482 



THE CHANGING GENERATIONS 



in that they lack a certain bone in the wrist which is present in nearly all 

 other primates. 



THE ANCESTRY OF MAN 



Man is unquestionably one of the giant primates and more closely 

 allied to the chimpanzee and gorilla than to any other living animals. 

 Nevertheless he differs from the great apes in important respects and is 

 placed in a separate family, the Hominidae. The distinctions grow less 

 as we trace the ancestry of man and of apes back in time. In order that 

 we may better appreciate the changes that occurred in the line that gave 



Fig. 29.13. Skulls of the four living genera of anthropoid apes, family Simiidae. From left 

 to right they are gibbon, orangutan, chimpanzee, gorilla. {Courtesy Ward's Natural Science 

 Establishment, Inc.) 



rise to modern man, let us consider the features that set him apart from 

 the great apes. 



Characteristics of man. Some of the anatomical characters that dis- 

 tinguish modern man from the apes and lower primates are: (1) the 

 posture is fully erect; (2) the legs are much longer than the arms; (3) the 

 great toe is not opposable to the other toes and is in line with them, 

 instead of being set off on the side like a thumb; (4) the foot is more rigid, 

 and is arched both transversely and from front to rear; (5) the spine is 

 doubly curved, with a forward convexity in the small of the back, called 

 the lumbar curve; (6) the human nose has a prominent bridge and a well- 

 developed, elongated, peculiar tip; (7) there is a median furrow in the 

 upper lip of man, and the lips are rolled outward so that the mucous 

 membrane is visible as a continuous red line ; (8) the brain is from two to 

 three times as large as that of the gorilla, which has the largest brain of 



