"The Richer Sex," by Liza Mundy Five or six years ago, my mother and I sat in a darkened theater talking about a couple we knew. The wife was an executive with Ivy League degrees. The husband had some nebulous part-time job, but mostly he stayed home with the kids. What, I wondered, does he have that's attractive to her? There was a pause. Sperm, my mother replied. Today, that conversation is as obsolete as "The Feminine Mystique." For one, as The New York Times recently reported, more women are having children without marrying. In 2009 more than half of all births to women under 30 occurred outside marriage - an institution that is losing popularity in historic proportions. Male underemployment, the surge in women's economic fortunes and the decline in marriage swirled into a meme in 2010, when an article in The Atlantic asked, "What if the modern, post­industrial economy is simply more congenial to women?" The next year, the magazine ran a long essay in which the writer observed that the pool of those considered "traditionally "marriageable" men" - the highly educated, the financially secure - was "radically shrinking." This is the terrain Liza Mundy strides into in her ambitious new book, "The Richer Sex." Mundy predicts that women's economic rise above men, which she calls "The Big Flip" - one of several cutesy terms she uses, along with "bread­women," her word for female breadwinners - will benefit everyone. "Women's earnings will bring about a new liberation for women but also for men," she writes. More women will marry down; more men will marry up. Sounds like something that happened on "Downton Abbey." Its utopianism is one thing separating "The Richer Sex" from earlier manifestos and exposés about women, as well as from tedious conservative declamations warning that anything less than some mythical 1950s ideal is bad news. Another is Mundy's fresh reporting and the reams of new social science research she summarizes to make her case. But one of the maddening things about this book is that Mundy never met a sociologist she didn't like. While it's provisionally heartening to read her gloss of a study tentatively arguing that "for the first time in modern history, mothers in some key professions may enjoy the same earnings boost that fathers have long enjoyed," I was less persuaded by her use of recent scholarship to overturn the gloomy conclusions of Arlie Hochschild's influential 1989 book "The Second Shift," which argued that even though women were entering the workplace, they also did a majority of the housework (thus the book's title). Mundy refers to a study showing that " "husbands average slightly more" total work per week" when one counts paid and unpaid work. But this doesn't tell the whole story, as respondents to the study did not always count child care as primary "unpaid work" - the bulk of which still falls mostly to women. Even so, given women's bleak economic past, Mundy's cheer about the research measuring women's rise is under­standable. She does a service reporting the numbers documenting women's increasing economic power: women hold 51 percent of jobs in "management, professional and related occupations," according to the Bureau of Labor Statistics; "wives are breadwinners or co-earners in about two-thirds of American marriages" - although to combine breadwinner and co-earner muddies her case. Education has become a woman's game: women earn 57 percent of bachelor's degrees and make up 60 percent of graduate students. Mundy notes that the wage gap between genders persists, but to her, the take-away is its shrinking. The statistics she quotes bring some good - or at least improved - news: In 2010, women earned 81.2 percent of men's earnings, up from 62 percent in 1979. "The same factors that have narrowed the gap are likely to close it," Mundy writes, pointing to jobs (postal workers, stock clerks) and demographics (younger women) for which the gap has already dwindled or disappeared. Rachel Shteir's most recent book, "The Steal: A Cultural History of Shoplifting," will be released in paperback next month.