tag:theconversation.com,2011:/uk/topics/homo-habilis-17175/articlesHomo habilis – 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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<a href="https://theconversation.com/south-africas-blombos-cave-is-home-to-the-earliest-drawing-by-a-human-103017">South Africa's Blombos cave is home to the earliest drawing by a human</a>
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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/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>
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<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">
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<span class="caption">Sahnouni excavating at the site.</span>
<span class="attribution"><span class="source">M. Sahnouni</span></span>
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<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>
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<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">
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<span class="caption">Stone tool cut marks on animal skeleton.</span>
<span class="attribution"><span class="source">I. Caceres</span></span>
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<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>
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<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">
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<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>
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<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>
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<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>
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<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>
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<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/714282017-03-03T02:08:35Z2017-03-03T02:08:35ZTooth be told: Millions of years of evolutionary history mark those molars<figure><img src="https://images.theconversation.com/files/159217/original/image-20170302-14709-cztki5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Upper teeth of a Neanderthal who lived about 40,000 years ago.</span> <span class="attribution"><span class="source">Debbie Guatelli-Steinberg</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>“Show me your teeth and I’ll tell you who you are.” These words, attributed to 19th-century naturalist George Cuvier, couldn’t be more correct. The pearly whites we use every day over and over and over again are clues not just to our own individual lives but also to our evolutionary history.</p>
<p>Teeth lock into their physical structure remarkable detail about the creatures whose mouths they’re in, whether our own or those of our ancient ancestors. Fossil teeth are tiny time capsules that provide insights into human evolution, including our diverse diets, extended childhoods and other unique features of our species. In my book, “<a href="http://www.cambridge.org/us/academic/subjects/life-sciences/biological-anthropology-and-primatology/what-teeth-reveal-about-human-evolution?format=PB">What Teeth Reveal about Human Evolution</a>,” I explore what anthropologists like me have learned about the past from teeth – and what our own teeth may tell future anthropologists about us.</p>
<h2>Glimpses of past diet through tooth chemistry</h2>
<p>Chemical evidence of diet rests on the principle that you are what you eat. Plants using different photosynthetic pathways incorporate <a href="http://www.jstor.org/stable/1310735">various proportions of carbon isotopes</a> – called C-13 and C-12 – into their cells. Chemists know that tropical grasses and sedges (C4 plants) have proportionally more C-13 in their cells, while other plants, like trees and shrubs (C3 plants), have proportionally less C-13 in their structures. </p>
<p>As tooth enamel forms during childhood, it locks the ratio of ingested C-13 to C-12 into its dense mineral structure. That ratio, which can be preserved unchanged for millions of years, allows anthropologists to determine what kinds of plants ancient teeth were chomping. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/158769/original/image-20170228-29917-1ct8r7h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/158769/original/image-20170228-29917-1ct8r7h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/158769/original/image-20170228-29917-1ct8r7h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=467&fit=crop&dpr=1 600w, https://images.theconversation.com/files/158769/original/image-20170228-29917-1ct8r7h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=467&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/158769/original/image-20170228-29917-1ct8r7h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=467&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/158769/original/image-20170228-29917-1ct8r7h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=586&fit=crop&dpr=1 754w, https://images.theconversation.com/files/158769/original/image-20170228-29917-1ct8r7h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=586&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/158769/original/image-20170228-29917-1ct8r7h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=586&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Chimps stick to woodland foods, such as figs growing on a tree.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Adult_male_chimps_in_mahale.jpg">Caelio</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Chimpanzees, our closest primate relatives, eat a variety of foods; however, the fruits, nuts and seeds they eat primarily come from trees and shrubs. Analyzing the ratio of carbon isotopes in tooth enamel, researchers found that as far back as 3.5 million years ago, Lucy’s species, <em>Australopithecus afarensis</em>, <a href="http://doi.org/10.1073/pnas.1222559110">diversified beyond the chimpanzee diet</a>.</p>
<p>These early human ancestors not only ate from trees and shrubs like chimps, but also from tropical grasses and sedges, <a href="https://blogs.scientificamerican.com/guest-blog/how-to-eat-like-a-chimpanzee/">something chimpanzees don’t do</a> even when these plants are available.</p>
<p>That shift in diet is consistent with the diversity of environments Lucy and her kind inhabited: from woodlands to open grasslands. Teeth tell us our ancestors were moving beyond the forests into new territory and eating what they found there.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/158766/original/image-20170228-29929-18j7c3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/158766/original/image-20170228-29929-18j7c3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=727&fit=crop&dpr=1 600w, https://images.theconversation.com/files/158766/original/image-20170228-29929-18j7c3v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=727&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/158766/original/image-20170228-29929-18j7c3v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=727&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/158766/original/image-20170228-29929-18j7c3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=914&fit=crop&dpr=1 754w, https://images.theconversation.com/files/158766/original/image-20170228-29929-18j7c3v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=914&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/158766/original/image-20170228-29929-18j7c3v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=914&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Barium to calcium ratios show that early <em>Homo</em> included more meat in its diet than did other hominin species.</span>
