132 HUMAN BIOLOGY 



if not in degree of complexity and usefulness, with human 

 speech, and whether the behavior of existing primates 

 suggests or definitely indicates the evolution of ability to 

 use symbols and the presence of hnguistic systems of expres- 

 sion. The first of these questions is easily answered; the 

 second is more difficult. 



Intercommunication evidently occurs in various types of 

 bird and mammal, as also in certain classes of primate; but 

 in most instances it appears to be primarily affective, 

 instead of serving to transfer such intellectual processes as 

 those of perception and ideation, inference and practical 

 judgment. Yet precisely these forms of experience are 

 accompaniments of, and presumably essential to, behavioral 

 adaptations with insight and foresight, which occasionally 

 are discoverable in the apes. The use of symbols, we venture 

 to assert, is not so highly developed in any bird or mammal 

 as to justify the application of the term language. When we 

 direct attention to the apes we at once discover diversity 

 of opinion and description, for there are those who attribute 

 vocal language both to apes and monkeys, whereas more 

 critical and conservative authorities assert that only man 

 may properly be said to speak. 



The following should bring us to a pause. We humans are 

 prone to consider ourselves the measure of all things. Unre- 

 flectingly we accept our most notable psychobiological 

 achievement, language, as a measure of the development 

 of mind. This surely is indefensible, for it may be that such 

 other varieties of symbol as gesture, facial and bodily atti- 

 tude, hmb and finger movements, are more naturally and 

 effectively employed by a particular type of animal than 

 are sounds. Actually, human deaf mutes use a sign language. 

 Why then may not infrahuman primates exhibit other modes 

 or even systems of linguistic expression than the vocal? 



Our reply is, they do. Especially in monkeys and apes 

 appear evidences of intercommunication through transfer 

 of mental state by such behavioral signs as we have 

 mentioned. Although we should hesitate to describe it as lan- 

 guage, we must nevertheless recognize its functional signifi- 

 cance and suggest that in all probability there is no greater 

 contrast between the status of the use of symbols by ape 



