Differences in Total Brain Size? Almost all studiesshow that at birth, a boy's brain is bigger than a girl's brain. Atbirth, the average brain of boys is between 12-20% larger than that ofgirls. The head circumference of boys is also larger (2%) than that ofgirls. However, when the size of the brain is compared to body weight atthis age, there is NO difference betweenboys and girls. So, a girl baby and a boy baby who weigh the same willhave similar brain sizes. In adults, the averagebrain weightin men is about 11-12% MORE than theaverage brain weight in women. Men's heads are also about2% bigger than women's. Remember though, men on average weigh morethan women and that absolute brainsize may not be the best measure of intelligence.Many behavioral differences have been reported for men and women. Forexample, it has been said that women are better in certain languageabilities and men are better in certain spatial abilities. Many studieshave tried to find differences in the right and left cerebral hemispheresto suggest that male and female brains are different. However, few ofthese experiments have found meaningful differences between men and women.If fact, there are many similarities between the cerebralhemispheres of men and women.
| Brain Weights 
(Data from Geigy Scientific Tables, 7th edition,edited by K. Diem and C. Lenter, 1970) |
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Bigger - Stronger - Faster...arethere really any differencesbetween female brains and male brains? Differences between the brains ofmen and women have generated considerable scientific and public interest.If there are differences in the way that men and women behave, then it isreasonable to suppose that their brains have something to do thesebehavioral differences. Just what are these differences and where in thebrain might these differences be located?
The major pathway that connects the rightand leftcerebral hemispheres is called the corpus callosum.(The corpus callosum is the fiber tract made up of 200-250 million axons that is cut in split brainpatients.) Many recent claims have been made that the corpus callosumis bigger and more developed in women than in men. These claims have evenbeen reported in the popular media (Time Magazine, Jan. 20, 1992,pp. 36-42; Newsweek Magazine, March 27, 1995, pp. 51). However,recent studies have told a different story. Using new magnetic resonanceimaging methods, researchers have found no differences in thesize of the corpus callosum in men and women. Further research thatcompares the size of the corpus callosum size in men and women is needed.
For hundreds of years,scientistshave searched fordifferences between the brains of men and women. Early research showingthat male brains were larger than female brains was used to "prove" thatmale brains were superior to female brains. Of course, this "proof" isNOT so simple and straight forward as youwill see. Nevertheless, even today, there is a lot of controversy aboutthe differences in the brains of men and women. Not only from ananatomical point of view, but also from a functional point of view - inother words, just what do the differences in the brains mean? 
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