1. Altruistic behavior: Behaviors benefit others rather than the individual committing the behavior. Human, rare in early childhood Nonhuman: sentinel behavior of meerkats—escape danger most quickly or surely.

2. 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.