That some major change in brain structure – in size and/or organisation – occurred about 2.5 million years ago is not in doubt. At one stage it was thought that tool-making was a defining characteristic of ‘humanity’ but that was before Jane Goodall in the 1960s observed chimpanzees pulling the leaves off twigs so they could insert the twigs into termite mounds, and then withdraw them – by now suitably coated with termites – to be eaten at leisure. Chimpanzees have also been observed cracking open nuts using stones as ‘hammers’ and, in Uganda, using leafy twigs as fans, to keep insects away. However, palaeontologists recognise two important ways in which early hominid stone tools differ from the tools produced by other primates. The first is that some of the stone tools were produced to manufacture other tools – such as flakes to sharpen a stick. And second, the early hominids needed to be able to ‘see’ that a certain type of tool could be ‘extracted’ from a certain type of rough rock lying around. The archaeologist Nicholas Toth of Indiana University spent many hours trying to teach a very bright bonobo (a form of pygmy chimpanzee), called Kanzi, to make stone tools. Kanzi did manage it, but not in the typical human fashion, by striking one stone against another. Instead, Kanzi would hurl the stones against the concrete floor of his cage. He just didn’t possess the mental equipment to ‘see’ the tool ‘inside’ the stone.15
Early stone tools similar to those found on the Gona river have also been found at Omo in southern Ethiopia, at Koobi Fora, on lake Turkana just across the border in Kenya and, controversially, in the Riwat area of northern Pakistan. In some circles these tools are referred to as the Omo Industrial Complex. The Omo industry is followed by the second type of stone tool, called Oldowan, after the Olduvai gorge, and dating to between 2.0 and 1.5 million years ago. Olduvai, in Tanzania, near the southern edge of the Serengeti plain, is probably the most famous location in palaeontology, providing many pioneering discoveries.
Stone tools, in general, do not occur in isolation. At several sites in Olduvai, which have been dated to about 1.75 million years ago, the tools were found associated with bones and, in one case, with larger stones which appear to be fashioned into a rough semi-circle. The feeling among some palaeontologists is that these large stones formed a primitive wind-break (man’s second idea?), offering shelter while animals were butchered with the early hand-axes. The stone tools in use 1.7 million years ago were already subtly different from the very earliest kinds. Louis and Mary Leakey, the famous ‘first family’ of palaeontologists, who excavated for many years at Olduvai gorge, carefully studied Oldowan technology and although by later standards the stone tools were very primitive, the Leakeys and their colleagues were able to distinguish four ‘types’ – heavy-duty choppers, light-duty flakes, used pieces and what is known as débitage, the material left over after the tools have been produced. There is still much discussion as to whether the early hominids at Olduvai were passive scavengers, or confrontational scavengers, as the Hadza are today.16
Who made these early tools? Nothing of the kind has ever been found associated with A. afarensis remains. By the time tools appear, various species of hominid co-existed in Africa, two or three of which are given the family name Paranthropus (‘alongside man’), also known as A. robustus and A. boisei, with the others belonging to Homo – these are H. habilis (‘Handy man’), H. rudolfensis and H. ergaster. These different hominids varied in interesting ways that make the exact line of descent to ourselves difficult to fathom. All had bigger brains than ‘Lucy’ (500–800 cc, as compared with 400–500 cc), but whereas H. habilis had an ape-type body with more human-like face and teeth, H. rudolfensis was the other way round – a human-type body and more ape-like face and teeth.17 In theory, any of these species could have produced the tools but two reasons seem to rule out Paranthropus. The first reason relates to the thumb of primitive man. The anthropologist Randall Susman has noticed that chimpanzees have very different thumbs from human beings. Chimps have curved, narrow-tipped fingers and short thumbs – ideal for grasping tree limbs. Humans, on the other hand, have shorter, straighter fingers with squat tips, and larger, stouter thumbs. This is a better arrangement for grasping things like stones. On examination, it turns out that A. afarensis had chimpanzee-like thumbs and so, probably, did Paranthropus. A second reason is that, if Paranthropus had manufactured tools, in addition to the Homo family, we should almost certainly find two separate tool traditions in the fossil record. We don’t.
Steven Mithen, an archaeologist at the University of Reading, in Britain, has conceived the primitive mind as consisting of three entities: a technical intelligence (producing stone tools), a natural history intelligence (understanding the landscape and wildlife around him/her), and a social intelligence (the skills needed to live in groups). At the level of H. habilis, says Mithen, there is no evidence that social intelligence was integrated with the other two. The stone tools are associated with animal bones – the victims of early hunters. But from the evidence so far obtained there is no social separation of tools and food, no evidence at all of organised group activity – the earliest archaeological sites are just a jumble of tools and bones.18
From this faltering beginning, a major step forward was taken some time between 1.8 and 1.6 million years ago, with the appearance of another new species, Homo erectus – upright man – found first at Koobi Fora and then in Java. With his ‘sad, wary face and flat nose’, H. erectus was the first human to leave Africa, other remains having been found in Dmanisi in Georgia, and in mainland Asia: in October 2004 stone tools believed to have been made by H. erectus were reported as having been found in Majuangou, west of Beijing, and dated to 1.66 million years ago.19 He or she shows a further increase in brain size, the second-most sizeable jump – but perhaps the most important of all – to 750–1,250 cc, though the skulls were also marked by robust brow ridges.20 After what we may call a ‘technology lag’ of about 400,000 years, we find that at around 1.4 million years ago, the earliest true hand-axes appear. These, the third type of hand-axe, are ‘true’ in the sense that they are now symmetrical, formed by knocking flakes off the core alternately from either side, to produce an elegant long point and a stone with a pear shape. These are known to professionals as Acheulian because they were first discovered by French archaeologists in the Amiens suburb of St Acheul. (Much stone-age terminology is based on the place names of French sites – Cro-Magnon, Mousterian, Levallois – where French archaeologists were the first to make the discoveries.) These hand-axes appear abruptly in the archaeological record in Africa, Europe and parts of Asia (though much less so in south-west Asia and not at all in south-east or east Asia). Some palaeontologists believe that H. erectus was a hunter, the first true hunter, rather than a scavenger, and that his better tools enabled him to spread across Eurasia, what is sometimes called the Old World.