How Monogamous Are Humans Really?

AAcross cultures and millennia, humans have adopted a diversity of sexual and marital arrangements – for example, approximately 85% of human societies in the anthropological record have allowed men to have more than one wife.

But in a broader evolutionary context, some researchers have argued that monogamy plays a dominant role in A wise man‘ evolution, allowing greater social cooperation. This theory aligns with research on mammals, birds and insects, which suggests that cooperative breeding systems – in which offspring receive care not only from parents, but also from other group members – are more prevalent among monogamous species.

To understand how monogamous humans have been throughout our evolutionary history and compare our reproductive habits to those of other species, University of Cambridge evolutionary anthropologist Mark Dyble collected genetic and ethnographic data on a total of 103 human societies around the world, dating back 7,000 years. He then compared this data to genetic data from 34 species of non-human mammals. Using this information, Dyble traced the proportion of siblings throughout history and across all 35 species. After all, higher levels of monogamy are linked to greater numbers of siblings, while the opposite is true in more polygamous or promiscuous contexts.

It is “a direct, theoretically important, but relatively neglected approach” to understanding specific mating systems, he wrote in a new paper published in Proceedings of the Royal Society B.

Dyble estimated the proportions of half-siblings in these populations and fed the genetic information into a model that calculated a monogamy rate for each population. This allowed him to compare different species.

On a descending list from most to least monogamous, the California deer mouse took first place, with 100% of its siblings estimated to be full siblings. Meanwhile, humans come in seventh, with 66 percent of siblings estimated to be full siblings, below the Eurasian beaver but above the white-handed gibbon.

“There is a premier league of monogamy, in which humans sit comfortably, while the vast majority of other mammals take a much more promiscuous approach to mating,” Dyble said in a statement, comparing the rankings to that of a professional football league in England.

This suggests that, despite the mix of marriages and matings throughout human history, we collectively appear to display higher levels of monogamy than most of the animals tracked in the study. Meanwhile, our primate relatives are mostly at the bottom of the list, including several species of macaque monkeys and the common chimpanzee.

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The list ranks humans highly among species known to be socially monogamous, but we have a few key differences from these animals. For example, we only give birth to a few pups per pregnancy, rather than entire litters, and live in social groups where multiple females have children. Dyble believes that human monogamy arose from non-monogamous group living, an unusual transition in the animal kingdom that may be due to the different evolutionary pressures humans face compared to other species.

Although these results are a rough estimate of monogamy across species and examine only a small portion of the large number of species on Earth, Dyble believes they provide strong evidence that this lifestyle was essential to human evolution — it helped give rise to large family networks that “were the first step in building the large-scale societies and cultural exchange networks that were crucial to our success as a species,” he wrote.

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Main image: NatalyaDDD / Shutterstock

• Molly Glick

  Published on December 9, 2025

  Molly Glick is the newsletter editor of Nautilus.