Sunday, August 10, 2008

Is religion a response to disease?

Corey Fincher and Randy Thornhill of the University of New Mexico have published a report in the Proceedings of the Royal Society in which they hypothesize that patterns of behavior that promote exclusivity act as a response to disease transmission, including both religion and language. They looked at the average number of religions per country and how disease-ridden each country is, and found a positive correlation between number of parasitic diseases and number of religions. The number of religions per country studied ranged from 3 to 643, with an average of 31; the number of parasitic diseases ranged from 178 to 248, with an average of 200. They also found that people in countries with more religions and diseases were less mobile--they moved shorter differences--than countries with fewer religions and diseases.

Does this mean that religion is a response to disease, prompting people to keep to themselves and be less mobile, or does it mean that religion acts similarly to disease (prompting people to behave in that same way)?

(Via The Economist, August 2, 2008, p. 83.)

1 comment:

workingsmart said...

Positive Correlation by itself cannot show causation.

There is a potentially infinite set of possible explanations for this correlation, the subset of posibilities that I see are:
1) Multiple religions cause diseases.
e.g. Perhaps differing human ritualistic behaviors allow different vectors to spread contagious diseases.
2) There is an underlying factor not tested in the study.
a. Perhaps the predisposition to immobility is caused by a gene that also increases susceptibility to parasitic disease.
b. Perhaps increased mobility is associated with increased access to medical care and exposure to memes that are destructive of tribal religions, thereby reducing the number of religions in mobile areas.
3) Lack of mobility causes disease.

Besides these possibilities, the argument has a fault in that if patterns of exclusivity are a response to disease transmission then the response is not an effective response or else exclusive groups would have fewer and not more diseases. Therefore there isn't an evolutionary survival benefit to exclusivity. In fact, if the studies hypothesis were true, areas with more isolated groups would have less disease and not more.

Corey Fincher and Randy Thornhill have made a logical error in their interperetation of their results and have only shown that reduced mobility and greater number of locally exclusive groups is not an effective protection from disease.