What drives the wage gap between men and women?

Subscribe to enjoy similar stories. “The Left Hand of Darkness", a classic science-fiction novel by Ursula K. Le Guin, imagines a faraway planet called Winter on which all people are “ambisexual".

Each month adults undergo “kemmer", a few days in which they develop sexual characteristics determined at random: either male or female. Anyone, in other words, might fall pregnant. After the kemmer, all sexual characteristics fade.

The dualism—the protected and protector; the dominant and submissive—that “pervades human thinking", writes Le Guin, is almost entirely absent on Winter. Such a planet would help answer an enduring question: why do men earn more than women? Perhaps male “dominators" succeed where female “submissives" do not. Yet the weight of research suggests that, after accounting for the constraints women face from bearing and rearing children, there is little left to explain.

The most effective economist in the field, Claudia Goldin of Harvard University, who won a Nobel prize in 2023, seemed to settle the debate. Motherhood, her work suggested, explains basically all of the wage gap. A handful of papers published over the past two years have reignited the debate.

They were based on powerful and novel datasets, which matched health records with income data in Scandinavian countries. This new evidence allowed economists to exploit the powerful natural experiment provided by variation in women’s fertility. Researchers took women undergoing in vitro fertilisation (IVF)—who clearly wanted children—and examined the difference in long-term wages between those who fell pregnant and those who did not.