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Evolution and Religion

The explanatory power of evolutionary theory is clear. However, these days, people seem to rush to evolutionary explanations for all sorts of real and perceived human behaviours. The danger of doing this is that in going straight to the question of the origins of what we’re trying to understand, we fail to put in the effort to adequately study the nature of the phenomenon, or even to establish satisfactorily that the phenomenon is real. As a result, it’s all too easy for commonsensical assumptions and misapprehensions to get incorporated into the story. And when it comes to human behaviour, things are often more complicated and more variable than common sense would lead us to expect.

It’s probably about affiliation and endogamy, Michael!

This is a particularly common problem, in my view, in evolutionary studies of religion, and I’ve just read a blog post that’s a case in point. In It’s about Fertility, stupid! The Evolutionary Adaptivity of Religion‘, Michael Blume claims that:

Religiosity (defined as behavior towards superempircal agents) is today clearly adaptive: Members of competitive religious communities are building stronger families with more offspring worldwide as their secular neighbours of the same education and income levels. This is observable in empirical studies, censusses worldwide, as well as in case studies (i.e. Amish, Hutterites, Mormons, Orthodox Jews). In contrast, non-religious populations and those religious communities who do not build and support families inevitably succumb to cultural evolution (i.e. late Greek and Roman Polytheism, Gnostic groups, the Shakers) and are replaced by demographically successful religious competitors.

Blume’s interpretation of the empirical data depends on the premise that affiliation to these groups as revealed in, say, censuses, is a reliable indicator of religiosity, on his definition. But there is a good deal of social scientific evidence that shows that this cannot be taken for granted.

To give just one example, a great study of belief in contemporary northern England published last year by Abby Day (Believing in Belonging) shows that ideas about belonging and ideas about the supernatural can be surprisingly independent of each other.

For years now, church attendance in Britain has been in decline, and sociologists have debated what this means. Some argued it was a sign of ‘secularization’–an inevitable loss of religious belief associated with the modernization and rationalization of society. Others argued that it was a result of individualization, and that Britons continued to believe in God, but now preferred to practise their religion quietly on their own.

Day’s study, which was based on interviews in Yorkshire villages, found a more complex picture. Her interviewees turned out to be quite polarized in their views. Some of them–she calls them ‘theocentrics’–place God at the centre of their lives, as a source of moral value, a cause of everyday events, and an object of their attention and affections. Others–Day calls these ‘anthropocentrics’–see no place for God, and instead locate value and meaning in their relationships with other humans. Anthropocentrics take a dim view of theocentrism and vice versa.

An everyday story of small town intolerance, then, and perhaps no surprise. So why did Day not just call her two groups ‘religious’, and ‘secularists’ instead of inventing two new terms? Well, it turned out that of the respondents who identified themselves as Christian, about half were anthropocentric, and many of those were assertively atheist. Many of those self-identified Christians said they were hostile to the idea of institutional religion.

Meanwhile, many of those who identified with no religion told Day that they prayed, believed in fate or some kind of providence, had seen ghosts or had communicated with deceased relatives.

In his article, Blume mentions that his work was partly based on census data. It’s worth noting that most of Day’s Christians, including the ‘anthropocentric’ atheists, said that they had answered ‘Christian’ in response to the religious affiliation question in the 2001 UK census (the first modern UK census to include a religion question).

Day’s work shows that being associated with, or feeling a sense of identity and belonging in respect of, a ‘religious community’ is quite a different thing to ‘religiosity (defined as behavior towards superempircal agents)’. Religiosity is neither exclusive to, nor universal among, members of ‘competitive religious communities’.

In fact, unless the empirical data are sufficient to distinguish between belonging and believing, there is no reason to suppose that religiosity, on Blume’s definition, has anything to do with the increased reproductive success Blume finds for religious communities through history.

Indeed, there is a simpler explanation at hand. Many of the historical and contemporary religious groups that we identify as such combine a self-conscious sense of identity with a greater or lesser degree of endogamy (marriage within the group) and they tend to value having and bringing up children and the relationships between kin. It would not be surprising if this combination of features were to lead to reproductive success.

Blume himself inadvertently suggests this explanation when he excludes from his analysis ‘those religious communities who do not build and support families … (i.e. late Greek and Roman Polytheism, Gnostic groups, the Shakers)’.


Day, Abby. 2011. Believing in Belonging. Oxford: Oxford University Press.


UPDATE: More on this in Evolution and Religion Part II, and Evolution and Religion Part III.


  1. Hi Jon,

    thanks for the lively interest.

    Actually, the blog post you quoted is only a very condensed version of many years of work in German, most of whom I have yet to made available in English, too. Here is, for example, a paper combining data from the Swiss Census and the World Value Surveys:


    And here’s a case study on the Amish:


    Although I’d agree that endogamy is “building” kinships, the Anabaptist Amish movement is a good example of a group that did not depend on it from the start.

    Here are some other studies and resources from me & other colleagues exploring religion & demography:


    Concerning your ideas, I like and share the approach of religious groups adopting kin-selective processes. As-if kin terms such as brother & sister, father (padre) etc. are very common among the world religions and the Nun is sharing etymological roots with the aunt and the Nanny (!). There are certainly many good examples in your field of study, too!

    Nevertheless, the fundamental questions remains: Why are only “religious” communities able to augment this in-group cooperation not, say, political parties or sport clubs? Secular jews do have kin-relations as their Orthodox cousins – but only the latter have the expanding demographics. (I wrote a German book about these issues together with a biologist. Although it reached it’s third edition, it was unfortunately never translated into English.)

    Looking forward to more of your thoughts & maybe papers!


    • Thanks Michael — looking forward to your comments and responding in due course.

      Hope your house is coming on well!

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