Populations that are Western, Educated, Industrialized, Rich and Democratic (WEIRD) are peculiar due to the medieval church's set of rules governing descent, marriage, residence, etc., leading to the predominance of nuclear families and impersonal institutions

Schulz, Jonathan, Duman Barahmi-Rad, Jonathan Beauchamp, and Joseph Henrich. 2018. “The Origins of WEIRD Psychology.” PsyArXiv. June 22. doi:10.17605/OSF.IO/D6QHU. Final version: The Church, intensive kinship, and global psychological variation, Science, Nov 2019, https://science.sciencemag.org/content/366/6466/eaau5141

Abstract: Recent research not only confirms the existence of substantial psychological variation around the globe but also highlights the peculiarity of populations that are Western, Educated, Industrialized, Rich and Democratic (WEIRD). We propose that much of this variation arose as people psychologically adapted to differing kin-based institutions—the set of social norms governing descent, marriage, residence and related domains. We further propose that part of the variation in these institutions arose historically from the Catholic Church’s marriage and family policies, which contributed to the dissolution of Europe’s traditional kin-based institutions, leading eventually to the predominance of nuclear families and impersonal institutions. By combining data on 20 psychological outcomes with historical measures of both kinship and Church exposure, we find support for these ideas in a comprehensive array of analyses across countries, among European regions and between individuals with different cultural backgrounds.

In the final version, link to full text above:

Structured Abstract

INTRODUCTION
A growing body of research suggests that populations around the globe vary substantially along several important psychological dimensions and that populations characterized as Western, Educated, Industrialized, Rich, and Democratic (WEIRD) are particularly unusual. People from these societies tend to be more individualistic, independent, and impersonally prosocial (e.g., trusting of strangers) while revealing less conformity and in-group loyalty. Although these patterns are now well documented, few efforts have sought to explain them. Here, we propose that the Western Church (i.e., the branch of Christianity that evolved into the Roman Catholic Church) transformed European kinship structures during the Middle Ages and that this transformation was a key factor behind a shift towards a WEIRDer psychology.

RATIONALE
Our approach integrates three insights. First, anthropological evidence suggests that diverse kin-based institutions—our species’s most fundamental institutions—have been the primary structure for organizing social life in most societies around the world and back into history. With the origins of agriculture, cultural evolution increasingly favored intensive kinship norms related to cousin marriage, clans, and co-residence that fostered social tightness, interdependence, and in-group cooperation. Second, psychological research reveals that people’s motivations, emotions, and perceptions are shaped by the social norms they encounter while growing up. Within intensive kin-based institutions, people’s psychological processes adapt to the collectivistic demands of their dense social networks. Intensive kinship norms reward greater conformity, obedience, and in-group loyalty while discouraging individualism, independence, and impersonal motivations for fairness and cooperation. Third, historical research suggests that the Western Church systematically undermined Europe’s intensive kin-based institutions during the Middle Ages (for example, by banning cousin marriage). The Church’s family policies meant that by 1500 CE, and likely centuries earlier in some regions, Europe lacked strong kin-based institutions and was instead dominated by relatively independent and isolated nuclear or stem families.

Our theory predicts that populations with (i) a longer historical exposure to the medieval Western Church or less intensive kin-based institutions will be more individualistic, less conforming, and more impersonally prosocial today; and (ii) longer historical exposure to the Western Church will be associated with less-intensive kin-based institutions.

RESULTS
We test these predictions at three levels. Globally, we show that countries with longer historical exposure to the medieval Western Church or less intensive kinship (e.g., lower rates of cousin marriage) are more individualistic and independent, less conforming and obedient, and more inclined toward trust and cooperation with strangers (see figure). Focusing on Europe, where we compare regions within countries, we show that longer exposure to the Western Church is associated with less intensive kinship, greater individualism, less conformity, and more fairness and trust toward strangers. Finally, comparing only the adult children of immigrants in European countries, we show that those whose parents come from countries or ethnic groups that historically experienced more centuries under the Western Church or had less intensive kinship tend to be more individualistic, less conforming, and more inclined toward fairness and trust with strangers.