<span class="attribution"><a class="source" href="http://doi.org/10.1038/nature11349">Reprinted by permission from Macmillan Publishers Ltd: Nature 489, 558–560, copyright 2012</a></span>
</figcaption>
</figure>
<p>From other chemical elements found in tooth enamel, anthropologists have learned that early members of our genus – <em>Homo habilis</em> from South Africa – <a href="http://doi.org/10.1038/nature11349">ate large quantities of meat</a>. This signifies further dietary diversification beyond the generally small amount of meat that chimpanzees eat.</p>
<p>It’s not such a far cry from here to Anthony Bourdain – we humans eat an enormous variety of foods. That versatility probably contributed to our ability to survive in a variety of environments and, ultimately, <a href="http://doi.org/10.1146/annurev.anthro.35.081705.123153">to our evolutionary success</a>. </p>
<h2>Counting the growth lines</h2>
<p>Another uniquely human trait is the extended length of our childhoods. Among primates, humans take the longest to grow up and become <a href="http://doi.org/10.1073/pnas.0402635101">reproducing adults</a> – and the length of time teeth take to grow and erupt into the jaw reflects that fact. While chimpanzee <a href="http://doi.org/10.1007/s10764-012-9607-2">first molars generally come in</a> at around four years of age, those of humans usually do so about two years later.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/159194/original/image-20170302-14706-17bpzks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/159194/original/image-20170302-14706-17bpzks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/159194/original/image-20170302-14706-17bpzks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1556&fit=crop&dpr=1 600w, https://images.theconversation.com/files/159194/original/image-20170302-14706-17bpzks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1556&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/159194/original/image-20170302-14706-17bpzks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1556&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/159194/original/image-20170302-14706-17bpzks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1955&fit=crop&dpr=1 754w, https://images.theconversation.com/files/159194/original/image-20170302-14706-17bpzks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1955&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/159194/original/image-20170302-14706-17bpzks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1955&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Growth lines on the surface of the enamel of an <em>Australopithecus africanus</em> incisor. Oldest growth is at the top edge of the tooth.</span>
<span class="attribution"><span class="source">Debbie Guatelli-Steinberg</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Like trees, tooth enamel grows in layers. Tree rings represent yearly growth; growth lines in enamel form much more quickly. Enamel retains daily growth lines as well as growth lines representing longer periods, centering around eight days. Though we reliably see this eight-day rhythm, it’s still a mystery what that time period reflects, biologically.</p>
<p>Anthropologists can count growth lines in fossil teeth to gauge the rates at which teeth developed in our ancestors. Are they more like chimps or more like us? In individuals who died before all their teeth formed, it’s even possible to count these growth lines (from an accentuated line in enamel that marks birth) to figure out how old they were when they died. Then, researchers can <a href="http://dx.doi.org/10.1371/journal.pone.0118118">compare the stage of dental development</a> – how far tooth growth had proceeded – to the stage of dental development that modern humans achieve at equivalent ages.</p>
<p>From such studies, anthropologists have found that early in human evolution, among Lucy’s kind, <a href="http://dx.doi.org/10.1038/317525a0">teeth developed on an accelerated schedule</a>, suggesting that our ancestors grew up more quickly than we do today. Later in time, with <em>Homo erectus</em>, periods of dental growth and development <a href="http://dx.doi.org/10.1038/414628a">began to lengthen</a>. Though not perhaps evolving for this reason, long childhoods afford humans time for learning and mastering complex skills that are crucial to our survival and reproduction.</p>
<p>In my own research, I’ve used teeth growth lines to understand patterns of enamel growth as well as enamel growth disruption. These have revealed some interesting things: Neanderthals, for example, show evidence of <a href="http://dx.doi.org/10.1016/j.jhevol.2004.05.004">living through physiologically stressful events</a>, such as illness or malnutrition, that disrupted their forming enamel during childhood. Some of these events may have lasted up to three months, as assessed through counting growth lines on the enamel surface.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/159190/original/image-20170302-14703-pc1zaj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/159190/original/image-20170302-14703-pc1zaj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/159190/original/image-20170302-14703-pc1zaj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=464&fit=crop&dpr=1 600w, https://images.theconversation.com/files/159190/original/image-20170302-14703-pc1zaj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=464&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/159190/original/image-20170302-14703-pc1zaj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=464&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/159190/original/image-20170302-14703-pc1zaj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=583&fit=crop&dpr=1 754w, https://images.theconversation.com/files/159190/original/image-20170302-14703-pc1zaj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=583&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/159190/original/image-20170302-14703-pc1zaj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=583&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Arrows point to areas of disrupted growth in the teeth of this ancient Inupiaq individual from Point Hope, Alaska.</span>
<span class="attribution"><span class="source">Debbie Guatelli-Steinberg</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>That finding makes sense, given Neanderthals have traditionally been thought to <a href="http://doi.org/10.1371/journal.pone.0096424">have had hard lives</a>. We’ve found similar enamel disruptions in the teeth of some traditional modern human hunter-gatherers. The teeth of ancient Inupiaq of Point Hope, Alaska, who lived between A.D. 1300 and 1700 exhibited these same <a href="http://dx.doi.org/10.1016/j.jhevol.2004.05.004">long periods of disrupted enamel growth</a>.</p>
