THE BRAIN OF APES AND OF MAN 257 



chasm between man and apes ; on the contrary, their 

 likeness in all important details of structure is very close. 



The comparison of the size of the brain in various 

 cases which has just been made is one of absolute size, 

 leaving out of consideration the size and weight of the 

 body and limbs. Putting aside the exceptional pygmy 

 races of man (which there is no reason to regard as 

 primitive), the average adult man is larger and heavier 

 than the chimpanzee, and taller than, though not so 

 powerful as, the -.orang. The gibbons are quite small 

 — rarely 3 feet in height — but the male gorilla is, when 

 adult, a much heavier animal than man, and often 

 measures 5 feet 8 inches from the heel to the top of 

 the head. Recently even larger specimens have been 

 measured, and 6 feet 6 inches is quoted (probably an 

 over-estimate) as the height attained by some specimens. 

 This fact removes any difficulty about comparing the 

 absolute size of brain in man and these apes. It also 

 renders it unlikely that the primitive ape-men or men- 

 apes were smaller than modern men, whilst the large size 

 and weight of some of the earliest " shaped " flints (of 

 Pliocene age) attributed to primitive man, make it 

 probable that the men who used these flints were larger 

 and more powerful, at any rate in the hands and arms, 

 than modern races of men. Size and strength are, then, 

 not points which offer any difficulty in the passage from 

 ape to man. 



What (it may well be asked) is the significance of 

 man's greater brain ? What was the advantage to man's 

 ape-like progenitors in an increased volume of brain ? It 

 should be noted at once that the pattern of the " con- 

 volutions" marked out on the surface of the brain by a 

 great series of winding " ditches " or " furrows " is based 



17 



