WSJ Reports on Brain Similarities Between Adolescents of Different Sex

Yesterday's Wall Street Journal reported findings of government research that casts doubt on assumptions that male and female brains are significantly different during adolescence. As the article put it:

A common stereotype is that boys develop more slowly than girls, putting them at a disadvantage in school where pressure to perform is starting ever younger. Another notion is that puberty is a time when boys' and girls' brains grow more dissimilar, accounting for some of the perceived disparities between the sexes. Now, some scientists are debunking such thinking. Although boys' and girls' brains show differences around age 10, during puberty key parts of their brains become more similar, according to recent government research. And, rather than growing more slowly, boys' brains instead are simply developing differently.

The article also described research that puts those differences into context:

Dr. Eliot cites a neuro-imaging study from last year that showed the female brain has stronger neuronal connections than the male brain in certain areas, and vice versa. But in general, the study found that the male and female brains show more commonality than difference, Dr. Eliot says. The study, which looks at about 1,100 brain scans, was published in the Proceedings of the National Academy of Sciences.

Dr. Giedd of the NIMH says his research also showed there are exceptions. In about 10% of the young people studied, boys' and girls' brains were more similar to the brains of the opposite sex than to others' of the same sex. Dr. Giedd says many factors can affect the rate of brain development, including the strength or weakness of testosterone receptors. Testosterone, a hormone usually associated with male traits, is present in both sexes and can help determine how quickly parts of the brain develop that account for typical male-dominated functions.

Because advocates of single-sex education point to such differences to defend the practice of separating boys and girls in the classroom, these findings could be relevant to the legal question of whether such efforts are based on generalizations about sex differences, and therefore impermissible under Equal Protection standards. They could also be relevant to the policy question of whether it makes sense to segregate on the basis of sex, rather than other indicators of learning styles and intellectual development.