Investment of a woman vs Investment of a man in sex and its consequences.
Men: having sex with lots of people spreads your seed around, maximising your chances that your genes will be passed on. It is a 'manly' thing to do, in the sense that evolution says that men should do this. The man that's not interested in sex will not have his genes passed on.
Women: having sex with lots of people isn't quite as beneficial: you have sex once and potentially that's it for the next 9 months at least. Your genes get passed on, too, if you have sex, so it's womanly to do so but the need isn't there to do it as often.
That said, today we have contraception preventing genetics and our brains/instincts to work as it should. Somewhere in there there's a feeling among people (both men and women) that women don't need to have sex a lot, or something along those lines, dating back to evolution. It's a matter of needs. You (guys or girls) don't NEED to have unnecessary sex; in fact, it's costly to do so, energy wise... however, no sex for a guy is unnecessary -- the more the better. However, that's not the same for girls. Too much sex is unnecessary, is a waste of time and energy, and therefore irrational.
That's at least a part of the "social values" that king_of_boredom highlights are involved... I can imagine that could lead to a slight 'distaste' for highly sexually active women, but 'slut' seems to have a stronger meaning to it than the above would suggest... Anyone else got any ideas?
