Humans rank 7th out of 35 mammal species for monogamy, according to a University of Cambridge study comparing the share of full siblings within populations. On average, 66% of human siblings share both parents, placing us above meerkats and gibbons, but still behind more loyal partners like Eurasian beavers at 72%.
The study found monogamy varies widely across human societies, from as low as 26% in some ancient populations to 100% in others. Most mammals are far less monogamous — chimpanzees, dolphins and mountain gorillas all scored extremely low due to promiscuous mating systems.
Scientists believe human monogamy likely evolved as a strategy tied to paternal care and offspring survival, though cultural and religious structures have also reinforced pair bonding throughout history.
In short — humans are notably monogamous among mammals, even if the beavers are still doing it better.
