Gender Differences in the Brain

Harvard University President Lawrence H. Summers created controversy when he suggested recently that innate differences in sex may explain why fewer women succeed in science and math careers.

He's already got me angry - my daughter and I are very good at both subjects! Where's my pitchfork and torch! I have some butt kicking to do whilst singing. "Anything You Can Do, I Can Do Better."

Personally I think there is an overlap in "typical" male and female characteristics and that various cultures push/encourage math and science upon sons more than they do upon daughters. I also think culture and attitudes are a strong influence, short of any brain damage or mental conditions.

Nancy Forger of the the University of Massachusettes wants you to consider examples that suggest actual differences between male and female brains. Why is depression twice as common in women as in men? Why are women with schizophrenia seeming to suffer less cognitive difficulties than do men with the same condition?

Most neuro-developmental diseases are either more common or more severe in one gender or the other. She says health conditions such as arthritis, heart disease, even lung cancer also seem to be influenced by a person's gender. I think lifestyle, as shaped by culture, account for those issues but I am no expert (just in my own mind!).

Research does show that men's brains are larger, on average, than women's by about 100 grams but this could be explained by the fact that the average man's skeleton is larger than the average women's.

There are studies that have shown women may use more parts of their brain at once while men are more inclined to have focused responses.

German studies on people with brain damage to the left side, for example, show that men are less likely to be able to recover their ability to talk than are women. This difference could partly explain why infant girls, on average, speak sooner and use more words than infant boys.

Drs. Ruben and Raquel Gur at the University of Pennsylvania have shown in MRI's that women's brains "light up" in more areas than do men's brains when given verbal and spatial tasks. They feel this extra activity gives women the ability to multi-task. Women may even use different pathways than men when thinking and encoding memories. Turhan Canli at Stanford tested 12 men and 12 women in functional MRIs and showed that women encode memories using different pathways than do men when memorizing something.

"At least 100 sex differences in male and female brains have been described so far," said Forger. "They keep cropping up in animal and human studies."

In mammals, testosterone appears to be a main player in brain differences. Forger's work with mice has shown that as mammals develop in the womb, testosterone and related hormones trigger cell death in some regions of the male brain and foster cell development in other regions. In this way, the hormone sculpts the male brain and how it will differ from the female version.
Remove or add testosterone to mice shortly after birth, and their brains develop according to the presence of the hormone, regardless of their gender.

Most researchers looking into differences of the brain point out that there are many more differences in the brain just between individuals than between the genders. I totally agree!
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