Differences in brain structure arise during development under the influence of sex-specific hormones and/or sex chromosomes. It is not known how these are linked to cognitive or behavioural differences between men and women.
Testosterone not only influences testicular descent, the development of the external genitals, internal ducts and structures, and body shape in a typical male, but also affects the development of the brain. As a result, the brain usually takes on some male-specific structural characteristics and functions. Further, some combinations of sex chromosomes are associated with specific behaviour patterns such as aggression, raising the possibility that sex chromosomes may directly influence brain structure or function.
What are the sex-specific features of the brain? Men have a larger average brain size than women, but it is not clear whether that is due to differences in body size. Male and female brains also show some differences in structure. Females reportedly have larger areas responsible for language processing, while men have larger areas devoted to visual and spatial processing. Females generally have faster blood flow to their brains and lose less brain tissue as they age than males do.
It should be noted that this sex-specific development and function of the brain is not generally considered to make either sex “smarter” than the other, but may affect behavioural responses (such as aggression), ways of processing information (such as spatial perception), and susceptibility to chemical imbalance and hence mood disorders.
Finally, it is not clear to what extent sex-specific development and function of the brain is associated with gender identity (whether a person adopts masculine or feminine characteristics, or identifies as male or female). Gender identity may have a biological component, meaning that it may be influenced in some way by genes and/or hormones, and may have a psychological component linked to social or environmental factors during childhood (see Sex, gender and sexual orientation).
Last updated: 16 July 2015 PK
Edit history: Author P. Koopman 9/09; revised PK 5/11, 9/12, 5/13, 7/13, 9/13