For the past few days I've been blogging on racial differences in the short and long distance Olympic races. I noted Jon Entine's argument that such differences may have a biological origin, a taboo subject because once we start talking about physical differences, perhaps some people might then begin to suspect differences of intelligence between the races.

In my book The End of Racism I argued against such differences, noting instead that culture is a far better explanation of ethnic differences in intellectual achievement and economic performance. But when we turn to the issue of men and women, I note an anomaly.

No one denies that men are taller and stronger than women on average. This explains of course why competitive sports is based on the "separate but equal" principle. Men play against men, and women play against women. Segregation on the basis of gender appears to have an obvious rational basis in physical contests of speed and strength.

Yet one of my favorite games, namely chess, is not such a contest. Rather, chess is entirely based on intellectual capacity. It involves planning, calculation, strategy. One would assume that since men and women are equally intelligent, therefore women should be fully competive with men in chess. But it is not so. Consider: of the top 100 players in the USA currently, only two are women. Even more startling, of the top 100 chess players in the world today, only one is a woman.

So embarrassing is male over-representation at the top level that most chess competitions today are divided into two categories. There is a general category that is almost inevitably won by a man, and then there is a separate women's championship obviously designed to give women a chance to succeed as well. Currently there is a World Chess Champion and a World Women's Champion. Somehow the chess world seem to have adjusted to the reality that int his particular mental contest, women simply aren't as good as men.

Can culture account for the difference between the sexes? Actually no. Culture can help to explain why certain countries like Russia are more dominant in chess. They simply play a lot more chess over there. But culture doesn't explain why Russian males are so much better than Russian females in chess. I am not aware of an historical exclusion of women from chess, and even if there was some past discrimination, how come women still fare so poorly in an age of equality? Of the top 20 junior chess players in the world, there isn't a single woman. So in these respects the cultural explanation falters.

Are we forced to conclude then that men are smarter than women, at least when it comes to chess? Not really. The average IQ of both groups is 100. But when it comes to the bell curve distribution, an interesting difference emerges. The female bell curve is taller and narrower, with the vast majority of women bunched in the middle. The male bell curve is shorter and flatter, with more men at both ends of the distribution. What this means is that there are more male geniuses and more male morons. And this would effectively account for why at the very top level of an intellectual contest like chess, we find far more men than women.