A post over at the Feminist Philosophers’ blog talks about an amazing woman, Alia Sabur, who is the world’s youngest professor in the history of academia. She also happens to be a Muslim. JJ ends her post stating that

in many Muslim countries women are a strong presence in science classrooms, as students and teachers.

This reminded me of an article I read in Free Inquiry about the dismal state of science in Muslim countries, written by a professor in Pakistan, which seemed to call into question any celebration of strong female presence. Either way, I was intrigued and tried to find information on women in science. I was looking for an international comparison of scientists in academia by gender. So far, I haven’t found much. In the process of looking I stumbled on a debate that took place in 2005: The Science of Gender and Science, a topic that I briefly mentioned earlier this year. As behooves the label dilettante, although I prefer the second definition, I abandoned my search for statistics and read the debate instead, which took me forever. This post has been a week or so in the making.

Both [Harvard psychology professors Steven Pinker and Elizabeth Spelke] presented scientific evidence with the realization and understanding that there was nothing obvious about how the data was to be interpreted. Their sharp scientific debate informed rather than detracted. And it showed how a leading University can still fulfill its role of providing a forum for free and open discussion on controversial subjects in a fair-minded way. It also had the added benefit that the participants knew what they were talking about.

As you may recall, in 2005, the president of Harvard, Lawrence Summers, caused a loud out-cry by remarking that maybe women are underrepresented in science because of innate ability differences. The Pinker-Spelke debate was intended to see what the science really says.

So, what does the science say? Here is Pinker’s position using a quote from Diane Halpern’s Sex Differences in Cognitive Ability (1986):

There are real and in some cases sizable sex differences with respect to some cognitive abilities. Socialization practices are undoubtedly important, but there is also good evidence that biological sex differences play a role in establishing and maintaining cognitive sex differences.

After affirming his feminism, Pinker points out that

it is crucial to distinguish the moral proposition that people should not be discriminated against on account of their sex – which I take to be the core of feminism – and the empirical claim that males and females are biologically indistinguishable. They are not the same thing. Indeed, distinguishing them is essential to protecting the core of feminism. Anyone who takes an honest interest in science has to be prepared for the facts on a given issue to come out either way. And that makes it essential that we not hold the ideals of feminism hostage to the latest findings from the lab or field. […] The truth cannot be sexist. Whatever the facts turn out to be, they should not be taken to compromise the core of feminism.

Well, no need to go to a lab… Just a cursery look at men and women shows some clear differences… You know, the clothes they’re wearing… Just kidding. There are clear biological differences obvious without even looking into the body. I thought, though, that this has been acknowledged a long time ago. It almost sounds like Pinker thinks that’s a new idea or an idea that somehow got lost. Yet, it’s important to keep this in mind since “if we want to change the world we must first understand it, and that includes understanding the sources of sex differences.” Pinker argues that statistics is important in understanding these differences.

Pinker suggests two important aspects to consider when comparing sex differences along normal distributions:

1. If there are small differences in the means of the two distributions, the differences will increase in size the further out on the tail we go.
2. The variance in the distributions are just as important as the means. Even if the means are identical, a larger variance will create larger differences in the tails. And “males are the more variable gender.”

The second point seems to be especially important regarding intelligence:

Men and women show no differences in general intelligence or g – on average, they are exactly the same, right on the money. Also, when it comes to the basic categories of cognition – how we negotiate the world and live our lives; our concept of objects, of numbers, of people, of living things, and so on – there are no differences.

Pinker then outlines six differences:

• Different priorities: “Men, on average, are more likely to chase status at the expense of their families; women give a more balanced weighting.”
• Different vocational interests: “There are consistent differences in the kinds of activities that appeal to men and women in their ideal jobs [such as] the desire to work with people versus things.” These differences can be used to fairly accurately predict the fields women choose when pursuing science.
• Risk: “In a large meta-analysis […], in 14 out of 16 categories of risk-taking, men were over-represented. […] two of the largest sex differences were in ‘intellectual risk taking’ and ‘participation in a risky experiment.'”
• Visualizing in 3-D: “For some kinds of spatial ability, the advantage goes to women, but in ‘mental rotation’,’spatial perception’, and ‘spatial visualization’ the advantage goes to men. […] In psychometric studies, three-dimensional spatial visualization is correlated with mathematical problem-solving.”
• Mathematical reasoning: “A meta analysis […] shows no significant difference in childhood; this is a difference that emerges around puberty, like many secondary sexual characteristics. But there are sizable differences in adolescence and adulthood, especially in high-end samples.”
• Sex difference in variability: “[Novell and Hedges in a 1995 Science paper] found that in 35 out of 37 tests, including all of the tests in math, space, and science, the male variance was greater than the female variance.”

