PSYCHOLOGY AND CULTURAL EVOLUTION
How Protestantism and Bans on Cousin Marriage Made the West Psychologically ‘WEIRD’
How new research in cross-cultural psychology and cultural evolution have uncovered the historical roots of Western psychology
Today, we’ll discuss cultural evolution and the origins of WEIRDness. Perhaps surprisingly, research suggests that the cultural evolution of the WEIRD world had a lot to do with cousin marriage and Protestantism. If you’re not familiar with the concept of WEIRDness, don’t worry, we’ll start with a crash course.
This article draws heavily on a 2020 book published by Harvard evolutionary anthropologist, Joe Henrich. The book is called The Weirdest People in the World: How the West Became Psychologically Peculiar and Particularly Prosperous. If you like this topic and want to learn more, I highly recommend Henrich’s book.
What does it mean to be WEIRD?
People like Henrich have pioneered cross-cultural research over recent decades, and it turns out that the West is more unusual than Westerners typically assume. In fact, Western psychology anchors the far end of the global distribution in a number of fascinating ways. And because Western psychology is so odd, researchers named it WEIRD: Western, Educated, Industrialised, Rich, Democratic.
We’ll talk loosely about the WEIRD and non-WEIRD worlds as if they’re separated by clear boundaries, but this is mostly for convenience. While there are major differences between the most and least WEIRD societies, there are also many shades and flavours of WEIRDness. Still, to keep things simple, we’ll talk about WEIRD psychology as if it’s a monolith.
How is WEIRD psychology different? We discussed WEIRD psychology in a recent series on emotions. Since the case of emotions gives a helpful introduction to WEIRD psychology, we’ll start with that example and build from there.
In many ways, WEIRD emotions are a microcosm of WEIRD psychology. WEIRD emotions emphasise internal experiences of individuals. WEIRD emotions are also viewed as essentially the same independent of the context in which they occur. The intensity and length of the feeling may depend on the context, but the internal essence of the emotion is innate and universal. The animated movie Inside Out captures this idea well.
The search for internal causes, focus on individuals, neglect of context, and belief in innate, universal essences are features of WEIRD emotions in particular, and WEIRD psychology in general. In short, WEIRD people believe that thoughts and actions are driven by an internal essence that makes us who we are. In this setting, people often strive to be their ‘real’ or ‘true’ selves, and adapting your actions, values and beliefs to the situation can be seen as a form of dishonesty.
By contrast, people outside the WEIRD world see things quite differently. To non-WEIRD people, the causes of thoughts and actions are found in the relations between people, and the situations in which they interact. They minimise or even dismiss the idea of internal causes and essences, and don’t share the WEIRD obsession with a true self buried deep inside. In this setting, a person who acts the same in all situations is viewed as lacking social skills, and behaving differently depending on the situation is considered a sign of maturity and cultural competence.
Although this description glosses over a lot of details, it captures the important differences between WEIRD and non-WEIRD psychology. But how did this come to be? What institutions are involved? And what events in Western history changed those institutions? This brings us to how banning cousin marriage made the West become psychologically WEIRD.
How did the West become WEIRD?
Nowadays, the nuclear family is the basic social unit of the WEIRD world. WEIRD work is based mostly on impersonal markets, and involves voluntary associations. While there are still many family businesses, most WEIRD workplaces hire people from different families. But until fairly recently, this was not the case.
For most of human history, it seems that kin-based institutions have been the default form of social organisation. In this world, the clan was the basic social unit. This brought with it a very different type of psychology. For example, legal codes focused on actions, and people’s intentions were not considered relevant to questions of guilt and punishment.
This was the case in Roman law, which pre-dates WEIRDness in Western Europe. Even in the heart of the future WEIRD world, the hallmarks of its unusual psychology were nowhere to be found. So when did the West begin down the road to WEIRDness?
There were several factors. A major one was the Catholic Church banning cousin marriage. Attempts to ban cousin marriage date back to the 4th century AD. But the ban was difficult to enforce after the Western Roman Empire was overrun by Germanic tribes in 476AD.
The ban got a boost in the 9th century, when it was supported by the Carolingian Empire of Charlemagne. And despite resistance from society, cousin marriage was gradually phased out of Europe. (Though cousin marriage was never fully expunged, and even historical figures like Charles Darwin married their cousins.)
This broke up the kin-based institutions on which Western societies had been founded, and provided an opportunity for change. The collapse of kin-based institutions left a void that was filled by nuclear families, impersonal markets, and voluntary associations. This invited a psychology that focused on the individual.
The need to trust and be trusted without the assurances of kinship forced people to develop new ways of vetting each other. In this regard, mental states were useful, as they allowed people in the proto-WEIRD world to explain the actions of others without kin-based concepts.
But the question then becomes, where do mental states come from? When we think mental states reflect deep truths about people, we’re on a slippery slope to essentialism. This is what happened as the West became WEIRD. Individualism and mental states biased us to imagine hidden essences that define our nature.
But banning cousin marriage wasn’t the only factor in the creation of WEIRDness. Henrich cites evidence that other influences also contributed, like the role of Protestantism in pushing literacy, especially among women. Protestants were encouraged to have a more personal relationship with God. Protestant ethics also gave more priority to the individual, who was expected to learn and interpret scripture for themselves.
By contrast, the Catholic Church wasn’t concerned with literacy among lay people. It took a more hierarchical approach, as lay people relied on Church officials like priests and bishops for scripture and salvation. Over 500 years after the start of the Reformation, this is largely still the case. As a result, even today, you see less WEIRDness in places with less Protestant influence, and vice versa.
Henrich argues that these developments led to other changes as well. For example, he suggests that it caused a shift towards valuing mutual benefits and positive-sum thinking, rather than being constrained by the narrower possibilities of kin-based institutions. Henrich believes this gave an edge to Europeans from the 16th century onwards, linking it to the WEIRD world’s conquest and domination of the rest of the globe for the last 500 years.
Cultural evolution can affect the brain
In addition to influencing our psychology, cultural evolution can also affect our biology. For example, studies have found that literacy changes the brain’s structure and function.
In the brain of a literate person, faces are preferentially processed by the right hemisphere. We also discussed this in a recent series on myths and ideas about the brain’s hemispheres. However, the brain of a non-literate person shows a much weaker preference, or none at all.
Literacy even impairs facial recognition compared to non-literate people. But it’s not all bad news, as literacy improves verbal memory. In line with all these functional differences, reading induces changes in the structure of many parts of the brain as well.
Key points
When the Catholic Church banned cousin marriage, and when Protestantism began, the West had no idea that they were about to become WEIRD. We didn’t expect that literacy would change our brains.
Examples like these highlight the deep links between culture, psychology and biology, and the powerful role played by environments. Although it often doesn’t get the respect it deserves, cultural evolution is clearly a potent force.
