> and people will start having many more kids again.

This has been my assumption, but now I question it. See

https://pmc.ncbi.nlm.nih.gov/articles/PMC1644264/

In this experiment, a mouse population grew quickly, then at high population density started falling quickly. But rather than recovering when the population decreased, it continued to fall until it was wiped out, in the presence of plentiful resources.

This keeps me up at night. Please someone tell me why it doesn't apply to us.

Yes, I'm well aware of that study and it kept me up at night a few times too.

Sorry I don't have a great answer to that. I don't think human population will drop to 0. That's a bit crazy and unlikely (gut feeling).

But it might be a few more generations longer than we think before population will grow again in developed countries.

Because we're not mice. Because he was actually studying the effects of overcrowding and not population growth & decline.

You'd need to look at more than just the population numbers, the issues were around high infant mortality and bad parenting, those are the things you should look out for over low birth rates.

Same reason the "all the horses are gone" argument doesnt apply to us. People are not horses or mice

it doesn't apply to us because generally speaking humans are able to identify and address threats to our existence.