China's ending its one-child policy for a two-child because of demographic issues. People predicted this decades ago: If China continued that path, the trajectory would end with a substantial elderly population overburdening the younger generation. Their factories would be denuded as people retired and no one would be available to refill positions.

Malthus' An Essay on the Principle of Population was filled with made-up numbers and facts, but I think some of his points apply. There were "preventative checks," i.e. abstinence, birth control, abortion, etc. And if the population got too large, we had "positive checks" that lowered it like famine, war, or disease.

Malthus wrote his work just as the Agricultural Revolution began, so many of the positive checks never came into place: Less and less people were one bad winter away from starvation, and more moved into the middle class. Throughout the 1800s we learned about germs and clean water, and then in the early 1900s we discovered antibiotics and used vaccines more efficiently. Population really skyrocketed.

But I can't help but feel it's not sustainable. It's literally impossible for humanity to expand exponentially, so at some point we'll have to stop. And then what? What would the checks be? Apparently the preventative ones are only good at keeping the population steady because otherwise you'd enter the situation that China has entered. So then we'd have to bring in the positive ones? Another Spanish Flu? Another World War? That shit sounds terrifying.