EyeEm / Alamy Stock Photo

Could the population bomb be about to go off in the most unexpected way? Rather than a Malthusian meltdown, could we instead be on the verge of a demographic implosion?

To find out how and why, go to Japan, where a recent survey found that people are giving up on sex. Despite a life expectancy of 85 and rising, the number of Japanese is falling thanks to a fertility rate of just 1.4 children per woman, and a reported epidemic of virginity. The population, it seems, are too busy (and too shy) to procreate.

It’s catching. Half the world’s nations have fertility rates below the replacement level of just over two children per woman. Countries across Europe and the Far East are teetering on a demographic cliff, with rates below 1.5. On recent trends, Germany and Italy could see their populations halve within the next 60 years.

The world has hit peak child, says Hans Rosling at the Karolinska Institute in Stockholm, Sweden. Peak person cannot be far behind.

For now, the world’s population continues to rise. From today’s 7.4 billion people, we might reach 9 billion or so, mostly because of high fertility in Africa. The UN predicts a continuing upward trend, with population reaching around 11.2 billion in 2100. But this seems unlikely. After hitting the demographic doldrums, no country yet has seen its fertility recover. Many demographers expect a global crash to be under way by 2076.

Governments may try to halt the fall – though Singapore has been trying for …