One of the first was made a century ago in Taung, South Africa, by mineworkers who came across the cranium of a\u00a02.8 million-year-old child with human-like teeth<\/a>. Its fossilised anatomy offered evidence of early human upright walking \u2013 and 50 years later, in the Afar region of northern Ethiopia that would become a hotspot for ancient human discovery, this understanding took another leap backwards in time with the\u00a0discovery of Lucy<\/a>.<\/p>\n The part-skeleton of this small-bodied, relatively small-brained female\u00a0captured the public\u2019s imagination<\/a>. Lucy the\u00a0\u201cpaleo-rock star\u201d<\/a>\u00a0took our major fossil evidence for bipedal walking, human-like creatures (collectively known as hominins) beyond 3 million years for the first time. The race to explain how humans became what we are now was well and truly on.<\/p>\n Since then, the picture has changed\u00a0repeatedly and dramatically<\/a>, shaped by waves of new fossil discovery, technology and scientific techniques \u2013 often accompanied by arguments about the veracity of claims made for each new piece of the puzzle.<\/p>\n Even the term \u201chuman\u201d is arguable. Many scholars reserve it for modern humans like us, even though we have Neanderthal genes and they shared at least 90 per cent of our hominin history from its beginnings around 8 million years ago<\/a>. The essence of hominin evolution ever since has been gradual change, with occasional rapid phases. The record of\u00a0evolution in our own genus<\/a>,\u00a0Homo<\/em>, is already full enough to show we cannot separate ourselves with hard lines.<\/p>\n Nonetheless, there is enough consensus to thread the story of human evolution all the way from early apes to modern humanity. Most of this story centres on Africa, of course, where countries such as Kenya, South Africa and Ethiopia are rightly proud of their heritage as\u00a0\u201ccradles of humankind\u201d<\/a>\u00a0\u2013 providing many of their schoolchildren with a much fuller answer then those in the west to this deceptively simple question: how did we get here?<\/p>\n The story of human evolution usually starts at the point our distant ancestors began to separate from the apes, whose own ancestors are traceable from at least 35 million years ago and are\u00a0well attested as fossils<\/a>. Around 10 million years ago, the Miocene world was warm, moist and forested. Apes lived far and wide from Europe to China, though we have found them especially in Africa, where sediments of ancient volcanoes preserve their remains.<\/p>\n This world was soon to be disrupted by cooling temperatures and, in places, great aridity \u2013 best seen\u00a0around the Mediterranean<\/a>, where continental movements closed off the Straits of Gibraltar and the whole sea evaporated several times, leaving immense salt deposits under the floor of the modern sea. Widespread drying was reported from around 7 to 6 million years ago, leading to a stronger expression of seasons in much of the world, and changes in plant and animal communities.<\/p>\n The\u00a0divergence from the apes<\/a>\u00a0of a lineage \u2013 the hominins \u2013 that eventually led to us had probably already begun 8 million years ago. But our knowledge of this date depends on molecular comparisons with other animals, rather than fossils.<\/p>\n DNA shows we are most closely related to\u00a0chimpanzees<\/a>\u00a0and their sister species,\u00a0the bonobo<\/a>. Branching points can be estimated by comparisons with other well-dated events, such as the separation of\u00a0South American monkeys<\/a>\u00a0from other primates about 35 million years ago.<\/p>\n A surprise from genetic science is that gorillas, the other African great apes, are\u00a0less closely related to chimpanzees<\/a>\u00a0than chimps are to us. A chimpanzee, if it could speak, might tell us: \u201cThese gorillas may look like my big brothers, but actually I\u2019m more closely related to you.\u201d They seem so similar because they are both tropical forest apes with similar adaptations, which underlines just how much \u2013 and how rapidly \u2013 the earliest hominins had to evolve to survive in their drier environments.