“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.
