How parasites spread religion

Several theories have been proposed for why religions and religious beliefs have evolved, but before now none of them have involved parasites.

Previous theories have suggested that religions help enforce group cooperation. Another suggestion is that religious thoughts and practices are a side-effect of mental abilities that have evolved for other purposes. For example, prayer is a small step from our evolved ability to rehearse what we plan to say to someone who isn’t physically with us right now.

Crucially, none of these accounts can readily explain why the diversity of religions varies so much around the world. Brazil, for example, has 159 religions compared with Canada’s 15, even though both countries are of comparable size.

Now Corey Fincher and Randy Thornhill have tested the idea that religious diversity is a side-effect of the fragmentation of cultures that tends to occur in the face of increased threat from infectious disease.

Fincher and Thornhill used the World Christian Encyclopedia and the Global Infectious Disease and Epidemiology Network to compare the spread of infections and religions across 219 countries. Their results were clear: in regions with a greater variety of infectious parasites, the diversity of religions also tends to be greater. This association held strong even after exploring the impact of other potential factors, such as differences in democratisation and histories of colonisation.

The researchers say the association between religion and parasites occurs because reducing contact with outsiders can help protect against disease. In turn, when cultures fragment and groups avoid making contact with each other, more religions are likely to spring up.

“Although religion apparently is for establishing a social marker of group alliance and allegiance, at the most fundamental level, it may be for the avoidance and management of infectious disease,” Fincher and Thornhill said. The pair also believe that the diversity of languages and parasites tends to co-vary across the globe for similar reasons.

ResearchBlogging.orgCorey L. Fincher, Randy Thornhill (2008). Assortative sociality, limited dispersal, infectious disease and the genesis of the global pattern of religion diversity Proceedings of the Royal Society B: Biological Sciences, 275 (1651), 2587-2594 DOI: 10.1098/rspb.2008.0688

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

5 thoughts on “How parasites spread religion”

  1. Oh yes, please let this be true. Religion itself is a parasite, draining people of energy that could be directed elsewhere, or at best, a symbiotic relationship.Seriously, it does go some way to explain the often violent antipathy displayed to other religious groups. That would make sense in disease control.


  2. Has anyone explored the possibility that the cause for the proliferation of religions could be spiritual in nature?I.e., that we were created with a need to connect with our creator?If so, our response to this need would certainly result in what we were seeing. Cultural expressions of this response (Brazil vs. Canada) would then explain why some cultures had “more religions” (when it comes to variety of expression) than others.However, what if ALL RELIGIONS were simply (at their root) the result of a need to connect with our creator? Like a homing instinct that person built into us?


  3. All religion are simply (at their root) the result of a need to soothe the most universal fear – the fear of death.The proliferation of religions has a lot of varied causes, mostly connected with the spread of dominant culture.Thast’s why, when there are more isolated communities the cultural divetsity occurs.


  4. to me it seems that rather than parasites being the /cause/ of religious diversity, perhaps both the diversity of religion and the spread of parasites are correlated with a much larger cause… the diversity of religion, the spread of parasites and the diversity of language, could all be the result of a larger causal influence: namely; population sizes in these areas….? in larger populations, especially in less economically developed contries, wouldn’t you expect to find more diverse cultural practices, langauge differences and greater spread of parasitical infections…?i don’t know what the evidence is for this, but i assume that where there are larger groups of people, there would be a greater diversity of language, perhaps a greater spread of infection (especailly in poorer countries) and perhaps a greater diversity of religion. i know there are countries that may refute this idea- the USA,..?-howver if you add to this the isolation hypothesis (i.e. isolation creates diveristy), then im guessing on large continents such as Africa, South America, where isolation may occur due to lack of communication devices, lack of transport structures etc…this may appear to be the case.interesting study!


  5. I find this finding very strange as I don’t see the correlation between epidemics and a spread of any particular religion across cultures. A typical example of religious diversity is India. Invasions brought in Islam into a Hindu land. A hindu prince’s journeys brough Buddhism and Christianity came in through colonisaiton of the East India Compay. Very confusing post anyway.


Comments are closed.