After doing a little research, here's what I've come up with. Average life expectancy doesn't begin to increase until about 1400. Population doesn't start growing until about 1600. It's fairly flat before then, though there are many ups and downs. Obviously, this is well after man begins farming, so it cannot be farming that creates the positive changes. Something else does that. "Public health" is surely one answer. The fall in infant mortality is another big reason.

Sheldon