In the state of nature, people were generally polygamous, as are most animals. With many animals, the male leaves the female soon after mating and long before any offspring are born.
According to genetic studies, it is only relatively recently, about 10,000 years ago, that monogamy began to prevail over polygamy in human populations. Monogamous unions may have developed in tandem with sedentary agriculture, helping to preserve land and property within the same narrow kin group.
Polygamy may enable a man to sire more offspring, but monogamy can, in certain circumstances, represent a more successful overall reproductive strategy. In particular, by guarding a single female, a male can ensure that the female’s offspring are also his, and prevent the infants from being killed by male rivals intent on returning the female to fertility.
Historically and still today, most cultures that permit polygamy permit polygyny (a man taking two or more …