by Paul Jordan
Australopithecine footprints from Laetoli.
The very footprints of afarensis have wonderfully come down to us at an East African site called Laetoli (where afarensis remains have been found), from 3.6 mya. Among many animal tracks and even raindrop marks preserved in volcanic ash that, after wetting, hardened in the sun and was subsequently buried under more protective layers of ash, there runs a 27 m line of hominid footprints, seventy or so in all. Here two Australopithecine individuals, perhaps a male and female or an adult and child, walked from south to north one day some 1.3 billion days ago, turning halfway along for a moment to look to the west. (A third individual seems to have walked in the steps of the larger of the original pair!) The impressions reveal that their big toes were in line like ours, and not opposable like apes’, and that their feet came down with a good heel strike in the way we would expect of accomplished walkers. We recall that the bipedalism of the Australopithecines had already been established just after the Second World War – at the South African site of Sterkfontein, where pelvis, femur and vertebrae revealed it in 1947.
Australopithecine spinal, pelvic and limb bones.
Australopithecines of various related sorts were possibly quite widespread in the unforested parts of Africa of their time (a find has been reported from Chad), but they have overwhelmingly been dug up as fossils in East and South Africa. A very early form of Australopithecine has recently been discovered in South Africa, dating to between 3.6 and 3.2 mya. This new find represents the most skeletally complete Australopithecine discovered to date and its foot bones confirm its bipedal status, though some features have been interpreted as indicating a certain extent of tree-living too, and it may be that South Africa was not at this time as unwooded as East Africa. The slightly later species called Australopithecus africanus is already well known from South Africa and looks in some ways like an evolutionary advance on afarensis (in the direction of humanity, at least). Africanus shows less sexual dimorphism, has still smaller canines and bigger molars with a slightly flatter face and higher, less heavily browed forehead. Australopithecines like africanus were probably living more in the open, with fewer arboreal episodes, than their predecessors, perhaps rather like baboon troops today. The diminished sexual dimorphism may well point to the beginnings of a more human sort of society with many males and many females in the group, organized into hierarchies rather more like baboons’ than chimps’.
Reconstructed skull of a gracile Australopithecine.
In both East and South Africa the relatively lightly skulled Australopithecines of the afarensis and africanus types and their descendants were joined after about 2.5 mya, when things were getting drier still in keeping with the glaciation of northern climes, by other forms with much more robustly turned out skulls. These robust Australopithecines had thick jaws with big back teeth that it is very tempting to link with a diet of chewing hardy vegetable matter in the increasingly arid world they inhabited. Their brains and bodies were not much bigger than those of the gracile forms, however. They were a long-lasting line of specialized hominids, so distinct in character in both South and East Africa (though showing different species in the two regions) that some anthropologists want to revive the old genus name Paranthropus for some of them to mark their particular evolution into something well off the general line of hominid descent from Australopithecus to Homo. But the evolutionary relationships of the various sorts of gracile and robust Australopithecines of Africa make a tangled web, with the distinct possibility that evolutionary convergence brought about the robust forms quite independently in different places out of different gracile species. We may note at this point the suggestion that has recently been made that a robust Australopithecine might be the ancestor of the gorillas of today, even that a gracile one might have evolved into the chimpanzees; intriguing as this idea might be, it seems unlikely if only because the modern chimps and gorillas are so anatomically non-bipedal when more in the way of bipedalism would be of quite frequent use to them, and it is hard to see them as creatures evolved from previously well and truly bipedal ancestors. At all events, chimps, gorillas and men are alike descended from some pongid, that is to say ape, ancestry. No Australopithecine remains of any sort have ever been discovered out of Africa.
A robust Australopithecine with keeled skull top and massive jaw.
