Religiosity may function as a mating strategy shaped by disease avoidance psychology

A recent study suggests that religiosity may serve an adaptive role in human evolution by supporting monogamous mating strategies. The researchers found that people who are more sensitive to pathogen-related disgust also tend to be more religious, and this connection is partly explained by a preference for more restricted sociosexual attitudes. In contrast, the study found no support for other theories that tie religiosity to adherence to tradition or avoidance of outgroups.

The findings, published in Evolutionary Behavioral Sciences, contribute to a growing body of research suggesting that religious behaviors and beliefs may serve deeper evolutionary functions, particularly in helping individuals avoid the costs associated with mating in a pathogen-rich environment.

Religiosity is one of the most widespread and persistent features of human culture, but from a strictly evolutionary standpoint, it presents something of a puzzle. Participating in religious rituals, adhering to religious norms, and avoiding counter-normative behaviors often entail significant opportunity costs. And yet, religiosity is a near-universal phenomenon across human societies. This raises a key question: Why would such a costly behavior persist throughout human evolution?

One line of research suggests that religiosity might be an adaptive response to the threat of infectious disease. The behavioral immune system—a set of psychological mechanisms evolved to detect and avoid pathogens—might influence how religious someone becomes. Since religious norms often promote cleanliness, discourage promiscuity, and sometimes limit contact with outsiders, they might serve to reduce exposure to disease.

Although past studies have linked disgust sensitivity to both religiosity and social conservatism, the specific psychological pathways that connect them remain unclear. The current study set out to test three possible explanations: first, that religiosity arises from a desire to adhere to traditional cultural practices; second, that it stems from a tendency to avoid contact with outgroup members who may carry unfamiliar pathogens; and third, that it is driven by a more monogamous sexual strategy designed to reduce disease risk from mating.

“Religiosity is an evolutionary puzzle, because it has evolutionary fitness costs but is ubiquitous throughout societies,” said study author Benjamin Zubaly, a PhD student at the University of Michigan and member of the Evolutionary Social Psychology Lab.

“Moreover, not everyone is religious to the same degree, and previous work has shown that the level of one’s religiosity is related to psychological disease avoidance processes. We were interested in understanding the nexus of these problems. That is, how can the psychology of disease avoidance help us to understand why people differ in how religious they are?”

The researchers recruited 289 adult participants from a broad range of national and ethnic backgrounds using the online platform Prolific. Participants completed a series of questionnaires assessing their religiosity, disgust sensitivity, sociosexual orientation, support for traditionalism, and ethnocentrism.

To assess how religious each participant was, the researchers used a brief but comprehensive tool known as the Centrality of Religiosity Scale, or CRS-5. This scale includes five items that reflect different dimensions of religious involvement. One item asks about how often participants think about religious issues, capturing their intellectual engagement with religion. Another item addresses their belief in core religious teachings, such as the existence of God or a higher power. Two more items ask about their behavior—how often they attend public religious services and how frequently they engage in private practices like prayer. The final item assesses religious experience, such as whether participants feel personally connected to the divine.

To measure disgust sensitivity, the researchers focused specifically on pathogen-related disgust—a type of emotional reaction believed to be part of the behavioral immune system. For this, the researchers used the pathogen disgust subscale of the Three Domains of Disgust Scale. This subscale includes items that ask participants to rate how disgusted they would feel in response to scenarios that involve potential contamination, such as stepping in dog feces, seeing moldy food, or coming into contact with someone who is sneezing without covering their mouth.

To capture participants’ sexual attitudes and strategies, the researchers administered the attitudes subscale of the Revised Sociosexual Orientation Inventory. This subscale asks participants how strongly they agree or disagree with statements about casual sex. For example, they are asked whether they believe that sex without love is acceptable or whether they think they need to be emotionally involved with someone before becoming sexually active.

