Studies of speed dating have shown that men typically ask for follow-ups with about half of the women they spend a few minutes with, while women only want to follow up with about a third of men. This is easy for the "evolution is psychology" crowd to explain: females are almost always pickier than males in choosing mates because they have to make a greater investment in any offspring that result.
Except it turns out that explanation is wrong, or at least suspect. As Nature reports, speed dating services typically have women stay seated while men walk around. Reverse that, and the follow-up rates even out. Who'd a thunk it?