Evolution of eusociality

Eusociality evolved repeatedly in different orders of animals, notably termites and the Hymenoptera (the wasps, bees, and ants). This 'true sociality' in animals, in which sterile individuals work to further the reproductive success of others, is found in termites, ambrosia beetles, gall-dwelling aphids, thrips, marine sponge-dwelling shrimp (Synalpheus regalis), naked mole-rats (Heterocephalus glaber), and many genera in the insect order Hymenoptera.^[1] The fact that eusociality has evolved so often in the Hymenoptera (between 8 and 11 times^[2]), but remains rare throughout the rest of the animal kingdom, has made its evolution a topic of debate among evolutionary biologists. Eusocial organisms at first appear to behave in stark contrast with simple interpretations of Darwinian evolution: passing on one's genes to the next generation, or fitness, is a central idea in evolutionary biology.

Current theories propose that the evolution of eusociality occurred either due to kin selection, proposed by W. D. Hamilton,^[3] or by the competing theory of multilevel selection as proposed by E.O. Wilson and colleagues.^[4] No single trait or model is sufficient to explain the evolution of eusociality, and most likely the pathway to eusociality involved a combination of pre-conditions, ecological factors, and genetic influences.