Back in the day, in the farming days, people still had only 2 children on average survive to the adulthood — the population growth only really took off after in

Back in the day, in the farming days, people still had only 2 children on average survive to the adulthood — the population growth only really took off after industrial revolution. The biggest problem back then was that having more than 2 children impoverished them in the long run — it ensured that each kid had less land to farm than their parents. If you kept having above replacement fertility rate for a while, after a few generations the descendants had no land to farm, and with few alternatives afforded by technology-less society, this meant absolute poverty and starvation.