[pbhjpbhj]

>But humans often lived in periods of high food availability. //

It's not just high food availability we have - I'm a few steps away from a ton of high calorie foods and could get more sent to my house without leaving my chair. In the past, even with plentiful supply, one had to [generally] put in some effort to get food. That doesn't seem to be the case for many now.

In the scenario of high food availbility meaning there's plenty of fruit to gather (and process to save for winter) and there's plenty of deer to chase then I can see I'd get more exercise.