<h2>What our teeth will tell the future</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/159197/original/image-20170302-14686-oh1km2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/159197/original/image-20170302-14686-oh1km2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/159197/original/image-20170302-14686-oh1km2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=640&fit=crop&dpr=1 600w, https://images.theconversation.com/files/159197/original/image-20170302-14686-oh1km2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=640&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/159197/original/image-20170302-14686-oh1km2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=640&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/159197/original/image-20170302-14686-oh1km2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=804&fit=crop&dpr=1 754w, https://images.theconversation.com/files/159197/original/image-20170302-14686-oh1km2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=804&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/159197/original/image-20170302-14686-oh1km2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=804&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Green arrows point to where laser ablations were used to analyze the isotopic composition of this 1.8-million-year-old Australopith tooth. Blue arrows point to long-period enamel growth lines. Will our teeth be treated the same in the distant future?</span>
<span class="attribution"><span class="source">SEM image by Debbie Guatelli-Steinberg</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Future dental anthropologists, say 10,000 years from now, will have a field day with our fossilized teeth. If they analyze our enamel chemistry, they’ll be able to determine which of us grew up as vegetarians and which did not. Perhaps they will be surprised to see that humans from the same population groups had such differences in diet. But, more likely, they’ll interpret these interpersonal differences as a natural extension of our evolutionary biology – our large brains allow us behavioral flexibility, including the adaptive ability to eat diverse foods.</p>
<p>Future anthropologists will also be amazed by the extent of our dental problems. A few cases of <a href="http://dx.doi.org/10.1002/9781444345940.ch30">dental disease exist in the human fossil record</a>, but today we are heavily afflicted by <a href="http://www.webmd.com/oral-health/tc/types-of-malocclusion-topic-overview">malocclusions</a> (when teeth don’t come together correctly), third molar <a href="https://medlineplus.gov/ency/article/001057.htm">impactions</a>, <a href="http://www.dentalhealth.ie/dentalhealth/causes/dentalcaries.html">caries</a>, <a href="https://medlineplus.gov/ency/article/001059.htm">periodontitis</a> and other dental maladies that will leave their marks in our remains.</p>
<p>Papers given at scientific meetings of the future may draw upon the idea of “evolutionary mismatch” – that the hunting and gathering diets of our ancestors did not prepare us for the rapid influx of soft and sugary foods that we eat today. Essentially, we are <a href="https://www.ncbi.nlm.nih.gov/pubmed/15699220%20">not adapted to the modern Western diet</a>. The foods our hunter-gatherer ancestors ate were tough to chew and did not include refined sugar. Soft foods don’t stimulate jaw growth during childhood, leading to malocclusions, and sugary foods provide environments for caries-causing bacteria to thrive.</p>
<p>In fact, by extracting bacterial DNA from calcified plaque in ancient teeth, one group of anthropologists found that caries-causing strains of bacteria became <a href="http://dx.doi.org/10.1038/ng.2536">more common with the advent of agriculture</a>. These strains especially flourished in human mouths during the Industrial Revolution, with the first mass production of processed sugar. We’re still suffering these effects today.</p>
<p>Finally, what will future anthropologists make of the myriad ways people alter their teeth? In Western cultures, people take great pains to artificially whiten their teeth. According to one study, conducted in the U.K., subjects found <a href="http://dx.doi.org/10.1371/journal.pone.0042178">whiter teeth more attractive</a>, especially in women. The researchers suggest that white teeth may serve as an age indicator in human mate choice, with males preferring white teeth as a signal of youth.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/158773/original/image-20170228-29933-1936ici.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/158773/original/image-20170228-29933-1936ici.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/158773/original/image-20170228-29933-1936ici.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=798&fit=crop&dpr=1 600w, https://images.theconversation.com/files/158773/original/image-20170228-29933-1936ici.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=798&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/158773/original/image-20170228-29933-1936ici.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=798&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/158773/original/image-20170228-29933-1936ici.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1003&fit=crop&dpr=1 754w, https://images.theconversation.com/files/158773/original/image-20170228-29933-1936ici.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1003&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/158773/original/image-20170228-29933-1936ici.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1003&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Detail from a woodcut of a geisha blackening her teeth.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Geisha_Blackening_Teeth_at_1-00_p.m._LACMA_M.84.31.68.jpg">Tsukioka Yoshitoshi</a></span>
</figcaption>
</figure>
<p>But, then, how does one explain the practice of “tooth blackening” in some traditional Asian cultures, which is also done for aesthetic reasons? And beyond that, how will future anthropologists make sense of the practices of notching teeth, sharpening them into points, inlaying them with jewels or gold, filing them down, or removing them altogether? <a href="https://strangeremains.com/2014/08/26/stylish-deformities-dental-edition/">These practices and others</a> are found in different cultures, and future scholars will likely debate their reasons.</p>
<p>So, the next time you forget to brush or find yourself in the dentist’s chair, remember this: Future anthropologists may ultimately be assessing those choppers.</p><img src="https://counter.theconversation.com/content/71428/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Debbie Guatelli-Steinberg has received funding from the Leakey Foundation and the National Science Foundation. She is affiliated with The Ohio State University and the University of Kent.</span></em></p>Anthropologists gather clues about how our ancient ancestors lived from their teeth. What will future anthropologists make of us based on the fossilized pearly whites we’ll leave behind?Debbie Guatelli-Steinberg, Professor of Anthropology, The Ohio State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/697122017-01-10T19:35:10Z2017-01-10T19:35:10ZWhy are most people right handed? The answer may be in the mouths of our ancestors<figure><img src="https://images.theconversation.com/files/152078/original/image-20170109-23468-nfbyxh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">How our ancestors ate could explain why today's humans are mostly right-handed. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/hugomartinsoliveira/14693903652/">Flickr/Hugo Martins</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>Roughly <a href="https://www.scientificamerican.com/article/why-are-more-people-right/">90% of humans are right-handed</a> and this is one of the traits that separates us from most other primates who don’t really show any overall preference for left or right handedness.</p>
