How Male and Female Brains Differ
Researchers reveal sex differences in the brain's form and function.
Disparities Start Early in Life continued...
Boys generally demonstrate superiority over female peers in areas of the brain involved in math and geometry. These areas of the brain mature about four years earlier in boys than in girls, according to a recent study that measured brain development in more than 500 children. Researchers concluded that when it comes to math, the brain of a 12-year-old girl resembles that of an 8-year-old boy. Conversely, the same researchers found that areas of the brain involved in language and fine motor skills (such as handwriting) mature about six years earlier in girls than in boys.
So, do these sex differences even out over time?
Females and males maintain unique brain characteristics throughout life. Male brains, for instance, are about 10% larger than female brains. But bigger doesn't necessarily mean smarter.
Disparities in how certain brain substances are distributed may be more revealing. Notably, male brains contain about 6.5 times more gray matter -- sometimes called 'thinking matter" -- than women. Female brains have more than 9.5 times as much white matter, the stuff that connects various parts of the brain, than male brains. That's not all. "The frontal area of the cortex and the temporal area of the cortex are more precisely organized in women, and are bigger in volume," Geary tells WebMD. This difference in form may explain a lasting functional advantage that females seem to have over males: dominant language skills.
How Males and Females Use Mental Skills
Geary suggests that women use language skills to their advantage. "Females use language more when they compete. They gossip, manipulate information," he says. Geary suggests that this behavior, referred to as relational aggression, may have given females a survival advantage long ago. "If the ability to use language to organize relationships was of benefit during evolutionary history, and used more frequently by women, we would expect language differences to become exaggerated," he tells WebMD. Women also use language to build relationships, theorizes Geary. "Women pause more, allow the other friend to speak more, offer facilitative gestures," he says.
When it comes to performing activities that require spatial skills, like navigating directions, men generally do better. "Women use the cerebral cortex for solving problems that require navigational skills. Men use an entirely different area, mainly the left hippocampus -- a nucleus deep inside the brain that's not activated in the women's brains during navigational tasks," Geary tells WebMD. The hippocampus, he explains, automatically codes where you are in space. As a result, Geary says: "Women are more likely to rely on landmark cues: they might suggest you turn at the 7-11 and make a right at the church, whereas men are more likely to navigate via depth reckoning -- go east, then west, etc."