After flap, gender truths revisited

Published: Tuesday, January 25, 2005 at 6:01 a.m.
Last Modified: Tuesday, January 25, 2005 at 1:38 a.m.
When Lawrence H. Summers, the president of Harvard, suggested this month that one factor in women's lagging progress in science and mathematics might be innate differences between the sexes, he slapped a bit of brimstone into a debate that has simmered for decades. And though his comments elicited so many fierce reactions that he quickly apologized, many were left to wonder: Did he have a point?
Has science found compelling evidence of inherent gender disparities in the relevant skills, or perhaps in the drive to succeed at all costs, that could help account for the persistent paucity of women in science generally, and at the upper tiers of the profession in particular?
Researchers who have explored the subject of gender differences from every conceivable angle and organ say that, yes, there are a host of discrepancies between men and women - in their average scores on tests of quantitative skills, in their attitudes toward math and science, in the architecture of their brains, in the way they metabolize medications, including those that affect the brain.
Yet despite the public's desire for tidy and definitive answers to complex questions, researchers warn that the mere finding of a difference in form does not mean that a difference in function or output inevitably follows.
"We can't get anywhere denying that there are neurological and hormonal differences between males and females, because there clearly are," said Virginia Valian, a psychology professor at Hunter College who wrote the 1998 book "Why So Slow? The Advancement of Women." "The trouble we have as scientists is in assessing their significance to real-life performance."
For example, neuroscientists have shown that women's brains are about 10 percent smaller than men's, on average, even after accounting for women's comparatively smaller body size.
But through history, people have cited anatomical distinctions in support of overarching hypotheses that turn out merely to reflect the societal and cultural prejudices of the time.
Mind over matter A century ago, the French scientist Gustav Le Bon pointed to the smaller brains of women - closer in size to gorillas', he said - and said that explained the "fickleness, inconstancy, absence of thought and logic, and incapacity to reason in women."
Overall size aside, some evidence suggests that female brains are relatively more endowed with gray matter - the prized neurons thought to do the bulk of the brain's thinking - while men's brains are packed with more white matter, the tissue between neurons.
To further complicate the portrait of cerebral diversity, new brain imaging studies from the University of California, Riverside, suggest that men and women with equal IQ scores use different proportions of their gray and white matter when solving problems like those on intelligence tests.
Men, they said, appear to devote 6.5 times as much of their gray matter to intelligence-related tasks as do women, while women rely far more heavily on white matter to pull them through a ponder.
What such discrepancies may or may not mean is anyone's conjecture. "It is cognition that counts, not the physical matter that does the cognition," argued Nancy Kanwisher, a professor of neuroscience at the Massachusetts Institute of Technology.
When they do study sheer cognitive prowess, many researchers have been impressed with how similarly young boys and girls master new tasks.
"We adults may think very different things about boys and girls, and treat them accordingly, but when we measure their capacities, they're remarkably alike," said Elizabeth Spelke, a professor of psychology at Harvard. She and her colleagues study basic spatial, quantitative and numerical abilities in children ranging in age from 5 months through 7 years.
"In that age span, you see a considerable number of the pieces of our mature capacities for spatial and numerical reasoning coming together," Spelke said. "But while we always test for gender differences in our studies, we never find them."
Adolescent shift In adolescence, though, some differences in aptitude begin to emerge, especially when it comes to performance on standardized tests like the SAT. While average verbal scores are very similar, boys have outscored girls on the math half of the dreaded exam by 30 to 35 points for the past three decades or so.
Nor is the masculine edge in math unique to the United States. In an international standardized test administered in 2003 by the Organization for Economic Cooperation and Development to 250,000 15-year-olds in 41 countries, boys did moderately better on the math portion in just more than half the nations. For nearly all the other countries, there were no significant gender differences.
But average scores varied wildly from place to place and from one subcategory of math to the next. Japanese girls, for example, were on par with Japanese boys on every math section save that of "uncertainty," which measures probabalistic skills, and Japanese girls scored higher overall than did the boys of many other nations, including the United States.
