The Rational Optimist (P.S.)

by Matt Ridley

Throughout the world, birth rates are falling. There is no country in the world that has a higher birth rate than it had in 1960, and in the less developed world as a whole the birth rate has approximately halved. Until 2002, the United Nations, when projecting future world population density, assumed that birth rates would never fall below 2.1 children per woman in most countries: that is the ‘replacement rate’, at which a woman produces enough babies to replace her and her husband, with 0.1 babies added in to cover childhood deaths and a slightly male-biased sex ratio. But in 2002, the UN changed this assumption as it became clear that in country after country the decline in baby-making went straight through the 2.1 level and kept on dropping. If anything, the decline may accelerate as the effect of small family size compounds. Nearly half the world now has fertility below 2.1. Sri Lanka’s birth rate, at 1.9, is already well below replacement level. Russia’s population is falling so fast it will be one-third smaller in 2050 than it was at its peak in the early 1990s.