<\/p>\n Yet, there is still some debate about whether the chimpanzee is our best model for the starting point: the\u00a0\u201clast common ancestor\u201d<\/a>. Better to call it the \u201cbest living model\u201d because the chimp has shown many adaptations of its own, especially in its limb proportions and locomotion, but also in its large shearing front teeth. But its social behaviour, communication and\u00a0tool-making<\/a>\u00a0have all provided invaluable insights into the processes that we can call \u201chominisation\u201d.<\/p>\n The\u00a0earliest hominin fossil<\/a>\u00a0yet known is about 7 million years old and comes from the middle of Africa, near Lake Chad. This rare find from 2001 is\u00a0Sahelanthropus tchadensis<\/a><\/em>, represented by a cranium (nicknamed\u00a0\u201cTouma\u00ef\u201d<\/a>\u00a0by its finders), a femur and teeth \u2013 all probably from the same species.<\/p>\n Although these finds were limited, they were enough to show a\u00a0bipedal creature<\/a>\u00a0probably still comfortable living in trees, who had teeth with hominin features. Many accompanying fossils of other species show this hominin lived in both woodland and grassland habitats.<\/p>\n Then, for over a million years, our record vanishes \u2013 other than for some fragmentary remains of\u00a0Orrorin tugenensis<\/a><\/em>, a different genus of hominin found in the Tugen Hills of Kenya and dating to about 6 million years ago.<\/p>\n Hominins appear again in plain sight with a new species dating back around 5.5 million years,\u00a0Ardipithecus kadabba<\/a><\/em>. The discovery of its\u00a0partial jawbone and teeth<\/a>\u00a0in the Middle Awash region of northern Ethiopia in 1997 shed more light on what may have been the\u00a0\u201cstem ancestor\u201d<\/a>\u00a0leading to all later hominins. Exceptionally thorough investigations have since revealed these creatures in\u00a0full anatomical detail<\/a>\u00a0and in remarkable environmental context, showing\u00a0Ardipithecus<\/em>\u00a0combined characters of both apes and later hominins.<\/p>\n A. kadabba\u2019s<\/em>\u00a0finders emphasised that it was not chimpanzee-like in limb proportions, nor did it have their exaggerated shovel-like front teeth. It also overturned the old theory of hominins coming down from the trees into savannas, and thus being forced to become bipedal. Rather,\u00a0Ardipithecus<\/em>\u00a0lived in thick woodland and supports the idea that bipedalism first arose as an adaptation to walking along tree boughs, perhaps while clasping the branches above.<\/p>\n The stem hominin idea may well be correct, but more recent finds suggest there were soon\u00a0multiple hominin species<\/a>. While\u00a0Ardipithecus<\/em>\u00a0is known from only one modern country, Ethiopia, there are huge areas of Africa that could have supported similar sibling species but which, for geological reasons, have not given up these secrets as generously as sections of the Great Rift Valley.<\/p>\n It is also striking that\u00a0Ardipithecus\u2019<\/em>\u00a0feet remained apelike, with a divergent big toe \u2013 a sign that climbing trees was still important. The other, later species of\u00a0Ardipithecus<\/em>\u00a0(Ar. Ramidus<\/a><\/em>) lived only half a million years before the famous\u00a0footprints found in Laetoli, Tanzania<\/a>\u00a0in 1976 \u2013 trails of footprints that displayed fully human characteristics. Evolution would need to have been rapid indeed for those two creatures to be directly related.<\/p>\n Even so,\u00a0Ardipithecus<\/em>\u00a0had features that are enormously valuable for showing the general state of hominins at this time. Its pelvis, the oldest known, was short and basin-like as in later hominins, although ape-like in its lower part. And its teeth had enamel that was thicker than in African apes but thinner than in modern humans, suggesting an omnivorous diet.<\/p>\n More than 4 million years ago, another group of hominins begins to appear on the scene: the genus\u00a0Australopithecus<\/em>, named after the \u201cTaung child\u201d whose skull was discovered 100 years ago by workmen in the South African limestone quarry.<\/p>\n While the name means \u201csouthern ape\u201d, the\u00a0australopithecines<\/a>\u00a0were certainly hominins. Fully bipedal, their teeth were arranged in a modern human pattern with their canines reduced \u2013 sometimes to an extraordinary degree \u2013 and they existed in great diversity.