Published online 1 August 2008 | Nature | doi:10.1038/news.2008.990

Column: Muse

Is religion good for your health?

Religion arose to protect us from disease, US researchers claim. Philip Ball unpicks the idea.

Science and religion, anyone? Come now, stifle those yawns. A paper published in the Proceedings of the Royal Society B1 this week claims to offer a fresh perspective, with the startling suggestion that religion is a way to protect us from disease.

The general idea behind this theory — that religion is mainly a social construct — is actually much older than the authors, Corey Fincher and Randy Thornhill of the University of New Mexico in Albuquerque, acknowledge. It harks back to classic works by two of sociology’s founding fathers, Emile Durkheim and Max Weber, who, around the start of the twentieth century, offered explanations of how religions around the world have shaped and been shaped by the societies in which they are embedded.

crossFantastically baroque, but does religion carry a health benefit?Daniel BOITEAU / Alamy

This idea has fallen out of fashion, but that may tell us more about our times than about its validity. The increasing focus on individualism in the Western world since Durkheim wrote that “God is society, writ large” is reflected in the current enthusiasm for what has been dubbed neurotheology: attempts to locate religious experience in brain activity and a genetic predisposition for certain mental states. Such studies might ultimately tell us why some people have religious tendencies, but they say very little about why this predisposition gives rise to a relatively small number of institutionalized religions.

Similarly, the militant atheists who gnash their teeth at the sheer irrationality of religious belief will be doomed to do so forever unless they recognize Durkheim’s point that, rather than being some pernicious mental virus propagating through cultures, religion has social capital and thus possible adaptive value2. Durkheim argued that religion once was, and still is in many cultures, the cement of society that maintains order. This cohesive function is as evident today in much of American society as it is in Tehran or Warsaw.

Keep out

But of course there is a flipside. A tightly-knit group tends to exclude outsiders, and this is no less true of religions than of any other club. Fincher and Thornhill now propose a specific reason for why some societies may benefit from religious insularity — it is, they say, a way to avoid disease.

The more a society disperses and mixes with other groups, the more it risks contracting new diseases — in other words, strangers are bad for your health. “There is ample evidence,” Fincher and Thornhill write, “that the psychology of xenophobia and ethnocentrism is importantly related to avoidance and management of infectious disease.”

Fincher and Thornhill have previously shown that the diversity of language within a society, for example, seems to correlate with the diversity of infectious disease3, suggesting that linguistic differences are a manifestation of disease avoidance strategies.

Now they have found that religious diversity is also greater in parts of the world where the risk of catching something nasty from outsiders, who are likely to have different immunity patterns, is higher.

They studied 339 societies from Asia, America, Africa and Australia, and found that people living in areas with a greater diversity of infectious disease (and thus a higher risk of contagion from outsiders) tend to have smaller 'social ranges': on average, they live their lives across smaller areas. And populations with smaller social ranges had more religious diversity.

Fantastically baroque and socially costly

It’s an intriguing observation. But as with all correlation studies, cause and effect are hard to untangle. One could equally argue that avoiding contact with other social groups simply prevents the spread of some cultural traits at the expense of others, and so merely preserves an intrinsic diversity that has a tendency to arise anywhere.

This, indeed, is the basis of some theoretical models for how cultural exchange and transmission occurs4. Where opportunities for interaction are fewer, ‘island cultures’ are more likely to coexist rather than being consumed by a dominant one.

And the theory of Fincher and Thornhill tells us nothing about religion per se, other than its simple function of keeping ‘insiders’ and ‘outsiders’ apart.

In fact, compared with other ‘in-group’ markers such as family names or styles of art and music, religion is a fantastically baroque and socially costly means of separating friend from presumed foe. As ethnic conflicts have long proved, humans are remarkably and fatefully adept at identifying the smallest signs of difference.

What we have here, then, is very far from a theory of how and why religions arise and spread. But it does suggest that there are hidden biological influences on the dynamics of cultural diversification. It is also a useful reminder that religion is not so much a personal belief as, in Durkheim’s words, a ‘social fact’. 

  • References

    1. Fincher, C. L. & Thornhill, R. Proc. R. Soc. B doi:10.1098/rspb.2008.0688 (2008).
    2. Wilson, D. S. Darwin's Cathedral: Evolution, Religion, and the Nature of Society (Univ. Chicago Press, 2002).
    3. Fincher, C. L. & Thornhill, R. Oikos doi:10.1111/j.0030-1299.2008.16684.x (2008).
    4. Axelrod, R. J. Conflict Resolut. 41, 203–226 (1997).
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