Why write another book about sex and gender - is there anything left to say? Judging from what I hear all around me, there's an endless amount to say. "It's a guy thing." "She just couldn't use the map." "What is it about men and commitment?" "No one criticizes a woman so savagely as another woman." "He just can't discuss his feelings." Gossip about colleagues, family and friends is almost impossible to separate from ideas - explicit or implicit, shrewd or stupid - about how men and women relate. If a man plays true to what someone thinks of as masculine type, it's a fact worth remarking. If he doesn't it's even more so. If a woman plays true to type, someone will slyly point it out. If she doesn't, someone else will bring the type up anyway.
Everyone's ideas of type are different, and most intelligent people nowadays feel a little guilty about having ideas about gender types at all. But, like snacking on unhealthy foods, people who disapprove of it do it all the same. People who cringe at the thought of repeating gender clichés worry that we can't all be as bloodlessly androgynous as we're told we should be. Scientists who would object to generalizations about gender in a seminar or an article will happily make them when discussing a friend's divorce over a gossipy lunch.
When so much of the talk about gender types is furtive and guilty, it's hard to bring science to bear. But the science, like the reality it describes, is developing all the time. Sometimes we don't need science to tell us that stereotypes are disappearing - remember the one that said women couldn't do comedy? There's one that doesn't stand up any more. But sometimes the science is really illuminating. What do we know about men's and women's preferences for competing versus cooperating? What are women's conversations like and how do they differ from those of men? And what's the truth about men, women and IQ?
We know much more about IQ than we did even 10 years ago, and I discuss it in chapter five of my book. The politically correct conclusion has been for some time that there's no real gender difference in IQ, and to my surprise, the politically correct conclusion is, well, correct! But not for the politically correct reasons: there are lots of gender differences in particular aptitudes and skills. The particular differences just don't add up to a general overall advantage for one sex over the other.
Any gender advantage that a particular measure claims to find will just depend on the arbitrary way these different aptitudes are weighted against each other - like the fact that different types of athlete will come out best overall in the pentathlon and the decathlon. I'll leave readers to go to the chapter to find out more. As I say there, the fact that there's no overall advantage tells us some really interesting things about the way we evolved. In particular, it tells us that women in prehistory can't have been as subordinate to men as they were in later historical societies.
I'm only an economist, and though the book covers much more than just economics it has a big focus on the world of work. I've tried to understand, for instance, why there are still so few women in senior positions in business - only 2.4% women among the CEOs of Fortune 500 companies in 2010. The old idea was that it was either because women have less aptitude for such positions, or because discrimination is keeping them out. There's growing evidence in favor of a third explanation: a difference in visibility. Talented but under-rewarded women are somehow flying under the radar of the still largely masculine recruiters to senior positions in business. And that seems to be both about the way women fly, and about the way the radar is calibrated.
In the book I return to prehistory, and explore how living in hunter-gatherer groups gave men and women different ways of constructing their networks of friends and allies. Women needed tight, loyal, stable networks while men could make do with more fluid, unstable, shifting coalitions, and they still have traces of that in the way they make friends today. Loyal, stable networks sound like a good thing to have. But in the vast world of modern business, loyal stable networks don't do enough to get you noticed.
Women's lack of visibility hits them in very specific ways. Employers value personality traits such as conscientiousness, and women tend to score a little higher than men on such traits. In hunter-gatherer societies women would display their conscientiousness in the way they raised their families, and this was visible to everyone including the men. But the modern workplace is separate from the modern home - so when women take career breaks to look after their families they pay a high price in loss of visibility.
Gender stereotypes make a huge difference to how we notice others and how their talents stand out to us. Similar behavior (such as toughness in bargaining) can be interpreted quite differently according to whether we see it in women or in men. I'm convinced we should be willing to talk more openly about the ways we expect men and women to behave, the well-founded expectations as well as the prejudices. Some people will reproach me for stirring up what's best left to simmer quietly. But we need to take the guilt out of our expectations if we want them to be better informed by science.
Paul Seabright is the author of The War of the Sexes [Princeton University Press, $24.95].