352 



THE RISE OF ANIMAL LIFE 



Fig. 13-70. This spicier monkey (Afe/es panrscus), a rep- 

 resentative of the New World Monkeys, possesses a 

 handy adaptation, namely, its prehensile tail which 

 functions as a fifth appendage. 



food or any other object that strikes their 

 fancy. Their large and forward-placed eyes 

 are probably as keen as those of humans 

 and in appearance they certainly resemble 

 them, even to the expression of emotions. 



The monkeys are divided into two 

 groups, New World forms of Central and 

 South America and the Old World forms 

 of Asia, Africa, and Europe (Fig. 13-67). 

 Two members of the New World monkeys 

 are of interest because of their specializa- 

 tion : the spider monkey, with its prehensile 

 tail (Fig. 13-70) which functions as a fifth 

 hand, and the howler monkey, which has 

 a remarkable voice made possible by modi- 

 fications of the throat into large, bony reso- 

 nating chambers. Each has specialized in 

 its own peculiar way and these variations 

 set them off from all other members of the 

 group. 



The Old World monkeys exhibit a wide 

 variety of form and habits, from the sacred 

 langur of India to the highly colorful 

 ground-dwelling mandrill (Fig. 13-71). 

 Most of them are tree-dwelling, although 

 the baboon lives on the ground entirely. 

 The baboon is of interest because some 

 have highly colored callosities (buttocks) 

 and dog-like snouts. When on the ground 

 they walk on all fours. The baboon is as 



firmly committed to life on the ground as 

 the spider monkey is to life in the trees. It 

 would be interesting to know how these 

 closely related animals came to adopt such 

 distinct habitats. When in the course of 

 events did man's precursor leave the trees 

 and come down to the ground? Had he 

 come with the baboons he would need 

 shoes on both hands and feet today; had he 

 stayed in the trees much longer he would 

 never have been able to come down be- 

 cause his body would have been so modi- 

 fied that it would be unwieldy on the 

 ground. He must have made the shift be- 

 fore his legs got too short or his arms too 

 long. 



The man-like great apes. These predomi- 

 nantly large primates, the gibbon, orangu- 

 tan, chimpanzee, and gorilla, separated 

 very early from the common stem that also 

 produced the monkeys, probably about the 

 same time a branch separated off on its 

 long course toward man. This appears to 



Fig. 13-71. The mandrill (Mandr'illus sphinx) is a color- 

 ful member of the Old World Monkeys. It is noted 

 for its dog-like face and its highly colored cheeks. 



