As Lukas demonstrates, however, libertine behavior exacts a heavier toll on females than males. Women are more susceptible to sexually transmitted diseases than men, for example. A woman is eight times more likely than a man to contract HIV from a single sexual encounter and four times more likely to get gonorrhea when exposed. Women are also more likely to suffer serious damage, such as sterility or cervical cancer, from STDs. And the risks are not just physical.

 Many studies show that promiscuous behavior entails greater psychological costs for even the most "liberated" women. One anthropologist cited by Lukas hypothesizes that the uncomfortable feelings many women experience after casual sexual encounters may be a warning system for women not to engage in behavior that would have been "maladaptive in earlier evolutionary eras. Casual sex with men unwilling to invest in them or their offspring is a prime instigator of such negative feelings."

 The girls baring all in these low-budget videos may think that guys like this kind of behavior. But as Steven E. Rhoads, author of "Taking Sex Differences Seriously" notes, "Men often prize promiscuous sex in the short term, but they want faithful wives. . . . If a man finds a woman hard to get, he will sense that she is more likely to be faithful after marriage." Plenty of men and boys will buy the "Girls Gone Wild" videos, but they're not likely to invite the amateur strippers home to meet Mom.