Birds do it. Bees do it. Even intertidal gonochoric prosobranchs do it. And human beings definitely do it. “It” is assortative mating, in which creatures tend to couple with those that are most like them. Case in point: One in four female physicians is married to another physician.
That’s a sweet Valentine’s factoid, right? Except that assortative mating appears to contribute to societal inequality when people use education or income as one of their sorting criteria. When a doctor marries a nurse or a teacher or a mechanic, societal inequality is lessened. When a doctor marries another doctor, the rich get richer.
There’s a scholarly debate over whether the preference for assortative mating has increased and, if so, whether that has contributed meaningfully to widening gaps in income and wealth. A 2018 paper found no evidence of assortative mating by education on mobile dating apps such as Tinder. (Looks seem to matter more there.) Another 2018 paper, based on Norwegian data, found “evidence of declining assortative mating over the last 30 years.”
I’m most impressed by new research by Anna Naszodi, an economist at the National Bank of Hungary (who began the work when she was at the European Commission’s Joint Research Center) and Francisco Mendonca, a data scientist at the bank Cofidis Portugal. Using a statistical technique of their own design, they concluded in a 2021 article in The Journal of Demographic Economics that changes in preferences are one factor — but not the only one — in the increase in educationally homogamous couples, namely ones in which the spouses have the same level of education.
When I interviewed Naszodi last week, she made a joke, with Valentine’s Day approaching, about “Cupid’s invisible hand.” She assured me that she does not specialize in the economics of romance. She said she studies mating behavior because it sheds light on inequality, one of her research topics. She also works on exchange rates, monetary policy and bank regulation.
The tricky part of figuring out what Cupid’s invisible hand is doing is that there are lots of driving forces. Opportunity matters as much as preference. For example, women used to be less educated than men, in general. As women became more educated, it became more likely that educated men would marry educated women, just by chance, even if there wasn’t a change in preference.
It’s easy enough for scholars to observe what people are doing; what’s hard is establishing the counterfactuals — how things might have gone differently. For example, what would marriage patterns look like if opportunities for marrying someone similar had not changed over the past 10 years? Naszodi and Mendonca came up with a way of establishing those counterfactuals, based on work by Haoming Liu and Jingfeng Lu of the National University of Singapore that was published in Economics Letters in 2006.
Using that method, Naszodi and Mendonca concluded that late baby boomers had a weaker preference for a spouse of the same education than early baby boomers had. That signaled a decrease in inequality. When late Gen Xers reached the marriage market, the preference for a spouse of the same education level had strengthened, a mark of increasing inequality, they concluded. (They looked at people when they were 30 to 34 and studied only heterosexual relationships.)
If you don’t have a date for Valentine’s Day, assortative mating could be one of your problems. Poor, uneducated men are being excluded from the marriage market because there are fewer women who want to marry them. Women have become better educated and prosperous, on average, and they would rather marry someone who is their socioeconomic equal. However, there’s a shortage of unmarried men with high socioeconomic status. So, many of the women with high aspirations remain single.
Naszodi and Mendonca’s latest finding, in a forthcoming paper, is that millennials are somewhat less picky about the education level of their mates than Gen Xers. “It gives rise to optimism,” Naszodi wrote me in an email. “Millennials have better chances to find a suitable partner than Gen Xers used to have.”
These are generalizations, of course. What’s true is that Cupid is as fickle as ever. It would be so much easier to be an intertidal gonochoric prosobranch (a kind of snail).
Outlook: Oren Klachkin and Matthew Martin
Stresses in U.S. supply chains fell in January and “further easing is likely” as the U.S. economy “enters a mild recession,” Oren Klachkin, the lead U.S. economist at Oxford Economics, and Matthew Martin, a U.S. economist, wrote in a client note on Friday. The company’s indicator of supply chain stress fell in January to its lowest in nearly two years as carrying capacity in ocean freight and airfreight routes improved.
Quote of the Day
“Wide contacts are earmarks of emancipated women.”
— Sadie T.M. Alexander, “The Emancipated Woman,” circa 1930, collected in “Democracy, Race, and Justice: The Speeches and Writings of Sadie T.M. Alexander,” edited by Nina Banks (2021)