The Christian Church, intensive kinship and global variations in peak HIV prevalence: an ecological study

Aim
An increasing body of evidence demonstrates that European and Westernized populations are unusual in a number of psychological dimensions. Their WEIRD (Western, Educated, Industrial/Individualistic, Rich and Democratic) psychology has been linked to a marriage and family project implemented by the Christian Church in the Middle Ages. One of the key components of this was the imposition of monogamy as the only tolerable form of sexual partnering. In this paper, we test the hypothesis that this process reduced the connectivity of local sexual networks, which made them more resistant to the spread of sexually transmitted infections (STIs) such as HIV.

Subject and methods
We used linear regression to assess the national association between three markers of Church exposure (kinship intensity index [KII], Western Church exposure, Eastern Church exposure) and the prevalence of two STIs (peak HIV prevalence and Herpes simplex virus-2 (HSV-2) prevalence.

Results
Both peak HIV prevalence and HSV-2 prevalence were positively associated with the kinship intensity index. The peak prevalence of HIV was negatively associated with the intensity of exposure to the Western and Eastern church.

Conclusions
There is an ecological association between the intensity of exposure to the Medieval Church's marriage and family project and the prevalence of two viral STIs. The imposition of this project and monogamy in particular may have had long reaching effects on the spread of STIs.