Roy Baumeister of Florida State Universty in Tallhassee said at an American Psychological Association meeting that because men want sex more than women, depending on the culture they get it more or less. Countries where men outnumber women, women tended to hold sex until marriage because sex for them has a higher value.

In places like a university, women who outnumber men tend to give out sex more because there are more women to compete with. It is what has driven the "hookup" culture on campuses.

Baumeister said, "Women's sexuality has a kind of value that men's sexuality does not. Men will basically exchange other resources with women to have sex, but the reverse doesn't work. Women … can trade sex for attention, for grades, for a promotion, for money, as in prostitution or sex with a celebrity."

The USA ranked 16th in gender equality. (c) tPC