Nonrelatives inherit colony resources in a primitive termite.

The evolution of eusociality, especially how selection would favor sterility or subfertility of most individuals within a highly social colony, is an unresolved paradox. Eusociality evolved independently in diverse taxa, including insects (all ants and termites; some bees, wasps, thrips, and beetles), snapping shrimp, and naked mole rats. Termites have received comparatively less focus than the haplodiploid Hymenoptera (ants, bees, and wasps); however, they are the only diploid group with highly complex colonies and an extraordinary diversity of castes.

Alternative mating behaviors of the queen polymorphic ant Temnothorax longispinosus.

Mating behaviors of ants fall into two categories: female calling, in which a female alate releases pheromones that attract males, and male swarming, in which large male aggregations attract females. Female calling is common in species with queens that return to their natal nest to found colonies dependently after mating, while male swarming is common in species with queens that disperse to found independently. In some species that display both founding strategies, a queen-size polymorphism has evolved in which dependent-founding queens are smaller than independent-founding queens.