Humans have been placed 7th out of 35 mammal species in a new study ranking monogamy, outperforming meerkats and gibbons — but falling short of more committed species such as Eurasian beavers and moustached tamarins.
The research, led by Dr Mark Dyble of the University of Cambridge, compared levels of genetic relatedness across species. By calculating how often siblings shared both parents rather than just one, scientists could estimate how monogamous each species tends to be. Humans showed 66% full siblings, placing us firmly within the “monogamous league”, while beavers scored 72% and meerkats 60%.
At the top of the table sits the California deermouse, while some of the least monogamous mammals include feral cats, bottlenose dolphins and chimpanzees. Mountain gorillas ranked especially low at just 6%, reflecting highly promiscuous breeding structures.
Dyble noted that human societies vary widely, with ancient populations showing monogamy levels anywhere from 26% to 100%. The findings suggest that, compared to other mammals, humans evolved a rare tendency toward pair bonding — though the reasons for this remain debated. Many researchers believe monogamy may have developed alongside paternal care, giving offspring a better chance of survival.
Experts caution that human relationships are shaped by far more than biology. Religious and cultural norms have historically enforced pair bonding, while modern societies still show frequent serial monogamy or polygamous tendencies.
Despite our high ranking, researchers say the real mystery lies not in how humans compare — but in how we became monogamous at all, given our closest relatives lean strongly toward promiscuity.
As it stands, humans make the top tier — just not quite at beaver level.
