Humans Rank Between Meerkats and Beavers in the Monogamy “League Table”

Genetic evidence suggests humans are far more reproductively monogamous than most primates and resemble other socially monogamous mammals.

Humans show levels of exclusive mating that are much closer to species such as meerkats and beavers than to most of our primate relatives, according to a new study from the University of Cambridge that ranks monogamy rates across different mammals.

In the past, researchers studying human sexual selection relied largely on fossil evidence and anthropological observations. By contrast, studies of other animals have typically drawn on long-term monitoring of social behavior and genetic paternity testing to understand how mating systems work.

Sibling genetics as a new metric

Dr. Mark Dyble from Cambridge’s Department of Archaeology introduces a different way to assess monogamy by examining the balance between full siblings and half-siblings in many animal species, as well as in human populations spanning different periods of history.

Dyble explains that species or societies with higher levels of monogamy tend to produce more siblings who share both parents. In groups where polygamous or more promiscuous mating is common, half-siblings are more frequent.

To quantify this pattern, he developed a computational model that links sibling data from recent genetic studies to established reproductive strategies. The result is an estimated monogamy score that can be compared across species.

Although the method is not exact, Dyble argues that it offers a more direct and tangible way to compare monogamy across a wide range of animals and across human societies over thousands of years than many earlier approaches.

Humans rank high but not alone

“There is a premier league of monogamy, in which humans sit comfortably, while the vast majority of other mammals take a far more promiscuous approach to mating,” said Dyble, an evolutionary anthropologist at the University of Cambridge.

“The finding that human rates of full siblings overlap with the range seen in socially monogamous mammals lends further weight to the view that monogamy is the dominant mating pattern for our species.”

Debate over human monogamy has a long history. Many scholars have suggested that stable pair bonds played a key role in fostering the cooperation that helped humans thrive globally.

At the same time, anthropologists have documented great diversity in human mating and marriage practices. Earlier studies indicate that 85% of pre-industrial societies allowed polygynous marriage, where a man is married to several women at the same time.

To estimate human monogamy levels, Dyble drew on genetic evidence from archaeological sites, including Bronze Age cemeteries in Europe and Neolithic settlements in Anatolia. He also incorporated ethnographic data from 94 societies worldwide, ranging from the Hadza hunter-gatherers of Tanzania to the rice-farming Toraja communities of Indonesia.

“There is a huge amount of cross-cultural diversity in human mating and marriage practices, but even the extremes of the spectrum still sit above what we see in most non-monogamous species,” said Dyble.

How humans compare across mammals

The study, published in Proceedings of the Royal Society: Biological Sciences, has humans at an overall 66% rate for full siblings, placing us seventh of eleven species in the study considered socially monogamous and preferring long-term pair bonds.

Meerkats come in at a 60% full sibling rate, while beavers just beat humans for monogamy with a 73% rate. As with humans, this suggests a significant trend towards monogamy for these species, but with a solid amount of flexibility.

The white-handed gibbon comes closest to humans in the study, with a monogamy rate of 63.5%. It’s the only other top-ranked “monotocous” species, meaning it usually has one offspring per pregnancy, unlike the litters had by other monogamous mammals.

The only other non-human primate in the top division is the mustached tamarin: a small Amazonian monkey that typically produces twins or triplets, and has a full sibling rate of almost 78%.

All other primates in the study are known to have either polygynous or polygynandrous (where both males and females have multiple partners) mating systems, and rank way down the monogamy table.

Mountain gorillas manage a 6% full sibling rate, while chimpanzees come in at just 4% – on a par with dolphins. Various macaque species, from Japanese (2.3%) to Rhesus (1%), sit almost at the bottom of the table.

An unusual evolutionary transition

“Based on the mating patterns of our closest living relatives, such as chimpanzees and gorillas, human monogamy probably evolved from non-monogamous group living, a transition that is highly unusual among mammals,” said Dyble.

Among the few with a similar evolutionary shift are species of wolf and fox, which have a degree of social monogamy and cooperative care, whereas the ancestral canid was likely to have been group-living and polygynous.

The Grey Wolf and Red Fox sneak into the upper league with full sibling rates of almost half (46% and 45% respectively), while African species have much higher rates: the Ethiopian wolf comes in at 76.5%, and the African Wild dog is ranked second for monogamy with a rating of 85%.

Top of the table is the California deermouse that stays paired for life once mated, with a 100% rating. Ranked bottom is Scotland’s Soay sheep, with 0.6% full siblings, as each ewe mates with several rams.

What sets humans apart

“Almost all other monogamous mammals either live in tight family units of just a breeding pair and their offspring, or in groups where only one female breeds,” said Dyble. “Whereas humans live in strong social groups in which multiple females have children.”

The only other mammal believed to live in a stable, mixed-sex, multi-adult group with several exclusive pair bonds is a large rabbit-like rodent called the Patagonian mara, which inhabits warrens containing a number of long-term couples.

Dyble added: “This study measures reproductive monogamy rather than sexual behavior. In most mammals, mating and reproduction are tightly linked. In humans, birth control methods and cultural practices break that link.”

“Humans have a range of partnerships that create conditions for a mix of full and half-siblings with strong parental investment, from serial monogamy to stable polygamy.”

Monogamy League Table

Reference: “Human monogamy in mammalian context” by Mark Dyble, 10 December 2025, Proceedings of the Royal Society B: Biological Sciences.
DOI: 10.1098/rspb.2025.2163

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