Perhaps it’s time to start rebranding bachelor’s degrees as “bachelorette’s degrees.”

For the first time in U.S. history, women are more likely than men to have a four-year college degree: 30.2 percent for all women 25 and older vs. 29.9 percent for men the same age.

It was destined to happen eventually; young women actually surpassed young men in newly awarded diplomas several decades ago. It just took a while for enough cohorts of young women to displace their older, less educated counterparts in population share.

But burning questions remain. Why, exactly, have women been investing so much more heavily in their schooling relative to men, given that women still are much less likely to be in the labor force? And why, when women invest in education, do they seem to choose majors that don’t pay off as well financially?

There are, of course, plenty of reasons to go to college other than improving your own earning potential: expanding your mind; raising your social status; increasing your odds of getting married (and, specifically, of marrying someone else with a college degree, who therefore has higher earning potential, too); improving your ability to teach your own children; etc.

Maybe these kinds of payoffs matter more to women than to men.

But it’s still a bit strange that women are more likely to spend money on ever-rising tuition when they’re not seeing the same financial upside as men.

College-educated women not only earn less than their equally educated male counterparts — such women don’t even earn as much as their less educated male counterparts. Median earnings for women whose highest credential is a bachelor’s degree were about $42,000 last year; median earnings for men whose highest credential is an associate degree were about $46,000.

There are certainly a lot of factors involved in this wage gap, including that women take off more time from their careers to care for children. But one of them is what men and women choose to study.

Don’t blame the usual degree scapegoats, such as women’s studies and art history. Yes, women are more likely to major in these psychically-but-not-very-financially-rewarding subjects than their male classmates are. But very, very few diplomas are awarded in such disciplines to people of either gender. Out of 1.8 million BAs handed out in 2012-13, only about 1,000 were in women’s studies and 3,000 were in art history.

The big disciplinary gap between the genders lies elsewhere. The three fields in which women outnumbered men in the highest numbers are more traditionally utilitarian: health professions (125,000 more women than men), education (61,000) and psychology (60,000).

The majors that had the most men relative to women, by contrast, were engineering (66,000 more men than women) and computer and information sciences (33,000). These also happen to be among the highest-paying majors.

Notwithstanding the stereotypes about financially oblivious (or at least financially unconcerned) gender studies majors, I suspect that women — particularly the women who are the most marginal college enrollees — by and large believe they’re majoring in subjects that are safe, practical and professionally useful.

True, they’re not funneling into fields that will maximize their earnings, the way college-enrolled men seem keen to do. But women are still studying subjects that sound like they will get them stable jobs. And not just any jobs — jobs that tend to offer more flexible work schedules and lower penalties for rotating in and out of the labor force, such as teaching and nursing. The big, female-dominated majors also tend to offer higher grades, which perhaps tricks students into thinking they’re especially good at those subjects and therefore will have better employment prospects upon graduation.

When it comes to the decision to enroll in college, and what to major in, women may view their studies more as an insurance policy, a way to set a floor on their wages. There are, at least for the time being, lots of decent, middle-class jobs predominantly held by men that don’t require higher education (such as construction and other trades); comparably paying jobs disparately held by less educated women are few and far between.

Meanwhile, the decline in marriage rates coupled with the rise of no-fault divorce may further encourage women to invest in schooling that will allow them to support themselves and their kids in a pinch — even if they know the subject they’re studying probably won’t ever make them rich.

When it comes to schooling decisions, perhaps men are more likely to have their eyes on the prize and women on the risks of poverty wages.