Men have bigger brains than women, and the gap is HUGE!

This meta-analysis synthesized the results of 126 studies that used various measures to compare the brains of males and females. The results are amazing. Males not only have larger brains than females, on average: the difference is huge! Depending on how the brain is measured, the difference is between 1 and more than 3 standard deviations. The average guy has a brain that is more than 50 milliliters larger than the average female.

Male and female brain volumes are different in almost 30 areas of the brain. And it's not just size: male grey matter is denser in 7 areas.

The most important region for the difference is the limbic system, which is an emotional center. The big male advantage is on the left side of the limbic. Females are larger in the language areas of the right hemisphere.

I was surprised to read that sex differences were not located in areas of the brain in charge of spatial tasks since men have an advantage here, nor did the researchers find a difference in the corpus callosum, the region that connects the two sides of the brain. Women are said to have better integrated hemispheres, but this region does not appear to be larger in females.

The authors did not go into sex differences in behavior that might stem from brain differences, although they did mention the language difference. Women might get their advantage over men in verbal fluency from larger language areas in the brain.

The large limbic system in men suggests males and females will differ emotionally. Perhaps the larger, more dense limbic system enables greater integration with the frontal lobes which are in charge of rational thought. Men might be better at disengaging the feeling-thinking connection, giving them an advantage at a detached, systematizing style of thinking. Women are much better than men at empathizing--a more personal, less abstract style of thinking. These differences produce many men who are good at, say, engineering, and many women who have excellent interpersonal skills.

The brain differences emerge in young children, although there aren't enough studies to show this definitively. So how boys and girls are brought up probably has little to do with the gender gap. Vive la difference!