In which John Green teaches you about one of the least funny subjects in history: slavery. John investigates when and where slavery originated, how it changed over the centuries, and how Europeans and colonists in the Americas arrived at the idea that people could own other people based on skin color. Slavery has existed as long as humans have had civilization, but the Atlantic Slave Trade was the height, or depth, of dehumanizing, brutal, chattel slavery. American slavery ended less than 150 years ago. In some parts of the world, it is still going on. So how do we reconcile that with modern life?