Rhesus monkeys can be trained to pull a chain to obtain food but will refuse to do so if this means another monkey receives an electric shock. How do those monkeys compare with Nazi concentration camp guards? It was childhood tales of Nazi atrocities that first set the Cambridge psychologist, Simon Baron-Cohen, on the path of studying human cruelty and empathy. Instead of "evil", Simon frames such acts as "empathy erosion" in his book, Zero Degrees of Empathy. Unempathic acts are simply the tail end of a bell curve, found in every population on the planet, and thus, any problem immersed in empathy becomes solvable.
