After being raised in a Mormon family in a devoutly religious Mormon community in Idaho, Jordan Moon went on the traditional Mormon mission. He then attended Brigham Young University’s Idaho campus, where a strict code of conduct prohibited not only consumption, but even facial hair. Jordan excelled as a psychology student there, and even published a paper on the psychology of moral judgments.

After graduating from BYU, Jordan (who now sports a long beard, and likes to drink an occasional beer) came to Arizona State to study the psychology of religion with my colleague Adam Cohen. Although he is only midway through graduate school, Jordan has already distinguished himself by publishing several papers in prestigious journals. One of Jordan’s papers, recently released in Current Directions in Psychological Science, has the provocative title “Is Nothing Sacred: Religion, sex, and reproductive strategies.”

The paper argues that people often think about religion in terms of profound and ideas: “concepts about eternal afterlife, immortal battles of good versus evil, transcending the flesh and devotion to the divine.” Those interested in the psychology of religion have also studied the rituals designed to “lift people’s thoughts and behaviors out of the metaphorical gutter of sex and selfishness toward lives full of meaning, contemplation, and community service.”

But the paper’s argument is that maybe those high and holy religious beliefs and practices are often secretly serving base selfish and sexual motivations. Religion may, on this view, be an instrument of people’s preferred reproductive strategies.

Do religions cause , or do monogamous people choose to be religious?

Social scientists have traditionally presumed that one’s religious upbringing is a powerful determinant of one’s sexual behavior. Most religions indeed have strong rules prohibiting premarital sex, extramarital sex, and even private erotic thoughts. I was in Catholic school when pubescent rudely disrupted the innocence of my , and I remember feeling intense about my sinful desires to look inside the provocative covers of the pornographic magazines on sale at the local newsstand. A regular Saturday ritual was to stand in line outside the confessional boxes at St. Joseph’s Catholic church, awaiting Father McNamara’s absolution for those evil thoughts, contingent on my saying five Our Fathers and ten Hail Marys as penance.

But some analyses by my colleague Jason Weeden suggest that, rather than religion dictatorially determining one’s attitudes toward sex, the causal arrow often goes in the opposite direction. For adults, their sexual strategies appear to determine their level of commitment to religion. People who are inclined toward monogamy choose to be religious, because traditional religions provide support for a family lifestyle, and discourage promiscuity. Promiscuity poses problems for family life from both the husband’s and the wife’s perspective. If there is a lot of promiscuity in the local society, then husbands (and their resources) may be easily tempted away from the responsibilities of fathering and family.

Men are, after all, notoriously easy, as attested to by data suggesting they have very low thresholds for a one-night stand, for example (Clark & Hatfield; Li & Kenrick, Kenrick et al., 1990; 1993). But if so, why would men, married or otherwise, want promiscuity discouraged? Weeden links that to paternal uncertainty: a married man is investing heavily in his offspring, and in a totally promiscuous society, the odds would be higher that his female partner’s children might not be his.

Not everyone wants strong constraints on , though. Highly educated people often wait many years past to settle down, as they delay starting a family for up to a decade while attending college and graduate school. Those individuals do not want strong prohibitions against premarital sexuality and birth control because it would mean they’d need to remain celibate for many years, and completely suppress their post-pubertal sexual urges until they get their Ph.D., M.D., or law degree, and then wait a little longer until they find a partner with whom to settle down. Weeden has suggested that the links between religion and reproductive strategy account for many of the heated moral conflicts between the religious right and the irreligious academic elitists on the left.

Several large data sets now provide results consistent with this view of reproductive , suggesting that people’s preferred mating strategies strongly influence their toward, or repulsion from, religion. Weeden finds that the normally high correlations between religious beliefs and other moral attitudes shrink if you control for people’s attitudes towards sex. And Mike McCullough, another prominent expert on the psychology of religion, finds that many people tend to become especially religious during the years when they have children, and then to become less devout later in life.

The reproductive religiosity model helps solve another logical puzzle. It has often been presumed that men use religiosity to control women’s sexuality. But then why is it that women are much more likely to embrace religious beliefs than are men? This becomes less puzzling when one considers that, because of their intrinsically higher initial investment in offspring, women are less likely to benefit from a sexually unrestricted strategy, and more likely to benefit if men’s unrestricted inclinations are kept in check. On this view, women may be actively choosing religion rather than being passively enslaved by it.

Anti-atheist bias may be linked to anti-promiscuity bias

Jordan Moon has contributed to another thought-provoking body of literature, on the against atheists. People really don’t trust atheists. It’s not just that religious people trust people who share their beliefs; they trust people of other religions more than they trust atheists. Even atheists themselves trust religious people more than they do other atheists (Gervais, 2013).

Moon and his colleagues have shown, consistently, that people trust religious people more than non-religious people. However, they did a clever study in which they gave judges information not only about someone’s religious beliefs, but also about their mating strategy. The results suggest that, if you know an atheist also happens to be a committed monogamist, you would trust that person more than you’d trust a religious person who is non-monogamous. Those findings suggest that the distrust of atheists is driven in large part by presumptions about their mating strategies (Moon, Krems, & Cohen, 2018).

Standing in the gutter looking up at the stars

“We are all in the gutter, but some of us are looking up at the stars.” Oscar Wilde

Thinking about human thought and behavior in evolutionary terms often involves mucking around in the gutter, taking a hard look at the underside of human nature. It might seem unseemly to explore the connections between religion and sex. But evolutionary psychologists delve into these topics with one eye on the stars, trying to integrate what we learn about the good, the bad, and the ugly aspects of human nature with what we know about the good, the bad, and the sometimes shocking behaviors of other animal species, from barking hyenas to resplendent peacocks.

Yes, everything human beings do can ultimately be connected to reproduction. My students and other evolutionary psychologists have done research connecting lowly reproductive motives to charity, artistic , self-actualization, and even the search for meaning in life (Kenrick, 2010; Griskevicius, et al., 2006; 2007; Krems, Neel, & Kenrick, 2017). But understanding how such exalted human pursuits connect with the rest of the natural world does not diminish them, any more than does understanding the displays of peacocks or the beautiful songs of hermit thrushes. It’s also important to remember that, for human beings, successful reproduction is about more than just sex (see What drives us more? Sex or Family Values?).

Our ancestors’ reproductive success depended not only on finding a mate, but also on maintaining a long-term relationship with that mate, caring for their children, developing a network of friends and relatives to protect and assist one another, and winning the respect and trust of those friends and relatives. And religion has intimate connections to every one of these fundamental human .

For some additional background on the Reproductive Religiosity Model