CONCLUSION
This research suggests that contemporary psychological patterns, ranging from individualism and trust to conformity and analytical thinking, have been influenced by deep cultural evolutionary processes, including the Church’s peculiar incest taboos, family policies, and enduring kin-based institutions.

As predicted by our theory, countries with a longer exposure to the medieval Western Church have lower rates of cousin marriage (A); countries with lower rates of cousin marriage have a more individualistic and impersonally prosocial psychology (B); and countries with a longer exposure to the medieval Western Church have a more individualistic and impersonally prosocial psychology (C). Blue dots, green diamonds, and gray triangles denote countries primarily exposed to the Western Church, to the Eastern Church, and with no church exposure, respectively. ρˆ denotes Spearman correlation.


Abstract

Recent research not only confirms the existence of substantial psychological variation around the globe but also highlights the peculiarity of many Western populations. We propose that part of this variation can be traced back to the action and diffusion of the Western Church, the branch of Christianity that evolved into the Roman Catholic Church. Specifically, we propose that the Western Church’s transformation of European kinship, by promoting small, nuclear households, weak family ties, and residential mobility, fostered greater individualism, less conformity, and more impersonal prosociality. By combining data on 24 psychological outcomes with historical measures of both Church exposure and kinship, we find support for these ideas in a comprehensive array of analyses across countries, among European regions, and among individuals from different cultural backgrounds.

A growing body of research suggests that populations around the globe vary substantially along several important psychological dimensions and that people from societies characterized as Western, Educated, Industrialized, Rich, and Democratic (WEIRD) are particularly unusual (1–3). Often occupying the extremes of global distributions, Western Europeans and their cultural descendants in North America and Australia tend to be more individualistic, independent, analytically minded, and impersonally prosocial (e.g., trusting of strangers) while revealing less conformity, obedience, in-group loyalty, and nepotism (3–12). Although these patterns are now well documented, efforts to explain this variation from a cultural-evolutionary and historical perspective have just begun (12–16). In this study, we develop and test a cultural evolutionary theory that aims to explain a substantial portion of this psychological variation, both within and across nations.

Our approach begins by considering how religions have evolved in ways that shape people’s institutions, social practices, economic outcomes, and psychology (17–22). Research in this area has, for example, documented the effect of Christian missions on both formal schooling and economic prosperity in places as diverse as Africa, China, and South America (23–26). Here, highlighting a less conspicuous channel, we go deeper into history and test the theory that the Western Catholic Church, primarily through its influence on marriage and family structures during the Middle Ages, had an important impact on psychological variation. Not only does our approach contribute to explaining why European and European-descent societies so often occupy the tail ends of global psychological distributions, it also helps explain variation within Europe—among countries, across regions within countries, and among individuals in the same country and region but with different cultural backgrounds.

To develop these ideas, our theory integrates three insights, drawing principally on anthropology, psychology, and history (27). First, anthropological research suggests that kin-based institutions represent the most fundamental of human institutions and have long been the primary framework for organizing social life in most societies (28–31). These institutions are composed of culturally transmitted norms that influence a broad range of social relationships by endowing individuals with sets of obligations and privileges with respect to their communities (supplementary text, section S1). Many kinship systems, for example, extend our species’s innate aversion to inbreeding (incest) to create taboos on marriage to more distant relatives, usually including particular types of cousins (32). By shaping patterns of marriage, residence, relatedness, and alliance formation, these norms organize interpersonal interactions and configure social networks in ways that profoundly influence social incentives and behavior (27, 33–35).

Although all premodern societies are organized primarily by kin-based institutions, evidence suggests that the character of these diverse institutions has been substantially influenced by ecological, climatic, and geographic factors (28, 30, 33, 34, 36–38). For instance, among mobile hunter-gatherers, cultural evolution has responded to ecological risk by favoring “extensive” kin ties, which create sprawling relational networks that can be tapped when local disasters strike (30, 37, 39). However, with the emergence of food production roughly 12,000 years ago, cultural evolution increasingly favored “intensive” kin-based institutions that permitted communities to unify larger groups to defend territories and organize production (30, 40–43). By constructing denser, tighter, and more interdependent social networks, these kin-based institutions intensified in-group loyalty, conformity, obedience to elders, and solidarity. For example, instead of favoring marriages to distant kin, cultural evolution often favored some form of cousin marriage, which tightened existing bonds among families (28). Cultural evolution thus led to a diversity of intensive kin-based institutions, including clans and kindreds (28, 32, 44), which dramatically restructured people’s social environments (27, 45, 46).

