Humans are now mostly monogamous, but this has been the norm for just the past 1,000 years. Scientists at University College London believe monogamy emerged so males could protect their infants from other males in ancestral groups who may kill them in order to mate with their mothers.

Are humans naturally monogamous?

Humans aren't sexually monogamous in the sense that many birds are. ... We are termed 'socially monogamous' by biologists, which means that we usually live as couples, but the relationships aren't permanent and some sex occurs outside the relationship.

Are humans monogamous or promiscuous?

In between is a whole range of unique love arrangements, from men with many wives to women who marry two brothers. Humans are also, by and large, less promiscuous than their primate cousins. Only about 30 percent of primates and 3 percent of all mammals are monogamous, Wlodarski told Live Science.