Thursday, July 31, 2008

Diseases - repsonsible for the success of religions?

This seems a bit odd to me. But here is a story about a study that claims that protection from infectious diseases may be the driving force behind religions (hat tip 3quarksdaily):

Dr Corey Fincher and Prof Randy Thornhill of the University of New Mexico, Albuquerque, come to this conclusion after studying why religions are far more numerous in the tropics compared with the temperate areas.

"Why does Cote d'Ivoire have 76 religions while Norway has 13, and why does Brazil have 159 religions while Canada has 15 even though in both comparisons the countries are similar in size?" they ask.

The reason is that religion helps to divide people and reduce the spread of diseases, which are more common the hotter the country, the research suggests.

Ok, I have to get hold of the published paper. Somewhere here there seems to be a causation/correalation problem, but I'll comment on it after seeing the paper. In the mean time, here is their prediction and test:

Any society that increased its coherence by adopting a religion, and dealt less with local groups with other beliefs as a result of cultural isolation, gained an advantage in being less likely to pick up diseases from its neighbours, and in the longer term to have a slightly different genetic makeup that may offer protective effects, for instance by making them less susceptible to a virus.

Equally, societies where infectious diseases are more common are less likely to migrate and disperse, not because of the effects of disease itself but as a behaviour that has evolved over time.

" If this argument is correct then, across the globe, religion diversity should correlate positively with infectious disease diversity," they say.

And the team finds evidence to back this.

"A sample of traditional societies shows that the range of those societies is lower in areas with more disease agents, compared with areas with few pathogens, and in countries religion diversity is positively related to two measures of stress caused by infection with parasites. Religion richness was positively related to disease richness (and significantly so)."

As predicted, "we found that religion diversity is the highest where disease diversity is also the highest and the lowest where disease diversity is also the lowest. To our knowledge, previous evolutionary models do not offer an explanation for why religion diversity varies spatially across the globe.

But what about other competing socio-poltical forces affecting the growth of religious groups? Or non-religious factors leading to the segmentation of the population? I will get a copy of the paper and get on this.

Read the full story here. And of course, for more on origin of religions, check out David Sloan Wilson, as part of our Science & Religion lecture series at Hampshire College.

6 comments:

Don said...

The other socio-political factors seem like they would be a lot more relevant, especially as the study seems to be examining modern religious diversity. The hypothesis that religious diversity is correlated with diversity of infectious disease might apply to the origin of religions, or how many religions have historically developed in an area, but it doesn't seem to apply to a study of modern religious diversity. I'm curious to see what the study authors had count as a religion-- especially in areas with high religious diversity, it would be interesting to see if they count what would be regarded as cults in more developed countries as full blown religions. This might indicate a bias in the paper-- if they don't count groups of comparable size within the developed world as religions, but count them in underdeveloped countries as religions, I imagine their results would be skewed.

Salman Hameed said...

I'm also curious about the definition of religions (and the boundaries they form around them). I couldn't get hold of the paper from the 5-colleges (most recent - 1 year, not available). I'll try to get it from the authors directly.

Edward Ott said...

Brazil might be comparable in size but it's population is probably 6 times canadas.

Tom Rees said...

The high prevalence of disease in tropical regions also seems to repress individualism, perhaps as a way to reduce transmission (see http://bhascience.blogspot.com/2008/04/did-disease-stop-science-developing.html). So barriers between groups may be higher in tropical regions, and the possibility of divergent religions in close proximity greater. Perhaps...

Don said...

Did you ever get a copy of the paper? Because I would also like to read it, if you did.

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