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Key points
- Religions often seem preoccupied with proper sexual behavior.
- The reproductive-religiosity model suggests religion’s interest in sex may be partly related to its facilitation of long-term mating strategies.
- Being religious may serve as a social signal that one is faithful or desires long-term commitment.
Religions (especially Western religions) concern themselves with proper behavior. This often includes sexual behavior: Religions have much to say on premarital sex, homosexuality, adultery, etc.
And religious individuals who fail to follow the religious rules regarding proper sexual behavior are frequently made to feel guilty, ashamed, and afraid (e.g., of social rejection by the community or punishment in the next world).
But why are there so many religious rules about sex? Why are many religions obsessed with sex?
An article published in the August issue of Current Opinion in Psychology, written by Jordan Moon of Arizona State University, sheds light on religion’s preoccupation with sexuality and sexual behavior. In this post, I summarize the major arguments of that paper on the link between religion and sex.
Religion and promotion of long-term mating
Religion must be so powerful, one may think, to be able to force its followers to abide by seemingly random rules concerning sex and relationships. But could it be that people who desire highly committed relationships are drawn to religious belief systems specifically because these practices promote committed relationships?
That is partly what Moon’s “reproductive-religiosity model” suggests. It claims religion promotes “committed, highly invested, and long-term mating strategies,” and imposes “costs on the behavior inconsistent with these mating strategies.”
Given its emphasis on the promotion of long-term mating strategies, religion could be particularly appealing to those who prefer committed and highly invested relationships, such as to individuals beginning to start a family and raise children.
Religion and sexual reproduction
Compared to the nonreligious, religious folks frequently have bigger families and more children. But how does religion influence reproduction?
For one, religion might make parenting less costly (and more so for men than women):
The evolutionary perspective suggests men usually benefit from having multiple mates and from minimizing their parenting efforts, especially given paternity uncertainty. The cost of paternity uncertainty is that fathers may, unknowingly, provide resources for children who are not theirs.
By making extramarital sex more costly (e.g., shaming, punishment), religion makes parenting investments safer for men.
Research support for this idea comes from different types of studies; for example, recent experimental work found reminding participants of their religious identity increases the likelihood that they will judge immoral behavior (e.g., promiscuity) more harshly.
And religious men, a study of Dogon men (in West Africa) found, were less likely to fall victim to cuckoldry (having an unfaithful wife). Why? Perhaps due to unique religious beliefs and practices, such as “menstrual taboos, including menstrual huts.” Note, these huts allow “men and their families to monitor wives during and after menstruation.”
Another way religion makes parenting a safer choice is by increasing the odds that one’s offspring survive. Studies have found “religious identification and ritual frequency” are positively linked with alloparenting—parenting by the community members who do not have young children at the time.
In summary, the relationship between religion and sexual reproduction may have to do with religion empowering people to follow a successful reproductive strategy—a strategy linked with “high fertility, high paternal certainty, and low child mortality rates.”
Religion as a social signal
Given the above associations between religion and long-term mating strategies (e.g., faithfulness, family orientation), religious views and practices can also serve as social signals for qualities desired in a long-term romantic partner.
To understand this implication, we first need to remember the difference between men and women in terms of relationship and mating preferences: Men may desire short-term relationships; women may desire long-term relationships. Thus, to mate, men sometimes deceive women by pretending to be interested in long-term relationships, just as women sometimes deceive men by feigning interest in short-term sex.
A person’s religiousness, however, could be a more reliable signal, suggesting the person is faithful, desires long-term commitment, or wants to start a family.
Even in domains other than mating, religious people are often seen as more trustworthy when compared to the nonreligious. Again, this may have little to do with the particular religion they follow and more to do with what religiousness suggests about those individuals—that they are committed, sexually restricted, invested in their families, not impulsive, etc.
The evolution of religions
The relation between religion and sex, particularly mating strategies, can also explain the evolution of world religions.
Consider monogamy (i.e., having sexual relations or being married to only one romantic partner at a time):
Monogamy, which is promoted and enforced by many religions (e.g., Christianity), is a successful mating strategy for a variety of reasons, some of which have group-level benefits. For instance, compared to single men, married men are less likely to engage in antisocial behaviors and criminal activities. And women in monogamous relationships do not have to compete with other women or worry about their children being harmed by other wives (as could occur in polygynous marriages).
Indeed, the Western Church—later evolving into the Roman Catholic Church—and its family policies (e.g., promotion of monogamy, taboos on cousin marriage) have been influential in cultural evolution responsible for Western culture’s characteristics, like high independence, individualism, and trust of strangers; and lower obedience and in-group loyalty.
Religion and the puzzle of celibacy
Let us end our discussion of religion and sex with a brief examination of celibacy, which, unlike other religious practices, does not increase fertility. So, how do we explain the puzzle of celibacy?
Moon offers three answers. For one, those who choose priesthood and celibacy may have less desire for (or access to) potential mates. Second, priesthood might help these individuals gain access to status or resources beneficial to their relatives, thus increasing their relatives’ attractiveness as mates (i.e., the individual’s cost of celibacy is offset by benefits to genetic relatives). Third, celibacy vows are not necessarily kept; indeed, due to being trusted by the community, priests often have numerous sexual opportunities available.
