(I'll acknowledge here that an over-heated sexual culture also puts tremendous pressure on men, particularly physically or socially disadvantaged men, while noting that men are typically rewarded for physical prowess and wealth accumulation—things that will benefit them in the long run—while women are rewarded for extreme dieting and plastic surgery.)
But it clearly is not the case that girls' academic achievement has suffered; as we've seen, just the reverse is true. What can we make of this? One explanation, what we might call the economic model, suggests that the apparent contradiction between female academic achievement and intense sexual competition can be explained by a classic supply-and-demand model. When women outnumber men in the social pool, even just slightly, they must compete more intensely for sexual status and partners. Thus we see a ramping up of sexual behavior in college women as their numbers increase on campuses. (This is not to place the blame on high-achieving women: we could just as easily blame their low-achieving male peers.) A similar dynamic might be in place even in environments where women don't appear to outnumber men—in high schools and in the workplace, for example—because high achieving women tend to prefer high-achieving males. So as female achievement rises, the pool of acceptable potential male partners proportionally declines.
This might answer Lisa Belkin's question—why do we see concomitant increases in female academic achievement and risky sexual behavior?—but it doesn't really answer mine: why doesn't risky sexual behavior seem to hurt young women's academic success? There are a few possible answers, the first being, of course, that I am simply wrong and sexual behavior is not costly for young women anymore, who after all now have access to contraception and abortion and cheap bikini-waxes.
But as I suggested above, at some threshold most people arrive at the intuition that extreme sexual behavior is harmful to young women. So there might be another explanation, what we might call the segmentation effect, related to the rise in inequality in American society. On this theory, there is growing inequality not only in the material resources available to children and young adults, but also in the social capital available to them. The rich have more than ever, but the poor are not keeping pace.
For advantaged young women, then, with not only material resources at their disposal but also resilient social networks, experience with institutions, positive life-scripts and habits of mind, the personal costs of sexual behavior can often be quietly absorbed. But for disadvantaged young women, it's a different game, and an ill-timed pregnancy, a series of loser boyfriends, a derailed educational trajectory, a damaged self-concept can set them back for years during the crucial early years of their children's lives. The academic triumphs of the sorority sisters on the other side of the tracks may bury the magnitude of these losses under a pile of cheery statistics, but they are real. Major setbacks during a woman's twenties have a way of rippling forward into middle-age and, especially, into her children's lives, reinforcing a generational of cycle of poverty, both material and social.
It's time for feminists to turn their attention from the trials of privileged women in the academy and the workplace to the formidable (if statistically low-profile) challenges still facing our less-privileged sisters.