Faith Goes Viral

Image Gallery David Gothard / www.davidgothard.com

Religious beliefs can shape key behaviors when it comes to dealing with disease, says David Hughes, an evolutionary biologist at Pennsylvania State University. In a presentation in August at the 13th Congress of the European Society for Evolutionary Biology in Germany, Hughes and colleagues reported that some of today’s major religions emerged at the same time as widespread infectious diseases, and they propose that the two helped shape one another.

Hughes has long been fascinated by religion’s power to compel people to behave in ways they might not have behaved other­wise, and in particular to extend help to nonrelatives, even at a significant cost to themselves. An extreme example is when someone tends to the sick, risking infection and, at least in earlier times, death—a behavior that doesn’t make much sense from an evolutionary perspective, particularly if the sick person is not kin.

Along with two Penn State colleagues, demographer Jenny Trinitapoli and historian of religion Philip Jenkins, Hughes read the historical literature and queried religious leaders and other experts about the world’s epidemics and the way religions deal with disease. They found that between 800 BCE and 200 BCE, cities flourished, deadly plagues capable of killing off up to two-thirds of a population arose, and several modern religions emerged. These religions all had different takes on disease, which affected how people responded to epidemics such as polio, measles, and smallpox. The belief systems influenced, for example, whether people fled from disease or tried to help those who were sick.

The Christian tradition, set by the example of Jesus as a healer, stands out, Hughes says. Helping the sick was one way to ensure a trip to heaven, so risking death from a disease’s spread was encouraged. Other religions did not promote such extreme altruism. Islamic teachings basically disavowed the existence of contagious disease, despite some Arabic scholars thinking otherwise at the time. Thus Muslims believed there was no sense in trying to avoid sick people, and the emphasis was on caring for one’s family. Jewish doctrine attributed death to God’s will and promoted the idea that only God could heal someone, so there was less incentive to treat the sick, conclude Hughes and his colleagues.