A recent article in New Scientist named altruism as one of the ten great mysteries of human behavior, alongside kissing, blushing and laughter. For scientists, altruism has long presented a conundrum: Why do people help others, even putting their own lives at risk, for no obvious reward Historically, attempts to explain such seemingly irrational behavior have fallen into three main theories: kin selection, group selection and reciprocity. According to these hypotheses, humans are fundamentally self-interested, and therefore we give only in order to get something, even if its a delayed reward, or to ensure benefits for our own genetics or those of our social group. More recent experiments, however, suggests that these ideas only partially explain the human impulse toward helping.