What's goin' on?

Why? What is causing these trends (and what can we all do to reverse them?)

Some of the more obvious explanations are weaker than you might think:

For example, these trends are not caused by women working longer hours than men. We know this because women don't work more hours than men. In a mammoth study of twenty-five countries, ranging from the U.S. to France to Slovenia to Madagascar, men and women were asked to keep track of what they were doing at various times during the day, and then the hours for each activity were calculated. The results: in developed countries, men average 5.2 hours of paid work a day, and 2.7 hours of homework, for a total of 7.9 hours a day; and women average 3.4 hours of paid work, and 4.5 hours of homework, for a total of, yes, 7.9 hours a day. These averages are statistically identical in virtually every developed country in the study: women and men work the same number of total hours in a day. (It is only in less developed countries such as South Africa or Benin, where women have fewer choices and are largely excluded from the workplace, that women actually work more hours per day than men.)

Nor are they caused by gender-based stereotyping. Sure, forty years ago such stereotyping was still dominant—in 1977, 74 percent of men agreed with the statement "Men should be the primary breadwinner and women should be the primary caretaker of home and family." Today, however, that number has fallen to only 42 percent—which happens to be almost exactly the same as the percentage of women who agree with it (39 percent). Your opinion of which roles are most appropriate for men and women to play is not now determined by your sex.

Nor, surprisingly, is it caused by women bearing a disproportionate burden of the workload at home, the 'second-shift' as some have labeled it. This explanation falls not because women don't do more cooking, cleaning and child-caring than men; they still do. It falls because when it comes to the sharing of 'home' duties, the trend lines are all moving in the direction you would predict would lead to greater happiness and less stress for women: namely toward greater parity. For example, between 1975 and today women's housework hours declined from twenty-one per week to seventeen, while men's jumped from six to thirteen. In 1977 dads with non-teen kids spent 2 hours with them on an average weekday, while moms spent 3.8 hours. Today moms still spend 3.8 hours, while dads' kid-time has climbed to 3 hours per week day—and if you are a Gen Y dad, you're all the way up to 4.3 hours per day (Gen Y dads actually spend more time with their non-teen kids than do Gen X moms.)

So if it's not the hours, or the attitudes, and if the inequality of home-work is fast disappearing, where does that leave us?

Male mid-life crisis? A youth obsessed culture that is harder on women than men? The hormonal fluctuations of menopause?

My own analysis leads me to a specific explanation and accompanying prescription—which I've written about in Find Your Strongest Life.

But I'd love to hear yours. What's your explanation for, to borrow the title of Stevenson and Wolfers' paper, "The Paradox of Declining Female Happiness"? Share your comments below.