If you think about what ancient food gathering habits used to be like, you see things like this where people are out gathering food that is growing naturally, and you can think about what would-- what sort of conditions this would create and what kind of hardships it would create.

如果你想知道古代食物采集的习惯,请看这张图,人类都在野外采集自然生长的食物,你可以设想到,条件有多恶劣,生存有多艰难

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选