Game theory explores the Golden Rule's place in biology
Charles Darwin's theory of natural selection seems to describe a brutal world in which creatures compete ruthlessly to promote their own survival. Yet biologists observe that animals and even lower organisms often behave altruistically. A vervet monkey who spots a leopard, for instance, warns his fellow monkeys, even though the call may attract the leopard's attention to the individual. A vampire bat that has hunted successfully shares nourishing blood with a fellow bat that failed to find prey.