Cranial size and shape
S. P. Pickering (Correlation of brain and head measurements, and relation of brain shape and size to shape and size of the head, American Journal of Physical Anthropology, Volume 15, Issue 1, Date: October/December 1930, Pages: 1-52):
It is general knowledge that an increase in brain size runs parallel with an increase in head size and with a change from dolichocephaly to brachycephaly as we ascend the scale from the anthropoids to modern man. This appears primarily to be a volume phenomenon.
A. Thomson (quoted in the above paper) notes that:
Given a cavity of oval or ellptical form with elastic walls, the more its contents are increased the greater will be the tendency to assume a spherical shape.
Pickering studied cadavers and their weight and volume directly, rather than relying on estimations from cephalic measurements:
The specimens used in this work gave an average capacity for dolichocephalic skulls of 1402.8 cc.; for mesocephalic, 1474.8 and for brachycephalic, 1520.6 cc.
The same tendency was shown in the size of the brains. The average size of the brains in this series was for the dolichocephalic heads, 1135.4 cc.; for the mesocephalic, 1144.2 cc., and for the brachycephalic, 1180.7 cc.
The figures show a marked increase from the dolichocephalic to the brachycephalic type. Though the number of specimens of the dolichocephalic type is not sufficient to be conclusive proof, the fact that brachycephaly runs parallel with an increase in brain and head size is very evident.
Interestingly, according to K. Beals et al. (Brain size, cranial morphology, climate, and time machines. Current Anthropology, 25, 301-330. ) there is a +0.37 correlation between cranial capacity and the cephalic index, i.e., broader-headed, more brachycephalic populations also have bigger cranial capacities.
Bookmarks