Why do you give a damn if your neighbor lights up a joint?  According to traditional views, people are raised in conservative homes and this leads them to have a range of conservative attitudes— with opposition to pot-smoking, opposition to premarital sex, and opposition to abortion all just downstream consequences of going to a conventional church on Sunday, and listening to a stern old pappy read the Bible on Monday. But a study by Penn’s Rob Kurzban, Amber Dukes, and Jason Weeden, slated to appear in the Proceedings of the Royal Society B, suggests that those traditional theories may have the causal arrow aimed in the wrong direction. Their data suggest that opposition to recreational drugs may be instead the result of an opposition to casual sex.

In an earlier posting, I discussed Jason Weeden’s related research with Adam Cohen and Jessica Li, which suggested that religious conservatism can be a result of, rather than a cause of, a monogamous mating strategy (click here to see a discussion of the links between those conservative mating strategies and lower intelligence). Weeden’s general theoretical approach is based on an evolutionary life-history model, and he presumes that our mating strategies are at the core of many of our other choices, with profound influences on our religious beliefs, our attitudes about whether it’s OK to meddle in other people’s sexual behaviors, and as his new research suggests, even our attitudes about recreational drugs.

I interviewed Jason Weeden, who explained how this all works:

"I see a variety of "family values" issues as ultimately rooted in competing reproductive strategies.  Some people build desirable lives around stable marriages. Those marriages are genuinely put at risk when your society doesn't discourage casual sex. Other people build desirable lives around a liberated sexual ethos, and those kinds of lives are made worse off when there are prudish people imposing punishments and social costs on them. It's very hard for these kinds of committed and promiscuous lifestyles to peacefully co-exist, because they really do threaten each other. You find them in conflict throughout human history and, indeed, throughout the animal kingdom."

Weeden continued: "People on the committed end of the spectrum end up not only trying to discourage casual sex, but they also go after the things that often accompany casual sex. These include things like dressing sexy, no-fault divorce, using recreational drugs, and even abortion."

To explore the causes of people’s opinions about drugs, Kurzban, Dukes, and Weeden analyzed questionnaires from 516 undergraduate students at the University of Central Florida and 471 individuals recruited from Amazon’s ‘Mechanical Turk’ website. Participants reported whether they identified as liberals or conservatives, whether they were religious or not, and also rated how they felt about a number of current political issues. They also answered questions about their personalities, disgust sensitivity, moral views, and their attitudes about sex. And they told the researchers how they felt about recreational drugs, and about whether they thought using marijuana, cocaine and Ecstasy were moral, and should or should not be legalized.

The researchers were able to predict people's views on drugs by ignoring their political beliefs and personality and just asking a few questions about casual sex, such as "Sex without love is OK." Contrary to the traditional causal models, once you know about someone’s casual sex attitudes, you don't gain much of anything by also knowing their religiosity, political ideology, or personality traits. 

As Weeden puts it:

"This is an important finding because it lets us compare two competing hypotheses about where moral attitudes about recreational drug come from in the first place. One model claims that people oppose recreational drugs or not because of how religious they are, how liberal or conservative they are, and their personality traits (for example, how "open to experiences" they are). The other model views sexual and reproductive strategies as really important in determining people's attraction to churches, or political views, or personality traits.  The data clearly supported the reproductive strategies model."

More broadly, this research fits with Kurzban and DeScioli’s ideas on morality, which I discussed in an earlier post on the moral reactions to Tiger Woods (click here to see that discussion)  Kurzban’s view is that moral beliefs are not so much about trying to inspire me to do the right thing myself, as they are about trying to control your behavior in ways that support my reproductive goals.

Related posts:

Atheistic liberal ARE smarter, but for a funny reason.

In “Defense” of Tiger Woods, AND of his critics

Religious piety as a mating strategy

Jew, Jesuits, and Geniuses: The religion-IQ link is JUST a correlation.

Why are pot-smokers less likely to be obese?


DeScioli, P., & Kurzban, R. (2009). Mysteries of morality, Cognition, 112, 281-299.

Kurzban, R. (2010).  Sex, Drugs, and Moral Goals: Reproductive strategies and views about recreational drugs.  Proceedings of the Royal Society B.  In press.

Li, Y.J., Cohen, A.B., Weeden, J., & Kenrick, D.T. (2010). Mating Competitors Increase Religious Beliefs. Journal of Experimental Social Psychology. 46, 428-431.

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

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