Reading further, I might be being too charitable.

Demographics are under government control, at very least at the dP/dt level. Much of the causality should be sought there.

Contraception, abortion access, immigration policy, tax incentives, childcare subsidies, parental leave, housing policy, education funding, propaganda. The levers are endless.

Until recently most governments were simply trying to level off their population. They may have succeeded a bit too well, but that's another story.

Somehow -in their essays so far- Tantaman has left out government policy almost entirely, which is a big elephant in the room to miss.