Religion
The importance of religion in the descent of human sociology cannot be overstated. Beyond family ties, religion played a critical role in establishing group solidarity and social order, particularly in codifying behavioral norms. It is difficult to imagine how humans could have evolved into tribes without religion and its associated rituals that form the basis for cultural indoctrination. Whereas conflict was the impetus for political evolution, religion was its glue.
Religious beliefs are never held by their adherents to be simple theories that can be discarded if proved wrong; they are held to be unconditionally true, and there are usually heavy social and psychological penalties attached to asserting their falsehood. ~ American political scientist Francis Fukuyama