But I think it became, in most ways and in most definitions, a slave society surely by the 1820s or the 1830s.

我认为最主流的定义是,奴隶社会确实起源于,十九世纪二三十年代

耶鲁公开课 - 美国内战与重建课程节选

Let's talk about more ancient societies and how food got started and what sort of phases we've gone through and how does that shape what's going on today.

让我们更深入地讨论古代社会及食品起源,还有我们经历了哪些阶段,这些阶段是如何影响我们现在的饮食

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选