Kira Pollack

Some of us are becoming the men we wanted to marry,” Gloria Steinem proclaimed 25 years ago. She meant, of course, that women in large numbers were seizing the places in higher education and the professions that had formerly been closed to them, becoming the doctors, lawyers and executives that they once hoped only to wed. Over the past generation, the liberal notion of egalitarian marriage — in which wives are in every sense their husbands’ peers — has gone from pie-in-the-sky ideal to unremarkable reality. But this apparently progressive shift has been shadowed by another development: America’s growing gap between rich and poor. Even as husbands and wives have moved closer together on measures of education and income, the divide between well-educated, well-paid couples and their less-privileged counterparts has widened, raising an awkward possibility: are we achieving more egalitarian marriages at the cost of a more egalitarian society?

Once, it was commonplace for doctors to marry nurses and executives to marry secretaries. Now the wedding pages are stocked with matched sets, men and women who share a tax bracket and even an alma mater. People, like other members of the animal kingdom, have always been prone to “assortative mating,” or choosing to have babies with a reassuringly similar partner. But observers like Geoffrey Miller, an evolutionary psychologist at the University of New Mexico and author of “The Mating Mind,” suggest that the innovations of modern society — from greater geographic mobility to specialized work environments to Internet dating — have made this matching process much more efficient. “Assortative mating is driven by our personal preferences, but also by whom we meet, and these days we have many more opportunities to meet others like ourselves,” he says. (As with most contemporary sociological phenomena, “Seinfeld” was there first: a 1996 episode featured the comedian finding “the female Jerry.”)

In particular, Americans are increasingly pairing off by education level, according to the sociologists Christine Schwartz and Robert Mare. In an article published last year in the journal Demography, they reported that the odds of a high-school graduate marrying someone with a college degree declined by 43 percent between 1940 and the late 1970s. In our current decade, the researchers wrote, the percentage of couples who are “educationally homogamous” — that is, share the same level of schooling — reached its highest point in 40 years. Assortative mating by income also seems to be on the rise. In a 2004 study of couples wed in the 1970s through the early 1990s, the researchers Megan Sweeney and Maria Cancian found an increasingly strong association between women’s wages before marriage and the occupational status and future earnings prospects of the men they married.

Why is this happening? For one thing, more couples are meeting in college and other educational settings, where prospective mates come prescreened by admissions committees as discerning as any yenta. Husbands and wives who begin their relationships during their school years are more likely to have comparable education (and, presumably, income) levels. Secondly, men and women have become more alike in what they want from a marriage partner. This convergence is both cultural — co-ed gyms and bars have replaced single-sex sewing circles and Elks clubs — and economic. Just as women have long sought to marry a good breadwinner, men, too, now find earning potential sexy. “There are fewer Cinderella marriages these days,” says Stephanie Coontz, author of “Marriage, a History.” “Men are less interested in rescuing a woman from poverty. They want to find someone who will pull her weight.” For this reason, the “marriage penalty” once paid by highly educated women has all but disappeared: among women born after 1960, a college graduate is more likely to marry than her less-educated counterpart. And finally, there’s what Schwartz calls the growing “social and economic distance” between the well educated and the less so, a gulf even ardent romantics may find difficult to bridge.

This last theory holds that disparities in wealth influence whom we marry, but there’s reason to think that our mating patterns could be producing economic inequality as well as reflecting it. A model constructed by the economists Raquel Fernández and Richard Rogerson, published in 2001 in The Quarterly Journal of Economics, led them to conclude that “increased marital sorting” — high earners marrying high earners and low earners marrying low earners — “will significantly increase income inequality.” A 2003 analysis by Gary Burtless, an economist at the Brookings Institution, found that a rising correlation of husband-and-wife earnings accounted for 13 percent of the considerable growth in economic inequality between 1979 and 1996.

Burtless himself does not think that assortative mating is necessarily becoming more prevalent. In fact, he says he believes that “the tendency of like to marry like has remained roughly unchanged over time. What have changed are the labor-market opportunities and behavior of women.” In this conception, men have always married women of their own social class, but such stratification was obscured by the fact that the female halves of these couples often did not work or pursue advanced degrees. Now that women who are in a position to do so are attending college and graduate school and joining the professions, the economic consequences of Americans’ assortative mating habits are becoming clearer.

If assortative mating does contribute to our growing gap between rich and poor, does that matter? Few people would question any individual’s romantic preferences. And yet as the current clash over gay marriage demonstrates, private choices about whom we marry — or don’t marry, or can’t marry — can have loud public reverberations. Not long ago, the marriages of whites and blacks, and the lifting of laws that once prohibited such unions, revealed a nation beginning to open its mind on matters of race; likewise, rates of marriage across lines of education and income provide an index of social mobility. If there are fewer such marriages, then there are “fewer sources of intimate ties” between groups, Schwartz says, making marriage one more brick in the wall that separates America’s haves and have-nots.

Of course, men and women don’t choose each other on the basis of education and income alone. Putting love aside, as men’s and women’s roles continue to shift, other standards for selecting a partner may come to the fore. Indeed, the sociologist Julie Press recently offered what she called “a gynocentric theory of assortative mating,” moving the focus from what men now desire in a marriage partner to the evolving preferences of women. What would-be wives may be seeking now, she proposed in The Journal of Marriage and Family, is “cute butts and housework” — that is, a man with an appealing physique and a willingness to wash dishes. Could this be a feminist slogan for our time?

Annie Murphy Paul is the author of "The Cult of Personality: How Personality Tests Are Leading Us to Miseducate Our Children, Mismanage Our Companies and Misunderstand Ourselves."

Copyright 2006 The New York Times Company. Reprinted from The New York Times Magazine of Sunday, November 19, 2006.