THE BRAIN 01 PREHISTORIC MAN 891 



To explain the increased dimensions characteristic of the Piltdow 11 Ijiain, 

 it seems necessary to presume that this race had made certain adaptations 

 which called for added neural ca|jacities. In all the \aricd adapti\e radia- 

 tions seen in otiui- mammals, there is no demand lor complex adjustments 

 comparable to that anectin<i mankind. Search as one may amongst all of 

 these variations, no inlluence, no single factor appears so compelling ol 

 cerebral specialization as the development of the hLiman hand. By this 

 means an entirely new world iiad been laid oj^cn tor man to concjuer, and a 

 still newer one waited for him to construct. So it was that a brain sullicient 

 for the simple living in plain and forest could no longer ser\c this new 

 mastery of life. 



The parietal lobe, although it primarily represents administration 

 in one of the chief departments of the scnsorium, also expresses the 

 externalizing capacity of the brain. This is likewise true to a somew hat less 

 extent of the other cerebral lobes representing the special senses. 



THE TE.MPOKAL AND OCCIPITAL LOBES OF THE DAWN MAX 



The temporal and the occipital lobes also reveal a marked advance. 

 The casts of the Piltdown endocranium are fortunate in showing most of 

 tlu' left temporal lobe. The reconstruction of Dr. Woodward dillers Irom 

 that of Sir Arthur Keith in disclosing but little of the superior temporal 

 coinolution. Keith belie\es that his reproduction is in better accord with the 

 conditions dI human anatomx. His east also obviates the marked dellection 

 inward of the tip of this lobe and thus gives it a less simian appearance. 

 Large portions of the middle and inferior temporal convolutions are clearly 

 delineated, together with a part of the temporo-sphenoidal surface of this 

 lobe. Both casts show a j)ronounced increase in the auditory eminence Jis 

 compared with pithecanthropus. This eminence is situated at the base of 

 the temporal lobe where the latter comes into relation with the occipito- 