Our second insight, drawing on psychology and neuroscience, recognizes how aspects of our cognition, emotions, perceptions, thinking styles, and motivations adapt—often over ontogeny—to the normative demands, reputational incentives, and values of the interdependent social networks threaded together by kin-based institutions (3, 13, 27, 47–52). In particular, within intensive kin-based institutions, people’s psychological processes adapt to the collectivistic demands and the dense social networks in which they are enmeshed (53, 54). These institutions, thus, incentivize the cultivation of greater conformity, obedience, nepotism, deference to elders, holistic-relational awareness, and in-group loyalty but discourage individualism, independence, and analytical thinking (55). Because the sociality of intensive kinship is based on interpersonal embeddedness, adapting to these institutions reduces people’s inclinations toward impartiality, universal (nonrelational) moral principles, and impersonal trust, fairness, and cooperation; these institutions instead foster a contextually sensitive morality rooted in in-group loyalty.

Finally, drawing on historical research, our third insight incorporates the role of religion and its influence on kin-based institutions (27). By the start of the Common Era (CE), universalizing religions with powerful moralizing gods (or cosmic forces), universal ethical codes, and contingent afterlife beliefs had emerged across the Old World. However, these competing religions varied greatly in how their religious beliefs and practices shaped kin-based institutions (20, 56). In Persia, for example, Zoroastrians glorified the marriage of close relatives, including siblings, and encouraged widespread cousin marriage. Later, Islam curbed polygynous marriage (limiting a man to no more than four wives) but also adopted inheritance customs that promoted a nearly unique form of cousin marriage in which a daughter marries her father’s brother’s son—patrilineal clan endogamy (57–59). Beginning in Late Antiquity, the branch of Christianity that eventually evolved into the Roman Catholic Church—hereafter, the Western Church or simply the Church—systematically undermined Europe’s intensive kin-based institutions through a combination of religious prohibitions and prescriptions (46, 59–62). Prior to the Church’s efforts, the kin-based institutions of most European populations looked much like other agricultural societies and included patrilineal clans, kindreds, cousin marriage, polygyny, ancestor worship, and corporate ownership (27, 59, 60, 63–73). Meanwhile, although the branch of Christianity based in Constantinople that eventually evolved into the Orthodox Church—the Eastern Church—did adopt some of the same prohibitions as the Western Church, it never endorsed the Western Church’s broad taboos on cousin marriage, was slow to adopt many policies, and was unenthusiastic about enforcement.

The Western Church’s policies, which we call the Marriage and Family Program (MFP) (27), began with targeted bans on certain marriage practices used to sustain alliances between families (e.g., levirate marriage); however, by the Early Middle Ages, the Church had become obsessed with incest and began to expand the circle of forbidden relatives, eventually including not only distant cousins but also step-relatives, in-laws, and spiritual kin. Early in the second millennium, the ban was stretched to encompass sixth cousins, including all affines. At the same time, the Church promoted marriage “by choice” (no arranged marriages) and often required newly married couples to set up independent households (neolocal residence). The Church also forced an end to many lineages by eliminating legal adoption, remarriage, and all forms of polygamous marriage, as well as concubinage, which meant that many lineages began literally dying out due to a lack of legitimate heirs. As a result of the MFP, by 1500 CE (and centuries earlier in some regions), much of Europe was characterized by a virtually unique configuration of weak (nonintensive) kinship marked by monogamous nuclear households, bilateral descent, late marriage, and neolocal residence (59–62, 64, 74, 75).

