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.
According to the New York Times, a 2011 paper showed that early humans, or hominids, began shifting towards monogamy about 3.5 million years ago—though the species never evolved to be 100% monogamous (remember that earlier statistic).
Monogamy as policy
As Christianity emerged in the Roman Empire in the first centuries AD, it embraced monogamy and took it further, insisting that two people must reserve their bodies and desires for each other, marriage becoming 'an everlasting threesome with God'.
Modern polyamory and modern polyamorous communities, as opposed to individually chosen group marriages that existed in mostly-hidden manners or religious groups with beliefs regarding plural marriage, have their basis in the 1960s and 1970s and the so-called Sexual Revolution.
Evolution dictates that genes have the final say. And if there is one thing genes want, it is to spread as far and wide as possible. That is why monogamy is rare among mammals. Females have to wait for a long gestation period to have a child, where as males could go and inseminate many other females in that time.
Although polygamy is practiced in various cultures, humans still tend toward monogamy. But this was not always the norm among our ancestors. Other primates – the mammalian group, to which humans belong – are still polygamous, too.
Monogamy, after all, does not come naturally; it is not the norm unless a society enforces it as such. There are immense benefits to doing so. But it is unclear how well we humans can achieve this aim in the present environment.
Monogamy has appeared in some traditional tribal societies such as the Andamanese, Karen in Burma, Sami and Ket in northern Eurasia, and the Pueblo Indians of the United States, apparently unrelated to the development of the Judeo-Christian monogamous paradigm.
Being in love with two people may be more common than some think. Studies show that many individuals worldwide identify as polyamorous, meaning they partake in relationships with or feel attracted to more than one individual at a time.
Monogamy the Jewish Ideal. In Judaism the Law tolerated though it did not enact polygamy; but custom stood higher than the Law. From the period of the return from the Babylonian Exile, monogamy became the ideal and the custom of Jewish married life.
As a polygynous society, the Israelites did not have any laws which imposed monogamy on men. Adulterous married and betrothed women, as well as their male accomplices, were subject to the death penalty by the biblical laws against adultery.
Some anthropologists believe that polygamy has been the norm through human history. In 2003, New Scientist magazine suggested that, until 10,000 years ago, most children had been sired by comparatively few men.
Humans are broadly monogamous, so the researchers suggested that there might be a link between a species' digit ratio and sexual strategy. If they are right, Neanderthals – who had ratios in between the two groups (0.928) – were slightly less monogamous than both early modern and present-day humans.
When asked in September 2016 about their ideal relationship, 61 percent said it would be completely monogamous. In January 2020, that number has dropped slightly, to 56 percent. Many Americans are already in non-monogamous relationships or marriages.
Genetic monogamy
Though individual pairs may be genetically monogamous, no one species has been identified as fully genetically monogamous. In some species, genetic monogamy has been enforced. Female voles have shown no difference in fecundity with genetic monogamy, but it may be enforced by males in some instances.
For humans, monogamy is not biologically ordained. According to evolutionary psychologist David M. Buss of the University of Texas at Austin, humans are in general innately inclined toward nonmonogamy.
In essence, men are only socially monogamous rather than genetically monogamous.
This means that of all marriages, 58 per cent are monogamous. Only men in the top 10 per cent of status married more than two women. The most wives that anyone has is four.
Roman marriage was a monogamous institution: Roman citizens could have only one spouse at a time but allowed divorce and remarriage. This form of monogamy in Greco-Roman civilization may have arisen from the relative egalitarianism of democratic and republican city-states. Roman marriage had precedents in myth.
We now know that the first hominins, which emerged more than seven million years ago, might have been monogamous. Humans stayed (mostly) monogamous for good reason: it helped them evolve into the big-brained world conquerors they are today.
In the Middle Ages, as in other ages, powerful men married monogamously, but mated polygynously. Both laymen and church men tended to have sexual access to as many women as they could afford. But first-born sons were allowed a legitimate wife, on whom they got legitimate heirs.
John Gill comments on 1 Corinthians 7 and states that polygamy is unlawful; and that one man is to have but one wife, and to keep to her; and that one woman is to have but one husband, and to keep to him and the wife only has a power over the husband's body, a right to it, and may claim the use of it: this power over ...
Most hunter-gatherers were monogamous. Most hunters could provide only enough meat for one wife and her children. The best hunters could support two wives (polygyny).