Are men's and women's brains really different?

Abstract

Sex hormones have been shown to determine basic sexual differentiation in utero, and to influence the level of certain cognitive abilities. Sex differences in brain morphology are known to be present and to undergo systematic changes throughout the prenatal period. In the adult, brain organization for basic speech and related motor praxic function is found to be more focally organized within the left hemisphere in women than in men. Such functions are particularly dependent on the left anterior region in women, and are not less asymmetrically organized than in men. Some verbal intelligence functions less specifically tied to speech mechanisms may be more bilaterally organized in women, but no such statement can be made for all verbal or indeed nonverbal functions. Adult cognitive sex differences may to some extent reflect pre- and peri-natal sexual dimorphism in brain organization at critical stages of development. Possible evolutionary bases for sex differences in brain organization are discussed.