Religion has a funny way of dividing people. But religious fervor and intolerance may also keep you from getting sick, according to evolutionary biologists Corey Fincher and Randy Thornhill of the University of New Mexico. They propose a theory that says religious diversity was an evolutionary adaptation to keep groups of people separate and prevent them from infecting each other with diseases.
The researchers noted that religious diversity varies significantly across the globe. Why does Brazil have 159 religions while Canada only has 15? Fincher and Thornhill believe there is a relationship between geography, climate, and religious diversity. Since warmer locales harbor more infectious diseases, it was a good survival strategy to keep to yourself and religion enforced isolation.
The researchers used the World Christian Encyclopedia and the Global Infectious Disease Epidemiology Network to compare infectious diseases and religions across 219 countries. Even after taking other factors into account, such as democratization and colonization, they found a correlation between religious diversity and the number of infectious parasites in a given place.
Their research falls into the realm of sociobiology, a field pioneered by E. O. Wilson, which uses evolution to explain the social behavior of species. Sociobiology is criticized by many for promoting a sense of biological determinism reminiscent of social Darwinism or eugenics—although, one has to wonder, does that mean proselytization is a form of evolutionary suicide?
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