scilogs Biology of Religion

The Reproductive Advantages of Religiosity

from Michael Blume, 24. August 2009, 21:01

Once and again, I have experienced heated debates whether "religion" qualifies as an adaptation, an exaptation or "only" as an epiphenomenon. The problem is: Although religion may be described as behaviour towards supernatural agents, there is no consensus available about the exact meaning of the other, biological terms. In fact, most of these cloudy discussions turn out to be rather ideological and emotional debates without much empirical foundation. For anyone really interested in evolutionary science, it is high time to proceed beyond!

Religious Affiliation is Adaptive

Let's go back to basics: If a trait helps phenotypes to reproduce successfully (on average) throughout generations, it is adaptive and will tend to evolve and spread (cp. the Post Homo religiosus - The Natural History of Religion). This is the case with religious behaviour and religious affiliation, as shown by international and Swiss census data (article "The Reproductive Benefits of Religious Affiliation" here, pdf). Did you know that the young Charles Darwin invoked religious language himself as he pondered to marry and to have children? And that his wife-to-be confronted him with the prominent "Gretchen's question"? Do you remember God's very first words according to the Bible? ("Be fruitfull and multiply", Gen 1,28)

For more empirical studies from demographers around, you might also want to take a look at the Web-Resources on Religion and Reproduction.

And for an overview over the most recent works in Evolutionary Religious Studies, see the upcoming (and online already available) "The Biological Evolution of Religious Mind and Behavior" in the Springer Frontiers Collection.

Voland, E., Schiefenhövel, W. (Eds.): The Biological Evolution of Religious Mind and Behavior. Springer 2009

Some thoughts...

At the end of the article about the reproductive advantages of religious behaviour, I allowed myself to share a surprising observation about the resurgence of Creationism and Intelligent Design: "Evolutionary Theorists brought up far more scientific arguments - but committed believers in supernatural agents brought up far more children. There is a certain irony in here: creationist parents unconsciously defend the reproductive success of their children and communities against evolutionist teachings, whereas some naturalists are trying to get rid of our evolved abilities of religiosity by quoting biology. But from an evolutionary as well as philosophic perspective, it may seem rather odd to try to defeat nature with naturalistic arguments."

Somehow, this song and clip from the biologists of Tübingen University squarely captures the topic!

Download: Blume, M. 2009: "The Reproductive Benefits of Religious Affiliation", Heidelberg 2009



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Comments

  1. Bjørn Østman Subject
    22.09.2009 | 00:40

    For religiosity to be adaptive, it is not enough to show that religious people have more children. Rates at which people change their religiosity must be incorporated. Do you have these data?

    For example, assuming that all children born of religious parents become religious themselves, it is very hard to explain that there are any atheists around at all.

    But from an evolutionary as well as philosophic perspective, it may seem rather odd to try to defeat nature with naturalistic arguments."

    Why? Nature can inform us, but that does not mean we should bow to it. This is the same thing with many other aspects of human life. It is "natural" to get diseases and die before the age of thirty, and yet we fight it.

    Lastly, I gather that when you say that there is no consensus on the meaning of the biological terms you mention (adaptation, etc.) that you mean among social scientists like yourself? Evolutionary biologists have strict definitions of the terms, of course.

  2. Michael Blume @ Bjorn Ostman
    22.09.2009 | 06:45

    Welcome and thank you very much for your comment!

    You wrote:

    For religiosity to be adaptive, it is not enough to show that religious people have more children. Rates at which people change their religiosity must be incorporated.

    No, that's not true. Musicality can be adaptive, even if not all children are as musical as their parents or sharing their musical cultures. Variety in expression is to be expected in all biocultural traits. In fact, parents tend to emphasize early education of their children regarding languages, musics and religions because all of these traits are tradited bioculturally.

    Do you have these data?

    Yes, we do explore the cultural side of biocultural evolution too. Data on the influences of mothers and fathers are available online i.e. here:
    http://www.blume-religionswissenschaft.de/...6.pdf

    For the US, there are even more data in the Pew Surveys on Religion, showing that the competitive religious market of the US is able to win higher percentages of the religiously inclined.

    Nature can inform us, but that does not mean we should bow to it. This is the same thing with many other aspects of human life. It is "natural" to get diseases and die before the age of thirty, and yet we fight it.

    Yes, here we agree absolutely. In fact, that was the thrust of my argument. If we want to criticize natural phenomena, we have to take philosophical or theological arguments from beyond nature (i.e. attributing special value to humans). Traditional "naturalistic" lines of criticism deeming religiosity and religion(s) non-natural are simply outdated.

