What if humanity's capacity for cruelty was actually one of our greatest moral achievements? That's just one of the provocative ideas philosopher Hanno Sauer explores in this conversation about his book The Invention of Good and Evil with EconTalk's Russ Roberts. Sauer tackles a fundamental puzzle: in a Darwinian world of selfish genes, how did humans become so extraordinarily cooperative? Sauer traces a fascinating journey from small hunter-gatherer bands to modern civilizations, revealing surprising mechanisms along the way--including the systematic killing of the most aggressive tribe members over millennia, which made humans the "golden retrievers of the primate kingdom." The conversation ranges from whether agriculture was history's worst mistake, to a spirited debate about religion and morality between Sauer (a German atheist who doesn't know any believers) and host Russ Roberts (a person of faith living in Israel).