MAN PAST, PRESENT AND FUTURE 935 



ha\(.' been straclil\ maintanu'cl ihrou^^lioul this sltics, but it is in the h'oiital 

 It)bc' that clrcisiw aclxancc has occurri'cl. 1 his area, so jx)()rl\ rcpri'sciitcd 

 in man's iR'art'st kni, the ^rcat anthropoid a|5c's, shows (.'MilHTant i^rowth in 

 pithrcantliropus. Its Icaturcs correspond with thost' of I lonio sajjicns in 

 iu-arl\ all ck'tails. Its only essential mleriority is its relative sniallness. ^ et 

 even its size is sullieieiit to iustily admission into the human lainily. Its 

 specializations in the i^refrontal area, and tlu' di\"elopnuMit of the inferior 

 frontal convolution denote the aec|iiisition of human si)eech and reason. 



l-*erhaps it is ha/.ardous to dehne any single area in the brain as the 

 region suj^reme in cerebral oi\i:ani/atioii, since the entire neopallium is viv- 

 tuallx interde[)endent throuiihout all of its special parts. The \ isual, the 

 auditory and the somesthetic sensory areas contribute so indispensably to 

 life's reactions, that one part may not be subordinated to another. This is 

 also true ol \hv motor area, the area regulatiiiij; skilled moxement and the 

 large intt'iniediate /one w Inch |)artakes of parietal, occii:)ital and temporal 

 characters. Each ol these art'as has proo;ressi\el\' expanded through the 

 se\'eral e\olutional stages ot the human bram. ^ et it is reasonable to attri- 

 bute a certain superiorit\ to that neopallia! region which is charged w ith the 

 iunctional repri'sentation ol all othc-r cortical territories, which combines 

 the highly particularized Junctions ot all other areas in broader impressions 

 ol human existence, which acts as the accumulator of experience, thetlirector 

 of behavior, and the instigator of ])rogress. Traced through all their inter- 

 mediate steps upw arc! it is exactly these prefrontal and frontal regions which 

 manifest the most conspicuous development. The process of this long con- 

 tinued progressive expansion in tlu' frontal lol)e, reaching back to the earliest 

 Pleistocene times, and it may be e\en into the Pliocene epoch, conve\s the 

 impression of a responsi\e plasticity in the human brain. This remarkable 

 anticiuity and this salutary plasticity ha\H' been largely overlooked. For the 

 most part the human cerebrum is regarded as a finished product. Itsevolu- 



