html">slaves</a>, as well as colonialism. It reached its pinnacle in eugenics, a "science” espoused by the British statistician and sociologist <a href="http://www.ncbi.nlm.nih.gov/pubmed/11700278">Francis Galton</a> at the end of the 19th century. </p>
<p>Eugenicists advocate the “improvement” of humanity by promoting reproduction between people with desired traits and reducing reproduction between people with less-desired traits. Eugenics featured in race-related legislation like Nazi Germany’s <a href="http://www.ushmm.org/outreach/en/article.php?ModuleId=10007695">Nuremberg Laws</a> and <a href="http://www.sahistory.org.za/article/apartheid-and-reactions-it">apartheid-era</a> South Africa’s edicts.</p>
<h2>Genetic evidence</h2>
<p>Genetic studies have examined “racial” variation from a molecular perspective. My early mentor <a href="http://sandwalk.blogspot.co.za/2008/07/good-science-writersrichard-lewontin.html">Richard Lewontin</a>, an evolutionary biologist from the University of Chicago, was a pioneer in this. His research suggested that 90% of modern human genetic diversity is found between individuals within populations. The tiny balance is due to variation between populations. </p>
<p>This view was confirmed by subsequent studies based on DNA by, among others, <a href="http://www.nature.com/ng/journal/v36/n11s/full/ng1435.html">Lynn B. Jorde and Stephen P. Wooding</a>. The DNA among all human populations is 99.5% similar. Populations of the geographically much more restricted chimpanzee exhibit more than four times the <a href="http://humanorigins.si.edu/evidence/genetics/skin-color/modern-human-diversity-genetics">genetic variation</a> that’s found between human populations. Chimpanzees are humans’ nearest living evolutionary “relative”.</p>
<p>Their research shows that when humans are studied from genetic or anatomical perspectives, the pattern that’s discovered is not diagnosable geographically discrete clusters. The norm is gradual, geographically uncorrelated variation in traits and genes. This is even true within peoples who are traditionally thought to be racially homogeneous. There is no evidence of evolutionarily significant racial variation in either genes or anatomy. </p>
<p>The exception is skin colour. Around 10% of the variance in skin colour occurs <a href="http://humanorigins.si.edu/evidence/genetics/skin-color/modern-human-diversity-skin-color">within groups</a> and about 90% between groups. People living near the equator have darker, more melanin-rich skin than those who live at higher latitudes. Darker skin is strongly selected for because it is a natural sunscreen that limits harmful effects of high ultraviolet rays. </p>
<p><a href="http://www.ucpress.edu/book.php?isbn=9780520275898">Recent genetic studies</a> indicate that skin colour may change radically within 100 generations because of natural selection.</p>
<h2>Genetic racism revived</h2>
<p>This overwhelming scientific evidence has not prevented recent studies based on <a href="http://ghr.nlm.nih.gov/glossary=allele">DNA allele frequencies</a> from claiming that there are as many as <a href="http://www.ncbi.nlm.nih.gov/pubmed/12493913">eight races of humans</a>. </p>
<p>British scientific journalist <a href="http://www.americanscientist.org/bookshelf/pub/a-troubling-tome">Nicholas Wade</a> used these studies to claim that natural selection between “races” produced differences in IQ, the efficacy of political institutions and countries’ levels of economic development. </p>
<p>These genetic studies are fundamentally flawed for three reasons: </p>
<ul>
<li><p>Taxonomic studies aimed at determining the validity of races should be based on characters. These are features that are invariant within populations. They should not be based on traits like eye colour and gene alleles, which vary within populations.</p></li>
<li><p>Samples used in the DNA-based studies mentioned above were “cherry picked” geographically to maximise differentiation between human populations, and </p></li>
<li><p>The DNA-based evolutionary racial “trees” were generated by a statistical technique that is designed to produce tree-like patterns which reflect average, not absolute, differences between sampled items. This technique formed the basis of an approach to the construction of evolutionary trees called “phenetics”. It has been decisively discredited and generally abandoned.</p></li>
</ul>
<h2>Evolutionary origins</h2>
<p>DNA and anatomy-based findings support the <a href="http://anthro.palomar.edu/homo/homo_2.htm">“Out of Africa” theory</a>. This holds that modern humans originated in Africa. Archaic African Homo erectus immigrated into Eurasia between 1.4 million to 1.6 million years ago. </p>
<p>About 90,000 to 92,000 years ago, a second form of humanity, modern H. sapiens, also emigrated out of Africa. This species replaced populations of Homo erectus already in the north. </p>
