Upheaval: Turning Points for Nations in Crisis

by Jared Diamond

Japan along with some other First World countries has an average total fertility rate below that replacement rate. For other First World countries, that’s not a problem, because immigration keeps the population size constant or even growing despite low fertility. However, Japan’s near-absence of immigration means that Japan’s population is actually declining, as we’ll discuss. Part of the reason for Japan’s falling birth rate is that Japan’s age of first marriage has been rising: it’s now around 30 for both men and women. That means fewer pre-menopausal years in which a woman can conceive children. A bigger reason for the falling birth rate is that the rate of marriage itself (i.e., the number of marriages per 1,000 people per year) is falling rapidly in Japan. One might object that the marriage rate is also falling in most other developed countries without causing the catastrophic drop in the birth rate that Japan is experiencing, because so many births are to unwed mothers: 40% of all births in the U.S., 50% in France, and 66% in Iceland. But that mitigation doesn’t apply to Japan, where unwed mothers account for a negligible proportion of births: only 2%.