Altruism

Altruism refers to behaviors that help others, improving their fitness while lowering the individual's own fitness.

For example, worker honeybees, females who do not reproduce, find and bring back food for the queen, the only female in the colony that does reproduce, and her offspring. The workers also build and maintain the hive and protect it from intruders by stinging them, killing the bee in the process.

Therefore, worker bees sacrifice their own lives and their ability to reproduce in favor of the queen. However, the workers are closely related to the queen, so this altruistic behavior helps their shared genes get passed down through the queen's offspring.

Altruism can also occur between unrelated or distantly related individuals, such as when one primate grooms another within a social group. This is called reciprocal altruism and is thought to be adaptive since the favor is often returned, ultimately benefiting both individuals.