After listing these differences, Pinker returns to the nature vs. nurture question. He stresses that both influence the sex differences he outlined. Since he wants to make the point that there are biological sources of these differences, in addition to socialization, he lists ten kinds of evidence to support his contention that “the contribution of biology is greater than zero.” This American Life has also presented some of the evidence, albeit in a more anecdotal fashion than Pinker. Especially interesting in this context is Act Two, in which we learn about the effects of testosterone injections on a woman.

In his conclusion, Pinker talks about stereotypes and makes this point:

There seems to be a widespread assumption that if a sex difference conforms to a stereotype, the difference must have been caused by the stereotype, via differential expectations for boys and for girls.

After stating the areas she agrees with Pinker, Elizabeth Spelke dives into the main area they disagree on:

We disagree on the answer to the question, why in the world are women scarce as hens’ teeth on Harvard’s mathematics faculty and other similar institutions?

Unlike Pinker, Spelke does not think that the influence of socialization is overrated. She thinks that the biggest factors that can account for the differences are social forces. Here is her main argument:

There are no differences in overall intrinsic aptitude for science and mathematics between women and men. Notice that I am not saying the genders are indistinguishable, that men and women are alike in every way, or even that men and women have identical cognitive profiles. I’m saying that when you add up all the things that men are good at, and all the things that women are good at, there is no overall advantage for men that would put them at the top of the fields of math and science.

She then takes apart three of the six differences Pinker outlined, including presenting evidence showing that there either is no sex difference or that it might be due to other reasons, such as the strategy utilized:

• Different vocational interests: “At the top of [Eleanor Maccoby and Carol Jacklin’s] list of myths [published in 1974] was the idea that males are primarily interested in objects and females are primarily interested in people. […] Do we see sex differences? The research [since their publication] gives a clear answer to this question: We don’t. […] The conclusions that Maccoby and Jacklin drew in the early 1970s are well supported by research since that time.”
• Mathematical reasoning: “We can ask, are there sex differences in the development of any of these systems at the foundations of mathematical thinking? Again, the answer is no.” Spelke concludes that “men and women have equal aptitude for mathematics. Yes, there are sex differences, but they don’t add up to an overall advantage for one sex over the other.”
• Sex difference in variability: I don’t think Spelke really addresses this point since she returns to the (largely uncontested) finding of no difference in general ability but ignores any potential differences in variability.

After addressing these potential intrinsic explanations for the “gender imbalance on faculties of math and science,” Spelke turns to social factors, in particular “how gender stereotypes influence the ways in which males and females are perceived.”

• Parental perceptions: Consistently, parents perceive their children differently along gender line. This is the case for health, strength, and ability and starts at a very early age. Most importantly for the current discussion, parents perceived their sons’ mathematical and scientific ability as higher even though objective measures showed no difference between boys and girls.
• Other adults’ perceptions: Even strangers perceive infants differently depending on the perceived gender (not necessarily actual). “Children with male names were more likely to be rated as strong, intelligent, and active; those with female names were more likely to be rated as little, soft, and so forth.” This biased evaluation even holds when faculty evaluate candidates for open positions.

Spelke summarizes the findings from this research into gender differentials in people’s perceptions:

From the moment of birth to the moment of tenure, throughout this great developmental progression, there are unintentional but pervasive and important differences in the ways that males and females are perceived and evaluated. […]

The equal performance of males and females, despite their unequal treatment, strongly suggests that mathematical and scientific reasoning has a biological foundation, and this foundation is shared by males and females.

After both Pinker and Spelke presented their case, a dialog follows around two issues: the variability and how the bias – that both agree is there – developed. Pinker reiterates that the bias originated from innate differences between men and women at the extreme ends of the distributions. Spelke counters that the bias is cultural and not build on innate differences. She then suggests to go back in history and imagine this debate about innate differences between European and Asian men since about 150 years ago, the overwhelming majority of scientists where European men. Pinker points out that fields where the barriers were removed saw an influx of the formerly excluded. But, unlike baseball where a homerun is a homerun, Spelke says, science is not objectively evaluated. I think Pinker misses this point when he replies that the more subjective sciences have higher proportions of women. Spelke argues not that the content of the science is more subjective but rather the hiring and treatment of scientists, which reflect gender bias.

The fascinating debate ends, essentially, undecided. Spelke’s suggested experiment, getting rid of the social forces behind the bias to measure the effect of biology alone, is virtually impossible to conduct. Both scientists agree that both nature and nurture play a role in answering the question of why there are more male mathematicians and physicists. The importance of each is still not quite answered, although I agree with Spelke that social forces play a larger role than Pinker wants us to believe.

(See here for more information on a more recent study that supports Spelke’s argument.)