Societies have developed almost continuosly since our simian ancesstors found themselves adrift on the savhana as a response to the chronic stress faced by a radically changed physical environment as the rainforests first retreated millions of years ago.

Social grouping and the associated grooming process evolved to provide protection and reduce fear - grooming, contact and conversation raised naturally occuring opiate levels and social systems only survive so long as they make the participants feel safe. Without that they disintegrate.