Why are there more men than women in the Sciences?

The answer appears to be complicated, part nature and part nurture. But what was most interesting to me is that the scales do appear to be tilting (one stat showed a shift from 13-1 to 3-1 over the last two decades). Whatever we're doing as a culture is having an effect.

The other interesting point, which I've heard over and over in other contexts, is that men and women do not appear to be much different in terms of their abilities "on average," but men appear to be much more variable. Women tend to cluster toward the middle, while men are more heavily represented at the ends of the scale. Nobel prizes are dominated by men, but so too are prisons.

http://www.sciam.com/article.cfm?id=sex-math-and-scientific-achievement&page=1