It was to be the gracile sort of Australopithecines that gave rise to the genus Homo; despite their unmistakably ape ancestry (including their long arms), none the less their enlarged brains relative to their body size (particularly in the cortical parts of the brain) and their bipedalism point equally unmistakably towards humanity. Sometime after 2.5 mya the gracile Australopithecines disappear from the fossil record, while the robusts continue on, down in fact to about 1 mya or even later. There is something of a fossil gap between the gracile Australopithecines (especially the East African ones) and the first representatives of the genus Homo at before 2 mya, but when that genus first appears in the shape of Homo habilis, the fossils in question so thoroughly hark back to Australopithecus afarensis in some respects that it is clear that evolution had been going on smoothly in the interval and it might be quite hard to assign definitively some fossil material to, say, Australopithecus afarensis or early Homo habilis. Some habilis specimens exhibit, for example, the rather long-armed character of afarensis. But the brain size of habilis was significantly greater than that of any Australopithecines: absolutely top size for them was about 600 ml whereas habilis ranges from about 650 ml to 750 ml or so. Teeth were more human in form than Australopithecine teeth, faces were flatter, skull bones thinner, foreheads higher. The oldest of the fossils of early Homo comes from Hadar in Ethiopia: a maxilla showing a more parabolic dental arcade than that of the Australopithecines (i.e. further away from the squarish shape of ape jaws), with less of their prognathism of the muzzle. The Homo maxilla from Hadar has been dated to about 2.3 mya. Significantly the geological horizon in which it was found also contains, in the same fresh condition, Oldowan tools; this is the oldest known association of hominid fossil material with tools, though a new find of a rather long-legged Australopithecine from Ethiopia, at about 2.5 mya, is reported to be associated with evidence of animal butchery.
Toolmaking to some recognizable pattern in stone certainly goes back beyond 2.3 mya. We recall that tools have never been found in association with the gracile Australopithecines – there is a little more to say about tools and robust Australopithecines – and it seems likely that the innovation of stone toolmaking belongs to early Homo in the form of something like H. habilis. The oldest tools, flakes smashed off pebbles found in the region of the Omo river in Ethiopia, date back to about 3 mya, which is the likely date for the beginning of the evolution of Homo out of Australopithecus (though representatives of both gracile and, later, robust Australopithecine species continued on in parts of Africa). The ongoing process of aridification through the millennia would have contributed to the development of toolmaking. Bipedalism, which perhaps first arose to get back from the savanna to the woods as quickly as possible, became the established posture of Australopithecus and even more so of Homo as the grasslands spread, releasing the hands from all arboreal preoccupations and promoting their use for throwing, carrying and tool-wielding purposes. In the dry savanna landscape it was by ponds and lakes and along the beds of streams that the hominids lingered, where pebbles for toolmaking purposes were easily to be found – and potential game came to water alongside the early humans. Ground-living, toolmaking and meat eating are the trinity of habits that made humanity.
An Oldowan pebble tool.
By the time of the Hadar Homo maxilla, the simple pebble-smashing of the Omo tool types had evolved into the Oldowan, the first toolmaking tradition of any recognizable distinction. This was the work of creatures with a socially shared habit of making stone tools to a definite pattern. The Oldowan, too, was based on pebbles, to manufacture both knapped flakes and their remanent cores, which served as some kind of gene
ral-purpose chopping tool. Finds of broken animal bones in association with these early tools suggest their use on meat-bearing animal parts, whether scavenged or even hunted on a limited scale. Raw material for tools was evidently acquired close to the sites of toolmaking and tool use, but not necessarily immediately to hand, for materials were transported some distances from their sources. The Oldowan tools are crude items and it took a million years for them to turn into anything better but they mark, for all that, another great progression in human evolution. We have seen that chimpanzees, the toolmaking non-human primates, make only the most minimally modified of tools, by means like chewing and tearing of twigs that barely exceed the natural procedures of fruit peeling and eating. Their only use for stone is as unshaped hammers and anvils for opening up difficult foods. They can scarcely be induced to produce anything like the knapped stone tools that we see even in the Omo material, let alone the Oldowan. The making of such tools is a concept beyond them.
Indeed, toolmaking in stone can fairly be called the first concept ever entertained by evolving humanity. To take a pebble and permanently modify it according to some pattern ‘in the mind’s eye’ is to first isolate it out of the general run of the world’s phenomena, and then transform it, in a way that preserves the evidence of the human agency of that transformation, into a long-lasting product with prospects of future use built into it. Present action results in a product with a past and a future; there is a sort of grammar in the hierarchy of operations and uses that go into making, through various steps of flaking to a socially shared pattern, and then employing the finished tool. Only the clever brain of a primate, whose line stretched back through millions of years of stereoscopically sighted and socially honed ancestry, could be in a position to undertake the revolutionary step of stone toolmaking. It may be that life in the grasslands enhanced the brain’s capacity to process the stereoscopically derived information in fine detail that came into it in abundance; it may be that social life in the open in multi-male/multi-female hierarchical groups further quickened the wits of the evolving Homo. It is certainly true that brain development, leaving the apes far behind, got under way with the Australopithecines and greatly accelerated with Homo habilis. It is in the neocortex of the brain that the spectacular developments of human cranial capacity have occurred: the neocortex where processing of sensory data is conducted without necessary reference back into the older, limbic and purely instinctive regions of the brain.