To measure traditionalism, the researchers used a modified version of the Conventionalism subscale from a broader authoritarianism questionnaire. This subscale typically assesses how strongly someone supports traditional norms and values, such as respect for authority, loyalty to established customs, and opposition to change. The modified version used in this study removed items with overt religious or sexual content in order to avoid overlap with the religiosity and sexual strategy measures. Instead, it focused on more general statements about preserving traditional ways of life and maintaining societal stability, allowing for a cleaner test of whether traditionalism—apart from religion or sexuality—helps explain the link between disgust sensitivity and religiosity.

Lastly, the researchers assessed outgroup avoidance tendencies through a measure of ethnocentrism, specifically using the in-group preference subscale of the Generalized Ethnocentrism Scale. This scale asks participants to rate how much they prefer members of their own cultural or national group over those from other groups. Items may include statements such as “I prefer to be with people of my own culture” or “I feel more comfortable around people who are like me.” In this study, ethnocentrism was used as a stand-in for a broader desire to avoid outgroup members, which, according to some disease-avoidance theories, may function as a way to reduce exposure to unfamiliar pathogens.

The strongest and most consistent finding was that individuals who were more sensitive to pathogen-related disgust tended to report higher levels of religiosity, and that this relationship was partially explained by more restricted attitudes toward casual sex. People who preferred a monogamous mating strategy were more likely to score higher on measures of religiosity.

This effect was statistically significant and accounted for approximately 34 percent of the total link between disgust and religiosity. The findings were robust across multiple statistical models, remained consistent when sex was controlled for, and held up even when looking only at participants who identified as religious.

“We tested a variety of explanations for why disease avoidance psychology may influence how religious one is. Our results showed that people who were more sensitive to experiencing disgust tended to be more religious to the extent that they also had more monogamous sexual attitudes. This suggests that one function of religiosity may be to support a monogamous mating strategy, thereby reducing disease risk on the mating scene.”

By contrast, the researchers found no support for the idea that the link between disgust and religiosity is driven by a desire to follow traditional norms. When using a version of the traditionalism scale stripped of explicitly religious or sexual content, the researchers found no significant relationship between disgust sensitivity and support for traditional values.

Similarly, there was no evidence that disgust leads to religiosity through a desire to avoid outgroup members. The researchers used a general measure of ethnocentrism to avoid cultural or sexual bias, but still found no significant associations. This suggests that previous findings tying disgust sensitivity to outgroup prejudice may reflect confounding with sexual norms, especially attitudes toward sexual minorities.

An exploratory analysis also tested whether other components of sociosexuality—such as sexual desire or behavior—might play a role in explaining the disgust-religiosity link. However, only sociosexual attitudes, which reflect personal views on the acceptability of casual sex, were found to be a significant mediator. Desire and behavior did not account for any part of the relationship.

“There were some surprising results. We found no evidence for the ideas that traditional practices or out-group avoidance may be playing a role in the relationship between disease avoidance and religiosity, despite previous research suggesting this may be the case. Additionally, we found that our results were primarily driven by sexual attitudes, rather than sexual desire. Future work can help to unpack the implications of this distinction.”

This finding suggests that what people believe or approve of when it comes to sex plays a stronger role than what they feel or actually do. While that might seem surprising, it aligns with the idea that religiosity functions more as a guide for managing mating norms than as a direct response to sexual impulses.

As with all research, the study has some limitations. The sample, while international, was composed mostly of individuals who identified as Christian. Since different religious traditions vary in how strongly they emphasize monogamy or regulate sexual behavior, the results may not apply equally across faiths. Future studies involving non-Western or non-Christian participants could help clarify whether the findings generalize.

Additionally, while the data support a model in which disgust sensitivity leads to religiosity through a preference for monogamous sexual behavior, the research is correlational and cannot establish causality. The researchers acknowledge that it is possible for religiosity to shape sexual attitudes or even disgust sensitivity, although prior work suggests that this direction of influence is less likely.

“This work is a part of a large body of research that aims to understand how the psychology of disease avoidance interacts with the social world. Future work in this area can help us to better understand those basic social processes.”

The study, “Sociosexual Attitudes Mediate the Relationship Between Behavioral Immune System Reactivity and Religiosity,” was authored by Benjamin Zubaly, Kelly Arbeau, and Jaime Palmer-Hague.