M. Bilalić and friends argue in Why are (the best) women so good at chess? Participation rates and gender differences in intellectual domains that "96 per cent of the observed difference would be expected given the much greater number of men who play chess" among the top 100 German male and female chess players".
A follow-up paper by M. Knapp criticizes (reasonably imho) their use of the normal distribution, and provides a statistical model that matches the observed ratings better, finding "between 41 and 71.1 per cent (mean value: 66.9%) of the actual rating differences are explained by different participation rates of men and women".
More recently, a paper published just this month by R. Howard, Gender Differences in Intellectual Performance Persist at the Limits of Individual Capabilities, tries to determine whether the differential participation explanation for chess holds up by comparing across countries that have very different participation rates among international players:
The hypothesis that males predominate because many more males play chess was tested by comparing gender performance differences in nations with varying percentages of female players. In well-practised participants, gender performance differences stayed constant even when the average national percentage of female international players increased from 4.2% to 32.3%.
I haven't read the paper, as I only have access to the abstract, but unless there are any flaws that come to light with the paper, it sounds like this puts to rest the argument that differential participation rates are the main reason for the observed discrepancies in ratings, which was the explanation that I thought most likely until now.
Plutonia, This is a stereotype and not really funny. That would be like someone saying that all guys just spend their time drooling over expensive cars and vegetating in front of the TV.
Ok. But what is not a stereotype, and it's a fact, is that men contributed and still contribute to the vast, vast majority of the intellectual achievements and creativity of society. I once challenged somebody on this forum to come up with some female writers. They mentioned the woman who wrote Harry Potter, I'm not kidding.
It again depends on how you set the standard in "intellectual achievements".
For me, rather than writers, it is more philosophers and poets. Being a writer (especially nowadays) take not much, just look at all the garbage that gets published. I could, though recommend you lots of female poets and philosophers that lived in ancient greece or china.
Things were a lot different in Europe, of course. After all, again, we could say that writing a book is another time consuming activitiy that women tend not to engage in while writing poems are usually more intuitive.