Social evolution is a subdiscipline of evolutionary biology that is concerned with social behaviors that have fitness consequences for individuals other than the actor. Social behaviors can be categorized according to the fitness consequences they entail for the actor and recipient.
This classification was proposed by W. D. Hamilton, arguing that natural selection favors mutually beneficial or selfish behaviors. Hamilton's insight was to show how kin selection could explain altruism and spite.
Social evolution is also often regarded (especially, in the field of social anthropology) as evolution of social systems and structures.
In 2010, Harvard biologist E. O. Wilson, a founder of modern sociobiology, proposed a new theory of social evolution. He argued that the traditional approach of focusing on eusociality had limitations, which he illustrated primarily with examples from the insect world.