OUR ANCIENT RELATIVES 



the nose. In the Old World, or catarrhine series 

 (including the monkeys, apes and man), the nos- 

 trils are drawn downward and inward toward the 

 mid-line, so that they tend to make a V, with the 

 tip pointing downward. The subsequent history 

 of the nose and lips will be considered below 

 (pages 129, 153). 



The external ears of the lower primates also 

 show many gradations from a more ordinary 

 mammalian type (see below, pages 211-213) to the 

 man-like ears of the chimpanzee and gorilla. 



The habit of living either in trees or in a forested 

 region, in so far as it afforded opportunities for 

 securing insects, buds, tender shoots and fruits, 

 made possible the various lines of evolution of the 

 teeth which we observe in studying the fossil and 

 recent primates. In the earliest forms the denti- 

 tion as a whole retains clearer traces of an earlier 

 insectivorous stage, with triangular sharp-cusped 

 upper molar teeth. In the anthropoid the habit 

 of eating tender shoots and buds is reflected in the 

 molar teeth, which now have broad crowns with 

 low-ridged cusps. The human dentition, while 

 secondarily adapted for a more varied diet, still 



bears many indubitable traces of its derivation 



57 



