THE BRAIN OF PREHISTORIC MAN 887 



gorilla, which is between ,■()() and ,45 c.c, is much ht'low {hv average adult 

 human brain of modern races. Professor Elliot Smith maintams that a brain 

 must reach the weight of ()5,- gms. (about 1000 c.c.) before it can serve the 

 ordinary needs of human t'xistence. Woodward eveiituallx t'stimated the 

 Nohime of tlie Piltdow n brain at i i()5 c.c, but Keith's investigation increased 

 this figure to approximatt'lx 1400 c.c, or well up to the a\erage ol tlie modern 

 man. The gorilla's brain xoluiiu' appears to be 5- per cent that ol jiithecan- 

 thropus, while pithecant hro|)us is about -2 pt'r cent ol the Piltdow n brain 

 xolume. Tliis difference denoti's more ra|)id brair. expansion in the direction 

 of the higlu'r human standard, once thi' limits of actual anthropoid conditions 

 are transcended. The impetus toward hLiman specializations, ex'en in their 

 earl\' human iiicipienc\, seems to hasten the [progressive development ol the 

 brain more than an\- of the less acKanced primate stages. Some ol the 

 increase in the brain ^()lume of most primates might be attributed to general 

 increase in body structure. Siich, however, can scarcely be the case, since a 

 gorilla weighing nearly four hundred pounds, or more than tw ice as much as 

 the axerage man, possessed a brain w hose \oIume was only 545 c.c, approx- 

 imately one-third that of man. Dubois and ki'ith endeavored to determine 

 how much of the brain is needed for purely animal contingencies and size 

 of body. They concluded that these factors are represented by not more than 

 6 per cent to 8 per cent of the entire cerebrum. Between ()2 per cent and ()4 

 per cent of the volume of the human brain is therefore determined 1)\ other 

 factors than the vital functions or the size ol body. 



The surfaces of the Piltdow n endocranial cast are shown in I'igures 

 376-380. 



THREE S.\LIENT LANDMARKS OX THE PILTDOWN ENDOCRANIAL CAST 



Three salient landmarks on the cast are, all things considered, less 

 impressive than in pithecanthropLis. The lissure of Sylvius ma\- be discerned 



