We're just talking about default assumptions here, so I'm not sure what you're getting at. Of course my default assumptions based on my own personal experience <i>might</i> be wrong; that's why they're just defaults.<p>&#62;Humans are great at separating groups, they are not so great at detecting small differences between groups.<p>Is this actually true? It seems like a bit of a sweeping statement, and I'd be surprised if you have any hard evidence to back it up. Also, the observed inequalities between men and women are currently quite large, so it seems unlikely that very small differences between men's and women's abilities could explain them.