<\/p>\n As finds accumulate, at least ten species of this group are now known, indicating\u00a0\u201cadaptive radiation\u201d<\/a>\u00a0\u2013 meaning that hominins had become highly successful and were by now adjusting to many different habitats and climates. While the australopithecines were confined to Africa, they extended widely from the south to the east and even towards the west near Lake Chad \u2013 close to the find of the older\u00a0Sahelanthropus<\/em>. This distribution underlines the argument for hominins having originated in Africa, as had been long suspected from the shared heritage with African apes.<\/p>\n The oldest\u00a0Australopithecus<\/em>\u00a0is\u00a0A. anamensis<\/a><\/em>, found in northern Kenya and dating to more than 4 million years ago, closely followed by\u00a0A. afarensis<\/a><\/em>\u00a0in Ethiopia \u2013\u00a0Lucy\u2019s species<\/a>\u00a0\u2013 and\u00a0A. prometheus<\/a><\/em>\u00a0in South Africa.<\/p>\n Then, in addition to species such as\u00a0A. africanus<\/a><\/em>\u00a0and\u00a0A. garhi<\/a><\/em>, there is a further group who combined enormous chewing teeth and ape-sized brains \u2013 their massive jaws and skulls led to them being dubbed the \u201crobusts\u201d. Often officially termed\u00a0Paranthropus<\/em><\/a>\u00a0rather than\u00a0Australopithecus<\/em>, they occurred as three separate species in\u00a0southern<\/a>\u00a0and\u00a0eastern<\/a>\u00a0Africa<\/a>, appearing at least 3 million years ago and surviving until about 1.4 million years ago.<\/p>\n The Great Rift Valley, Kenya. Photo by Ninara (Flickr CC)<\/a><\/em><\/p><\/div>\n While\u00a0microwear studies of their teeth<\/a>\u00a0suggest a mixed diet, the huge size of those teeth implies it was of low quality, with grasses and sedges providing the bulk. Indeed, the dominance of these creatures\u2019 massive molars meant their front teeth shrank to the extent that their incisors and canines were consistently smaller than ours today.<\/p>\n Although the African Rift Valley running down the east side of the continent is often celebrated as the focus of hominin origins, the\u00a0distribution of australopithecines<\/a>\u00a0is just wide enough to show the rift is not necessarily the cradle of humankind \u2013 although it is the region where most fossils have been found. South Africa\u2019s dolomite caves are strong competitors in importance, while the discovery of\u00a0A. bahrelghazali<\/a><\/em>\u00a0in Chad is far west of the rift.<\/p>\n It is certain that our own genus,\u00a0Homo<\/em>, emerged at some point from within the australopithecines. But exactly how and when is still difficult to ascertain, because cranial remains \u2013 skulls \u2013 are very scarce in the period between 3 and 2 million years ago.<\/p>\n This is a matter of chance; before and after, we have plenty of them. Large numbers of teeth prove that hominins were in eastern and southern Africa during this period, and rare finds of crania such as\u00a0P. aethiopicus<\/em>\u00a0and\u00a0A. garhi<\/em>\u00a0make the point that others could be found at any moment.<\/p>\n In later times,\u00a0Homo<\/em>\u00a0is distinguished by its very large brain \u2013 about three times the size of a chimpanzee\u2019s brain \u2013 but this was not so in the beginning. At the start,\u00a0Homo<\/em>\u00a0would have been almost indistinguishable from australopithecines, with just some small anatomical details picking it out, especially the shape of its molar and premolar teeth. Fragmentary jaws and teeth from\u00a0Ledi Geraru<\/a>\u00a0and Hadar in Ethiopia, then from Chemeron in Kenya, trace the early story of our direct ancestors from 2.8 to 2.4 million years ago.<\/p>\n As we approach 2 million years,\u00a0Homo<\/em>\u00a0appears much more clearly in famous skull and other fossil discoveries from\u00a0Olduvai Gorge<\/a>\u00a0(Tanzania) and\u00a0East Turkana<\/a>\u00a0(Kenya), and latterly\u00a0South Africa<\/a>. As well as at least three species in Africa \u2013\u00a0Homo habilis<\/a><\/em>,\u00a0Homo rudolfensis<\/a><\/em>\u00a0and\u00a0Homo erectus<\/a><\/em>\u00a0\u2013\u00a0Homo<\/em>\u00a0of similar age is suddenly found outside Africa, especially at\u00a0Dmanisi<\/a>\u00a0in modern-day Georgia, where the finds are as old as those from Olduvai.