Could a marriage policy first pursued by the Catholic Church a millennium and a half ago explain what made the industrialized world so powerful—and so peculiar?
round 597 a.d., Pope Gregory I dispatched an expedition to England to convert the Anglo-Saxon king of Kent and his subjects. The leader of the mission, a monk named Augustine, had orders to shoehorn the new Christians into Church-sanctioned marriages. That meant quashing pagan practices such as polygamy, arranged marriages (Christian matrimony was notionally consensual, hence the formula “I do”), and above all, marriages between relatives, which the Church was redefining as incest. Augustine wasn’t sure who counted as a relative, so he wrote to Rome for clarification. A second cousin? A third cousin? Could a man marry his widowed stepmother?
He could not. Pope Gregory wrote back to rule out stepmothers and other close kin not related by blood—another example was brothers’ widows. He was lax about second and third cousins; only the children of aunts and uncles were off-limits. By the 11th century, however, you couldn’t get engaged until you’d counted back seven generations, lest you marry a sixth cousin. The taboo against consanguineous family had expanded to include “spiritual kin,” who were, mostly, godparents. (It went without saying that you had to marry a Christian.) Pope Gregory and Augustine’s letters document a moment in a prolonged process—begun in the fourth century—in which the Church clamped down, and intermittently loosened up, on who could marry whom. Not until 1983 did Pope John Paul II allow second cousins to wed.
You might assume that this curious story of how the Church narrowed the criteria for marriageability would be relegated to a footnote—a very interesting footnote, to be sure—but Joseph Henrich puts the tale at the center of his ambitious theory-of-everything book, The WEIRDest People in the World: How the West Became Psychologically Peculiar and Particularly Prosperous. Consider this the latest addition to the Big History category, popularized by best sellers such as Jared Diamond’s Guns, Germs, and Steel: The Fates of Human Societies and Yuval Noah Harari’s Sapiens: A Brief History of Humankind. The outstanding feature of the genre is that it wrangles all of human existence into a volume or two, starting with the first hominids to rise up on their hind legs and concluding with us, cyborg-ish occupants of a networked globe. Big History asks Big Questions and offers quasi-monocausal answers. Why and how did humans conquer the world? Harari asks. Cooperation. What explains differences and inequalities among civilizations? Diamond asks. Environment, which is to say, geography, climate, flora and fauna. Henrich also wants to explain variation among societies, in particular to account for the Western, prosperous kind.
Henrich’s first cause is culture, a word meant to be taken very broadly rather than as referring to, say, opera. Henrich, who directs Harvard’s Department of Human Evolutionary Biology, is a cultural evolutionary theorist, which means that he gives cultural inheritance the same weight that traditional biologists give to genetic inheritance. Parents bequeath their DNA to their offspring, but they—along with other influential role models—also transmit skills, knowledge, values, tools, habits. Our genius as a species is that we learn and accumulate culture over time. Genes alone don’t determine whether a group survives or disappears. So do practices and beliefs. Human beings are not “the genetically evolved hardware of a computational machine,” he writes. They are conduits of the spirit, habits, and psychological patterns of their civilization, “the ghosts of past institutions.”
One culture, however, is different from the others, and that’s modern WEIRD (“Western, educated, industrialized, rich, democratic”) culture. Dealing in the sweeping statistical generalizations that are the stock-in-trade of cultural evolutionary theorists—these are folks who say “people” but mean “populations”—Henrich draws the contrasts this way: Westerners are hyper-individualistic and hyper-mobile, whereas just about everyone else in the world was and still is enmeshed in family and more likely to stay put. Westerners obsess more about personal accomplishments and success than about meeting family obligations (which is not to say that other cultures don’t prize accomplishment, just that it comes with the package of family obligations). Westerners identify more as members of voluntary social groups—dentists, artists, Republicans, Democrats, supporters of a Green Party—than of extended clans.
In short, Henrich says, they’re weird. They are also, in the last four words of his acronym, “educated, industrialized, rich, democratic.” And that brings us to Henrich’s Big Question, which is really two linked questions. Starting around 1500 or so, the West became unusually dominant, because it advanced unusually quickly. What explains its extraordinary intellectual, technological, and political progress over the past five centuries? And how did its rise engender the peculiarity of the Western character?
Given the nature of the project, it may be a surprise that Henrich aspires to preach humility, not pride. WEIRD people have a bad habit of universalizing from their own particularities. They think everyone thinks the way they do, and some of them (not all, of course) reinforce that assumption by studying themselves. In the run-up to writing the book, Henrich and two colleagues did a literature review of experimental psychology and found that 96 percent of subjects enlisted in the research came from northern Europe, North America, or Australia. About 70 percent of those were American undergraduates. Blinded by this kind of myopia, many Westerners assume that what’s good or bad for them is good or bad for everyone else.
