throughout the world; nothing could do this but the gradual attainment of erect gait adapted to running down his prey. Hence the numerous modifications of structure necessary to it, whenever from time to time they occurred, were preserved and accumulated by natural selection: namely, the curving of the vertebral column, the balancing of the head upon a relatively slender neck, changes in the joints, bones and muscles of the legs, the lengthening of the leg and the specialisation of the foot (in which the heel is developed more than in the gorilla, and the great toe is lengthened and lies parallel with the other toes).

(4) The specialisation of the legs and feet, as it proceeded, made possible the specialisation of the hands: being gradually rid of the task of assisting locomotion, whether in trees or on the ground, they were used in grappling with prey, seconded by massive jaws and powerful canine teeth. In course of time they brought cudgels and stones to the encounter, and after many ages began to alter such means of offence into weapons that might be called artefacts. These simple beginnings probably occupied an immense time, perhaps more than half of the total period down to the present. The utility and consequent selection of hands had been great throughout; but their final development may be referred to the making and using of weapons fashioned according to a mental pattern. Those who had the best hands were selected because they made the best weapons and used them best; but we know from remains of several palæolithic stages of the art of manufacturing implements how very slowly the art improved.

(5) Along with specialisation of the hands went a reduction in the length and massiveness of the arms; and this must have been disadvantageous in directly grappling with prey. But it was necessary to the runner in order to lessen the weight and cumbersomeness of the upper part of the body and to improve his balance and agility. The change may also have been beneficial by affording physiological compensation for the lengthening and strengthening of the legs. And as soon as unwrought stones and clubs came into use there was mechanical compensation for the shortening of the arms. The result is an adaptive co-ordination of the total structure to the life of a two-footed hunter.

(6) Darwin says: “The early male forefathers of Man were, as previously stated, probably furnished with great canine teeth; but as they gradually acquired the habit of using stones, clubs, or other weapons, for fighting with their enemies or rivals, they would use their jaws and teeth less and less. In this case the jaws, together with the teeth, would become reduced in size, as we may feel almost sure from numerous analogous cases.”

(7) Hence the profile began to approach the orthognathous type; and it progressed further in that direction on account of accompanying changes in the skull. The skull became less thick and rough, (a) because, as the hands (using weapons) superseded the teeth in fighting, jaws and neck grew less massive, and their muscles no longer needed such solid attachments; (b) because the head was less liable to injury when no longer used as the chief organ in combat. At the same time the skull slowly increased in capacity and became vaulted to make room for the brains of an animal, which (as we shall see) acquired much knowledge (parietal association area) and lived by the application of its knowledge to the co-ordination of increasingly complex and continuous activities (anterior association area).[5]

(8) Monkeys of most species, whether in the New World or in the Old, are social, living in bands of from ten to fifty or more, and may co-operate occasionally in mutual defence or in keeping watch. Baboons, indeed, are seen in herds of several hundreds; and they are credibly reported to co-operate in raiding plantations, and in defending themselves against leopards, other baboons and even human hunters.[6] Gibbons, again, are social, going in bands to the number of fifty. But the large anthropoids live only in families—the male orang being even of a somewhat solitary habit; three or four families of chimpanzees may for a time associate together. Man, however, is everywhere—with a few doubtful exceptions, probably degenerate—both social and co-operative; and the purpose of his co-operation at the level of the Australian or the Semang is instructive. It is not, as we might suppose, in industry, but in hunting, war, or tribal ceremonies that tribesmen work together—the last no doubt of comparatively recent origin: so that a few thousand years ago there was no co-operation except hunting and war (which come to the same thing).

That the large anthropoids are neither gregarious nor co-operative follows from their having no task in which co-operation would be useful, no common purpose: they are able alone to defend themselves and their families; and when families range apart through the woods their food is in better supply. But the ancestor of Man found an object for association and co-operation in the chase. Spencer, indeed, says that a large carnivore, capable of killing its own prey, profits by being solitary; and this may be true where game is scarce: in the Oligocene and Miocene periods game was not scarce. Moreover, when our ape first pursued game, especially big game (not being by ancient adaptation in structure and instinct a carnivore), he may have been, and probably was, incapable of killing enough prey single-handed; and, if so, he will have profited by becoming both social and co-operative as a hunter, like the wolves and dogs—in short, a sort of wolf-ape (Lycopithecus). The pack was a means of increasing the supply of food per unit; and gregariousness increased by natural selection up to the limit set by utility. Hence (as will be shown at length in the next chapter) Man is in character more like a dog or a wolf than he is like any other animal.

(9) Some development of the rudiments of speech may be confidently traced to social co-operation. The gibbon, most social, is also the most vocal of anthropoids; but having no common task in which united action is necessary, he uses his remarkable power of voice (apparently) merely to express his feelings and to keep the troop together. The chimpanzee and the gorilla enjoy probably a close and affectionate family life, but one that makes little or no demand for concerted effort. Hence their vocalisation is very rudimentary. According to R. L. Garner, it is true speech: a chimpanzee (he says) knows the meaning of the sounds he makes, and intends to convey it to some definite individual at whom he looks. But he has at command very few sounds, and those mainly expressive of natural wants.[7] If it be urged that anthropoids do not talk because their lower jaw and tongue have not the special adaptation to speech that is found in Man, it should be considered (a) that if such structure had been useful to them it would have been acquired, as at some time it must have been by Man himself; and (b) that even without any change they might have jabbered well enough to convey a good many discriminated, objective meanings if they had needed to do so: for Man must have begun in that way; he cannot have waited for the development of physical structure before trying to talk. Sufficient intelligence is