The ‘grammar’ that we can see in the processes of toolmaking and tool use, with their insinuations of tense and mood (making a tool now, according to a necessary sequence of steps to a standardized pattern derived from the past, for potential use in the future) raises the question of language development among the earliest species of Homo. The chimps, as we have seen, cannot produce the necessary sounds for language and can only learn the most rudimentary use of human sign language, with no proven grammar to it at all beyond the imperative (‘Gimme!’). The distribution of the various parts of the vocal tract needed to assume a far more human character than the chimps display before the physiological capacity for language sounds could arise. Bipedalism with its balancing of the head on the top of the spinal column and allowance for the pulling-in, under the skull, of the jaw initiated the required alteration to the vocal tract and later representatives of the genus Homo do start to show a more human configuration of the vocal tract, which suggests the use of language at some level – unfortunately no habilis remains include the parts that would throw light on the positioning of the larynx in this species. But habilis brains (and even those of the Australopithecines) display the markedly lopsided character that is associated in us with handedness and most of the Oldowan tools appear to be the work of right-handed makers – handedness is present to a much less marked degree in the apes and the cortical areas associated with it are also identified with speech production and reception in modern human beings. Handedness may be a brain development associated with toolmaking that played in with the evolution of language use. Going by the crudity and extreme slowness of evolution of the toolmaking of the early species of Homo, we can safely conclude that language, too, though probably primitively present among these remote ancestors of ours, was correspondingly crude in its utterance and in its range of expression and very, very slow to evolve. The probability of its presence is buttressed by its likely conceptual relationship to toolmaking and by its adaptive usefulness to tool-using, socially organized creatures like Homo habilis. Just as human babies before they learn to talk are given to a stream of burbling that resembles speech in rhythm without having any words, so it is possible that language use evolved in our ancestors out of a stream of mood-communicating vocalization (of which they had become physiologically capable) that first supplemented, then stood in for and finally superseded the mutual grooming habits that are seen today to ease social relations among chimpanzees. Much of what passes between ourselves by way of chatting is scarcely more than mutual grooming to this day. Such vocalization would have evolved into a primitive language for use in social exchanges. Language may have been pregnant with possibilities for mind expansion into abstract thought in directions that we shall discuss later on, but in its initial manifestations it is likely to have been very limited in scope and chiefly employed in the social sphere, in line with the special character of primate, hominid and human cleverness which excels in social awareness and manoeuvring. Any use in more objective contexts, as with toolmaking, may well have been a rather unconscious affair; tools would have been made, and remarks about the natural world passed, in automatic mode, as it were, without being brought into the sphere of social consciousness. (Of course, all the caveats as to what we mean by consciousness continue to apply.) Early language can have had little or no symbolic content, one of its chief glories among its best practitioners today; indeed, symbolism of every sort is conspicuously lacking in the archaeological record until the arrival of the modern form of humanity. From an Australopithecine site in South Africa there has come a small water-worn ironstone pebble whose natural face-like appearance seems to have been appreciated enough to cause it to be carried at least 30 km home from its source as long as 3 mya. But it is an utterly stray find on which nothing can be built against a desert of signally lacking evidence of any sort of art or symbol over millions of years. Incipient language is likely to have been a very concrete, as well as socially orientated, affair.
Homo habilis.
Stereoscopic vision had already equipped the brains of our remote primate ancestors with a capacity for highly detailed analysis of the material (non-social) world about them, allowing them to isolate parts of it (like food) that concerned them with great precision and thus laying the basis for a mental categorization of experience into related but discrete parts that simpler creatures just cannot achieve. Toolmaking, in taking hold of such discrete components of the world as pebbles and endowing them as tools with new features related to the habits and intentions of their makers, extended the categorization of the world into a new mental area; in place of the lower animals’ instinctive interaction with the world outside itself, with little or no awareness of self vis-à-vis the wide world, there was now an intermediary zone of things that were neither mere natural details of the external realm nor parts of oneself, but rather features of the wide world given human significance through human action upon them. With the progress of language, words of standardized meaning arranged in complex sentences were to fulfil a similar role, but inside the mind, as intermediaries between the self and the world outside the self, making it possible to construct and experiment with whole microcosms in our imaginations that model the world in which we live, first perhaps the all-important social world in particular and eventually everything that we can know.
