IT’S THE DEMOGRAPHY, STUPID: The global fertility crisis is already here.

For anyone tempted to try to predict humanity’s future, Paul Ehrlich’s 1968 book The Population Bomb is a cautionary tale. Feeding on the then popular Malthusian belief that the world was doomed by high lbirth rates, Ehrlich predicted: “In the 1970s hundreds of millions of people will starve to death.” He came up with drastic solutions, including adding chemicals to drinking water to sterilize the population.

Ehrlich, like many others, got it wrong. What he needed to worry about was declining birth rates and population collapse. Nearly sixty years on, many predict the world will soon reproduce at less than the replacement rate.

But by my calculations, we’re already there. Largely unnoticed, last year was a landmark one in history. For the first time, humans aren’t producing enough babies to sustain the population. If you’re fifty-five or younger, you’re likely to witness something humans haven’t seen for 60,000 years, not during wars or pandemics: a sustained decrease in the world population.

Don’t worry though — Yahoo says that’s for the best: America is facing a diaper crisis, and the anti-abortion movement is making it worse.

(Classical reference in headline.)