<p>It’s believed that handedness played an important role in human evolution, with a <a href="http://www.sciencedirect.com/science/article/pii/S0047248416300719">recent study</a> on the earliest evidence of right-handedness in the fossil record shedding light on when and why this trait arose. Interestingly, the clues were found not in our ancient hands, but in our ancient teeth.</p>
<p>We have long known that the human brain is composed of two roughly similar halves. The left hemisphere controls language and motor abilities, whereas the right hemisphere is responsible for visual-spatial attention.</p>
<p>It is less well known that brain lateralisation, or the dominance of some cognitive processes in one side of the brain, is a distinctive feature of humans, and one associated with <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3767540/">improved cognitive ability</a>.</p>
<p>Could handedness have played a role in brain lateralisation? Ancient stone tools made and used by our earliest ancestors reveal some clues. </p>
<h2>Use of tools</h2>
<p>The earliest stone tools date to <a href="http://www.nature.com/nature/journal/v521/n7552/full/nature14464.html">3.3 million years ago</a> and were found in modern day Kenya, Africa. Early stone tool making would have required a high level of dexterity. We know from <a href="https://scholarblogs.emory.edu/stoutlab/files/2013/07/Stout-et-al-2000.pdf">experiments</a> that have replicated tool-making processes that the brain’s left hemisphere, which is responsible for planning and execution, is active during this process.</p>
<p>At the same time, humans are overwhelmingly <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1439-0310.1995.tb00362.x/abstract">right-handed</a> when it comes to tool making compared to other species. This is most likely because the left and right hemispheres control motor action on the <a href="https://theconversation.com/how-childrens-brains-develop-to-make-them-right-or-left-handed-55272">opposite sides</a> of the body. </p>
<p>While this relationship is <a href="https://www.scientificamerican.com/article/why-are-more-people-right/">not straightforward</a>, it would appear that, in most cases, handedness and brain lateralisation go hand in hand (pun intended).</p>
<p>So why use teeth to investigate handedness? The answer lies in the scarcity of matching left and right arm bones in the fossil record, particularly those belonging to our earliest ancestors. </p>
<p>Without matching left and right sets, it is impossible to examine differences in size and shape to determine which hand an individual favoured when completing manual tasks.</p>
<p>Teeth, on the other hand, tend to <a href="http://anthro.palomar.edu/time/time_1.htm">survive relatively well</a> in the fossil record and can preserve scratches, or “striations”, that establish handedness.</p>
<p>In an <a href="http://www.sciencedirect.com/science/article/pii/0047248488900292">earlier study</a>, researchers noted striations on the front side of teeth belonging to European Neanderthals. They hypothesised that these marks were made when material was held in one hand and gripped between the front teeth and worked by the other hand with a stone tool, with the stone tool occasionally striking these teeth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/152077/original/image-20170109-23477-16z32g9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/152077/original/image-20170109-23477-16z32g9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/152077/original/image-20170109-23477-16z32g9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=368&fit=crop&dpr=1 600w, https://images.theconversation.com/files/152077/original/image-20170109-23477-16z32g9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=368&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/152077/original/image-20170109-23477-16z32g9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=368&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/152077/original/image-20170109-23477-16z32g9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=462&fit=crop&dpr=1 754w, https://images.theconversation.com/files/152077/original/image-20170109-23477-16z32g9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=462&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/152077/original/image-20170109-23477-16z32g9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=462&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Study finds striations on teeth of a <em>Homo habilis</em> fossil 1.8 million years old moved from left to right, indicating the earliest evidence in the fossil record for right-handedness.</span>
<span class="attribution"><a class="source" href="https://www.eurekalert.org/multimedia/pub/125005.php">David Frayer</a></span>
</figcaption>
</figure>
<p>These actions were replicated during experiments in which participants wore mouthguards. The results indicated that right-slanting striations are made on teeth when material is pulled with the left hand and struck with the right hand. Right-slanting striations are therefore a good indicator of right handedness.</p>
<p>The subject of the <a href="http://www.sciencedirect.com/science/article/pii/S0047248416300719">new study</a> – an ancient upper jawbone – provides the oldest evidence for right-handedness known in our genus <em>Homo</em>.</p>
<p>The jawbone belonged to one of our earliest human ancestors, <a href="http://australianmuseum.net.au/homo-habilis"><em>Homo habilis</em></a> (literally, the “handy man”), who roamed Tanzania in Africa around 1.8 million years ago. The jaw was identified at Olduvai Gorge in the Serengeti Plain, which has yielded some of the <a href="http://science.sciencemag.org/content/299/5610/1217">earliest archaeological traces</a> in the world. </p>
<h2>Marks on teeth</h2>
<p>The authors of the study noted a number of striations on the front side of the teeth. They used high-powered microscopes and digital cameras to investigate these striations, particularly patterning in their direction. </p>
<p>Interestingly, nearly half of all striations were right-slanting. Right-slanting striations were particularly dominant on four of the front teeth (left and right central incisors, right second incisor and right canine).</p>
<p>This led the authors to argue that most marks were made with the individual’s right hand. They also suggested that the four front teeth with many right-slanting striations were the focus of most processing activities.</p>
<p>The <em>Homo habilis</em> jaw is important as it provides the oldest evidence for right-handedness in the fossil record. But it is also significant as it suggests that a major level of brain organisation had occurred in humans by at least 1.8 million years ago.</p>
