Eusociality is a specific type of colonial social organization among specific animal species including the honeybee, the naked mole rat, ants and termites, and some varieties of pistol shrimp.
While there are other animal colony structures which are not eusocial, such as prairie dogs and meerkats, these are distinguished from eusocial colonies by their lack of division of labour, which is a defining trait of a eusocial colony. In eusocial colonies, reproduction itself is often a specialized task, and only a small group (or even a single female member and several male drones) within the colony is fertile and able to produce young, such as a queen bee.
Another defining characteristic is that in eusocial colonies, the task of caring for offspring is shared by the entire colony: the colony members who reproduce are not solely responsible for feeding and protecting the colony's offspring. In this way, while humans can live in very large social groups with elaborate caste systems and division of labour, and while human societies feature generational overlap like all eusocial colonies do, as a rule humans are not eusocial: in most human cultures, raising offspring is solely the responsibility of the child's biological parents, or a household of people including those parents, rather than an entire large community.
Kin altruism is another important feature of eusocial colonies; one of the divided labours of the colony is defense of the colony, and entire populations within the colony will have the sole task of fighting external threats, including dying for the colony. This is especially the case with honeybees, because any use of the stinger will result in the bee's death, although among honeybees, colony defense is a distributed activity rather than a specialized activity: every worker bee is equally a soldier, both obtaining food and protecting the queen and offspring.
Iron Noder 2015, 09/30