Life on the open savannah with a multitude of predators was a dangerous affair. Humans are not strong animals, and the early hominids were much smaller than modern humans. They possessed neither strong claws nor powerful teeth, nor could they outrun lions and other four-footed predators. The only way to survive was by developing a highly organised and co-operative community for the collective exploitation of scarce food resources. But the decisive step was without doubt the manufacture of artefacts, beginning with the stone scrapers, used for a variety of purposes. Despite their deceptively simple appearance, these were already highly sophisticated and versatile tools, the production of which implies a significant degree of organisation, planning, and at least the elements of a division of labour. Here we have the real beginnings of human society. In the words of Engels:

As already said, our simian ancestors were gregarious; it is obviously impossible to seek the derivation of man, the most social of all animals, from non-gregarious immediate ancestors. The mastery over nature, which begins with the development of the hand, with labour, widened man’s horizon at every new advance. He was continually discovering new, hitherto unknown, properties of natural objects. On the other hand, the development of labour necessarily helped to bring the members of society closer together by multiplying cases of mutual support, joint activity, and by making clear the advantage of this joint activity to each individual. In short, men in the making arrived at the point where they had something to say to one another. The need led to the creation of its organ; by modulation the undeveloped larynx of the ape was slowly but surely transformed for ever more developed modulation, and the organs of the mouth gradually learned to pronounce one articulate letter after another.[39]

The production of tools, the beginnings of a division of labour, originally between men and women, the development of language, and a society based on co-operation – these were the elements which marked the real emergence of humankind. This was not a slow, gradual process, but represents yet another revolutionary leap, one of the most decisive turning points in evolution. In the words of the palaeontologist Lewis Binford, “Our species had arrived – not as a result of gradual, progressive processes but explosively in a relatively short period of time.”[40]

The relation between labour and all the other factors was explained by Engels:

First labour, after it, and then with it, articulate speech – these were the two most essential stimuli under the influence of which the brain of the ape gradually changed into that of man, which for all its similarity to the former is far larger and more perfect. Hand in hand with the development of the brain went the development of its most immediate instruments – the sense organs. Just as the gradual development of speech is necessarily accompanied by a corresponding refinement of the organ of hearing, so the development of the brain as a whole is accompanied by a refinement of all the senses. The eagle sees much farther than man, but the human eye sees considerably more in things than does the eye of the eagle. The dog has a far keener sense of smell than man, but it does not distinguish a hundredth part of the odours that for man are definite features of different things. And the sense of touch, which the ape hardly possesses in its crudest initial form, has been developed only side by side with the development of the human hand itself, through the medium of labour.

The earliest hominids had a predominantly vegetarian diet, although the use of even the most primitive tools like digging sticks gave them access to supplies of food not available to other apes. This diet was supplemented by small quantities of meat, obtained mainly by scavenging. The real breakthrough came when the production of tools and weapons permitted humans to pass over to hunting as the primary source of food. The consumption of meat undoubtedly led to a rapid further increase in brain size and this was recognised by Engels:

A meat diet contains in an almost ready state the most essential substances required by the organism for its metabolism. It shortened the time required, not only for digestion, but also for the other vegetative bodily processes corresponding to those of plant life, and thus gained further time, material, and desire for the active manifestation of animal life in the proper sense of the term. And the further that man in the making became removed from the plant kingdom, the higher he rose also above animals. Just as becoming accustomed to a plant diet side by side with meat converted wild cats and dogs into the servants of man, so also adaptation to a flesh diet, side by side with a vegetable diet, considerably contributed to giving bodily strength and independence to man in the making. The most essential effect, however, of a flesh diet was on the brain, which now received a far richer flow of the materials necessary for its nourishment and development, and which therefore could become more rapidly and perfectly developed from generation to generation.[41]

Exactly the same point is made by Richard Leakey, who relates it to a fundamental change in social organisation. In most other primates, there is fierce competition between males to mate with the females. This is reflected in the very considerable differences in body size between, say, male and female savannah baboons. Such a difference can be seen in the earliest hominids, such as Australopithecus afarensis. This suggests a social structure closer to the apes than to humans. In other words, physical adaptations such as bipedalism, vital as it undoubtedly was as a precondition for human evolution, does not yet entitle us, contrary to what Richard Leakey suggests, to characterise these early hominids as humans.

Among savannah baboons, the males (who are twice the size of the females) leave the troop as soon as they reach maturity, and join another troop, where they immediately enter into competition with the established males for access to the females. Thus, in Darwinian terms, these males have no (genetic) reason for co-operating with each other. Among chimpanzees, on the other hand, for reasons not yet understood, the males remain in the group where they were born, and the females migrate. The male chimpanzees, being genetically related, have a Darwinian reason to co-operate, which they do, both to defend the group against outsiders, and even occasionally combining to hunt a monkey to supplement their diet. The difference in body size between male and female chimpanzees is only 15-20 per cent, reflecting the predominantly co-operative nature of this society.

Whereas the difference in size between male and female members of the Australopithecus afarensis group was so great that they were at first thought to be fossils from two entirely different species, the situation is radically different when we come to the earliest members of the human species, where males were no more than 20 per cent larger than females, as with chimpanzees, our closest genetic relatives. On this, Leakey remarks:

As the Cambridge anthropologists Robert Foley and Phyllis Lee have argued, this change in body-size differential at the time of the origin of the genus Homo surely represents a change in social organisation, too. Very probably, early Homo males remained with their natal groups with their brothers and half brothers, while the females transferred to other groups. Relatedness, as I’ve indicated, enhances co-operation among the males.

We can’t be certain what prompted this shift in social organisation: enhanced co-operation among males must have been strongly beneficial for some reason. Some anthropologists have argued that defence against neighbouring troops of Homo became extremely important. Just as likely, and perhaps more so, is a change centred on economic needs. Several lines of evidence point to a shift in diet for Homo – one in which meat became an important energy and protein source. The change in tooth structure in early Homo indicates meat eating, as does the elaboration of a stone-tool technology. Moreover, the increase in brain size that is part of the Homo package may even have demanded that the species supplement its diet with a rich energy source.[42]

It is well known that the brain is a metabolically expensive organ, which in modern humans absorbs 20 per cent of energy consumed, despite only amounting 2 per cent of total body weight. The Australian anthropologist Robert Martin has explained that the increase in brain size in early Homo could only have occurred on the basis of an enhanced energy supply, which could only come from meat, with its concentration of calories, proteins and fat. Originally, this would have come from scavenging, and some hunting activity (which, as we know, occurs even among chimpanzees). But later there is little doubt that hunting played an increasing role in providing a more varied and nutritional diet, with far-reaching evolutionary consequences.

  1. Engels, F. The Dialectics of Nature, pp. 231-2.

  2. Quoted in Leakey, R. op. cit., p. 67.

  3. Engels, F. The Dialectics of Nature, pp. 233-4 and 237.

  4. Leakey, R. op. cit., p. 54.