“HERE’S what nobody is telling you: Find a husband on campus before you graduate,” wrote Susan Patton, a human-resources consultant, in 2013. In an infamous letter to the editor of Princeton’s student newspaper, Ms Patton warned female students at the university that they will “never again be surrounded by this concentration of men who are worthy of [them]”. Critics responded harshly. Ms Patton recalls that she was branded “a traitor to feminism, a traitor to co-education and an elitist”.
Economists might offer yet another critique of Ms Patton’s letter: it was largely unnecessary. It is clear to academics that people tend to marry spouses with similar levels of education. They also know that “assortative mating”, as the practice is called in the jargon, is exacerbating income inequality. In America, Britain, Denmark, Germany and Norway, they have found that household income would be more evenly spread if couples were less keen…