<\/p>\n Together with first archaeological finds of stone tools and cutmarks on animal bones indicating butchery, these fossils combine to show us that\u00a0Homo<\/em>\u00a0had become highly successful within a million years of its origins, and had spread out far across Asia as far as China. These first arrivals must have been a species of early\u00a0Homo<\/em>, but it is only at Dmanisi and Lantien in China that we have early fossil remains.<\/p>\n Technology was almost certainly part of the adaptation that allowed this great expansion. Tool-making is the most obvious part of early cultural behaviour, and it is preserved as hard evidence by the presence of stone tools.<\/p>\n First dates for stone tool-making have moved back in an exciting way. The 2 million-year barrier was broken around 1970, then the 3 million-year barrier just recently with discoveries of stone tools at\u00a0Lomekwi<\/a>\u00a0and\u00a0Nyayanga<\/a>\u00a0in Kenya. We do not know who made these tools, but it means stone artefacts emerged around the same time that early\u00a0Homo<\/em>\u00a0appeared alongside the australopithecines. As \u201cstone age visiting cards\u201d \u2013 as the\u00a0archaeologist Glynn Isaac<\/a>\u00a0labelled them \u2013 they are hugely useful for telling us where hominins went, and what they were doing.<\/p>\n A generation ago, it would have been axiomatic that the emergence of tools and\u00a0Homo<\/em>\u00a0were linked, and that they signalled a major step forward \u2013 the development of early human culture. Now, there is a different perspective, largely owing to\u00a0detailed studies of living animals<\/a>.<\/p>\n To a striking degree, chimpanzees make a range of tools as well as use them, and so do the small\u00a0capuchin monkeys<\/a>\u00a0of South America. Birds too are in the picture, especially the\u00a0New Caledonian crow<\/a>. Their tools may be simple \u2013 mainly made from plant materials \u2013 but they include stones used for hammering.<\/p>\n There are many indications that this animal behaviour is\u00a0cultural<\/a>, handed on as learned tradition. Granted that we,\u00a0Homo sapiens<\/em>, are the most cultural animal of all, there has to be a possibility that all hominins were toolmakers and users, given that all fossil hominins are more closely related to us than to the chimpanzee, which is itself a habitual toolmaker.<\/p>\n Having said that, we don\u2019t know who made the earliest stone tools. We know that when\u00a0Paranthropus<\/em>\u00a0and other australopithecines eventually disappeared, toolmaking continued \u2013 but this does not rule out earlier tool use by some of them.<\/p>\n Most early stone artefacts, from about 3 to 1.8 million, are placed in the\u00a0\u201cOldowan tradition\u201d<\/a>\u00a0\u2013 named after\u00a0Olduvai Gorge<\/a>\u00a0where so many tools have been discovered, typically made from carefully selected lava or quartzite rocks. Both heavy core tools such as \u201cchoppers\u201d and sharper stone flakes were used for a variety of tasks \u2013 certainly including animal butchery, and almost certainly in the preparation of plant foods and shaping of wooden tools (although these did not survive for our discovery\u00a0until much later<\/a>).<\/p>\n This toolkit literally gave early\u00a0Homo<\/em>\u00a0species a cutting edge in the struggle for survival in varied environments, and may have been a key factor underlying their ability to expand their niche into new areas, including\u00a0Jordan<\/a>,\u00a0north India<\/a>\u00a0and\u00a0China<\/a>\u00a0well over 2 million years ago.<\/p>\n Continue to Part 2<\/strong><\/em><\/a>.<\/p>\n This article was originally published in<\/em> The Conversation<\/a>. It is republished here as a two-part series.\u00a0<\/em><\/strong><\/p>\nEarly apes to \u2018hominisation\u2019\u00a0(around 35m to 8m years ago)<\/em><\/h2>\n
Earliest hominins\u00a0(about 7m up to 4m years ago)<\/em><\/h2>\n
Australopithecines\u00a0(about 4.3m to 1.4m years ago)<\/em><\/h2>\n
![\"\"](\"https:\/\/rationalemagazine.com\/wp-content\/uploads\/2024\/12\/GreatRiftValley.jpg\")
Beginnings of\u00a0Homo<\/em>\u00a0(from about 2.8m years ago)<\/em><\/h2>\n