<p>Attempts to justify the scientific reality of human races warrant no further discussion. They cannot be used to assess racial “superiority”. “White” and other non-African people are in fact evolutionary refugees from Africa. After settling in Eurasia, it took only an evolutionary heartbeat for them to lose much of their epidermal melanin. </p>
<p>Dark-skinned humans outside of Africa are descended from migrants who “regained” their “blackness” in <a href="http://faculty.washington.edu/charles/562_f2011/Week%201/Jablonski%202004.pdf">equatorial regions</a> elsewhere.</p><img src="https://counter.theconversation.com/content/50629/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>While he was an academic at the University of Cape Town, his and his students' research was supported by South Africa's National Science Foundation, in some instance in collaboration with other international agencies.</span></em></p>Despite science refuting the existence of different human races, people have used “race” throughout history to divide and denigrate certain people while promoting their claims of superiority.Tim Crowe, Emeritus Professor, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/478402015-09-25T04:31:27Z2015-09-25T04:31:27ZHomo naledi: determining the age of fossils is not an exact science<figure><img src="https://images.theconversation.com/files/95463/original/image-20150920-11714-78ktva.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The skull of Homo naledi is built like those of early Homo species but its brain was just more than half the size of the average ancestor from 2 million years ago. </span> <span class="attribution"><span class="source">SUPPLIED</span></span></figcaption></figure><p>Age is nothing but a number when it comes to unravelling the relationships of species from our past. We do not know the actual geological age of the <a href="http://www.wits.ac.za/homonaledi/">Dinaledi fossils</a>, the single largest fossil hominin find in Africa, but the discovery of <a href="http://voices.nationalgeographic.com/blog/rising-star-expedition/">Homo naledi</a> still provides insight into how our ancestors evolved. </p>
<p>The Dinaledi fossil collection is one of the most complete ever discovered, representing nearly the entire anatomy of a previously unknown species. Yet our team made no statement or conclusion about the fossils’ geological age. I reviewed with Ed Yong some of the <a href="http://www.theatlantic.com/science/archive/2015/09/why-dont-we-know-the-age-of-the-new-human-ancestor-homo-naledi/405148/">reasons</a> why it is difficult to determine the age of the fossils. </p>
<p>The bottom line is that, for now, we have little idea how old the fossils may be. </p>
<p>Most fossil hominins are found in association with extinct animals, which give us at least a general indication of their age. Famous fossil discoveries from more than a century ago, such as the Spy Neanderthal skeletons from Belgium and the first Homo erectus from Java, were found together with long-extinct creatures that indicated they were of great antiquity. This won’t work for Homo naledi because we have found no other animals in association with the hominin bones. </p>
<p>Even today, with methods that rely upon radioactive isotopes to determine the absolute ages of rock layers, geologists often have to revise their initial ideas of the ages of fossils. </p>
<p>Across the last 45 years, the age of the famous KNM-ER 1470 skull of Homo rudolfensis, from Koobi Fora, Kenya, has swung upward and down by more than a half million years as geologists revised age estimates of the famous KBS Tuff. The age of the Sterkfontein Member 4 fossils has been notoriously difficult to determine. Different teams have produced very different ages for the famous Little Foot skeleton from the Silberberg Grotto of Sterkfontein, ranging over more than a million years. </p>
<p>In other words, it pays to be cautious about geology. </p>
<h2>But how old is it?</h2>
<p>Our lack of a geological age for the fossils caught some other experts by surprise. Carol Ward, of the University of Missouri, <a href="http://www.theatlantic.com/science/archive/2015/09/homo-naledi-rising-star-cave-hominin/404362/">commented</a> to The Atlantic:</p>
<blockquote>
<p>“Without dates, the fossils reveal almost nothing about hominin evolution, beyond supporting the growing realisation that there was much more species diversity than previously thought.”</p>
</blockquote>
<p>William Jungers, from Stony Brook University, said in The <a href="http://www.theguardian.com/science/2015/sep/10/new-species-of-ancient-human-discovered-claim-scientist">Guardian</a>. </p>
<blockquote>
<p>“If they are as old as two million years, then they might be early South African versions of Homo erectus, a species already known from that region. If much more recent, they could be a relic species that persisted in isolation. In other words, they are more curiosities than game-changers for now.”</p>
</blockquote>
