[rsj_hn]

> The regime then was high fertility and high mortality. Now, it's low and low, and both the fertility and mortality declines have strong economic, institutional and cultural drivers.

Everything in life is on average 50% genetics, and nature has a way of weeding out those who have a lower propensity to reproduce. I wouldn't worry at all about population declines in and of themselves.

All over the world, we have transitioned from more traditional societies to more liberated societies that are failing to reproduce. That collapse in fertility goes lockstep with modernism. As a fun fact: there were studies that in 19th C France those postal codes in which large numbers of Diderot's encyclopedia were sold saw rapid fertility drops. Something about modernism is incompatible with human reproduction, so either we will evolve to thrive in the more liberal societies, or the future will belong to those subpopulations that reject modernity, whether orthodox jews in Israel or Amish in the US, or more fundamentalist islamic groups in the middle east, which have already taken over the dead carcasses of modern secular societies that thrived in the 60s and 70s. So either modernism will die or people will evolve to have more kids in modernist societies, but in either case, population will be increasing again in the future, which belongs, as the old saw goes, to those who show up. Eventually there will be a harmonization where our environment is suitable for reproduction.