I n the roughly 250 years since the Industrial Revolution the world’s population, like its wealth, has exploded. Before the end of this century, however, the number of people on the planet could shrink for the first time since the Black Death. The root cause is not a surge in deaths, but a slump in births. Across much of the world the fertility rate, the average number of births per woman, is collapsing. Although the trend may be familiar, its extent and its consequences are not. Even as artificial intelligence ( ai ) leads to surging optimism in some quarters, the baby bust hangs over the future of the world economy.
自工业革命以来，大约250年来，世界人口像其财富一样爆炸了。然而，在本世纪末之前，地球上的人数自从黑死病以来就可以第一次缩小。根本原因不是死亡的激增，而是出生的低迷。在世界各地，生育率是每个女性的平均分娩数量正在崩溃。尽管趋势可能很熟悉，但其范围及其后果并非如此。即使人工智能（AI）在某些方面导致乐观情绪激增，婴儿的胸围也会在世界经济的未来中悬而未决。
