Sex differences in relative brain size: The mismeasure of woman, too?

Abstract

Although it has long been known that women have absolutely smaller brains than men, it is widely thought that relative brain size, that is, brain size corrected for variation in body size, does not differ between the sexes. However, by reanalyzing a large data set on brain mass of black and white men and women, I show that, after correcting for body height or body surface area, men's brains are about 100 g heavier than female brains in both racial groups. This remarkable result leads to fascinating questions about the relation between brain size and intelligence, and about the evolution of brain size in humans.