The WEIRDest People in the World: How the West Became Psychologically Peculiar and Particularly Prosperous

Monogamous marriage changes men psychologically, even hormonally, and has downstream effects on societies. Although this form of marriage is neither “natural” nor “normal” for human societies—and runs directly counter to the strong inclinations of high-status or elite men—it nevertheless can give religious groups and societies an advantage in intergroup competition. By suppressing male-male competition and altering family structure, monogamous marriage shifts men’s psychology in ways that tend to reduce crime, violence, and zero-sum thinking while promoting broader trust, long-term investments, and steady economic accumulation

Perhaps you are WEIRD, raised in a society that is Western, Educated, Industrialized, Rich, and Democratic. If so, you’re likely rather psychologically peculiar.

Each century of Western Church exposure cuts the rate of cousin marriage by nearly 60 percent.

The assembly of the innovation engine that propelled the Industrial Revolution becomes easier to see once we recognize how the psychology of premodern Europeans had been quietly evolving in the background for at least eight centuries. Of course, there are many economic and geographic factors that matter too, but if there’s a secret ingredient in the recipe for Europe’s collective brain, it’s the psychological package of individualism, analytic orientation, positive-sum thinking, and impersonal prosociality that had been simmering for centuries.

the particular idea of endowing individuals with “rights” and then designing laws based on those rights only makes sense in a world of analytical thinkers who conceive of people as primarily independent agents and look to solve problems by assigning properties, dispositions, and essences to objects and persons. If this approach to law sounds like common sense, you are indeed WEIRD.

When the Church banned marriage to in-laws, classifying them as “siblings” to make such unions incestuous, the bonds between kin-groups were broken by the death of either spouse, since the surviving wife or husband was prohibited from incestuously marrying any of their affines.

Intentions and beliefs, or what’s in a person’s heart, are most important.

The most prominent approach argues that humans have five largely independent dimensions of personality: (1) openness to experience (“adventurousness”), (2) conscientiousness (“self-discipline”), (3) extraversion (vs. introversion), (4) agreeableness (“cooperativeness” or “compassion”), and (5) neuroticism (“emotional instability”). These have often been interpreted as capturing the innate structure of human personality. Psychologists call these personality dimensions the “BIG-5,” but I’ll call them the WEIRD-5.

The radial patterning of Protestantism allows us to use a county’s proximity to Wittenberg to isolate—in a statistical sense—that part of the variation in Protestantism that we know is due to a county’s proximity to Wittenberg and not to greater literacy or other factors. In a sense, we can think of this as an experiment in which different counties were experimentally assigned different dosages of Protestantism to test for its effects. Distance from Wittenberg allows us to figure out how big that experimental dosage was. Then, we can see if this “assigned” dosage of Protestantism is still associated with greater literacy and more schools. If it is, we can infer from this natural experiment that Protestantism did indeed cause greater literacy.16 The results of this statistical razzle-dazzle are striking. Not only do Prussian counties closer to Wittenberg have higher shares of Protestants, but those additional Protestants are associated with greater literacy and more schools. This indicates that the wave of Protestantism created by the Reformation raised literacy and schooling rates in its wake. Despite Prussia’s having a high average literacy rate in 1871, counties made up entirely of Protestants had literacy rates nearly 20 percentile points higher than those that were all Catholic.18 FIGURE P.2. The percentage of Protestants in Prussian counties in 1871.17 The map highlights some German cities, including the epicenter of the Reformation, Wittenberg, and Mainz, the charter town where Johannes Gutenberg produced his eponymous printing press. These same patterns can be spotted elsewhere in 19th-century Europe—and today—in missionized regions around the globe. In 19th-century Switzerland, other aftershocks of the Reformation have been detected in a battery of cognitive tests given to Swiss army recruits. Young men from all-Protestant districts were not only 11 percentile points more likely to be “high performers” on reading tests compared to those from all-Catholic districts, but this advantage bled over into their scores in math, history, and writing. These relationships hold even when a district’s population density, fertility, and economic complexity are kept constant. As in Prussia, the closer a community was to one of the two epicenters of the Swiss Reformation—Zurich or Geneva—the more Protestants it had in the 19th century. Notably, proximity to other Swiss cities, such as Bern and Basel, doesn’t reveal this relationship. As is the case in Prussia, this setup allows us to finger Protestantism as driving the spread of greater literacy as well as the smaller improvements in writing and math abilities.

Having completed their Penance, Catholics are forgiven and can merge back on the fast track to heaven (or so they think). For Protestants, in contrast, there’s no straightforward route from sin to confession, penance, and forgiveness. Instead, doing something sinful—which includes things like thinking about forbidden sex—seems to evoke a compensatory response that involves doing more “good stuff.” Since many Protestants see their occupations as divine callings, or simply see productive work as purifying, their compensatory response is often to work harder.

