nearest to man. His arms are much shorter than the gorilla's, reaching only a little below the knees; he also has a betterdeveloped head, great toe, and thumb; his whiskers, eyebrows, lashes, and teeth approach the human in character; he is said to be naturally more tractable and social, living not only in family groups but in parties of several families; the male builds tree shelters for the female and young, and sleeps lower down to protect them.

Peter has been taken away from his African arboreal environment, has been put into evening clothes, and brought before the audiences of large cities. To come at close range with Peter's powers, Dr. Witmer made several private examinations, and finally brought him before his psychological clinic, subjecting him to certain mental tests used in diagnosing the intellectual grade of backward and defective children. All these observations resulted in the interesting conclusion that Peter ranks upon the plane of a low or middle-grade human imbecile. He has decided motor dexterity; he skates on roller skates, learning by himself in a few hours; he rides a bicycle, drinks from a tumbler, eats with a fork, threads a needle, lights and smokes a cigarette, strings beads, and puts pegs in a board; he shows a high degree of practical judgment in opening a strange lock and selecting a needed key from a key ring; he can use a hammer, drive a nail, drive a screw, and select the proper screw driver for his purpose; he partially succeeded even with the classic test of inserting various geometrical blocks into a special form board with shallow depressions; but most mirabile dictu, after a W had been drawn on the blackboard he copied it in direct tracery imitation. He can articulate “mama,” and learned in a five-minute phonic drill to pronounce "P." He shows decided powers in comprehension of language. His emotional traits are no less

wonderful, for his mobile face expresses in turn nonchalance, eagerness, disappointment, courage, distress, protest, inquiry, affection, and at times he even has something very like a momentary grin of humor, albeit ghastly because of the cavernous mouth and huge jaw."

A

W

B

It has been suggested that the apelike man of Java may be regarded as an intermediate transitional form which fills the anatomical gap between modern man and his brute ancestors. There is a similar psychological gap or chasm. This chasm, Dr. Witmer holds, Peter's mind practically bridges. Since mind cannot be preserved for us in osseous fossils, we cannot look elsewhere for a bridge. or link. When we reflect that many cases of feeblemindedness are really to be interpreted as instances of arrest of development on a primitive racial level, a very significant and legitimate conclusion is that" the study

24

FIG. 11. PETER'S WRITING ON THE

BLACKBOARD

A, the letter W drawn twice, one tracing over the other; A1, Peter's copy after the second tracing; A2, Peter's second

effort when told to make a W again;

B, a scrawl following the first tracing

of this ape's mind is a subject fit, not for the animal psychologist, but for the child psychologist."

To come back to the first dispersion of the human species. No one can, of course, say how long it took for man to spread over the whole habitable globe. His rate of increase may have been fast, but, while nimble in the trees, his progress on the ground must have been gradual. The climate, however, was uniformly mild, and his complete occupation of the world was probably under way by the close of the Tertiary epoch. In this remote age there were of

course no nations, - not even races. This early man was a generalized ancestor, from whom the four primary divisions of the human species- Negro, Mongolian, American, Caucasian were not to diverge until hundreds of thousands of years had elapsed.

The home of most primitive man was like that of the Swiss family Robinson. Not only in appearance, but to some extent in habits, he must have resembled his nearest kin. His food consisted of roots, berries, plants rich in cellulose, nuts, honey, and insects. He had few ornaments of beauty and tools of utility. Some writers have even questioned whether he had the cortical neurons that would enable him to talk. At any rate his utterances were thick and clung to the base of his tongue; for nimbleness and subtlety of articulation go with the development of abstract ideas, of which he possessed very few. His life was probably arboreal until the increasing cold climate drove him into caves.

With the close of the Tertiary epoch a great meteorological and geological change came over the earth, which had a powerful effect upon the natural history of man. Mysteriously, from the north, crept a great ice cap, which covered a good part of the northern hemisphere with glaciers and icebergs. As mysteriously it retreated, to reappear at least once again. In the warm interglacial period - a duration of perhaps five hundred thousand years — the first achievements of truly human culture were made. In this period fall the eolithic and the paleolithic age, — the latter lasting, according to Keane, about three hundred thousand years. Even though these figures are but an estimate, they will serve to impress the thoughtful reader with the comparative brevity of our historical era, the ancient lineage of our civilization, and the very primitive ancestry of the modern child.

Paleolithic man

and woman too was a hunter. The ice invasion may have exterminated some of his most dangerous foes, but there were enough ferocious species left to call forth all his fear and fight and cunning. His contemporaries, although he lived as far north as England, were the cave bear, the cave lion, the cave hyena, the wild ox, wild boar, wild horse and wolf, hippopotamus, and woolly rhinoceros. But most terrible of all was the huge, sabertoothed tiger, with his enormous jaw, his dagger teeth, and

(From the painting by John W. Alexander in the Congressional Library)

powerful wrenching neck muscles. This most deadly of all beasts struck terror even to the shaggy-maned mammoth. With such enemies, and no protection but the caverns and overhanging cliffs, the primeval savage was put to his wit's end. In the beginning he did not even have fire to drive the wild beasts away. The night was utterly dark, filled with ominous silences and terrifying soundsbellowing, splashing, roars, snorts, and howls; and if he heard the voice of his own humankind, it usually was nothing more than jabber, grunt, or cry.

But though he had not the brute strength of the beasts, he had intelligence in greater measure than any of them. Intelligence is the capacity to profit by experience. It depends upon a nervous system plastic enough to form habits. Professor Yerkes built an experimental aquarium to test whether the frog has such a nervous system. A hungry frog was introduced at the aperture a, shown in the accompanying diagram. The question was, Would the frog learn the direct route a -b, or would he do no more than instinct prompted him; that is, move about aimlessly and unintelligently? He proved to be educable. After some

FIG. 13. TEST OF ANIMAL INTELLIGENCE IN THE FROG

fifty to one hundred trials he pursued the proper path, and when retested a few weeks later showed that he had retained his acquisition. The ability and propensity to swim, snap at flies, and hibernate were provided by nature in the inborn constitutional organization of the frog's nervous. system. Habit formation, on the contrary, depends upon the connections between neurons which are established only through the touch of experience. Intelligence does not supplant instinct, but supplements it. Both instinct and intelligence increase with the evolution of the nervous system. Primitive man, therefore, was superior to the animals with whom he contended in natural instinctive endowment