Animals Humans are less monogamous than beavers
Modern humans belong to the small minority of monogamous mammals - and rank between the Eurasian beaver and the primate species white-handed gibbon in terms of mate fidelity.
10.12.2025, 01:01
SDA
This is the conclusion drawn by evolutionary anthropologist Mark Dyble from the University of Cambridge in England from a comparison of Homo sapiens with 34 other mammal species.
The researcher examined the ratio of full siblings to half siblings - i.e. offspring with only one common parent - in the offspring of these species. The proportion of full siblings in humans averages around 66 percent.
By comparison, in the Californian mouse (Peromyscus californicus), the proportion is 100 percent. For the African wild dog (Lycaon pictus) it is 85 percent, and for the Damara graumull (Fukomys damarensis) and the Ethiopian wolf (Canis simensis) just under 80 percent each.
Humans rank between the Eurasian beaver (Castor fiber, 73 percent) and the white-handed gibbon (Hylobates lar; just under 64 percent) in the list of species included, as Dyble writes in the journal "Proceedings of the Royal Society B: Biological Sciences". The vast majority of non-monogamous mammals include the black rhinoceros (Diceros bicornis) and the European badger (Meles meles), in each of which the proportion of full siblings is roughly 20 percent.
Soay sheep brings up the rear in terms of monogamy
At the bottom of the list are the bottlenose dolphin (Tursiops truncatus) with 4 percent, the orca (Orcinus orca) with 3 percent and various macaque species with roughly 1 to 2 percent. At the bottom of the monogamy list is the Soay sheep. In this feral domestic sheep, which lives on the Scottish island of the same name, full siblings are extremely unusual with a proportion of 0.6 percent.
"Monogamy is the dominant mating pattern in our species," concludes Dyble in a statement from his university. "In contrast, the vast majority of other mammals have a far more promiscuous approach to mating." Overall, only nine percent of mammal species are monogamous.
In order to determine the monogamy level of a species, Dyble compared sibling data from genetic studies in different mammals. Although this is somewhat crude in view of the patchy data, it is the most direct and concrete method of investigation, he explains.
Monogamy crucial for success
Monogamy in humans also applies to those societies in which men have several wives or women have several husbands. "There is huge cultural diversity in human mating and marriage practices," says Dyble. "But even the extremes in this spectrum are above what we see in most non-monogamous species."
In contrast to humans, our closest relatives, the great apes, are highly promiscuous: In the eastern gorilla (Gorilla beringei), the proportion of full siblings is only around 6 percent. In the common chimpanzee (Pan troglodytes), it is only 4 percent - similar to dolphins.
The moustached tamarin (Saguinus mystax), which lives in the Amazon region, occupies a top position among the monogamous non-human primates. In this species, which belongs to the marmoset family (Callitrichidae), full siblings account for 78 percent of the offspring.
The evolutionary anthropologist Dyble assumes that human monogamy favored the development of large kinship networks. This was the first step towards the creation of large societies and networks of cultural exchange, which in turn were decisive for the success of mankind.