<p>Whether it turns out to be 20 000 years or 2 million years old, Homo naledi is equally distinct from Homo erectus either way. The age of the fossils is simply not relevant to their relationships with other hominins. In the study of anatomy, we focus on the shared features of different species, not their age. </p>
<p>Indeed, so-called relic species can be among the most important indicators of biological relationships, survivors that carry anatomical features from deep time. The coelacanth is much more than a curiosity: its anatomy provides vital clues that helped scientists understand how early land creatures could evolve from lobe-finned fish ancestors.</p>
<h2>How our ancestors evolved</h2>
<p>No matter its geological age, Homo naledi may provide vital clues about the way our ancestors stepped along a humanlike evolutionary path. This is where the real mystery comes in.</p>
<p>When we look across the skeleton of Homo naledi, we see some puzzling combinations of features. Homo naledi has a foot nearly the same as our own, much more humanlike than any early hominin we’ve discovered so far. Yet its hip and thighbone seem more primitive.</p>
<p>Likewise, Homo naledi had a hand and wrist that were largely humanlike, suitable for manipulating objects and possibly making tools. Yet powerful thumbs, curved finger bones and a shoulder canted upward like an ape’s shoulder suggest that its arms were used for climbing much more than any human today.</p>
<p>The skull of Homo naledi is built like those of early Homo species, especially Homo erectus, but its brain was just more than half the size of the average Homo erectus. Meanwhile, Homo naledi had teeth that were smaller than average for any early Homo species, a trait we have usually linked to eating better, more calorie-rich foods like meat or starchy tubers.</p>
<p>It’s almost as if Homo naledi evolved from the outside in. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/95560/original/image-20150921-31531-1530wz1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/95560/original/image-20150921-31531-1530wz1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=318&fit=crop&dpr=1 600w, https://images.theconversation.com/files/95560/original/image-20150921-31531-1530wz1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=318&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/95560/original/image-20150921-31531-1530wz1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=318&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/95560/original/image-20150921-31531-1530wz1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=400&fit=crop&dpr=1 754w, https://images.theconversation.com/files/95560/original/image-20150921-31531-1530wz1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=400&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/95560/original/image-20150921-31531-1530wz1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=400&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Homo naledi skull DH3 compared with an example of Homo erectus from East Africa.</span>
<span class="attribution"><span class="source">SUPPLIED</span></span>
</figcaption>
</figure>
<p>The traits in direct contact with its environment, used for walking, handling things, and eating, are the most humanlike. The core of Homo naledi’s body, its brain, ribcage and hips, were more like our very distant relatives, the australopiths.</p>
<p>These combinations make it hard to be sure exactly where Homo naledi fits on our family tree. If we trust the humanlike foot and hand, and the Homo erectus-like cranial form, then Homo naledi looks like it may be closer to us than Homo habilis, the famous handy man. </p>
<p>Whether it is closer or not, Homo naledi’s features show that the key changes leading to our genus may have had nothing to do with a large brain. Testing this will bring us closer to understanding the causes that made us human. </p>
<p><em>John <a href="http://johnhawks.net">Hawks</a> is a core scientist on the Rising Star Expedition team and co-author on the papers describing Homo naledi.</em></p><img src="https://counter.theconversation.com/content/47840/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Hawks 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>Despite claims about its age, puzzling combinations of features from Homo naledi gives it an uncanny resemblance to human beings.John Hawks, Paleoanthropologist, University of Wisconsin-MadisonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/203172014-03-03T03:38:33Z2014-03-03T03:38:33ZHuman global domination began with fire, not factories or farms<figure><img src="https://images.theconversation.com/files/38699/original/mspfqvn3-1389218849.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">For millennia, humans have had the tools to change the atmosphere: when will we develop a sense of caution?</span> <span class="attribution"><span class="source">AK Rockefeller/Flickr</span></span></figcaption></figure><p>The era in which humans have had the power to alter the conditions for all life on Earth is widely thought to have begun with the Industrial Revolution 250 years ago.</p>
