PECULIAR ITEMS OF MAN'S BODILY FORM At this juncture the question arises, what was there peculiar in man's physical make-up that enabled him to initiate civilization and build up a mind which he could use to increase his resources so far beyond that of any other animal? Before proceeding we should recollect that the ways of all living creatures are manifold and astonishing. Even a single-celled organism can marvellously adjust itself to altered conditions. It seems to learn by ex perience, it appears to have a sort of memory, it is modified by happenings which interrupt its comfortable routine. It is in genious in defending itself, in seeking food and reproducing. It is, in short, purposive in its conduct. The tiger and the frog are able to adjust themselves to very different modes of life, and so are the orioles and cacti. Before man began to accumulate civili zation we are forced to assume that he too made terms with the daily need of adjustment which faced him, otherwise we should not be here to write the tale. These are the salient essentials of Life, and man is a part of what Julian Huxley calls "the stream of life." All these possibilities lay behind the development of man's intelligence. They are the hinterland from which civilization emerged and to whicl, it ever tends to retreat.
In order to begin and carry on the accumulation of civilization, man had of necessity to be so constructed physically that he could perceive more clearly than his predecessors, make more accurate distinctions and so remember and imagine better; for all these are essential to talking and thinking. The awareness of animals is of a low, vague type, and so must pristine man's have been. The one-celled animals behave in a purposive way, but they have no eyes or ears or noses. They must live in silence and darkness like a human blind, deaf mute. They will never theless take in certain food and reject other things. They per ceive and act without, so far as we can see, being conscious of their actions. They make the necessary decisions without deciding in a human sense. They have no nervous system, but, as has lately been discovered, the promise of one. The creatures most like ourselves have eyes, ears and noses, and evidently see, hear and smell; and they have an elaborate nervous system. Of these resources they make constant use. But compared with man they are ill-qualified to make careful distinctions and discriminations and remember clearly. They take note of far fewer factors in their situation. They must act somewhat as our digestive system does. It is a sort of animal within us which performs wondrous feats when given food. It works purposively, as does our heart and blood circulation. We can become conscious of these un conscious achievements when we choke, because the switch is not thrown promptly enough to prevent a morsel from going down our windpipe instead of taking the route to the stomach. Palpitation of the heart is a conscious suggestion of the faithful pump, which rarely reminds us of its constant attention to busi ness. Let it neglect two or three beats and we are dead.
The essentials of man's physical equipment for initiating and piling up civilization have been dwelt upon by many writers. He has sensitive hands, and (after he got securely on his hind legs) he could use them far more freely than if he had to employ them as auxiliary feet. His thumb can be readily placed against any one of his fingers. There is no such expert feeler and handler as he to be found among his kindred. He could learn much of shape and form, of softness and hardness, of weight, texture, heat and cold, toughness, rigidity and flexibility, which could be but vaguely sensed with hoof or paw. Had he had ears that he could turn about like a jack-rabbit, and a prehensile tail, he might have been able to learn faster. And all these things were the beginning of knowledge. He could not only strike but hurl. His eyes were so placed that he was always looking through a stereoscope, so to speak, and seeing things in the round. His vocal organs promised a great range of delicate discrimination in the sounds he made. Then he was a helpless dependent for many years on his elders so that their acquired ways could become his.
Lastly there is man's brain with its complex cerebral cortex and its association paths, which develop astonishingly as a child grows up. The cortex is the prime correlator of impressions, and is modified through individual experience in a higher degree than any other part of the nervous system. Its functioning is still very mysterious, but no one doubts its essential role in the process of human learning and the increase of intelligence. Its operations are not, however, autonomous but closely associated with the ex periences of the whole human organism and dependent on those singular capacities of mankind already mentioned.
So it becomes apparent that after hundreds of millions of years during which nature's experiments have been going on in physical structure and function, which have enabled creatures of the most diverse types to meet the absolute requisites of life—growing up and reproducing their species—a kind of animal finally appeared on the earth so constructed that he could become civilized. Man's biological make-up represents a unique combination of physical characteristics. Most of these, as we have seen, occur in other mammals. Even those which seem peculiar to him would not serve, however, as a foundation for the development of civiliza tion except in a highly complex union. Cows might have a human cerebral cortex, foxes apposable thumbs, birds stereoscopic eyes, dogs vocal organs similar to ours, and yet civilization would be far beyond their reach. Man can teach all of them tricks. They themselves can learn something as their life goes on. Chimpanzees may under favourable circumstances, as Kohler has shown, make very simple, human-like inferences; but none of them could initiate and perpetuate the arts and sciences as a heritage of their species.