SUB-HUMAN CULTURE BEGINNINGS 



32.7 



THE BEHAVIOR OF APES 



Fortunately, however, the last fifteen 

 years have seen a burst of interest in 

 those of the mammals most nearly related 

 to ourselves, the Primates, and among the 

 Primates in the anthropoid or man-like 

 apes. This interest has been partly popu- 

 lar, but has also been reflected in the en- 

 deavors of biologists and psychologists 

 to secure reliable evidence and a sound 

 understanding of the behavior of these 

 apes. The work of Koehler, Kohts, 

 Boutan, Yerkes, Furness, has been as 

 critical as is possible in the present de- 

 velopment of science. Controlled ex- 

 periments have been added to systematic 

 observations. Strangely enough, not one 

 of the studies of the great apes has been 

 made by an anthropologist. But there is 

 in this at least the advantage that an 

 anthropological interpretation cannot be 

 challenged on the ground of bias or pre- 

 conception. 



All of the four types of man-like apes 

 have been studied, but the chimpanzee 

 has provoked most interest. The gibbon 

 is very different from ourselves in propor- 

 tions and behavior; he is thoroughly 

 arboreal. The orang approaches him in 

 this respect; he possesses a sluggish and 

 melancholy temperament. The gorilla, 

 perhaps anatomically closest to man, has 

 been difficult to capture and keep in con- 

 finement. His study has yielded some 

 results; but his attitude toward human 

 beings is aloof. The chimpanzee is about 

 equally similar to man, shows definite 

 responsiveness to human association, and 

 is relatively hardy and docile. 



the ground in walking; but locomotion 

 is on two feet. The differentiation of the 

 limbs into a locomotory and a manipula- 

 tive pair is not as marked as in man, but 

 approaches it. There are few if any 

 human manual abilities which the chim- 

 panzee does not possess. He is endowed 

 with much greater strength. The avail- 

 able data suggest that his muscular power 

 may be estimated at three times our own. 

 The infant chimpanzee begins to teethe 

 within two months, walks at the end of 

 six, has all its milk teeth within twelve 

 months, and possesses at that age suffi- 

 cient muscular coordination to secure for 

 itself part of its food, although it may 

 continue to nurse. A period of playful- 

 ness and activity follows . Growth is at 

 first slower than in man, but rapid toward 

 adolescence. Sexual maturity comes at 

 about eight to ten years in females and 

 ten to twelve in males. Accompanying 

 sexual maturity there is a change of tem- 

 perament. Playfulness diminishes, in- 

 dolence and irritability increase, the in- 

 dividual becomes less exuberant in his 

 manifestations of sociability, and, on 

 account of his great strength, somewhat 

 dangerous. This appears to be part of a 

 wider process involving a slowing down or 

 at least change in direction of what we 

 call intelligence. In experiments, young 

 chimpanzees have made the best perform- 

 ances. The one adult female of Koehler, 

 for instance, was rated by him near the 

 bottom of his list of seven immature 

 chimpanzees. A human parallel is ob- 

 vious. The duration of chimpanzee life 

 is not known, but is estimated at not very 

 much less than that of man. 



THE CHIMPANZEE 



The chimpanzee's life is primarily 

 terrestrial, although he is a splendid 

 climber. The body is not carried fully 

 erect, and the knuckles frequently touch 



CHIMPANZEE PSYCHOLOGY 



The senses of the chimpanzee are similar 

 to our own. Sight, which is the easiest to 

 test in both species, is much alike in per- 

 ception of color, form, and distance. 



