How medieval Church ban on incest shaped Western world
Laws forcing people to look further for partners were key to creating today’s society, say researchers
THE Catholic Church has a reputation for strict, unbending theology, but it may have inadvertently triggered the nonconformist and individual culture of today’s Western societies.
Academics believe that rules enshrined in canon law in the 9th century – which limited the marriage of relatives to prevent incest – fundamentally changed the culture of Europe, breaking apart old clans and ushering in a new era of cooperation.
Western societies are generally viewed as quite odd by sociologists because they tend to regard individuals as more important than the group, they conform less to a central ideal and they have a much greater trust of strangers.
In contrast, older, more traditional societies tend to comprise tight-knit tribes where members show fierce loyalty, obedience, adherence to tradition and a general mistrust of outsiders.
Academics had been puzzled as to what caused the transition, but they have discovered that areas that were early adopters of the medieval Catholic Church marriage rules transitioned into modern Western societies.
The rules forced communities to cast their net wider for marriage partners, splitting apart tight networks and allowing new alliances to be embraced.
Prof Joseph Heinrich, the chairman of human evolutionary biology at Harvard University, said: “The Western Church in Europe, the branch of Christianity that eventually evolved into the Roman Catholic Church, had transformed human society from the grassroots by dismantling the intensive kin-based institutions, leaving much of Europe with monogamous nuclear families. And monogamous families are vanishingly rare outside of Europe in an anthropological perspective. The longer the duration under the Church, the greater the individualism, less conformity, more obedience, more cooperation and more trust with strangers”
Until the medieval period, the Church placed restrictions on marriages to very close relatives such as parents, siblings and first cousins. But by the 9th century, it widened the rule to include up to sixth cousins and even non-related spiritual kin such as godparents, forcing communities to search for marriage partners far outside their families. The Church was so preoccupied with incest that natural disasters such as the plague were said to be God’s punishment for the sin.
By the 12th century, banns of marriage were made compulsory so familial links could be investigated, while wedding congregations began to be asked if they knew of any impediment why the marriage could not take place.
Dr Jonathan Shultz, an assistant professor of economics at George Mason University, one of the authors of the research, added: “There is good evidence that Europe’s kinship structure was not much different from the rest of the world before the Church instituted its marriage prohibitions.”
Today in non-christian countries that do not share Western principles – such as Iran, Afghanistan and Pakistan – the rate of cousin marriage is still between 30 and 60 per cent.
Iranian-born Duman Bahrami-rad, a postdoctoral researcher from Harvard who helped with the study, added: “When I moved to Canada, I was so surprised to discover Canadians don’t marry their cousins. I thought it was weird that Westerners don’t fall in love with their cousin.”
Sociologists dub Western populations as “Weird” – Western, educated, industrialised, rich and democratic – because they are so strikingly different to traditional societies. The research was published in the journal Science.