The above map is from a new preprint, The Origins of WEIRD Psychology. If you don’t know, WEIRD refers to “western, educated, industrialized, rich and democratic.” And, it focuses on the problem that so much of psychological research has been done through surveys and experiments on university students, who tend to be from the more privileged half of developed societies in the West.

Despite the title, this preprint is less about the particularity and distinctiveness of WEIRD psychology subjects, but rather the socio-historical and cultural context from which WEIRD has developed. From the abstract:

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.

The hypothesis itself is not entirely novel. I first encountered the argument that the Western Church was critical in eliminating the familial strategies used by Late Antique Roman elites to maintain their power and wealth in Adam Bellow’s book In Praise of Nepotism. This preprint outlines the exact process which Bellow described: the Western Church constrained and limited the pool of possible mates through incredibly stringent incest regulations, as well banning adoption and other ways to prevent lineage extinction. Bellow presents an almost materialist thesis, whereby the Western Church consolidated its power and wealth through regulating the personal lives of Western Europe’s ruling elite. By destroying powerful pedigrees not only did the Church eliminate a temporal rival, but often the wealth of these elite lineages went to the Church if there were no heirs.

I’ll get back to the history in a bit. But first it has to be admitted that formalizing and quantifying these patterns is the value of this preprint. It would be easy for me to critique a particular set of variables, but there are so many, and they did so many robustness checks, that it hard to deny that the authors picked up some signal in the data. Probably the most persuasive aspect is that some of the signals persist within countries. That is, areas subject more to Western Church coercion for longer periods exhibit reduced kinship intensity down to the present. In most of the world lineage groups and familialism were and are much more pervasive and powerful than in the medieval West, where non-familial organizations such as guilds and monasteries stepped into the gap. What we might call “civil society” or the “small platoons.” These became “high trust” societies, and set the stage for the cultural and economic revolution of early modernity, from science to industrialization and the flourishing of democratic liberalism.

There have been many debates about why Europe underwent lift-off after 1500. Some of the models rely on exceedingly simple causes, such as the discovery of the New World releasing parts of Atlantic Europe from Malthusian pressures, as well as the location of coal in accessible regions of England. It seems possible that a single necessary and sufficient cause does not exist. The combination of the European discovery of the New World, along with their relatively open and high-trust societies engendered by the dissolution of extended clan structures by the Western Church was likely a potent cocktail.

In any case, I want to revisit the issue of how and why the Western Church went the route that it did. Because Christians in other parts of the world did not reform family structure in the say way. As hinted in the preprint, it may have to with the fact that the collapse of the imperial order in the West resulted in the devolution to the Church certain powers that would otherwise have been accorded to the state. In the lands of post-Roman West local bishops had the power of princes. Even the Pope in Rome took the role of a prince on more than one occasion. But, they also had the power of religion, which for all practical purposes was magic. To make a nerdy allusion, the bishops of the post-Roman world were both Aragorn and Gandalf in one. They were priest-kings.

The same did not hold in the East Roman Empire. Though the Eastern Orthodox Churches have often clashed with rulers, they were much more subordinate for all practical purposes than the Western Church. The East Roman Empire maintained the bureaucratic function of the Roman world down to the medieval period. In contrast, much of the apparatus of state control withered in the post-Roman West, as it devolved into feudalism. The Western Church maintained the cultural connection with Romanitas in the West in a landscape where the authority of Rome had vanished. That cultural connection was channeled through Christianity, where marriage was a sacrament which the Church controlled. Though there were plenty of aristocrats in the post-Roman West, the political systems of control were relatively weak. The Western Church was a solid and critical institution which spanned the patchwork of independent dominions which characterized the political landscape. It was indispensable.

In a world where Rome did not fall, which to all practical purposes was the case in the East, the Church would have had a more normal role in society. It would not have been able to engage in a social engineering project, because established powers would have blunted its will. This is clearly the case in other societies. In addition, the Church also had accrued to itself a monopoly on provision of religious services in Late Antiquity, and so it had recourse to avenues of leverage not feasible for secular rulers.

The pervasive power of the Western Church even in the face of the rise of social and political complexity in the late medieval period is illustrated by the impact of the Reformation. In Protestant areas of Europe religion became much more strictly subordinated to the ruler. Pastors became more like civil servants than independent sources of power. Two dynamics emerged rapidly with the adoption of Protestantism. First, the cousin marriage became more common among elite lineages again (e.g., Charles Darwin married his cousin). Second, young women were forced into marriages against their will more often than in Catholic Europe, where becoming a nun was often an option. To some extent Protestantism exacerbated the tendency to treat and see women bargaining chips in negotiations between elite lineages.

As the authors note in the preprint inbred lineage groups to come to the fore and operate as the atomic units of social organization in a society among agriculturalists. This is in contrast to hunter-gatherers, who seem to want to create kinship ties to distant people. There are clear differences between foragers and farmers in this model. Dense sedentary living fosters the emergence of endogamous kinship groups as natural cultural adaptations. The peculiarity about Western Europe is that this society broke out of this “default state,” and even after the Protestant Reformation it never went back. It may be that European society is now at a different equilibrium, or, that the economic lift-off of the last 500 years has allowed for individualism to persist even where the role of the Church in breaking up tight kinship groups has been blocked.

This preprint is a big deal, because it brings quantitative methods to a field which has been long on speculation. But there’s a real phenomenon that needs to be explored.

Addendum: The blogger “hbd chick” has suggested that she should have been cited, as she has been talking about these issues relating to family structure and the Church for many years.  I am not taking any sides, but just pointing that out.