Is monogamy actually better than non-monogamy?

It’s still very much an open question—and one with no clear answers, in part because scientists can’t break free of a certain worldview gripping their field.

Monogamy is so much a part of the emotional makeup of Western culture that even people who study relationships fail to notice their biases towards it, according to research due to be published this week. And that means the very way we study intimacy has some fundamental flaws.

The primacy given to monogamous unions isn’t surprising given the historically patriarchal societies that dominate the world: An economic system predicated upon handing down property from father to son is invested in certainty about paternity and on clear family lines.

But times have changed. Researchers from the University of Michigan set out to determine whether the ways psychologists and other scientists study relationships are geared up to deliver results that—even unconsciously—promote monogamy. They concluded that the very way we study intimacy is problematic.

Terri Conley, the study’s lead author, said that our attitudes to monogamy are “so ingrained as to be invisible.”

“It’s not even that we think about it being right,” she said. “We just see it as the only way.” The way that science assesses relationships has skewed what researchers find, according to the study, due to be published in Perspectives on Psychological Science.

First, a review of literature revealed a number of examples where the approach taken by researchers could have made it more likely for monogamy to “score” higher than alternative styles of relationship. One example is a measure called the “Passionate Love Scale,” developed in the 1980s and used to gauge the strength of affection within relationships. The scale includes a question about how jealous it would make the respondent if their partner began falling in love with someone else—with greater jealousy leading to a higher “passion” score for the current relationship. A relationship that was consensually non-monogamous, or CNM, wouldn’t necessarily be free from jealousy. But it might allow for a partner to love someone else, so the question wouldn’t be a good measure of whether the feelings within it were “passionate.”

The researchers also point out that in relationship surveys non-monogamy is often referred to using language that isn’t neutral: Asking people about “infidelity,” or “cheating” is directive, they say; as is referring to one person as the “offended party” or the “betrayed partner”—all terms that have appeared in academic studies.

Conley, who runs the Stigmatized Sexualities Lab at the University of Michigan, has often questioned the orthodoxies of research on sexuality in relationships, and says that she has encountered resistance from other researchers, and reviewers of the papers she has published over the past years—with some responding emotionally to her raising the very concept of exploring non-monogamy. In one study, Conley found that consensually non-monogamous couples were more likely to practice safer sex than monogamous couples who were secretly cheating on their partners. One reviewer called the paper “irresponsible.” In another case, a reviewer referred to gay relationships that “deteriorate” into non-monogamy.

“The fact that we can allow our discussion to be so emotionally led probably doesn’t allow us to really think in a logical manner” about it, Conley said.

The Michigan study also argues, based on a survey of couples in a variety of relationships, that consensually non-monogamous relationships are just as “functional,” based on a number of indicators, as monogamous ones. The researchers surveyed over 2,000 people over the age of 25, 617 of whom were in CNM relationships, and all of whom were in primary relationships with a person of the opposite gender. Based on a range of measures including trust, jealousy, passion, and overall satisfaction, they found no difference in relationship-functioning between the groups.

In a final, separate study they also looked at how people reacted to researchers when those researchers were asking about non-monogamous relationships. The researchers themselves were seen as more biased when they asked questions about polyamory than when they asked about monogamy. (This was a much smaller study of 100 people recruited through Mechanical Turk, a platform on which people are paid to answer questions, so methodologically less sound than the larger study.)

In recent years, polyamory and other alternative relationship styles have begun to be normalized, in some quarters, Conley said. But for now, the study found, “the premise that monogamy is superior to other types of non-monogamous relational arrangements continues to permeate the ways in which researchers construct and test theories of love and intimacy.”

We’re unlikely to get a clear picture of what kind of relationships work best for humans until science acknowledges its own tendency to cling to monogamy as the ideal.

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