922 -MAN 



of structural detail which proclaims the ultimate ascendency of the human 

 brain. The fissure of Sylvius may be easily identified and the fissure of 

 Rolando allocated according to accepted computation. \\ ith these two bound- 

 aries in place it is obvious at once that the Pfedmost brain has expanded 

 in all of its neopallial areas. The parietal, the occipital and the temporal 

 lobes have all alike assumed greater proportions than in any of the earliest 

 races of mankind. But it is in the frontal lobe that the most remarkable 

 gains are apparent. Not only are the frontal convolutions more prominent 

 and better defined, but that flatness so characteristic of the Neanderthal 

 vertex has disappeared, and there is no sign of that coronal constriction which 

 seemed to characterize the earliest efforts of the cerebrum in the acquisition 

 of its frontal areas. 



Metric E\ idence of Brain E\olution' in Man 



The manner in which evolutional progress of the brain has gone forward 

 is readily discerned in the accompanying tabulation. From the Javan man 

 to Homo sapiens there has been a gradual increase in all of the major cerebral 

 diameters. In one particular only has there been the slightest faltering in 

 these increments. The Neanderthal brain shows the greatest transverse 

 diameter. But its superiority in this respect is more than overcome by its 

 marked flatness. A distinguishing metrical feature in the development of 

 the human brain is the consistent gain in length and height from Pithe- 

 canthropus erectus to Homo sapiens. The gain in length is to be ascribed 

 largely to frontal increments; that in height is dependent in part upon parietal 

 expansion but also to some extent upon frontal accessions. The bearing of 

 such pronounced frontal evolution upon the ascent of man is evident in the 

 progressive development of human intelligence. 



