Eusociality

Eusociality is a social organization marked by cooperative brood care, overlapping generations, and reproductive division of labor, in which some individuals forgo reproduction.

Kin selection: Natural selection favoring traits that increase the reproductive success of genetic relatives. Helping relatives reproduce can spread genes even when helpers leave no offspring.
Cooperative breeding: A social system in which individuals help raise offspring that are not their own. It includes helping behaviors that occur without the full combination defining eusociality.
Ant: A social insect in the family Formicidae, with colonies organized around reproductive and worker roles. Ant colonies are among the clearest and most diverse examples of eusociality.
Charles Darwin: The English naturalist who developed the theory of evolution by natural selection. Sterile worker insects posed a challenge to his explanation of evolution by natural selection.
Solitary behavior: A lifestyle in which individuals live and reproduce largely on their own rather than as members of persistent social groups. It contrasts with the persistent cooperation and reproductive specialization of eusocial colonies.
Inclusive fitness: An individual's genetic success through both its own reproduction and effects on relatives' reproduction. It accounts for direct and indirect genetic contributions within colonies.
Brood care: Behaviors that protect, feed, and otherwise support developing offspring. Cooperative care of young is one of the defining features of eusocial organization.
Honey bee: A bee species, Apis mellifera, that lives in colonies with a queen, workers, and seasonal drones. Its colony provides a familiar example of eusocial reproduction and cooperative brood care.
W. D. Hamilton: The evolutionary biologist who formalized inclusive fitness and the conditions for kin-selected behavior. His theory supplied a major framework for explaining the evolution of sterile helpers.
Subsociality: A social system in which parents care for their offspring but generations do not form a cooperative, reproductive division of labor. It can include extended family living without the full eusocial combination.

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