IN 1964, the world record for the women's marathon was around 3 hours, 30 minutes, and the men's record was around 2:10. At the time, most people believed that this huge performance difference was based on biological differences between the sexes.
Fast forward to 2005. The women's world record (2:15.25) is still slower than the men's (2:05.38). But in the past 40 years, the best-performing woman has trimmed an hour and 15 minutes off her time. The best-performing man, less than 10 minutes.
What appeared in 1964 to have been a robust sex difference turns out to be minuscule, and who is to say that some talented woman might not someday eclipse the men's record?
Recently, Harvard President Lawrence Summers caused an uproar by suggesting that the lack of women in the sciences at Harvard might be due to biological differences between the sexes.
Reading between the lines of his statement, I think he was saying something like this: a) The world is a fair place with equal opportunities for men and women; b) Harvard is a gender-neutral institution that judges people only according to merit and has no sexist prejudices whatsoever; c) Harvard never makes a mistake; and d) Women are inferior. I will leave you to construct counterarguments at each step.
Summers called for research into the "innate differences" between males and females in science and mathematics. Apparently, he was not aware that there is at least 35 years of research comparing the sexes on a wide variety of dimensions. With very few exceptions, it has not panned out into much more than a footnote in gender studies. At one time, there was a small difference in mathematics performance. But like the discrepancies in the marathon records, it has virtually disappeared.
The marathon story contains valuable lessons for sex comparison and parallels the findings in mathematics and sciences. First, there are enormous variations within each sex. I ran the marathon in 1986, and by the time I had finished, both the men's and the women's winner could have gone home, taken a shower, had lunch, and settled halfway into a long afternoon nap. Men are all different from one another, and so are women.
Second, even when we find average sex differences, they never account for more than 10 percent of the variance in behavior, with four exceptions: impregnation, lactation, gestation, and menstruation. As psychologist Sandra Bem told her children, "What sex you are doesn't matter unless you're trying to make a baby." In most cases, there are no differences at all.
Averages discount individualsThird, even if we discover one of these small sex differences, we cannot know why it exists without further research. If you had attributed that 80-minute marathon gap in 1964 to some vague biological essence, it turns out that you would have been wrong, because once we added training opportunities, athletic facilities, resources, role models, and yes, Title IX, to the mix, the sex difference shrank considerably.
Finally, and most importantly, average sex differences tell us nothing about individuals. Paula Radcliffe, the women's marathon world record holder, can outperform more than 99 percent of men. Even if there were a large gap between men and women in mathematical performance (and there is not), it would tell us nothing about the male or the female aspiring assistant professor who lands an interview at the Harvard Mathematics Department.
The anatomy-is-destiny belief persists despite these realities of sex similarity and within-sex variation. The argument is that men's and women's brains evolved differently through the evolutionary process. For example, with regard to mathematical and spatial skills, men's brains evolved differently from women's because of the experience of hunting. Because men with good spatial skills were more likely to survive and reproduce, genes for that trait evolved through the process of natural selection.
That argument is turned on its head by one sticky detail: Males have an X chromosome. Therefore, if I have a characteristic that provides an evolutionary advantage, I will pass it on to my daughters as well as my sons. As biologist Richard Francis points out, it is not enough to show that a trait confers a competitive advantage for one sex and not the other. One must also demonstrate that the same trait confers a disadvantage to the other sex.
For example, bright coloration on male birds makes males more attractive mating partners but also renders them more vulnerable to predators. Therefore, female birds tend to be less colorful. On the other hand, men have nipples--completely useless as far as I know--but they exist because they don't cost us anything, evolutionarily speaking. I cannot fathom what biological price a woman would pay for having good mathematical or spatial skills.
Evolutionary types are notorious for their circular reasoning: If there is a difference, it must be biological, and if it is biological, it must continue to exist. It is a way of making biological claims without actually doing any biology.
I believe that biological explanation should carry the burden of proof, not the default option. You can say that something is, for example, genetic only if you can isolate the actual gene or genes and demonstrate the effect. In other words, arguments that appeal to biology must describe the biological mechanism, not merely tell a story that sounds plausibly Darwinian.
Justifying discriminationWhy this obsessive search for sex differences? First, we live in a culture that expects them. We use the term "opposite sex" despite the fact that the sexes are not opposite at all.
I challenge student and other audiences to tell me a way in which the sexes are opposite. Sometimes people answer, "reproductive functions." Well, they're complementary, but not opposite--you will not convince me that a nut is the opposite of a bolt. Calling the sexes opposite is like saying that an IBM-type computer is the opposite of an Apple.
Second, and more importantly, cloaking your prejudices in science is a time-honored way of justifying discrimination while at the same time appearing to be polite and socially concerned. Arguments about biological racial, and sex differences have been used to justify slavery and to deny access to higher education and the right to vote.
And I'm not saying that the people who advance these arguments are malevolent, although some may be. I am saying that they're clueless. Because they are unnerved by changes in the social order that threaten to empower people other than them, they see what they believe.
Prejudices are not just consciously held attitudes; they are inequalities of outcome. Maybe Lawrence Summers is a nice guy--I don't know. But I do know that nice guys can do a lot of damage.
Scholar Virginia Valian points out that there is a disproportional number of Asians in mathematics and the sciences and asks why Summers didn't call for research into innate differences among the races.
I think the answer is that most people at least know that they're not supposed to be racist. Sexism sometimes seems more acceptable. Although I do not think that it's a good idea to start a "which is worst?" contest, sometimes racism provides a good parallel for helping people to understand sexism.
Science has yet to convince me that men's and women's brains are hard-wired differently enough that it matters for social policy, political decisions, educational practices, hiring and firing, or anything else except baby-making (and even that is coming into doubt).
But science has more than convinced me of the profound effects of things over which we have some measure of influence: education, opportunity, media images, self-awareness, and social justice.
We would do well to concentrate our efforts toward expanding these things in healthy ways to enhance the quality of life for both women and men, who, contrary to popular belief, are not enemies.
CHRISTOPHER T. KILMARTIN is a professor of psychology at the University of Mary Washington.