134 



ROBERT M. YERKES 



Sub-divisions of the Order Primates 



Order Sub-orders Families 



a. Prosimii (Lemurs and Aye-Ayes) 



i. Hapalidae (Marmosets) 



Primates. . . { ii. Cebidae (Howling Monkeys, Tee Tees, 



Squirrel Monkeys, Spider Monkeys, 

 and Capuchin Monkeys) 



b. Anthropoidea . 



iii. Cercopithecidae (Baboons and Macaques) 



iv. Simiidae (Gibbons, Orangs, Chimpanzees, 

 and Gorillas) 



V. Hominidae (Man) 



are almost no satisfactory physiological descriptions of the 

 monkeys, anthropoid apes, or lower primates. 



When we turn to the science of genetics we meet a similar 

 condition, for the literature reveals only scattered bits of infor- 

 mation concerning heredity in the primates. No important 

 experimental studies along genetic lines have been made with 

 them, and such general observations from nature as are on 

 record are of extremely uncertain value. Were one to insist 

 that we know nothing certainly concerning the relation of her- 

 edity in other primates than man, the statement could not well 

 be disputed. 



Occasionally in recent years students of human diseases have 

 employed monke^^s or apes for experimental tests, but aside 

 from the isolated results thus obtained, extremely little is known 

 concerning the diseases peculiar to the various types of infra- 

 human primates or the significant relations of their diseases to 

 those of man. 



Next in order of extent to our morphological knowledge of 

 these organisms is that of their behavior, mental life, and social 

 relations. But certainly no one who is conversant with the 

 behavioristic, psychological and sociological literature could do 

 otherwise than emphasize its incompleteness and inadequacy. 

 For our knowledge of behavior has come mostly from natural- 

 istic observation, scarcely at all from experimentation; our 

 knowledge of social relations is obviously meager and of un- 

 certain value; and finally, our knowledge of mind is barely 

 more than a collection of carelesslv drawn inferences. 