<p>This brain development enabled us to master crucial early skills such as <a href="http://www.nature.com/scientificamerican/journal/v314/n4/full/scientificamerican0416-28.html">stone tool making</a> and potentially also paved the way for <a href="http://www.sciencemag.org/news/2013/08/striking-patterns-skill-forming-tools-and-words-evolved-together">language development</a>. Right-handedness therefore means a lot more to us than simply a preference for using the right hand.</p>
<p>Just some food for thought next time you are brushing your teeth, sending a text message or high-fiving someone.</p><img src="https://counter.theconversation.com/content/69712/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Caroline Spry has previously received funding from the Australian Government and La Trobe University.</span></em></p>The way early humans learned to handle food could explain why the majority of people today are right handed.Caroline Spry, Honorary Associate, PhD, La Trobe UniversityLicensed 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/462842015-08-18T16:36:15Z2015-08-18T16:36:15ZOldest human-like hand bone may help us understand the evolution of tool making<figure><img src="https://images.theconversation.com/files/92266/original/image-20150818-12440-16z3azj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hands down amazing: nearly 2 million year-old pinkie bone.</span> <span class="attribution"><span class="source">M. Domínguez-Rodrigo</span></span></figcaption></figure><p>It may not have quite have the same wow factor as a skull, but the <a href="http://nature.com/articles/doi:10.1038/ncomms8987">discovery of a pinkie bone</a> that is more than 1.8 million years old may help us solve the puzzle of stone-tool use among our early ancestors. The bone, which is the earliest modern human-like finger bone ever found, could come from a number of species that were around at the time, including <em>Homo erectus</em>.</p>
<p>The international research team that made the discovery spent hours patiently excavating under the punishing Tanzanian sun at the famous <a href="http://www.livescience.com/40455-olduvai-gorge.html">Olduvai Gorge site</a>. And luckily, they didn’t come away empty-handed. The finger bone they found is remarkably similar to those of modern humans, suggesting the ancestry of the modern hand may be much older than we thought. </p>
<h2>The hand that rocks the evolutionary cradle</h2>
<p>Our fingers have three bones, known as <a href="http://classes.kumc.edu/sah/resources/handkines/bone/phal.html">phalanges</a>; the tip, the middle, and the basal one that connects to the bones of the hand at the knuckle. It is this last one that has been recovered from sediments dated to more than 1.84 million years ago. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/92268/original/image-20150818-12436-1vhq0vb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/92268/original/image-20150818-12436-1vhq0vb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=622&fit=crop&dpr=1 600w, https://images.theconversation.com/files/92268/original/image-20150818-12436-1vhq0vb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=622&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/92268/original/image-20150818-12436-1vhq0vb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=622&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/92268/original/image-20150818-12436-1vhq0vb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=782&fit=crop&dpr=1 754w, https://images.theconversation.com/files/92268/original/image-20150818-12436-1vhq0vb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=782&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/92268/original/image-20150818-12436-1vhq0vb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=782&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Tiny but significant.</span>
<span class="attribution"><span class="source">Credit: Jason Heaton</span></span>
</figcaption>
</figure>
<p>The new specimen comes from the little finger of the left hand – a stunning discovery given that these bones don’t preserve as well as skulls and the bigger, more robust bones of the body. For that reason it is hard to find these types of bones from this time period.</p>
<p>The researchers describe the bone as “modern human-like” because it is straighter than the bones of apes and early hominins who typically lived in trees and therefore had more curved finger bones. This is another reason why the bone is so exciting – modern humans as we define them did not appear on the scene for another 1.6 million years or more. </p>
<h2>Meet the candidates</h2>
<p>So which species were around at Olduvai at the time that could have had manual dexterity in the palm of its hand? <em>Paranthropus boisei</em> was a very robust <a href="http://humanorigins.si.edu/evidence/human-fossils/species/paranthropus-boisei">ape-like creature</a>, probably adapted to eating the toughest fruits and nuts. Although by no means certain, the evidence suggests this species may have lived at least some of the time in forested environments. Hand bones from <a href="http://swartkrans.org/">Swartkrans in South Africa</a> have been attributed to this species, and some palaeolanthropologists have argued they show the right kind of manipulative ability to make stone tools. But others disagree, so <a href="http://discovermagazine.com/1997/may/hominidhardware1135/">the jury is still out</a>. </p>
<p><em><a href="http://archaeologyinfo.com/homo-habilis/">Homo habilis</a></em> is another potential candidate for having lost its pinkie at Olduvai, but even with this species there are uncertainties. Research in recent years has shown that the skeleton of this species also point to it being <a href="http://humanorigins.si.edu/evidence/human-fossils/species/homo-erectus">adapted to living in trees</a>. Its fingers are not a good match for the new discovery. Yet when first discovered and described it was thought that <em>Homo habilis</em> was the real maker of the <a href="http://lithiccastinglab.com/gallery-pages/oldowanstonetools.htm">Oldowan stone tool kit</a> – its name actually means “handy man”. </p>
<p>The <em>Homo habilis</em> <a href="http://www.talkorigins.org/faqs/homs/typespec.html">type specimen</a>, which is the particular specimen against which all others are compared to confirm their identification, include a number of bones from the left hand. Researchers <a href="http://australianmuseum.net.au/homo-habilis">first analysing it in the 1960s</a> thought of it as human-like partly because of its potential for a precision grip – essential for tool manufacture. But nowadays researchers are aware how long and curved its fingers are and see them as more comparable with apes.</p>
<p>However, the fact that <em>Homo habilis</em> did not have human-like fingers does not mean it couldn’t make tools, just like _P. boisei. _The earliest tools we have to date are 3.3 million years old – <a href="https://theconversation.com/discovered-stone-tools-that-go-back-beyond-earliest-humans-42133">pre-dating the earliest examples we have of our own genus</a> by perhaps as much as half a million years or more. Tool use is an adaptive strategy, and one that may have been experimented with by more species than just our own.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/92269/original/image-20150818-12433-1r05144.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/92269/original/image-20150818-12433-1r05144.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/92269/original/image-20150818-12433-1r05144.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/92269/original/image-20150818-12433-1r05144.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/92269/original/image-20150818-12433-1r05144.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/92269/original/image-20150818-12433-1r05144.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/92269/original/image-20150818-12433-1r05144.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Excavation team. Definitely not all thumbs.</span>