In Iceland, girls broke the mold completely and outshined Icelandic boys by a significant margin on all parts of the test, as they habitually do on their national math exams. "We have no idea why this should be so," said Almar Midvik Halldorsson, project manager for the Educational Testing Institute in Iceland.
The modest size and regional variability of the gender differences in math scores, as well as an attitudinal handicap that girls apparently pack into their No. 2 pencil case, convince many researchers that neither sex has a monopoly on basic math ability, and that culture rather than chromosomes explains findings such as the gap in math SAT scores.
Male extremes Yet Summers and others have observed that while average math skillfulness may be remarkably analogous between the sexes, men tend to display comparatively greater range in aptitude. Men are much likelier than women to be found on the tail ends of the bell curve, among the superhigh scorers and the very bottom performers.
Among college-bound seniors who took the math portion of the SAT in 2001, for example, nearly twice as many boys as girls scored over 700, and the ratio skews ever more male the closer one gets to 800, the top tally. Boys are also likelier than girls to get nearly all the answers wrong.
For Summers and others, the overwhelmingly male extremes are telling. Such results, taken together with assorted other neuro-curiosities such as the comparatively greater number of boys who suffer from learning disorders, autism and attention deficit disorder, suggest to them that the male brain is a delicate object, inherently prone to extremes, both of incompetence and of genius.
But few researchers who have analyzed the data believe that men's greater representation among the high-tail scores can explain more than a small fraction of the sex disparities in career success among scientists.
For one thing, said Kimberlee A. Shauman, a sociologist at the University of California, Davis, getting a high score on a math aptitude test turns out to be a poor predictor of who opts for a scientific career, but it is an especially poor gauge for girls. Catherine Weinberger, an economist at the University of California, Santa Barbara, has found that top-scoring girls are only about 60 percent as likely as top-scoring boys to pursue science or engineering careers, for reasons that remain unclear.
Moreover, men seem perfectly capable of becoming scientists without an SAT math score of 796. Surveying a representative population of working scientists and engineers, Weinberger has discovered that the women were likelier than the men to have very high test scores. "Women are more cautious about entering these professions unless they have very high scores to begin with," she said.
Professional divide In many formerly male-dominated fields such as medicine and law, women already have reached parity, at least at the entry levels. At the undergraduate level, women outnumber men in some sciences such as biology.
Thus, many argue that it is unnecessary to invoke "innate differences" to explain the gap that persists in fields such as physics, engineering, mathematics and chemistry. Might scientists just be slower in letting go of baseless sexism?
"He thinks he was being provocative," C. Megan Urry, a professor of physics and astronomy at Yale, said of Summers. "In fact, he was being ignorant."
Urry, who led the U.S. delegation to an international conference on women in physics in 2002, said there was clear evidence that societal and cultural factors still hindered women in science.
She cited a 1983 study in which 360 scientists - half of them men, half women - rated scientific papers on a five-point scale. On average, the male scientists rated them a full point higher when the author was "John T. McKay" than when the author was "Joan T. McKay." There was a similar, but smaller, disparity in the scores the female scientists gave.
A recent experiment showed that when Princeton students were asked to evaluate two highly qualified candidates for an engineering job, one with more education, the other with more work experience, they picked the more educated candidate 75 percent of the time. But when the candidates were designated as male or female, and the educated candidate bore a female name, suddenly she was preferred only 48 percent of the time.
"It's hard for me to get excited about small differences in biology," said Spelke, of Harvard, "when the evidence shows that women in science are still discriminated against every stage of the way."
But Sandra F. Witelson, a professor of psychiatry and behavioral neurosciences at McMaster University in Hamilton, Ontario, defended Summers' remarks and said the debate was far from resolved.
"People have to have an open mind to say, 'Could there be a biological contribution that is part of the story?' " Witelson said.

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