The evolutionary significance of religion is a hot topic. Several researchers have suggested that religious belief is one or another sort of parasitic meme that exploits the existing architecture of the human mind (I made joking reference to this view in my earlier post How the Dawkins Stole Christmas, but I suggest a couple of serious readings below). Others have asked whether religious beliefs might be adaptive in some way -- inspiring group cohesiveness or helping us stay in line when we're not sure whether anyone is watching.

But in some recently published findings Jessica Li, Jason Weeden, Adam Cohen, and I have approached religion from another adaptationist angle. Rather than searching for the causes of heavenly beliefs inside people's heads, we started the search in their corporal bodies, investigating how religious participation might directly serve some people's reproductive strategies.



In a pair of experiments now in press at the Journal of Experimental Social Psychology, we asked people about their belief in God and about the importance of religion in their lives. The most fascinating aspect of the research was this: seeing a lot of highly attractive and available fellow students made subjects profess more belief in God.

Want to guess how it worked? Was it seeing attractive members of the opposite sex that made people more religious? That's what I would have predicted. And I'd have guessed further that the effect would be found in men, for whom a lot of beautiful and available women would mean more opportunities for unrestricted sex. But I was wrong.

What we found instead was this: Women professed more religious piety when they saw beautiful women; men were more likely to look to the heavens when they saw a lot of handsome men.

The findings fit with some earlier research we reported in Evolution and Human Behavior. Weeden, Cohen and I had analyzed data from 21,131 people in the U.S. General Social Survey. We also asked 902 students at four American universities about their family plans, their sexual attitudes, their religious attendance, their moral feelings about stealing, lying, and so on. We found the strongest predictors of attending church were those related to sexual and family values (opposition to infidelity, to premarital sex, to abortion, and the like). When we statistically controlled for the sexual and family value items, the links between religious attendance and the other moral values disappeared.

These earlier findings made two important points. First, conservative attitudes about sex and reproduction are at the heart of people's participation in traditional religious groups. Second, attitudes about sex and family are causes of religious attendance, and not just effects of religious training. The traditional view was that religious teachings cause people to hold conservative attitudes about sex; our findings suggested that conservative attitudes may cause people to become involved in religion.

If our Reproductive Religiosity theory was correct, we reasoned that people might decide to increase or decrease their level of religious participation as a function of whether that participation would advance or hinder their current sexual and reproductive strategies. In fact, we began to wonder whether the link between religiosity and reproduction was malleable enough to move around with a laboratory manipulation. The results of the two experiments in press - showing that people in fact become more religious after seeing attractive competitors - are consistent with this reasoning.

Why does this happen? We think the results fit with the idea that people must choose between a conservative monogamous lifestyle and a more freewheeling unrestricted approach. When you become aware that there are a lot of highly attractive mating competitors out there, it reduces the perceived benefits of playing a fast and loose mating strategy (popular among many undergraduates at schools like Arizona State or UCLA, where mating opportunities might sometimes seem unlimited). For women, a lot of beautiful competitors means less attention from the attractive men who might provide good genes, and perhaps even vie to support your offspring. For men, an abundance of especially handsome and available guys means that if you're playing the field, you may be playing with yourself for most of the game. When circumstances suggest limited opportunities, any normal person -- who does not look like a fashion model - could benefit from those religion-based supports for monogamy.

These findings are especially interesting in light of the traditional tendency to focus on religiosity's roots in genes, temperament, and early childhood upbringing. They suggest that religiosity can also be a flexible strategic response to the current mating environment.

Doug Kenrick is the author of the recent book Sex, Murder, and the Meaning of Life: A psychologist investigates how evolution, cognition, and complexity are revolutionizing our view of human nature.  


Li, Y.J., Cohen, A.B., Weeden, J., & Kenrick, D.T. (2010). Mating Competitors Increase Religious Beliefs. Journal of Experimental Social Psychology. In press

Weeden, J., Cohen, A.B., & Kenrick, D.T. (2008). Religious attendance as reproductive support. Evolution & Human Behavior, 29, 327-334.

More on the evolutionary psychology of religious beliefs:

Boyer, P. (2003). Religious thought and behaviour as by-products of brain function. Trends in Cognitive Science, 7, 119-124.

Johnson, D., & Bering, J. (2006). Hand of God, mind of man: Punishment and cognition in the evolution of cooperation. Evolutionary Psychology, 4, 219-233.

Kirkpatrick, L. A. (2005). Attachment, evolution, and the psychology of religion. New York: Guilford.

Shariff, A. F., & Norenzayan, A. (2007). God is watching you: Priming God concepts
increases prosocial behavior in an anonymous economic game. Psychological Science,18, 803-809.

Wilson, D. S. (2002). Darwin's Cathedral: Evolution, Religion, and the Nature of Society. Chicago: University of Chicago Press.

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