I found a nice paper by Richard Lynn and Satoshi Kanazawa discussing sex differences in IQ.  The point of the paper is that females mature earlier than males so females are smarter in childhood, but after puberty males are smarter.  This fits Lion of the Blogosphere’s theory that puberty stunts certain parts of intelligence.  As to why females mature earlier, the authors speculate that perhaps females had to compete for mates during evolution, but males not so much.

Here are the scores of the males and females in a large UK sample:


Here are the tests they took with the respective g loadings:


Interesting that reading and math skills should each have such high g loadings.  Maybe the SAT’s more g loaded than I think.

I’m sure the sex differences (after puberty) were much smaller than Lynn would have liked since he virtually pioneered the men are smarter than women theory, overturning a near century consensus that the sexes were equally intelligent.

Lynn might argue that the lack of spatial tests at age 16 underestimates the male advantage.  I would counter that the lack of social cognition tests overestimates the male advantage.  Perhaps just testing reading and math is a good compromise, since these were probably selected because they’re the most valued cognitive skills in modern society and not because they favor or don’t favor one sex or another.