THE STUDY OF HUMAN PREHISTORY 
belonged. Fortunately, also, the very part of the skeleton 
most apt to be preserved is the one which reveals to us 
more about the living creature than any other, namely, 
the skull, which in life contains the brain, the seat of 
man’s intelligence—precisely what we are studying. The 
size of this organ, as shown by that of the brain-case 
Fic. 7. The lower surfaces of the skulls of a chimpanzee, a Neanderthal man, 
and a modern European; showing progressive shifting of the opening for the spinal 
cord toward the center of the skull. After Boule 
itself, provides us with many clues of the highest im- 
portance. Among normal white male adults the size of 
the brain averages around 1,550 cubic centimeters, al- 
though in different individuals this figure may vary as 
much as 200 cubic centimeters either way. The skulls of 
certain less cultured modern peoples, however, as well 
as those of some prehistoric races, fall decidedly below 
this capacity. In the three higher apes, the gorilla, the 
chimpanzee, and the orang-utan, the average sizes of 
the brain rarely if ever exceed 600, 400, and 400 cubic 
centimeters, respectively. 
Hence, speaking very generally, the lower we go in 
the scale of intelligence the smaller and lighter in weight 
do we find the brain. More than that, it is simpler and 
less convoluted, so that in creatures like some of the 
South American monkeys, for example, the surface of the 
[45 ] 
