Social structure was the distinctive, stable system of social relations that existed in any Human society.
Spock observed that the development of Delta Theta III aborigines, as of 2269, appeared to be "in a late primitive state". He noted them to be "[o]bviously intelligent, [as] they seem to have a basic language and social structure". He added, "I would assume [they have] fairly well developed mores and traditions as well." (TAS: "Bem")