> Slavery is probably the worst thing that happened to humanity. I saw an opinion (really can't remember the source now) that slavery was a major improvement a

> Slavery is probably the worst thing that happened to humanity. I saw an opinion (really can't remember the source now) that slavery was a major improvement at the time when people who won a war used to simply eradicate conquered populations completely. With invention of slavery, strong and otherwise useful individuals had a chance to survive a bit longer. There is no one worst things that happened to humanity. I'm sure there are plenty of contenders if one looks hard enough.