incidental consequence, a hunger to watch violence and to see it as entertainment. It allowed our feelings of inequity and envy to morph into schadenfreude, retaliation, and spite. It allowed us to enjoy violence as perpetrators and spectators. It allowed us to put our money on feeling good about righting an injustice. Why oh why? Why did evil, expressed as excessive harm to innocent others, evolve? The answer lies, so I suggest, in a special property of the human brain. Some time after we diverged from a chimpanzee-like common ancestor, the human brain was remodeled to allow promiscuous connections between previously unconnected circuits. Promiscuity enabled us to explore new problems using a combination of older, but nonetheless adaptive parts. Some of these novel explorations led to highly adaptive consequences, as when we developed the ability to self-deceive in the service of pumping ourselves up to do better in the context of competition; or when we invented new technologies to solve difficult environmental problems, such as using spears to capture prey at a distance; or, when we acquired the know-how to stockpile and enhance resources such as food, water and fertile land that are critical to individual survival and reproduction; or when we evolved the richly textured social emotions of jealousy, shame, guilt, elation, and empathy, feelings that motivate individuals to recognize the importance of others’ well-being and interests and to correct prior wrongs; or, when we tapped into the rich connection between reward and aggression to punish cheaters trying to destabilize a cooperative society. But these same adaptive explorations also resulted in incidental costs that have destroyed the lives of innocent individuals. The capacity to deny others’ moral worth enabled us to justify great harms, including self-sacrifice as living bombs designed to annihilate thousands of non-believers. The capacity to create advanced weaponry enabled us to kill at a distance, there