Our theory, by synthesizing these insights, predicts that populations with a longer exposure to the medieval Western Church or less-intensive kin-based institutions will be less conforming but more individualistic and impersonally prosocial. At the same time, longer exposure to the Western Church should be associated with less intensive kin-based institutions. Of course, our theory does not preclude the existence of other important contributors to psychological variation, such as influences from the Church via channels other than kin-based institutions.

We emphasize that, in the absence of a decisive natural experiment in history, it is difficult to establish unassailable causal links between the Church’s MFP, kin-based institutions, and psychology (supplementary text S3). Our empirical approach has been to select both our psychological outcomes and explanatory variables ex ante on the basis of our theoretical predictions and then to repeatedly test for the expected relationships at different levels of analysis while controlling for an extensive battery of individual, regional, and historical covariates.

Years of education significantly raises suicide mortality risk in the US after controlling for initial self-reported health; this is robust to regression specification, replication & the inclusion of covariates

The education–suicide mortality gradient. Adam Cook. Applied Economics Letters, https://doi.org/10.1080/13504851.2018.1489499

ABSTRACT: Using the fifth release of the National Longitudinal Mortality Survey, I examine the role of educational attainment and self-reported health on 6- and 11-year suicide mortality risk in the United States. I first replicate the original results reported by Hamermesh and Soss. . Then, augmenting the Hamermesh model with initial educational attainment and self-reported health status, I find that years of education significantly raises suicide mortality risk in the US after controlling for initial self-reported health. This result is robust to regression specification, replication and the inclusion of covariates.

KEYWORDS: Suicide, education, health, mortality, human capital
JEL CLASSIFICATION: I12, I21, C21

Humility does not necessarily lead to more pleasant or fulfilling experiences, but psychological well-being is conducive to cultivating humility

Concurrent and Temporal Relationships Between Humility and Emotional and Psychological Well-Being. Eddie M. W. Tong et al. Journal of Happiness Studies, https://link.springer.com/article/10.1007/s10902-018-0002-3

Abstract: The present research is a preliminary investigation of the concurrent and temporal relationships between humility and two forms of well-being: emotional and psychological well-being. Humility, emotional well-being and psychological well-being were measured twice 6 weeks apart. Humility correlated positively with psychological well-being at both time-points, but was positively related to emotional well-being at only one time-point. In addition, we used structural equation modeling to perform cross-lagged panel analyses, and found that psychological well-being predicted an increase in humility over time, but humility did not predict changes in psychological well-being over time. In addition, there were no cross-lagged associations between emotional well-being and humility. The results suggest that humility does not necessarily lead to more pleasant or fulfilling experiences, but psychological well-being is conducive to cultivating humility.

Those who kill in dreams have been more violent in the past than those who do not have such dreams, scored higher in neuroticism & aggression, reported more creative achievements, & had more creative achievements than persons without those dreams

Mathes, J., Renvert, M., Eichhorn, C., von Martial, S. F., Gieselmann, A., & Pietrowsky, R. (2018). Offender-nightmares: Two pilot studies. Dreaming, 28(2), 140-149. http://dx.doi.org/10.1037/drm0000084

Abstract: Being the victim of an aggressor in nightmares is quite common for most persons, but there are also nightmares where the dream-self can become the offender. Two studies were conducted in two nonclinical samples of participants with frequent nightmares to investigate the so-called offender-nightmares. Study 1 served to assess the frequency of offender-nightmares in persons with frequent nightmares and the motives and actions in these dreams during a 28-day interval, whereas in Study 2, correlations to personality variables were investigated. The results indicate that the occurrence of offender-nightmares is not negligible; about 18% to 28% of the reported nightmares were classified as offender-nightmares. Most of the aggressive acts in these dreams were intentional, and killing a person was the most prominent offender’s act, with self-defense being the most common motive. Persons with offender-nightmares were also found to have been more violent in the past than persons without offender-nightmares and persons without nightmares. In addition, they scored higher in neuroticism and aggression, reported more creative achievements than persons without nightmares, and had more creative achievements than persons without offender-nightmares. The results suggest that offender-nightmares are rather common in people who frequently have nightmares and that these dreams are related to aggressiveness, creativity, and previous violent experiences.

