Some guy who calls himself La Griffe du Lion sent me a link to his new article debunking the notion that there are no sex differences in math ability.
Doing some Googling, I found a report about the latest SAT scores (from the class of 2008).
Girls continue to outperform boys on the writing section of the SAT (501 vs. 488). Girls' average score on the reading section was 500, while boys' was 504. But that was a narrowing of a gap that stood at 7 points a decade ago. Girls continue to lag in math, where boys on average scored 33 points higher (533 vs. 500).
These results show important sex difference in abilities. Boys score 29 points higher on the math section than they do on the reading section. Girls score exactly the same on both sections. This is not a huge difference, but a difference of between one-third and one-quarter of a standard deviation will show up at the highest levels of ability--for example, there will be a big shortage of girls who are mathetmatical enough to attend a school like MIT, thus explaining the unfortunate (for horny male students) male to female sex ratio at MIT.
Because people value what they are good at, and because women rather than men control what society considers prestigious (because men have to compete for women in order to mate), the result is lack of prestige of mathematical oriented professionas (such as computer programmers and engineers) compared to verbal oriented professions (such as lawyers).
Why do girls outperform boys on the writing section? My theory is that girls have better handwriting, and the graders are more kindly disposed when they can more easily read the essays.
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The most interesting thing about the sex differences, which the Lion mentions in his article, is that they don't show up until the age of puberty. Obviously, sex hormones somehow affect the mathematical development of the brain. Boys have much more testosterone than girls, but the stereotypical math nerd is a low testosterone male. Boys enter puberty later than girls. Entering puberty probably harms the mathematical development of the brain.