278 



THE LOWER PRIMATES 



This would scum to si<i;nily that the auditory function in passing from 

 the lower to the upper end of the primate order has tended to lose much of 

 its immediate reactive force; in other words, auditory impulses transmitted 

 to the central nervous system become progressively more in need of the 

 supervision by higher synthetizing areas. In these newer cortical areas they 

 are more complexly associated, more extensively evaluated. Apparently 

 the need of immediate rellex reactions in response to auditory stimulation is 

 less important to the higher members of the primate group than to the lower 

 species. Thus a sudden sound coming into the lemur's field of consciousness 

 immediately provokes a motor response in the interest of defense or escape. 

 The same sound arising in the auditory sphere of man is first subjected to 

 more extensive associational review before action is determined by it. The 

 difference in behavior manifested by these two types of reaction indicates 

 that a greater number of alternatives are possible to man than to such a low 

 form of primate as the lemur. In the latter, the quick response to auditory 

 stimuli would undoubtedly prove more to its advantage than a course of 



