The December issue of Scientific American Mind has a comprehensive piece on why men dominate the fields of math and science, especially engineering.

While the piece is written by 4 women (and 2 men), if you wipe away the article's academic sensibility (and sensitivity), the recounting of recent research on sex differences bears a striking resemblance to a certain former Harvard president's 2005 speech. But while Larry Summers brushed aside the possibility that discrimination and socialization might account for some of the gap, the SciAm piece suggests otherwise.

Here are the major highlights:

- Women have constituted the majority of college enrollments in the U.S. since 1982.

- Women get better grades, even in mathematics and science.

- "Preschool children seem to start out more or less even, because girls and boys, on average, perform equally well in early cognitive skills that relate to quantitative thinking and knowledge of objects in the surrounding environment."

- But the sexes start to diverge when school starts.

- Women have better verbal abilities while men can better mentally navigate and model movement of objects in three dimensions.

- "By the end of grade school and beyond, females perform better on most assessments of verbal abilities."

- "Between the ages of four and five, boys are measurably better at solving mazes on standardized tests."

- The difference in average quantitative abilities of boys and girls is very small, but "what sets boys apart is that many more of them are mathematically gifted."

- Women don't do as well on standardized tests used for entrance into colleges and graduate schools.

- A study of tens of thousands of gifted 12- to 14-year-olds in the 1980's revealed sex differences in the math part of the SAT but not in the verbal part. "There were twice as many boys as girls with math scores of 500 or higher (out of a possible score of 800), four times as many boys with scores of at least 600, and 13 times as many boys with scores of at least 700 (putting these test takers in the top 0.01 percent of 12- to 14-year-olds nationwide).

- "Although it has drawn little media coverage, dramatic changes have been occurring among these junior math wizards: the relative number of girls among them has been soaring. The ratio of boys to girls, first observed at 13 to 1 in the 1980s, has been dropping steadily and is now only about 3 to 1. During the same period the number of women in a few other scientific fields has surged. In the U.S., women now make up half of new medical school graduates and 75 percent of recent veterinary school graduates. We cannot identify any single cause for the increase in the number of women entering these formerly male-dominated fields, because multiple changes have occurred in society over the past several decades.

- Hormones play a major role in cognitive development. "Researchers found, for example, that people undergoing female-to-male hormone treatment show 'masculine' changes in their cognitive patterns: improvements in visuospatial processing and decrements in verbal skills."

- "Imaging studies assessing brain function support the notion that females perform better on tasks such as language processing that call on more symmetric activation of brain hemispheres, whereas males excel in tasks requiring activation of the visual cortex. Even when men and women perform the same task equally well, studies suggest they sometimes use different parts of their brain to accomplish it."

- The article's writers stress that sex differences in brain structures don't mean that nothing else influences cognitive differences between men and women. Their different life-experiences could also affect brain structures.

- "What leads one little Einstein to choose electrical engineering and the other law? A 10-year study of 320 profoundly gifted individuals (top one in 10,000) found that those whose mathematical skills were stronger than their verbal ones (even though they had very high verbal ability) said math and science courses were their favorites and were very likely to pursue degrees in those areas. On the other hand, those kids whose verbal skills were even higher than their math skills said humanities courses were their favorites and most often pursued educational credentials in the humanities and law. It appears then that highly gifted kids ask themselves, 'What am I better at?' rather than 'Am I smart enough to succeed in a particular career?'"

- And let's not forget discrimination: A 1997 study of the peer-review process in Sweden showed that the "process in what is arguably the most gender-equal nation in the world is rife with sexism."

- Oh, and there's also the whole working-mother thing: "Even when husbands and wives both work full-time, women continue to assume most of the child care duties and to shoulder most of the responsibility for tending to sick and elderly family members. Women work, on average, fewer hours per week and spend more time on family and household tasks than comparably educated men do. For women, having children is associated with lower income and a reduced probability of attaining tenure. In contrast, men show a slight tendency to benefit professionally when they become fathers. Thus, the different roles women and men play in family care can also explain their differential participation in demanding careers."