Well, the key is in that assumption, and also in the shape of that data. It could be that the average woman is slightly more intelligent than the average man:

Well, the key is in that assumption, and also in the shape of that data. It could be that the average woman is slightly more intelligent than the average man: 55% of American college freshmen are female. But men have a greater variance which brings them out at both ends. So the outlying geniuses like Einstein and Jobs and Feynman tend to be male, and at the other end so does the prison population.