xxiv. 5 (633) 



4. The ancestry of man 



In order to discover the position of man in relationship to the living 

 and fossil ape populations we may try to specify the characters distinc- 

 tive of the family Hominidae and then discuss whether they could have 

 been derived from those of monkeys or apes. Schultz, who has made 

 careful measurement of many features of primates, lists the following 

 as the chief specializations of man: (i) elaboration of the brain and 

 behaviour, including communication by facial gestures and speech; 

 (2) the erect posture; (3) prolongation of post-natal development; and 

 (4) the great rise in population in recent years. Others might make up 

 the list differently, but we may use it as a basis for discussion of the 

 differences between men and other creatures. 



5. Brain of apes and man 



The brain is much larger absolutely and relatively in man than any 

 living ape; Fig. 382 shows that man stands farther apart from the apes 

 in this respect than they do from other anthropoids. The cranial 

 capacity for males of modern (Caucasian) man may be taken as 1,500 

 c.c, whereas that of chimpanzees is given as 410, gorillas as 510, and 

 orangs as 450. The general arrangement of function within the brains 

 is similar in man and apes, but the parts especially well developed in 

 man are the frontal and occipital lobes. The latter are concerned with 

 the sense of sight and are related to our intensely visual life. The 

 frontal lobes, so far as is known, serve to maintain the balance between 

 caution or restraint and sustained active pursuit of distant ends, which, 

 above all else, ensures human survival in such a variety of situations, 

 and makes possible the social life by which so great a population is 

 maintained. The difference of behaviour between men and apes 

 exceeds all the structural differences; our lives are so widely different 

 from theirs that any attempt to specify the divergences in detail is apt 

 to seem ridiculous. Perhaps the more striking of them are related to 

 the powers of communication by speech which, besides its obvious 

 social advantage, gives to man the power of abstract thought. Whatever 

 we may think about the consciousness of animals there is no doubt 

 that our own awareness of life, being expressed in words, is widely 

 different from that of all other creatures. The speech system depends 

 upon a complex of features of the brain, larynx, tongue, mouth, 

 and auditory apparatus. In addition, the facial musculature is more 

 fully differentiated even than in apes, especially around the eves and 

 mouth. 