In the urban communities of medieval Europe, the success of merchants, traders, and artisans depended—in part—on their reputation for impartial honesty and fairness, and on their industriousness, patience, precision, and punctuality. These reputational systems favored the cultivation of the relevant social standards, attentional biases, and motivations that apply to impersonal transactions. I suspect these changes in both people’s psychology and society’s reputational standards are an important part of the rapidly rising availability of credit, which helped fuel the commercial revolution.57

Believing in just heaven (but not hell) doesn’t increase growth; neither does believing in God once the influence of contingent afterlife beliefs have been accounted for. Since many people seem keen to believe in heaven, it’s really adding hell that does the economic work (believing only in hell is rare).42

To tighten the synergy between beliefs and rituals, the gods evolved desires and commandments that motivated people to participate in rituals, stick to fasts, maintain taboos, and make credible vows. The new doctrinal rituals more effectively transmit the faith, and, in turn, the new faith motivates the reinforcing rituals through the threat of supernatural punishment. This interlocking cycle helps perpetuate the faith from one generation to the next.50

More individualistic countries are also richer, more innovative, and more economically productive.

you can capture much of human morality along five major dimensions, or what they call “foundations.” The five foundations involve people’s concerns about (1) fairness (justice, equity), (2) harm/care (not harming others), (3) in-group loyalty (helping one’s own), (4) respect for authority, and (5) sanctity/purity (adhering to rituals, cleanliness, taboos, etc.)

The later gods of ancient Greece and Rome, contrary to the popular impressions created by later Christian spin doctors, were the upholders of public morality and would bestow divine favor on individuals, families, and cities. Though subject to the same moral shortcomings as their Mesopotamian forebearers, the Greek gods legitimized rulers, inspired armies, and policed corrupt practices.

In 315 CE, for example, the Synod of Neocaesarea (now Niksar, Turkey) banned men from marrying the wife of a dead brother—no levirate marriage. A decade later, in 325, the Council of Nicaea prohibited men from marrying the sister of a dead wife—no sororate marriage—and from marrying Jews, pagans, and heretics.

monogamous marriage suppresses men’s competitiveness, risk-taking, and revenge-seeking while increasing their impersonal trust and self-regulation.31

People from more individualistic countries, for example, possess weaker family ties and show less nepotism, meaning that company bosses, managers, and politicians are less likely to hire or promote relatives. Further, more individualistic countries are less inclined to distinguish in-groups from out-groups, more willing to help immigrants, and less firmly wedded to tradition and custom.

In places where people would help their friends by testifying, they also report a willingness to (1) give their friends insider company information, (2) lie about a friend’s medical exam to lower his insurance rates, and (3) exaggerate the quality of the cuisine at a friend’s restaurant in a published review. In these places, the “right” answer is to help your friend. People aren’t trying to distinguish themselves as relentlessly honest individuals governed by impartial principles. Instead, they are deeply loyal to their friends and want to cement enduring relationships, even if this involves illegal actions. In these places, being nepotistic is often the morally correct thing to do. By contrast, in WEIRD societies, many people think badly of those who weight family and friends over impartial principles and anonymous criteria like qualifications, merit, or effort.

greater market integration can cause a psychological shift toward greater impersonal prosociality (arrow A). Greater impersonal prosociality (measured as conditional cooperation) fosters the formation of vol- untary organizations (arrow B) that develop formal institutions, which often involve explicit rules, written agreements, and mutual monitoring (arrow C). Both these formal institutions (arrow D) and people’s motivations for impersonal prosociality (arrow E) contribute to provisioning public goods,

Friar Toribio’s writings show something else central to our story: Christian missionaries are relentless. Whether in Anglo-Saxon Kent around 600 CE, the Aztec Empire in 1530, or the Peruvian Amazon in 1995, they never stop and never give up; when proselytizing preachers fail or get themselves killed, they are soon replaced by fresh recruits who continue to push the Church’s package of supernatural beliefs, rituals, and family practices.

This is interesting because it means that, although the Church’s policies also built on Mosaic law, the MFP overruled implicit biblical endorsements of levirate, cousin, and polygynous marriage.36

In this world, the Church maneuvered to benefit itself by promoting individual ownership and inheritance by personal testaments (wills).

When the Reformation reached Scotland in 1560, it was founded on the central principle of a free public education for the poor. The world’s first local school tax was established there in 1633 and strengthened in 1646. This early experiment in universal education soon produced a stunning array of intellectual luminaries, from David Hume to Adam Smith, and probably midwifed the Scottish Enlightenment. The intellectual dominance of this tiny region in the 18th century inspired Voltaire to write, “We look to Scotland for all our ideas of civilization.”24

To see the power of kinship, consider that pushing down cousin marriage prevalence from 40 percent to zero is associated with an increase of 40 points on individualism (going from India to the United States, say). Notice that in Figure 6.4A, countries high on KII are always low on individualism, but those low on KII span the full range of individualism. Many of the countries that have both low KII and low individualism are in Latin America. This suggests that breaking down intensive kinship opens the door to developing the full individualism complex, but that other institutions—and perhaps other factors—are necessary to really drive up individualism.

Given the roughness of our data, the strength of the relationships between so many aspects of psychology and both kinship intensity and MFP dosages is striking.

Psychologists have shown, for example, that priming people with settling down in a city vs. visiting it briefly immediately evokes different preferences: settling down causes people to facultatively value loyal friends, while shorter visits spark more egalitarian motivations. Meanwhile, research also points to developmental effects: young adults who moved geographically as children make less of a distinction between friends and strangers. Overall, greater residential mobility and more relational freedom (i.e., fewer constraints on new relationships) lead individuals to form larger social networks, favor new experiences, prefer novelty, and perhaps even think more creatively (see Appendix C).23

Overall, greater residential mobility and more relational freedom (i.e., fewer constraints on new relationships) lead individuals to form larger social networks, favor new experiences, prefer novelty, and perhaps even think more creatively (see Appendix C).23

Impersonal Prosociality (and Related Worldviews)