Henrich’s ambition is tricky: to account for Western distinctiveness while undercutting Western arrogance. He rests his grand theory of cultural difference on an inescapable fact of the human condition: kinship, one of our species’ “oldest and most fundamental institutions.” Though based on primal instincts— pair-bonding, kin altruism—kinship is a social construct, shaped by rules that dictate whom people can marry, how many spouses they can have, whether they define relatedness narrowly or broadly. Throughout most of human history, certain conditions prevailed: Marriage was generally family-adjacent—Henrich’s term is “cousin marriage”—which thickened the bonds among kin. Unilateral lineage (usually through the father) also solidified clans, facilitating the accumulation and intergenerational transfer of property. Higher-order institutions—governments and armies as well as religions—evolved from kin-based institutions. As families scaled up into tribes, chiefdoms, and kingdoms, they didn’t break from the past; they layered new, more complex societies on top of older forms of relatedness, marriage, and lineage. Long story short, in Henrich’s view, the distinctive flavor of each culture can be traced back to its earlier kinship institutions.
The Catholic Church changed all that. As of late antiquity, Europeans still lived in tribes, like most of the rest of the world. But the Church dismantled these kin-based societies with what Henrich calls its “Marriage and Family Program,” or MFP. The MFP was really an anti-marriage and anti-family program. Why did the Church adopt it? From a cultural evolutionary point of view, the why doesn’t matter. In a footnote, Henrich skates lightly over debates about the motivations of Church leaders. But his bottom line is that the “MFP evolved and spread because it ‘worked.’ ” (Henrich’s indifference to individual and institutional intentions is guaranteed to drive historians nuts.)
Forced to find Christian partners, Christians left their communities. Christianity’s insistence on monogamy broke extended households into nuclear families. The Church uprooted horizontal, relational identity, replacing it with a vertical identity oriented toward the institution itself. The Church was stern about its marital policies. Violations were punished by withholding Communion, excommunicating, and denying inheritances to offspring who could now be deemed “illegitimate.” Formerly, property almost always went to family members. The idea now took hold that it could go elsewhere. At the same time, the Church urged the wealthy to ensure their place in heaven by bequeathing their money to the poor—that is, to the Church, benefactor to the needy. In so doing, “the Church’s MFP was both taking out its main rival for people’s loyalty and creating a revenue stream,” Henrich writes. The Church, thus enriched, spread across the globe.
Loosened from their roots, people gathered in cities. There they developed “impersonal prosociality”—that is, they bonded with other city folk. They wrote city charters and formed professional guilds. Sometimes they elected leaders, the first inklings of representative democracy. Merchants had to learn to trade with strangers. Success in this new kind of commerce required a good reputation, which entailed new norms, such as impartiality. You couldn’t cheat a stranger and favor relatives and expect to make a go of it.
By the time Protestantism came along, people had already internalized an individualist worldview. Henrich calls Protestantism “the WEIRDest religion,” and says it gave a “booster shot” to the process set in motion by the Catholic Church. Integral to the Reformation was the idea that faith entailed personal struggle rather than adherence to dogma. Vernacular translations of the Bible allowed people to interpret scripture more idiosyncratically. The mandate to read the Bible democratized literacy and education. After that came the inquiry into God-given natural (individual) rights and constitutional democracies. The effort to uncover the laws of political organization spurred interest in the laws of nature—in other words, science. The scientific method codified epistemic norms that broke the world down into categories and valorized abstract principles. All of these psychosocial changes fueled unprecedented innovation, the Industrial Revolution, and economic growth.
If Henrich’s history of Christianity and the West feels rushed and at times derivative—he acknowledges his debt to Max Weber—that’s because he’s in a hurry to explain Western psychology. The bulk of the book consists of data from many disciplines other than history, including anthropology and cross-cultural psychology, to which he and colleagues have made significant contributions. Their Kinship Intensity Index, for instance, helps them posit a dose-response relationship between the length of time a population was exposed to the Catholic Church’s Marriage and Family Program and the WEIRDness of its character. Henrich gets amusingly granular in his statistics here. “Each century of Western church exposure cuts the rate of cousin marriage by nearly 60 percent,” he writes. A millennium of the MFP also makes a person less likely to lie in court for a friend—30 percentile points less likely. Henrich anticipates a quibble about what he calls “the Italian enigma”: Why, if Italy has been Catholic for so long, did northern Italy become a prosperous banking center, while southern Italy stayed poor and was plagued by mafiosi? The answer, Henrich declares, is that southern Italy was never conquered by the Church-backed Carolingian empire. Sicily remained under Muslim rule and much of the rest of the south was controlled by the Orthodox Church until the papal hierarchy finally assimilated them both in the 11th century. This is why, according to Henrich, cousin marriage in the boot of Italy and Sicily is 10 times higher than in the north, and in most provinces in Sicily, hardly anyone donates blood (a measure of willingness to help strangers), while some northern provinces receive 105 donations of 16-ounce bags per 1,000 people per year.
