Kevin Simler

"Because superstition" is an explanation of last resort. Very intellectually lazy.

Fukuyama is right that there's a puzzle, though: Individuals have almost no reason to prefer their fourth cousin to a friendly stranger. So how do tribes of distant relatives cohere?

It's not fear of supernatural retribution. Rather, the shared ancestors serve as a focal point for coordination.

If everyone formed political alliances only with their friends, the resulting network would be a stringy mesh, centerless and incoherent. Instead, when people unite around a common (patrilineal or matrilineal) ancestor, the political network takes the shape of a firm knot.