you can make a simpler experiment: try going a week with only food you can forage in nearby forests and fields, plus some meat you'd buy (you're not expected to be able to hunt).

I love eating wild weeds and berries, but it takes _a lot_ of time to get enough to fill yourself, and it's not a case that people have only eaten stuff like acorns only in times of famine.

This fact by itself made me question a lot of what's in "Sapiens".