The roots of human altruism.

Human infants as young as 14 to 18 months of age help others attain their goals, for example, by helping them to fetch out-of-reach objects or opening cabinets for them. They do this irrespective of any reward from adults (indeed external rewards undermine the tendency), and very likely with no concern for such things as reciprocation and reputation, which serve to maintain altruism in older children and adults. Humans' nearest primate relatives, chimpanzees, also help others instrumentally without concrete rewards. These results suggest that human infants are naturally altruistic, and as ontogeny proceeds and they must deal more independently with a wider range of social contexts, socialization and feedback from social interactions with others become important mediators of these initial altruistic tendencies.