Who's Open to Non-Monogamy, and to Which Type

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Having a "one-sided" multiple-partner relationship means you're either cheating or you have an approved relationship where you maintain more than one partner. Does that sound appealing to you?

Monogamy Norms May Ignore Some Evolutionary Pressures

Traditionally, multiple-partner relationships have not been sanctioned in Western cultures. Indeed, Western norms tend to emphasize monogamy, the practice of having one partner at a time; yet, from a global and historical perspective, monogamy is only one type of relationship structure. Ancestrally, evolutionary pressures may have favored non-monogamy in some situations, such as when sex ratios are imbalanced, resources are scarce, or, in other ways, provided a critical reproductive advantage.

Today, about one in five Americans/Canadians (20 percent) have had some experience with consensual non-monogamy (CNM), a rate similar to cat ownership (Moors, 2023). CNM is not the most common approach to relationships, but it is not uncommon.

Perhaps these statistics reflect a human evolutionary history that benefited from diverse mating strategies. Keep in mind, however, that CNM is a broad category. What is less understood today are rates of specific types of CNM.

New Research Surveys Interest in Polygyny and Polyandry

Are Westerners open to polygamy? This empirical question was put to the test by Thomas and colleagues (2023). In polygamous relationships, one person maintains multiple sexual partners, but those partners are not in sexual relationships with each other. Globally, the most common subtype of polygamy is polygyny, wherein one man has access to multiple women. Less common is its counterpart, polyandry (i.e., where one woman has access to multiple men).

Researchers (Thomas et al., 2023) invited approximately 400 people from the U.K. to imagine that social rules allowed for polygamy. In this legal and social hypothetical, would they want to participate as the "one" with multiple partners? Would they want to participate as a partner of the "one?"

Researchers also asked participants about their preferences for different relationship structures. A second study (approximately 750 participants) replicated their key findings.

Men Are More Open to Polygyny than Women to Polyandry

Are people OK with polygamy? Generally, no. Most people find polygamy undesirable, a key finding that deserves attention. Indeed, most people prefer monogamous relationships or being single to the experience of polygamy.

At the same time, in approximately one-third of the study, one respondent was not opposed to participating in polygamy. This is a sizeable minority. A clear gender difference emerged, such that men were more likely to say "yes" to polygyny than women were to polyandry, which was generally unpopular.

Interestingly, people's preference for polygyny appeared stronger than other types of multi-partner relationship structures, such as having ongoing secret affairs or the occasional known liaisons with casual partners.

Hypothetical Questions Offer Insight to a Point

This research offers a fascinating window into the mating brain (Thomas et al., 2023). If people truly knew what they would do in hypothetical circumstances that allowed for it, then perhaps non-monogamy would be more frequent than it is today. A third of people, after all, suggested openness to polygamy.

Hypothetical questions, however, are hypothetical. The extent to which responses would translate into reality is impossible to know, given the strong social and cultural norms surrounding monogamy today.

Further, can we truly answer a hypothetical question about non-monogamy participation when our minds have been immersed within a cultural context that favors monogamy?

People reported strong preferences for monogamy and indicated more favorable ratings of being single than having multiple partners (Thomas et al., 2023). This preference perhaps reflects the many evolutionary advantages of mating with one partner (e.g., lower paternity uncertainty, faithful co-parent, resource access).

Indeed, a brain wired towards monogamy may drive the cultural focus on monogamy, yet this preference may also reflect that emphasis. Either way, most Western people today are oriented towards the most common relationship structure: monogamy.

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