Altruistic behavior: Behaviors benefit others rather than the individual committing the behavior.

Human, rare in early childhoodNonhuman: sentinel behavior of

meerkats—escape danger most quickly or surely.

Evolution of Altruistic Behaviors

Two possible explanations for altruistic behavior

Kin selection: selection in favor of a gene because it benefits the animal’s relatives who are likely to carry the same gene. This would be

“nepotistic altruism”

Reciprocal altruism: the idea that animals help those who help them in return. Requires good

sensory organs and a well-developed brain to recognize those who did the favor.