Altruism puzzled Charles Darwin. If evolution was propelled by natural selection — by the gradual predominance within species, including Homo sapiens, of those individuals best adapted genetically for survival and reproduction — where do generosity and compassion come from? Why don’t societies grow more pitiless and cutthroat over time? How did selflessness, charity, and integrity ever establish a foothold, let alone become moral virtues that all enlightened communities esteem?
Darwin could see the clear evolutionary benefit to groups that inculcated ethical values in their members. Imagine, he wrote in “The Descent of Man,” two competing primitive tribes, equally matched — except that “one tribe included a great number of courageous, sympathetic, and faithful members, who were always ready to warn each other of danger, [and] to aid and defend each other.” There was little doubt that tribes highly endowed with such virtues “would spread and be victorious over other tribes.”