Believing in Witchcraft May Have Helped People Avoid Disease and Contagion, Study Says

Belief in Satan and the witches of Salem may have developed as a way to explain and predict disease. At least, that is the argument put forward by an international team of researchers writing in Proceedings of the Royal Society B on Wednesday.

The core of the argument is that belief in an evil supernatural power like the devil contributes to the "behavioural immune system"—a set of beliefs that protect the believer from infectious disease by altering their behavior. A person with a strong belief in the devil, for example, might be more likely to avoid a person who appears "possessed," or, to use today's language, diseased.

The authors of the paper used statistical data to back up their hypothesis, showing moral vitalism (defined as beliefs related to the spiritual forces of evil) appears to be higher in historical periods and across geographical regions where pathogen rates are higher.

"We conclude that moral vitalism may be adaptive: by emphasizing concerns over contagion, it provided an explanatory model that enabled human groups to reduce rates of contagious disease," state the authors.

Moral vitalism has been observed in cultures across the world and continues to exist in some communities today, with practices such as spiritual healing.

The researchers use the Black Death that struck Eurasia in the fourteenth century as a prime example of a historical moment that triggered a rise in moral vitalism (specifically, the escalation of witch hunts) in people who could not otherwise explain the sudden onslaught of death and disease.

devil costume
A reveller takes part in the Devils parade during the Devil's Carnival, in Riosucio, Caldas department, Colombia, on January 5, 2019. JOAQUIN SARMIENTO/AFP/Getty

Factually inaccurate as these supernatural scapegoats may have been, they gave people a sense of control and a false belief that they could somehow predict the spread of the disease, the study authors argue.

The researchers point to three studies to support this argument—two from the archive and one large multi-national survey involving 3,202 university students from countries in North and South America, Europe, Asia and Australasia.

The first archival study involved observational data on 186 distinct cultures, from preindustrial societies to technologically-advanced civilizations, and beliefs in the Evil Eye and witchcraft. The second contained responses of people from 50 countries collected from the World Values Survey (WVS), relating to their belief in the devil. Both showed a strong positive correlation between belief in these evil supernatural beings and disease prevalence.

A strong relationship between belief in the devil and disease prevalence was also detected in the survey. It asked the student volunteers to rate statements such as, "There are underlying forces of good and evil in this world" and "Good and evil are aspects of the natural world" in addition to completing 14 moral relevance items.

These were designed to measure three moral binding foundations: in-group/loyalty; authority/respect; and purity/sanctity.

The results graph shows north and central European countries such as Germany, Finland and Switzerland at one end of the spectrum with low moral vitalism and low historic disease prevalence, reflecting surveys finding lower rates of "highly religious" adults in these countries. While China and Indonesia sit at the opposite end. The U.S. is an unusual case with traditionally low disease rates but high moral vitalism.

"Moral vitalism may have emerged as humans tried to explain the spread of disease and persisted because it conferred an adaptive advantage to groups who were threatened by pathogens," state the authors.

The researchers also note a connection between moral vitalism and conservatism—a correlation that may partially explain support for Trump in the evangelical Christian community—suggesting the latter may have "reinforced" the emergence of the latter within areas of high pathogen rates.

For example, culturally evolved norms (such as food preparation) and ethnocentrism (i.e. the avoidance of strangers, a behavior that may limit exposure to pathogens the body has not previously been exposed to and thus, might not be prepared for) are both associated with conservatism and may prevent disease spread.

"This is consistent with prior work showing that endorsement of moral vitalism is associated with conservative attitudes, fundamentalist thinking and religiosity," the authors conclude.

Of course, correlation does not equal causation and there are likely to be several other factors contributing to a person's belief in witchcraft and other evil beings. But the researchers argue the strength of the results of the three studies combined suggest there may be something to the idea that belief in the devil is, in part, a psychological reaction to disease.