§ 5 Conclusion
From the addiction of some ancestral ape to animal food, and to the life of a hunter in order to obtain it, then, the special characteristics of Man seem to be natural consequences. The hypothesis from which everything follows is exceptionally simple and moderate. It is generally admitted that our ancestor was a large anthropoid—possibly more gregarious than others, possibly more apt to live upon the ground; but neither of these suppositions is requisite. He was adapted to his life, as the chimpanzee and gorilla are to theirs: in which, probably, they have gone on with little change for ages. But into his life a disturbing factor entered—the impulse to attack, hunt and eat animals, which extensively replaced his former peaceable, frugivorous habit. The cause of this change may have been a failure in the supply of his usual diet, or an “accidental variation” of appetite. Not a great number need have shared in the hunting impulse; it is enough that a few should have felt it, or even one. If advantageous and inheritable, it would spread through his descendants. It was advantageous (a) in enlarging their resources of nutrition, and (b) in enabling them to escape from the tropical forest. On the other hand, to those least fit for the new life it brought the disadvantages of more strenuous exertion and of competition with other carnivorous types. But with hands and superior intelligence, those that had the requisite character succeeded. There was rapid selection of those whose variations of structure, character, activity were most effective in dealing with game and with enemies; especially of those who combined and co-operated, and learned to direct co-operation by some rudimentary speech.
But, again, the hunting impulse here assumed to have possessed some anthropoid was not something entirely new; anthropoids and many other Primates are known to seize and devour birds, lizards and even small mammals when chance offers an easy opportunity. It is merely a greater persistence in this behaviour that turns it into hunting. How very improbable that such a change should not sometimes occur! Is it not likely to have occurred often, and with many failures? Similarly, of the resulting changes: the differentiation of our hands and feet is only an advance upon what you see in the gorilla; as for our ground-life, can the adult male gorilla be fairly called arboreal? Several Primates use unwrought weapons; most of them lead a gregarious life, to which our own is a return; they are co-operative at least in defence; like many other animals, they communicate by gestures and inarticulate vocal cries. Co-operative hunting, indeed, seems to be new in our Order; but since wolves and dogs, or their ancestors, fell in with it some time or other, why should it be beyond the capacity of apes? On second thoughts, is the co-operative raiding of plantations by baboons something altogether different from hunting in pack? Thus at each occasion of change in structure or function, Lycopithecus merely carried some tendency of the other Primates a little further, and a little further; until, certainly, he went a long way. The whole movement can be distinctly pictured throughout, and it has an air of being natural or even inevitable. Few hypotheses ask us to grant less than this one.
Moreover, if the story is not true, Man is an exception to the rule of animal life, that the structure of every organism is made up of apparatus subserving its peculiar conditions of nutrition and reproduction. Indeed, conditions of nutrition are the ground of the differentiation of animals and plants. Conditions of reproduction need not here be considered, as the apparatus is the same in the anthropoids and in ourselves. With many species to avoid being eaten and to mate are the reasons for some secondary characters, such as protective armour or coloration, fleetness with its correlative structures, nuptial plumage, and so forth. But to avoid being eaten and to mate, it is first of all necessary to eat and live; and accordingly, for each sort of animal, starting from the organisation of some earlier stock, its structure and activities are determined by the kind of food it gets, and the conditions of getting it: in our case, the hunting of game afoot.