Daniel C. Dennett in The New York Times:
According to copies of copies of fragments of ancient texts, Pythagoras in about 500 B.C. exhorted his followers: Don’t eat beans! Why he issued this prohibition is anybody’s guess (Aristotle thought he knew), but it doesn’t much matter because the idea never caught on. According to Joseph Henrich, some unknown early church fathers about a thousand years later promulgated the edict: Don’t marry your cousin! Why they did this is also unclear, but if Henrich is right — and he develops a fascinating case brimming with evidence — this prohibition changed the face of the world, by eventually creating societies and people that were WEIRD: Western, educated, industrialized, rich, democratic. In the argument put forward in this engagingly written, excellently organized and meticulously argued book, this simple rule triggered a cascade of changes, creating states to replace tribes, science to replace lore and law to replace custom. If you are reading this you are very probably WEIRD, and so are almost all of your friends and associates, but we are outliers on many psychological measures.
The world today has billions of inhabitants who have minds strikingly different from ours. Roughly, we weirdos are individualistic, think analytically, believe in free will, take personal responsibility, feel guilt when we misbehave and think nepotism is to be vigorously discouraged, if not outlawed. Right? They (the non-WEIRD majority) identify more strongly with family, tribe, clan and ethnic group, think more “holistically,” take responsibility for what their group does (and publicly punish those who besmirch the group’s honor), feel shame — not guilt — when they misbehave and think nepotism is a natural duty.