Quote from : Sex at Dawn: The Prehistoric Origins of Modern Sexuality Book

Marriage," "mating," and "love" are socially constructed phenomena that have little or no transferable meaning outside any given culture. The examples we've noted of rampant ritualized group sex, mate-swapping, unrestrained casual affairs, and socially sanctioned sequential sex were all reported in cultures that anthropologists insist are monogamous simply because they've determined that something they call "marriage" takes place there. No wonder so many insist that marriage, monogamy, and the nuclear family are human universals. With such all-encompassing interpretations of the concepts, even the prairie vole, who "sleeps with anyone," would qualify.