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Key points
- Polygamy (having multiple spouses) has been an enduring fixture of human mating, leaving a mark on our mating psychology.
- We can see evidence of this today in how modern humans approach polygamy.
- New research shows that interest in polygamy exists in the UK, despite people being socialized otherwise.
From marriage to friends with benefits, intimate relationships come in different varieties. Recently, a polyamorous wave has spread over the Western world, with increased discussion around, and interest in, multi-partner relationships.
One type of multi-partner relationship is polygamy, whereby one person has multiple spouses. The most common form is polygyny, where a man marries several women and, according to anthropological records, 85% of human cultures permit it.
A mating arrangement largely ignored by the West
If 85% seems suprisingly large, it’s because the practice of marrying more than one partner (bigamy) is banned in most modern Western cultures. And while the West contains a large proportion of the world’s population, it holds a much smaller percentage of its cultures.
Polygamy isn't necessarily the default mating arrangement even within cultures that practice it, further masking its significance. Polygyny (where one man has several wives) tends to be reserved for a small number of high-status men who can offer co-wives a better deal than they could get from lower-status monogamous partners.
What about the other way around? When it comes to polyandry — the practice of women marrying several husbands — we find very few cultures practice this at all and when they do it tends to be out of necessity, like in historic Tibet where economic conditions made it desirable for brothers to share a wife to avoid dividing family assets.
Nonetheless, polygamy is a very real part of the human mating landscape and brings costs and benefits to those who enter into these multi-partner unions.
Polygamy has likely been around for a while
While we don’t see polygamy very often in the West, it might be premature to say that interest in it doesn’t exist. With polygamy present in most human cultures, and all hunter-gatherer cultures (whose living conditions are the closest match to those of early humans), it’s possible that polygamous relationships have been part of the human mating landscape for a long time and that our mating psychology has evolved to accommodate them.
Polygamous interest in a mono-normative culture
This then begs the question: Although polygyny is banned in Western cultures, do people still show an interest in it? Recently, we tried to answer this question by running two studies in the UK, where bigamy has been banned since the early 17th century and is currently punishable by up to seven years in prison.
We asked 393 heterosexual men and women if they would be interested in entering into a committed long-term relationship resembling polygyny and polyandry if it were both legal and consensual. Men, for example, were first asked if they would be willing to be shared by more than one girlfriend or wife and then asked if they would be willing to share a girlfriend or wife with another man.
If polygamous interest was a product of culture alone and malleable, then we’d expect interest to be quite low in the UK given the clear societal and legal pushback against it. However, we actually found that 35% of people were open to the idea of polygyny — answering either “Yes” (19%) or “Unsure” (16%) rather than “No”. For polyandry, 25% of people answered either “Yes” (10%) or “Unsure” (15%).
The sexes differ in their polygamous interest
We also found some interesting sex differences. For polygynous relationships, men were more than twice as likely to be open to the idea than women. However, for polyandry both sexes showed similar, low levels of interest. This polygyny-polyandry difference reflects the fact that men have evolved a tendency to be drawn to the idea of having multiple partners because biological differences allow for men to increase their number of offspring by mating with several women — while women gain no such benefit from mating with multiple men.
These findings replicate across different samples
Were the results a fluke? We repeated the study with 735 more participants, this time focusing just on polygyny. The results were very similar – 38% selected either “Yes” (24%) or “Unsure” (14%) and men were four times more likely to be open than women were. Of course, interest is one thing and acting upon interest is another. But these findings provide some initial evidence that polygynous interests persist despite cultural forces acting against them.
We explored even more in our study, finding that while both sexes preferred monogamy and singlehood over either type of polygamy, polygyny was one of the “least undesirable” types of mating arrangement involving more than two people. You can read the full article as a pre-print here.
References
Thomas, A. G., Harrison, S., Stewart-Williams, S., & Workman, L. (2022). Polygamous Interest in a Monogamous Nation: The Role of Sex and Sociosexuality in Openness to Polygamy in a UK Sample.
