OUR FACE FROM FISH TO MAN 



man is especially evident in the front views of the 

 young skulls (Fig. 102). 



Meanwhile we observe a general progression in 

 the character of the hands, which in the lemuroids 

 are hardly more than forefeet, while in the gibbon, 

 chimpanzee and gorilla the anterior extremities 

 are true hands, adapted primarily for brachiation 

 or leaping with the arms, a habit which requires the 

 greatest quickness in adjusting the focus of the 

 eyes and in correlating the locomotor activities 

 with the rapidly changing visual data. 



To the brachiating habit of his ancestors man 

 doubtless owes much of his skill in discriminating 

 the relative nearness of different objects. Brachia- 

 tion would also seem to be greatly facilitated by 

 bicon jugate movements of the eyes. Broman and 

 John I. Hunter have shown that in the chimpanzee 

 the nucleus in the brain of the oculomotor nerves, 

 which controls several of the eye muscles, has 

 essentially the same pattern as in man and differs 

 widely from that of the lower primates which have 

 not attained bicon jugate movement of the eyes. 



The surface of the iris as seen through an 

 ophthalmoscope differs widely in different kinds 



of animals. Lindsay- Johnson in his beautiful 



198 



