First, the Atlantic magazine announced "the end of men." Then a Time cover story in March proclaimed that women are becoming "the richer sex." Now a Pew Research Center report tells us that young women have become more likely than young men to say that a high-paying career is very important to them. Are we really in the midst of what Pew calls a "gender reversal?"

One stubborn fact of the labor market argues against the idea. That is the gender-hours gap, close cousin of the gender-wage gap. Most people...