Sex ratio consequences

Girls outnumber boys in college today, and Mark Regnerus wrote this popular essay about it in 2011:

If women were more fully in charge of how their relationships transpired, we'd be seeing, on average, more impressive wooing efforts, longer relationships, fewer premarital sexual partners, shorter cohabitations, and more marrying going on. Instead, according to the National Longitudinal Study of Adolescent Health (which collects data well into adulthood), none of these things is occurring. Not one.The terms of contemporary sexual relationships favor men and what they want in relationships, not just despite the fact that what they have to offer has diminished, but in part because of it. And it's all thanks to supply and demand. ...

And yet despite the fact that women are holding the sexual purse strings, they aren't asking for much in return these days—the market "price" of sex is currently very low. There are several likely reasons for this. One is the spread of pornography: Since high-speed digital porn gives men additional sexual options—more supply for his elevated demand—it takes some measure of price control away from women. The Pill lowered the cost as well. There are also, quite simply, fewer social constraints on sexual relationships than there once were. As a result, the sexual decisions of young women look more like those of men than they once did, at least when women are in their twenties. The price of sex is low, in other words, in part because its costs to women are lower than they used to be.

But just as critical is the fact that a significant number of young men are faring rather badly in life, and are thus skewing the dating pool. It's not that the overall gender ratio in this country is out of whack; it's that there's a growing imbalance between the number of successful young women and successful young men. As a result, in many of the places where young people typically meet—on college campuses, in religious congregations, in cities that draw large numbers of twentysomethings — women outnumber men by significant margins. (In one Manhattan ZIP code, for example, women account for 63 percent of 22-year-olds.)

The idea that sex ratios alter sexual behavior is well-established. Analysis of demographic data from 117 countries has shown that when men outnumber women, women have the upper hand: Marriage rates rise and fewer children are born outside marriage. An oversupply of women, however, tends to lead to a more sexually permissive culture. The same holds true on college campuses. In the course of researching our book Premarital Sex in America, my co-author and I assessed the effects of campus sex ratios on women's sexual attitudes and behavior. We found that virginity is more common on those campuses where women comprise a smaller share of the student body, suggesting that they have the upper hand. By contrast, on campuses where women outnumber men, they are more negative about campus men, hold more negative views of their relationships, go on fewer dates, are less likely to have a boyfriend, and receive less commitment in exchange for sex.

The NY Times just printed an article about how today's college girls want casual sex:

These women said they saw building their résumés, not finding boyfriends (never mind husbands), as their main job at Penn. They envisioned their 20s as a period of unencumbered striving, when they might work at a bank in Hong Kong one year, then go to business school, then move to a corporate job in New York. The idea of lugging a relationship through all those transitions was hard for many to imagine. Almost universally, the women said they did not plan to marry until their late 20s or early 30s.

In this context, some women, like A., seized the opportunity to have sex without relationships, preferring “hookup buddies” (regular sexual partners with little emotional commitment) to boyfriends.