Fruitful and Multiply: Integrating Rowthorn’s work into a framework in which religion and science complement

(The family pictured above is the Duggar family. They have 19 kids and are the subject of the TLC show 19 and Counting.  As stated on their website, "They asked God to bless them with as many children as He saw fit in His timing".  The mother gives birth around every 1.5 years)

If religious people have more children, will their genes and behaviors take over the world?

I believe in religion and science and their capacity to complement.  As an example: whatever happens to you has to engage biology, chemistry, and physics.  Let’s say I have a new idea for an experiment or for one of my courses that will change the world.  Regardless of where that idea came from—God, my own experience, some combination—to ‘have’ the idea, my brain, neurons, ions, and genes had to undergo a complex bunch of biologic events, and all these events follow the principles of physics and chemistry.  More than that, insights and principles from science, I believe, can get us thinking in new ways about religion and society and vice versa.

So, Robert Rowthorn’s recent study caught my eye.  Rowthorn starts with two points: first, evolution affects culture and culture affects evolution.  Twin studies suggest genes play a significant role in our moral compasses and behaviors, and recent work says that human culture—due to its massive and constant migrations, globalization, and innovation—probably actually speeds up genetic evolution. 

And second, there’s the well-established observation that religious folks have, on average, more kids than the non-religious. This is true even when controlling for education or income, and it’s due not just to the ultra-religious groups that encourage larger families. For example, surveys find if you go to religious services at least once a week, on average you have more kids than if you go once a month, and those people average more kids than people who don’t go at all.

Rowthorn then builds some models based on evolutionary biologists’ understanding of how genes move in a population (genes are inherited or ‘move’ from one’s parents and are passed to one’s offspring, but only, of course, if one has them).  To better understand phenomena, scientists often take observations, make some assumptions and simplifications within reason, and then develop mathematical models to make predictions.  This is more than just an exercise in nerdiness, but good models can help us make solid policies, prevent and cure disease, etc. 

So, Rowthorn says we inherit both our genes and initial religious affiliation from our parents, then he makes the reasonable assumption that genes can affect our religiosity, but culture drives how many children we have.  For simplification his models also assume religiousness is related to one gene, and religious people marry only other religious people, or, if a ‘mixed’ marriage occurs, one partner converts to the other’s religiosity.

What happens in these models?  Well, if one group has especially high fertility rates, the people in that group can affect the overall human gene pool by growing larger internally as a group or by defecting and bringing their genes and genetic capacity outside the group.  Either way, more religiosity genes get into the gene pool, increasing the chances that humans as a whole get more religious.  If the very fertile folks stay within their group, there’s still more of them and their genes; if they defect, those genes move into those outside their group. 

Who cares?

Well, if the very-fertile groups keep marrying within their group, the groups will most likely continue to grow at their current rate and the result will be vast, unsustainable numbers of people in these groups.  Cultural constraints—resources, more defections, general increased secularity—might work to constrain growth. Even if they marry externally, they are bringing more religiosity genes into the gene pool overall, which might have intriguing effects on societal evolution. Genetic constraints will also be at work. Are ‘religiosity’ genes more advantageous in one environment than another?

As scientists can only do in obscure journals (and even then only at the very end of their papers), Rowthorn gets a little tongue-and-cheek and goes out on a limb in discussing possible societal implications for his findings.  He quotes a study that suggests religiosity is associated with conservatism and ‘obedience to authority’, so if more religiosity genes are out there, well. . . make your own conclusions.  Or, as Rowthorn says, ‘The implications of such a development are beyond the scope of this paper to consider’.

Yes, being tongue-in-cheek in such circumstances can get you in trouble, but I prefer to take the long view of such work, that is, to integrate work like Rowthorn’s into a framework in which religion and science complement, rather than contend.  Science, then, is to religion as genes are to environment—wholly reliant and intra-resonant.   

Questions arising from such a view might move and extend our cultural evolution.  Questions like: All complex human traits involve genes and the environment; how does religion help us to understand each other and our world more effectively?  All of us share the same gene pool; what are the moral and scientific implications of this most fundamental connection?  Can biology help us better understand the creation of a sustainable world?  In such questions, live potentially rich (and fertile) conversation.

Arri Eisen

Arri Eisen is a Senior Lecturer in Biology for Emory University's Center for Ethics and co-editor of Science, Religion, and Society: History, Cultures, and Controversies (M. E. Sharpe, 2007). His Science in Your Life radio spots, which aired on Atlanta's NPR affiliate, can be found here.