To go further afield: While Europe was first compiling its legal codes, China was punishing crimes committed against relatives more harshly than those against nonrelatives; especially severe penalties were reserved for crimes against one’s elders. As recently as the early 20th century, Chinese fathers could murder sons and get off with a warning; punishments for patricide, by contrast, were strict. Asymmetries like these, Henrich writes, “can be justified on Confucian principles and by appealing to a deep respect for elders,” even if the WEIRD mind finds them disturbing.
Henrich’s most consequential—and startling—claim is that WEIRD and non-WEIRD people possess opposing cognitive styles. They think differently. Standing apart from the community, primed to break wholes into parts and classify them, Westerners are more analytical. People from kinship-intensive cultures, by comparison, tend to think more holistically. They focus on relationships rather than categories. Henrich defends this sweeping thesis with several studies, including a test known as the Triad Task. Subjects are shown three images—say, a rabbit, a carrot, and a cat. The goal is to match a “target object”—the rabbit—with a second object. A person who matches the rabbit with the cat classifies: The rabbit and the cat are animals. A person who matches the rabbit with the carrot looks for relationships between the objects: The rabbit eats the carrot.
You have to wonder whether the Triad Task really reflects fundamentally different cognitive bents or differences in subjects’ personal experience. Henrich cites a Mapuche, an indigenous Chilean, who matched a dog with a pig, an “analytic” choice, except the man then explained that he’d done so for a “holistic” reason: because the dog guards the pig. “This makes perfect sense,” Henrich muses. “Most farmers rely on dogs to protect their homes and livestock from rustlers.” Exactly! A Western undergraduate, probably not having grown up with dogs protecting her pigs, sees dogs and pigs as just animals.
Henrich is more persuasive when applying his theory of cumulative culture to the evolution of ideas. Democracy, the rule of law, and human rights “didn’t start with fancy intellectuals, philosophers, or theologians,” Henrich writes. “Instead, the ideas formed slowly, piece by piece, as regular Joes with more individualistic psychologies—be they monks, merchants, or artisans—began to form competing voluntary associations” and learned how to govern them. Toppling the accomplishments of Western civilization off their great-man platforms, he erases their claim to be monuments to rationality: Everything we think of as a cause of culture is really an effect of culture, including us.
Henrich’s macro-cultural relativism has its virtues. It widens our field of vision as we assess Western values—such as objectivity, free speech, democracy, and the scientific method—that have come under sharp attack. The big-picture approach soars above the reigning paradigms in the study of European history, which have a way of collapsing into narratives of villains and victims. (Henrich forestalls the obvious objections with this jarringly offhand remark: “I’m not highlighting the very real and pervasive horrors of slavery, racism, plunder, and genocide. There are plenty of books on those subjects.”) He refutes genetic theories of European superiority and makes a good case against economic determinism. His quarry are the “enlightened” Westerners—would-be democratizers, globalizers, well-intended purveyors of humanitarian aid—who impose impersonal institutions and abstract political principles on societies rooted in familial networks, and don’t seem to notice the trouble that follows.
It should be said, though, that Henrich can make a person feel pretty helpless, with his talk of populations being swept along by cultural riptides that move “outside conscious awareness.” Cultural evolutionary determinism may turn out to be as disempowering as all the other determinisms; a WEIRD reader may feel trapped inside her own prejudices. But perhaps some comfort lies in Henrich’s dazzling if not consistently plausible supply of unintended consequences. Who would have imagined that the Catholic Church would have spawned so many self-involved nonconformists? What else might our curious history yield? Henrich’s social-scientist stance of neutrality may also relieve Westerners of some (one hopes not all) of their burden of guilt. “By highlighting the peculiarities of WEIRD people, I’m not denigrating these populations or any others,” he writes. WEIRDos aren’t all bad; they’re provincial. Henrich offers a capacious new perspective that could facilitate the necessary work of sorting out what’s irredeemable and what’s invaluable in the singular, impressive, and wildly problematic legacy of Western domination.