<span class="attribution"><span class="source">Credit: M. Domínguez-Rodrigo</span></span>
</figcaption>
</figure>
<p><a href="http://humanorigins.si.edu/evidence/human-fossils/species/homo-rudolfensis"><em>Homo rudolfensis</em></a> is another species that may be contemporary with the new finger bone, and it is certainly contemporary with <em>Homo habilis</em>. However, while it is contemporary with Oldowan and Oldowan-like tools in Koobi Fora, Kenya, it has never before been discovered in Olduvai Gorge. There there really isn’t enough isn’t enough evidence to link the two.</p>
<p>Perhaps more promising is the final a candidate for the bone: <a href="http://anthro.palomar.edu/homo/homo_2.htm"><em>Homo ergaster</em> </a>, as the earliest examples of <em>Homo erectus</em> are called. Some hand bones from Swartkrans in South Africa have suggested that it may have had the right kind of manipulative ability to make complex stone tools. But without any <em>H. ergaster</em> fossils from Olduvai from the same time as little finger, its still an open question.</p>
<p>The researchers, who have a justifiable reputation for scientific rigour, are not pointing the finger at one hominin or another – yet. However, I get the feeling they may just have a hunch about <em>H. ergaster</em> . </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/92302/original/image-20150818-12428-16v056s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/92302/original/image-20150818-12428-16v056s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=720&fit=crop&dpr=1 600w, https://images.theconversation.com/files/92302/original/image-20150818-12428-16v056s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=720&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/92302/original/image-20150818-12428-16v056s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=720&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/92302/original/image-20150818-12428-16v056s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=905&fit=crop&dpr=1 754w, https://images.theconversation.com/files/92302/original/image-20150818-12428-16v056s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=905&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/92302/original/image-20150818-12428-16v056s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=905&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Could the little finger belong to Homo ergaster?</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Homo_ergaster#/media/File:Homo_ergaster.jpg">Luna04~commonswiki</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Not long after (in evolutionary terms) the time of little finger there was a <a href="https://anthromuseum.missouri.edu/minigalleries/handaxes/intro.shtml">major revolution in stone-tool making</a>, including the invention of the handaxes of the Acheulean, which overtook the Oldowan as the main signature of stone tool production after 1.6 - 1.4 million years ago. The earliest dated Acheulean is about 1.75 million years ago from southern Ethiopia and from <a href="http://whc.unesco.org/en/list/801">Lake Turkana in Kenya</a>. </p>
<p>It would be exciting indeed if the team turn out to have identified early <em>H. ergaster</em> as the owner of the finger, perhaps just before they started making handaxes. Half a kilometre away from where the bone was found, and in the same clay bed, is the <a href="http://www.geocaching.com/geocache/GC2A1M7_zinj-site?guid=0560fbb8-d247-49bd-a00d-742c0bfc09bd">Oldowan site of FLK 22 Zinj</a>, with abundant stone tools, none of them handaxes. Did the new tool type require a new kind of grip? Or, did forsaking a life in the trees inadvertently put new potential in the palm of their hands? </p>
<p>As the discoverers are at pains to note, until more fossils are discovered to clarify these questions, we can only guess. But until then let’s give the team a big hand, they deserve it.</p><img src="https://counter.theconversation.com/content/46284/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>The discovery of the oldest modern human-like pinkie bone suggests that hands emerged very early in human evolution.John McNabb, Senior Lecturer in Palaeolithic Archaeology, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/421032015-05-20T17:00:55Z2015-05-20T17:00:55ZOur stone tool discovery pushes back the archaeological record by 700,000 years<figure><img src="https://images.theconversation.com/files/82384/original/image-20150520-11422-mfqdv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Excavating stone artifacts that date from 3.3 million years ago in Kenya.</span> <span class="attribution"><span class="source">MPK-WTAP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>On the morning of July 9 2011, we were climbing a remote hill near the western shore of Lake Turkana in northern Kenya.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/82389/original/image-20150520-11456-18ro69n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/82389/original/image-20150520-11456-18ro69n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/82389/original/image-20150520-11456-18ro69n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=570&fit=crop&dpr=1 600w, https://images.theconversation.com/files/82389/original/image-20150520-11456-18ro69n.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=570&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/82389/original/image-20150520-11456-18ro69n.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=570&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/82389/original/image-20150520-11456-18ro69n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=716&fit=crop&dpr=1 754w, https://images.theconversation.com/files/82389/original/image-20150520-11456-18ro69n.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=716&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/82389/original/image-20150520-11456-18ro69n.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=716&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sammy Lokorodi, who made the initial discovery.</span>
<span class="attribution"><span class="source">MPK-WTAP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Our field team had accidentally followed the wrong dry riverbed, the only way of navigating these remote desert badlands, and we were scanning the landscape for a way back to the main channel. Something felt special about this particular place, so before moving on, we all fanned out and surveyed the patch of craggy outcrops. By teatime, local Turkana team member Sammy Lokorodi had helped us spot what we had come searching for.</p>