    Lastly, I gather that when you say that there is no consensus on the meaning of the biological terms you mention (adaptation, etc.) that you mean among social scientists like yourself? Evolutionary biologists have strict definitions of the terms, of course.

    Unfortunately, this is not true again. There is no consensus i.e. about the term adaptation, with sometimes small shifts in word use having enormous consequences in analyzes and interdisciplinary cooperation. You may easily falsify that by naming the definition to which all or most biologists agree.

    Maybe you would like to read the opening chapter of the aforementioned book by biologist and philosopher Prof. Eckart Voland about the subject:
    http://www.springer.com/...-0-45-782304-p173894206

    Thank you very much for your sound interest and good questions regarding this expanding topic!

  3. Bjørn Østman Subject
    28.09.2009 | 22:28

    Me: For religiosity to be adaptive, it is not enough to show that religious people have more children. Rates at which people change their religiosity must be incorporated.

    David: No, that's not true. Musicality can be adaptive, even if not all children are as musical as their parents or sharing their musical cultures. Variety in expression is to be expected in all biocultural traits. In fact, parents tend to emphasize early education of their children regarding languages, musics and religions because all of these traits are tradited bioculturally.

    Let me clarify what I meant. Yes, it is adaptive to be religious if religious people have more children. However, whether religiosity will increase or decrease in the population depends on the rates of change of religiosity in individuals. You said "If a trait helps phenotypes to reproduce successfully (on average) throughout generations, it is adaptive and will tend to evolve and spread." Again, this is only true if the heritability is high, and that might not be the case with religiosity. Rates of conversion will cause the two populations to reach an equilibrium, even if the rate of conversion from non-believers to believers is higher than from believers to non-believers.

    Unfortunately, this is not true again. There is no consensus i.e. about the term adaptation, with sometimes small shifts in word use having enormous consequences in analyzes and interdisciplinary cooperation. You may easily falsify that by naming the definition to which all or most biologists agree.

    Okay, sure. "Adaptation is the process whereby an organism becomes better suited to its habitat. Better adapted organisms have higher fitness on average than less well adapted organisms."

    Do you dispute that most biologists will agree with this definition? On what basis?

    I will read your paper from 2006. Thanks.

  4. Michael Blume @ Bjorn
    30.09.2009 | 09:42

    Thanks for your sound post! I'll gladly answer!

    Yes, it is adaptive to be religious if religious people have more children.

    Thanks, that's my point.

    However, whether religiosity will increase or decrease in the population depends on the rates of change of religiosity in individuals. You said "If a trait helps phenotypes to reproduce successfully (on average) throughout generations, it is adaptive and will tend to evolve and spread." Again, this is only true if the heritability is high, and that might not be the case with religiosity.

    A trait could be adaptive even if the heritabiliyt would be low. But available Twin-studies point to the fact that the heritability of religiosity is medium to high, comparable to intelligence and musicality. See:
    http://www.scilogs.eu/...partly-inherited-by-genes

    Rates of conversion will cause the two populations to reach an equilibrium, even if the rate of conversion from non-believers to believers is higher than from believers to non-believers.

    I could agree with that, but it doesn't change the evolutionary picture. Even if we would imagine an equilibrium, the religious part would pass on their genes more succesfully - thereby increasing aspects of religiosity in the overall gene pool. In fact, that's what we see in the evolutionary history of Homo sapiens: Although the short-term levels of religious practice are fluctuating, the long-term path is indicating an increase from the first burials in the Upper Paleolithic to today's universality of complex rituals. We don't know of a single population without religious behavior (not even North Korea or China were able to stamp it out) and we don't know of a single secular population not imploding.

    "Adaptation is the process whereby an organism becomes better suited to its habitat. Better adapted organisms have higher fitness on average than less well adapted organisms."

    Do you dispute that most biologists will agree with this definition? On what basis?

    Thanks, Bjorn - this sentence illustrates my point nicely! It's depicting yet another use of the term "adaptation", without naming any requirements for a trait to be accepted as "adaptation". For example, the ability to read and write sure helps human organisms to become "better suited to its habitat." This may help them to "have higher fitness on average than less well adapted organisms." Nevertheless, most biologists wouldn't count reading and writing as an adaptation, because it's historically very young and not universal.

    I would be interested in your personal opionion. Would you name i.e. reading and writing, musicality and religiosity as adaptations?

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