<p>This era has been dubbed the “Anthropocene”, the age in which humankind has become the dominant influence on the planet, causing widespread mass extinctions in the process. But this era arguably began earlier – much, much earlier – than we think.</p>
<p>In a recent <a href="http://www.sciencedirect.com/science/article/pii/S2213305414000046">paper</a> I argue that humans began dominating the planet not at the Industrial Revolution, or with the advent of farming 10,000 years ago, but deep in the mists of time, back when <em>Homo erectus</em> tamed fire 1.8 million years ago.</p>
<p>Of course our potential influence on the globe is more powerful now, in this age of greenhouse emissions and nuclear technology. But I argue that the crucial step came with fire. That was the moment when humans first learned to unlock large amounts of energy for their own benefit.</p>
<h2>Millennia of development</h2>
<p>Martin Rees, the British Astronomer Royal, has an image he uses during presentations of <a href="http://www.ted.com/talks/martin_rees_asks_is_this_our_final_century.html">Earth as seen by an extraterrestrial witness</a>. During the past 8000 years signatures appear of green cultivation, the lights of big cities, and later an atmosphere clouded with aerosols and greenhouse gases, intermittent nuclear explosions and satellites fired into outer space. And from the perspective of astronomy, geology, the history of life and human evolution, Martin Rees asks a poignant question: Is this our final century?</p>
<p>Of all the factors which allow life on Earth one stands out: the presence of liquid water. And water has been vital for human development. Since the Neolithic and throughout history, cultivation and agriculture-based civilisations concentrated along rivers, such as the Nile, Euphrates and Yellow River, or above groundwater reservoirs, such as in the Yucatan Peninsula, Mexico. </p>
<p>Our development relies on availability of water. Water, in turn, depends on the the hydrological cycle and therefore the climate, including annual river rhythms controlled by melt and freeze relations in source mountain glaciers, the effects of forests on microclimate, soil erosion, and - in some parts of the world such as the Indonesian islands - on volcanic regimes.</p>
<p>Earth’s water is permitted by the planet’s unique orbital position around the Sun, its active tectonic and volcanic nature and its evolving atmospheric composition, which regulates surface temperatures in the range of about -90C to +58C. </p>
<p>The atmosphere, mediating the carbon, oxygen, nitrogen and sulphur cycles, acts as lungs of the biosphere. It allows the existence of an aqueous medium where metabolic microbiological processes occur. These range from chemo-bacteria around volcanic fumaroles, to nanobes in deep crustal fractures, to near-surface phototrophs. </p>
<p>The histories of the atmosphere and of life are inherently interdependent.</p>
<p>Earth started with a Venus-like atmosphere, dominated by CO<sub>2</sub>, CO, SO<sub>2</sub>, N<sub>2</sub>O, CH<sub>4</sub>, H<sub>2</sub> and likely H<sub>2</sub>S. The sequestration of CO<sub>2</sub> and the build-up of nitrogen — a stable non-reactive gas — have led to intermittent ice ages from at least as early as around 3 billion years ago.</p>
<h2>Atmospheric change and extinctions</h2>
<p>We now know periods of gradual evolution were interrupted by abrupt events which transformed the physical state of the atmosphere-ocean system and the state of habitat of plants and organisms and resulted in mass extinction of species. </p>
<p>We mostly <a href="https://theconversation.com/another-link-between-co2-and-mass-extinctions-of-species-12906">think of mass extinctions of species</a> in terms of extreme shifts in the climate, usually from events such as volcanic eruptions, asteroid impacts or massive methane release. </p>
<p>There have been many such extinctions through Earth’s history, but the phenomenon of a biological species perpetrating a mass extinction of species through the fastest-rate climate change recorded, at least for the last 65 million years, is not easily reconciled with the principle of natural selection inherent in Darwinian evolution.</p>
