530 



THE THEORY OF EVOLUTION 



pre-human races indicate the Hne of human descent. On man's 

 intellectual side, Psychology is showing the animal nature of 

 human intelKgence, and the foundations of morality are beheved 

 by some to exist in the higher MammaHa. By another fifty years 

 it is safe to assert that many other facts bearing upon human 

 origins will have been discovered. 



Anatomical Evidence. — The anatomical details of the human 

 body are fundamentally Kke those of other Mammaha, particularly 

 the Family Simiidce, which includes the four species of tailless 

 apes: the gibbon, orang, gorilla, and chimpanzee. There is no 

 essential detail of structure in human anatomy that is not repre- 



FiG. 286. — Ears of apes and men. 



A, Barbary ape. B, chimpanzee, one of the anthropoid apes. C, hairy human ear. 

 D, human ear with point (a), supposedly comparable with the point in A folded inward. 

 (From Romanes, " Darwin and after Darwin," copyright, 1896, by Open Court Publishing 

 Co., reprinted by permission.) 



sented in these apes; although the more erect posture of man has 

 resulted in characteristic speciahzations of the pelvis and viscera, 

 the fore limbs, and the foot. The brain, of course, is the most dis- 

 tinctive feature of man. It exceeds in relative bulk that of any 

 other animal except some very small vertebrates Uke the humming 

 bird (c/. Fig. 288). In specialization of function it exceeds the 

 brain of any other mammal, but here again the structural and 

 functional relationships are all paralleled in the higher apes. The 

 psychology of these apes Hkewise resembles that of man in the 

 earlier states, but later undergoes a retrogression. It is reasonable 

 to believe that the ancestors of man went on to articulate speech 

 and the development of hand and brain, while another Hne of 

 descent, which produced the tailless apes, failed to progress and 

 perhaps underwent regression. 



What are called vestigial organs are often cited as evidences 