<p>We, and the <a href="http://www.westturkanaarcheologicalproject.com/Home.html">West Turkana Archaeological Project</a> which we co-lead, had discovered the <a href="https://doi.org/10.1038/nature14464">earliest stone artifacts</a> yet found, dating to 3.3 million years ago. The discovery of the site, named Lomekwi 3, instantly pushed back the beginning of the archaeological record by 700,000 years. That’s over a quarter of humanity’s previously known material cultural history. These tools were made as much as a million years before the earliest known fossils attributed to our own genus, <em>Homo</em>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/82390/original/image-20150520-11435-zszysn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/82390/original/image-20150520-11435-zszysn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/82390/original/image-20150520-11435-zszysn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=531&fit=crop&dpr=1 600w, https://images.theconversation.com/files/82390/original/image-20150520-11435-zszysn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=531&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/82390/original/image-20150520-11435-zszysn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=531&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/82390/original/image-20150520-11435-zszysn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=668&fit=crop&dpr=1 754w, https://images.theconversation.com/files/82390/original/image-20150520-11435-zszysn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=668&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/82390/original/image-20150520-11435-zszysn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=668&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Harmand unearthing a stone tool at the site.</span>
<span class="attribution"><span class="source">MPK-WTAP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Stretching the record further back</h2>
<p><em>Stone tools are fossilized human behavior. – Louis Leakey</em></p>
<p>In the 1930s, famed paleoanthropologists Louis and Mary Leakey unearthed early stone artifacts at <a href="http://www.livescience.com/40455-olduvai-gorge.html">Olduvai Gorge in Tanzania</a>. They named them the Oldowan tool culture. Later, in the 1960s, they found hominin fossils in association with those Oldowan tools that looked more like later humans than the Australopithecines discovered there previously. The Leakeys <a href="https://doi.org/10.1038/202007a0">assigned them to a new species</a>: <em>Homo habilis</em>, or handy man.</p>
<p>Since then, conventional wisdom in human evolutionary studies has supposed that the origins of knapping stone tools by our ancestors – that is, chipping away flakes from a stone to make a tool – were linked to the emergence of the genus <em>Homo</em>. The premise was that our lineage alone took the cognitive leap of hitting stones together to strike off sharp flakes, and that this was the foundation of our evolutionary success. Scientists thought this technological development was tied to climate change and the spread of savanna grasslands; our ancestors innovated with new tools to help them survive in an evolving landscape. </p>
<p>Over the last few decades, however, subsequent discoveries pushed back the date for the earliest <a href="http://www.nature.com/nature/journal/v385/n6614/abs/385333a0.html">stone tools to 2.6 million years ago (Ma)</a> and the earliest fossils attributable <a href="http://www.sciencedirect.com/science/article/pii/S0047248405000643">to early <em>Homo</em> to only 2.4-2.3 Ma</a>. By necessity, there’s been increasing openness to the possibility of tool manufacture before 2.6 Ma and by hominins other than <em>Homo</em>.</p>
<p>A series of papers published in rapid succession in early 2015 have solidified these ideas into an emerging paradigm shift in paleoanthropology: the fossil record of the genus <em>Homo</em> now <a href="https://doi.org/10.1126/science.aaa1343">extends back to 2.8 Ma</a> in the Ethiopian Afar; <a href="https://doi.org/10.1038/nature14224">cranial</a> and <a href="https://doi.org/10.1016/j.jhevol.2015.01.005">post-cranial diversity</a> in early <em>Homo</em> is much wider that previously thought, already evincing several distinct lineages by 2 Ma; and <em>Australopithecus africanus</em> and other Pleistocene hominins, traditionally considered not to have made stone tools, have a <a href="https://doi.org/10.1126/science.1261735">human-like trabecular bone pattern</a> in their hand bones that’s consistent with tool use.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/82391/original/image-20150520-11453-h5ddbh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/82391/original/image-20150520-11453-h5ddbh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/82391/original/image-20150520-11453-h5ddbh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/82391/original/image-20150520-11453-h5ddbh.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/82391/original/image-20150520-11453-h5ddbh.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/82391/original/image-20150520-11453-h5ddbh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/82391/original/image-20150520-11453-h5ddbh.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/82391/original/image-20150520-11453-h5ddbh.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">View of the excavation underway in the Lake Turkana basin.</span>
<span class="attribution"><span class="source">MPK-WTAP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Now, the Lomekwi artifacts show that those ideas are correct – at least one group of ancient hominin started intentionally knapping stones to make tools long before previously thought. These new archaeological finds are yet another paradigm-shifting discovery from the Lake Turkana basin. This area’s been made famous over the past five decades through the work of the second and third generation of the Leakey family (Richard, Meave and their daughter Louise), and has produced much of the world’s <a href="http://www.turkanabasin.org/">most important fossil evidence</a> for human evolution.</p>
<p>The Lomekwi area where the tools were found had already produced the <a href="https://doi.org/10.1038/35068500">fossil skull of early hominin <em>Kenyanthropus platyops</em></a> by Meave and her team. And our West Turkana Archaeological Project has previously discovered the <a href="https://doi.org/10.1038/19959">earliest artifacts from the Oldowan culture known from Kenya</a>, and the world’s <a href="https://doi.org/10.1038/nature10372">oldest Acheulean bifaces</a> – considered a kind of “stone Swiss army knife” characteristic of the period.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/82395/original/image-20150520-11417-1c2igwn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/82395/original/image-20150520-11417-1c2igwn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/82395/original/image-20150520-11417-1c2igwn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/82395/original/image-20150520-11417-1c2igwn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/82395/original/image-20150520-11417-1c2igwn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/82395/original/image-20150520-11417-1c2igwn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/82395/original/image-20150520-11417-1c2igwn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/82395/original/image-20150520-11417-1c2igwn.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">A stone tool in situ being unearthed at Lomekwi 3 excavation.</span>
