THE WEIRDEST PEOPLE IN THE WORLD
How the West Became Psychologically Peculiar and Particularly Prosperous
By Joseph Henrich

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.

These differences, and more, are manifest in surveys of attitudes and many other data sources, and more impressively in hundreds of psychological experiments, but the line between WEIRD and not WEIRD, like all lines in evolution, is not bright. There are all manner of hybrids, intermediates and unclassifiable variations, but there are also forces that have tended to sort today’s people into these two kinds, genetically indistinguishable but profoundly different psychologically.

WEIRD folk are the more recent development, growing out of the innovation of agriculture about 10,000 years ago, the birth of states and organized religions about 3,000 years ago, then becoming “proto-WEIRD” over the last 1,500 years (thanks to the prohibition on marrying one’s cousin), culminating in the biologically sudden arrival of science, industry and the “modern” world during the last 500 years or so. WEIRD minds evolved by natural selection, but not by genetic selection; they evolved by the natural selection of cultural practices and other culturally transmitted items.

Henrich is an anthropologist at Harvard. He and his colleagues first described the WEIRD mind in a critique of all the work in human psychology (and the social sciences more generally) built on experimental subjects almost exclusively composed of undergraduates — or the children of academics and others who live near universities. The results obtained drawing on this conveniently available set of “normal” people were assumed by almost all researchers to be universal features of human nature, the human brain, the human emotional system. But when attempts were made to replicate the experiments with people in other countries, not just illiterate hunter-gatherers and subsistence farmers but the elites in Asian countries, for instance, it was shown in many cases that the subject pool of the original work had been hugely biased from the outset.

One of the first lessons that must be learned from this important book is that the WEIRD mind is real; all future investigation of “human nature” must be complicated by casting a wider net for subjects, and we must stop assuming that our ways are “universal.” Offhand, I cannot think of many researchers who haven’t tacitly adopted some dubious universalist assumptions. I certainly have. We will all have to change our perspective.

Many of the WEIRD ways of thinking, Henrich shows, are the result of cultural differences, not genetic differences. And that is another lesson that the book drives home: Biology is not just genes. Language, for instance, was not invented; it evolved. So did religion, music, art, ways of hunting and farming, norms of behavior and attitudes about kinship that leave measurable differences on our psychology and even on our brains.

To point to just one striking example: Normal, meaning non-WEIRD, people use left and right hemispheres of their brains about equally for facial recognition, but we WEIRD people have co-opted left-hemisphere regions for language tasks, and are significantly worse at recognizing faces than the normal population. Until recently few researchers imagined that growing up in a particular culture could have such an effect on functional neuroanatomy.

The centerpiece of Henrich’s theory is the role played by what he calls the Roman Catholic Church’s Marriage and Family Program, featuring prohibitions of polygamy, divorce, marriage to first cousins, and even to such distant blood relatives as sixth cousins, while discouraging adoption and arranged marriages and the strict norms of inheritance that prevailed in extended families, clans and tribes. “The accidental genius of Western Christianity was in ‘figuring out’ how to dismantle kin-based institutions while at the same time catalyzing its own spread.”

The genius was accidental, according to Henrich, because the church authorities who laid down the laws had little or no insight into what they were setting in motion, aside from noticing that by weakening the traditional bonds of kinship, the church got rich fast. One of Henrich’s goals is to devalue the residual traces of “Great Man” history, so he would be reluctant to rely on any ancient documents that came to light recounting the “real” reasons for the church’s embattled stand on these issues. As a good evolutionist, he can say, “The church was just the ‘lucky one’ that bumbled across an effective recombination of supernatural beliefs and practices.” But as for why the church fathers enforced these prohibitions so tenaciously against resistance over the centuries, this is still a bit of a mystery.

Around the world today there is still huge variation in the societies where cousin marriages are permitted and even encouraged, and societies in which it is close to forbidden. There are good reasons for supposing that our early hominin ancestors were organized for tens of thousands of years by tight kinship relations, which still flourish today in most societies. So what happened in Europe starting in the middle of the first millennium was a major development, largely restricted to or at least concentrated in certain cultures where positive feedback turned small tendencies into large differences that then turned further differences into the birth of WEIRD culture and WEIRD minds.

This is an extraordinarily ambitious book, along the lines of Jared Diamond’s “Guns, Germs and Steel,” which gets a brief and respectful mention, but going much farther, and bolstering the argument at every point with evidence gathered by Henrich’s “lab,” with dozens of collaborators, and wielding data points from world history, anthropology, economics, game theory, psychology and biology, all knit together with “statistical razzle-dazzle” when everyday statistics is unable to distinguish signal from noise. The endnotes and bibliography take up over 150 pages and include a fascinating range of discussions.

The book bristles with apologies for not having gathered quite enough data on various questions and hence settling for somewhat tentative hypotheses, warnings about not confusing correlation with causation, and occasionally tart admonitions, like “Some critics will ignore these points and pretend I never made them.” One can often discover a lot about an organism’s predators by seeing what defenses it has put in place. Henrich is expecting a battle, and well he might.

There has long been a hostile divide between physical anthropologists, who have labs and study hominid bone fossils, for instance, and cultural anthropologists who spend a few seasons in the jungle learning the language and ways of a hunter-gatherer tribe, for instance, or today, spend a few seasons studying the folkways of stock traders or baristas. Henrich is a cultural anthropologist but he wants to do it right, with controls, experiments, statistics and factual claims that can be shown to be right or wrong. In 1960 the field of cliometrics was born, history done with large data sets and statistics, and Henrich wants to show just how far this approach can be pushed. Traditional historians and the more informal cultural anthropologists will see themselves being confronted with a methodology few of them use and challenged to defend their impressionistic hypotheses against his lab-based results.

The virtues of having a theory to guide investigation are vividly displayed. Who would have thought to ask if the prevalence of rice paddies in different small regions of China played the same causal role that distance from a monastery played in Europe? Or why blood donations are strikingly lower in southern Italy than in northern Italy today. Or how testosterone levels differ dramatically during the life histories of men from WEIRD societies and men from kin-intensive societies. Henrich has found dozens of ways of testing aspects of his theory, and it stands up remarkably well, yielding many surprising predictions that find multiple sources of confirmation, but that is not enough.

He admits that his research overlooks (so far) large portions of the world’s population, and when he counts societies instead of people to get his measure of how abnormal we WEIRD people are, one can wonder what percentage of the world’s population is WEIRD today. The normals are turning into WEIRDs in droves, and almost nobody is going in the other direction, so if we WEIRDs aren’t the majority yet, we soon will be, since societies with high Kinship Intensity Indexes evolve or go extinct almost as fast as the thousands of languages still in existence.

A good statistician (which I am not) should scrutinize the many uses of statistics made by Henrich and his team. They are probably all sound but he would want them examined rigorously by the experts. That’s science. Experts who don’t have the technical tools — historians and anthropologists especially — have an important role to play as well; they should scour the book for any instances of Occam’s broom (with which one sweeps inconvenient facts under the rug). This can be an innocent move, since Henrich himself, in spite of the astonishing breadth of his scholarship, is not expert in all of these areas and may simply be ignorant of important but little-known exceptions to his generalizations. His highly detailed and confident relaying of historical and anthropological facts impresses me, but what do I know? You can’t notice what isn’t mentioned unless you’re an expert.

This book calls out for respectful but ruthless vetting on all counts, and what it doesn’t need, and shouldn’t provoke, is ideological condemnations or quotations of brilliant passages by revered authorities. Are historians, economists and anthropologists up to the task? It will be fascinating to see.