<p>The great late dinosaurs, having survived for nearly 200 million years, vanished unaware through an asteroid strike that <a href="http://press.princeton.edu/titles/8650.html">raised global temperature by 7.5C</a>. But Homo sapiens has over only a couple of centuries raised mean global temperature by near 2C and is proceeding toward 4C (see figure below), despite <a href="http://resources.news.com.au/files/2011/05/22/1226060/682675-aus-news-file-climate-change-11-05-22.pdf">warnings</a> from its <a href="http://www.pik-potsdam.de/news/press-releases/archive/2012/4-degrees-briefing-for-the-world-bank-the-risks-of-a-future-without-climate-policy">own scientists</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/38568/original/vkbm49s2-1389071008.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/38568/original/vkbm49s2-1389071008.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/38568/original/vkbm49s2-1389071008.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=707&fit=crop&dpr=1 600w, https://images.theconversation.com/files/38568/original/vkbm49s2-1389071008.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=707&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/38568/original/vkbm49s2-1389071008.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=707&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/38568/original/vkbm49s2-1389071008.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=888&fit=crop&dpr=1 754w, https://images.theconversation.com/files/38568/original/vkbm49s2-1389071008.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=888&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/38568/original/vkbm49s2-1389071008.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=888&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Jos Hagelaars/Max Edkins/World Bank</span></span>
</figcaption>
</figure>
<h2>The sixth mass extinction</h2>
<p>The Anthropocene – the era of man – has been defined by <a href="http://www.pik-potsdam.de/news/public-events/archiv/alter-net/former-ss/2007/05-09.2007/steffen/literature/ambi-36-08-06_614_621.pdf">Crutzen and Steffen</a> in terms of the onset of the industrial age and by Ruddiman in terms of <a href="http://en.wikipedia.org/wiki/Early_anthropocene">Neolithic agriculture</a>. In this article I refer to the mastery of fire about 1.8 million years ago as the “<a href="http://www.springer.com/earth+sciences+and+geography/earth+system+sciences/book/978-94-007-7331-8">early Anthropocene</a>”.</p>
<p>When a species - such as humans - learns to master ignition and energy output, it leads to an increase in entropy in nature by orders of magnitude. This sets up a biological and cultural chain reaction and a blueprint for that species’ future.</p>
<p>The genus Homo evolved in relatively sheltered sub-tropical rift valleys. Unique among all genera, we learned how to <a href="https://theconversation.com/the-discovery-of-fire-initial-steps-toward-anthropogenic-climate-change-6266">ignite and transfer fire</a> and through this to modify extensive land surfaces of Earth. This had potentially profound consequences for the composition of the atmosphere, a process culminating in the Anthropocene and leading toward the <a href="http://www.actionbioscience.org/newfrontiers/eldredge2.html">sixth mass extinction</a> of species.</p>
<p>Nature includes species whose activities are capable of devastating environments. Toxic viruses, methane- and hydrogen sulphide-emitting bacteria, fire ant armies, locust swarms and rabbit populations can lay waste to their surroundings. Host-destroying organisms include species of fungi, worms, arthropods, annelids and vertebrates such as oxpeckers and vampire bats. The mastery of fire enabled the genus Homo to magnify its potential to harness and release energy by orders of magnitude, potentially adding its name to that list. From the mid-20th century, the splitting of the atom allowed humans to trigger a chain reaction potentially devastating much of the biosphere.</p>
<p>Since the onset of the industrial age in the 18th century and accelerating since the mid-1980s, the release of more than 560 billion ton of carbon (GtC) through industrial emission and land clearing has triggered unprecedented developments in the terrestrial climate at a rate which, with rare exceptions, is faster by an order of magnitude than natural geological warming events. </p>
<p>Whereas comparisons can be made with the “Paleocene-Eocene Thermal Maximum” of about 55 million years ago, the scale and rate of modern global warming may compare more closely with those triggered by major volcanic and asteroid impact events. The non-linear nature of current climate change, multiple feedbacks and their synergy are driving the climate to uncharted territory and possible tipping points. </p>
<p>A species able to magnify its entropy effect in nature by orders of magnitude, as the genus Homo has done through mastery of fire and the splitting of the atom, would need to be a perfectly wise and controlled species, lest its <a href="http://www.springer.com/earth+sciences+and+geography/earth+system+sciences/book/978-94-007-7331-8">invention gets out of hand</a>.</p><img src="https://counter.theconversation.com/content/20317/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Glikson 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 era in which humans have had the power to alter the conditions for all life on Earth is widely thought to have begun with the Industrial Revolution 250 years ago. This era has been dubbed the “Anthropocene…Andrew Glikson, Earth and paleo-climate scientist, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.