<span class="attribution"><span class="source">MPK-WTAP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>New find of oldest tools</h2>
<p>We dated the Lomekwi 3 tools by correlating the layers of rock in which they were discovered with well-known radiometrically dated tuffs, a type of porous rock formed from volcanic ash. We also could detect the paleomagnetism of the rocks, which in different periods of the past were either normal like today or reversed (the north magnetic pole was at the south pole). These are the standard ways fossils and sites from this time period are dated, and the hominin fossils found just 100 meters from our excavation were dated by another team to the same date.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/h87V0aOkzrg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Interview with the authors about their discovery.</span></figcaption>
</figure>
<p>These oldest tools from Lomekwi shed light on an unexpected and previously unknown period of hominin behavior and can tell us a lot about cognitive development in our ancestors that we can’t understand from fossils alone. Our finding finally disproves the long-standing assumption that <em>Homo habilis</em> was the first toolmaker.</p>
<p>These tools are unique compared to the ones known from later periods. The stones are much larger than Oldowan tools, and we can see from the scars left on the stones when being knapped that the techniques used were more rudimentary. They apparently required holding the stone in two hands or resting the stone on an anvil when hitting it with a hammerstone. The gestures involved are reminiscent of those used by chimpanzees when they use stones to break open nuts. It is unclear at the moment who the most likely maker of the tools was. We can be fairly certain it was a member of our lineage and not a fossil great ape, as modern apes have never been seen knapping stone tools in the wild.</p>
<p>Our study of the Lomekwi 3 artifacts suggests they could represent a transitional technological stage, a sort of behavioral missing link, in between the pounding-oriented stone tool use of a more ancestral hominin and the flaking-oriented knapping behavior of later, Oldowan toolmakers.</p>
<p>Reconstructions of the environment around Lomekwi 3, based on animal fossils and isotopic analyses of the site’s soil, surprised us too. The area was much more wooded than the paleoenvironments associated with East African artifact sites from later than 2.6 million years ago. The Lomekwi hominins were most likely not out on a savanna when they knapped these tools.</p>
<p>While it is tempting to assume that these earliest artifacts were made by members of our genus <em>Homo</em>, we urge caution. It’s extremely rare to be able to pinpoint what fossil species made which stone tools through most of prehistory, unless there was only one hominin species living at the time, or until we find a fossil skeleton still holding a stone tool in its hand.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/82398/original/image-20150520-11456-1luj248.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/82398/original/image-20150520-11456-1luj248.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/82398/original/image-20150520-11456-1luj248.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/82398/original/image-20150520-11456-1luj248.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/82398/original/image-20150520-11456-1luj248.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/82398/original/image-20150520-11456-1luj248.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/82398/original/image-20150520-11456-1luj248.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/82398/original/image-20150520-11456-1luj248.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">Careful excavation.</span>
<span class="attribution"><span class="source">MPK-WTAP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Deciphering what the stones say</h2>
<p>The Lomekwi 3 discovery raises many new challenging questions for paleoanthropologists. For one, what could have caused hominins to start knapping tools at such an early date? The traditional view was that hominins started knapping to make sharp-edged flakes so they could cut meat from animal carcasses. Maybe they used the larger cobbles to break open animal bones to get at the marrow. While the Lomekwi knappers certainly made sharp-edged flakes from stone cores, the tools’ size and the battering marks on their surfaces suggest they were doing something different as well. And we know they were in a more wooded environment with access to various plant resources. We’re conducting experimental work to help reconstruct how the tools were used.</p>
<p>Another unknown is what was happening archaeologically between 3.3 and 2.6 Ma. We’ve jumped so far back with this discovery, we need to try to connect the dots forward to what we know was happening in the early Oldowan.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/82408/original/image-20150520-11422-1ahh49c.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/82408/original/image-20150520-11422-1ahh49c.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/82408/original/image-20150520-11422-1ahh49c.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/82408/original/image-20150520-11422-1ahh49c.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/82408/original/image-20150520-11422-1ahh49c.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/82408/original/image-20150520-11422-1ahh49c.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/82408/original/image-20150520-11422-1ahh49c.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/82408/original/image-20150520-11422-1ahh49c.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">What other tools remain yet undiscovered?</span>
<span class="attribution"><span class="source">MPK-WTAP</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Of course, the most intriguing question is whether even older stone tools remain to be discovered. We have no doubt that these aren’t the very first tools that hominins made. The Lomekwi tools show that the knappers already had an understanding of how stones can be intentionally broken – beyond what the first hominin who accidentally hit two stones together and produced a sharp flake would have had. We think there are older, even more primitive artifacts out there, and we’re headed back out into the badlands of northern Kenya to look for them.</p>
<hr>
<p><em>For another archaeologist’s take on the significance of the Lomekwi 3 stone tools, <a href="https://theconversation.com/discovered-stone-tools-that-go-back-beyond-earliest-humans-42133">read Matt Pope’s article here</a>.</em></p><img src="https://counter.theconversation.com/content/42103/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Stone tools excavated in Kenya date back 3.3 million years – making them about a million years older than the oldest known fossils from our own hominid genus Homo. Who made and used these tools?Jason E. Lewis, Research Assistant Professor of Anthropology and Director Turkana Basin Institute Origins Field School, Stony Brook University (The State University of New York)Sonia Harmand, Research Associate Professor of Anthropology, Stony Brook University (The State University of New York)Licensed as Creative Commons – attribution, no derivatives.