Media use & gender relationship to nightmares

Gackenbach, J., Yu, Y., & Lee, M.-N. (2018). Media use and gender relationship to the nightmare protection hypothesis: A cross-cultural analysis. Dreaming, 28(2), 169-192. http://dx.doi.org/10.1037/drm0000066

Abstract: Chinese and Canadian people answered surveys in their native languages about their self-construal, media use history, and dreaming experiences. This included reporting a recent dream. The nightmare protection thesis was investigated. Sex was found to be modulated by culture in terms of the relationship between types of media used and negative dream content. This was particularly evident for men in Greater China versus Canada along the self-construal dimension of interdependence. As both cultures reported no difference in independent self-construal, it was argued that it is the role of interdependence that accounts for male differences between cultures. In addition, each media type highlighted a different cultural value. Specifically, gaming seemed more consistent with independence, whereas social media was consistent with interdependence. When dreams were considered, source data were important. Specifically, when respondents answered in terms of their impressions of their dream history, high social media users reported more bad dreams across sex and country. However, for the video game groups, a 3-way interaction emerged where country, sex, and gaming evidenced different patterns of bad dream scores. The other self-report dream measure was emotions felt during a recent dream, with general negative and positive emotions showing group differences. Finally, the judges’ coding of negative elements of dreams, threat and aggression, was most sensitive to social media effects. Across all the threat simulation interactions where country was an independent variable, the male sex in each country was most likely to show opposite results from the female sex.

Gender Equality and the Gender Gap in Mathematics: Improvement in gender equality does not reduce the gender gap

Gender Equality and the Gender Gap in Mathematics. Hung-Lin Tao & Christos Michalopoulos. Journal of Biosocial Science, Volume 50, Issue 2, March 2018 , pp. 227-243. https://doi.org/10.1017/S0021932017000141

Summary: A gender gap has been found in mathematics (boys outperform girls) that has prevailed across countries for many decades. Whether this gap results from nature or nurture has been hotly debated. Using the evidence of PISA 2003 and the gender equality index of 2003, some researchers have argued that an improvement in gender equality reduces the gender gap in mathematics. This study used five waves of country-level PISA data and, controlling for country fixed effects, found no evidence to support this argument. Furthermore, individual data for PISA 2012 and the multilevel data model were used. The conclusion drawn also does not support the argument. In fact, the relationship between gender equality and the gender gap in mathematics vanished after PISA 2003.

h/t: Rolf Degen https://twitter.com/DegenRolf

Monozygotic twin differences in school performance are stable and systematic: Non‐shared environmental factors affect school performance in systematic ways that have long‐term & generalist influence

Monozygotic twin differences in school performance are stable and systematic. Sophie von Stumm, Robert Plomin. Developmental Science, https://doi.org/10.1111/desc.12694

Abstract: School performance is one of the most stable and heritable psychological characteristics. Notwithstanding, monozygotic twins (MZ), who have identical genotypes, differ in school performance. These MZ differences result from non‐shared environments that do not contribute to the similarity within twin pairs. Because to date few non‐shared environmental factors have been reliably associated with MZ differences in school performance, they are thought to be idiosyncratic and due to chance, suggesting that the effect of non‐shared environments on MZ differences are age‐ and trait‐specific. In a sample of 2768 MZ twin pairs, we found first that MZ differences in school performance were moderately stable from age 12 through 16, with differences at the ages 12 and 14 accounting for 20% of the variance in MZ differences at age 16. Second, MZ differences in school performance correlated positively with MZ differences across 16 learning‐related variables, including measures of intelligence, personality and school attitudes, with the twin who scored higher on one also scoring higher on the other measures. Finally, MZ differences in the 16 learning‐related variables accounted for 22% of the variance in MZ differences in school performance at age 16. These findings suggest that, unlike for other psychological domains, non‐shared environmental factors affect school performance in systematic ways that have long‐term and generalist influence. Our findings should motivate the search for non‐shared environmental factors responsible for the stable and systematic effects on children’s differences in school performance.

h/t: Rolf Degen https://twitter.com/DegenRolf