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).
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.
They found convincing support for the hypothesis that monogamy arose as a mating strategy where males could not defend access to more than one female. Monogamy is associated with low density of females, low levels of home-range overlap, and indirectly, with their diets.
“We have a very big advantage over many other species by having pair bonds,” says University of Montreal anthropologist Bernard Chapais. The monogamous couple also forms the basis for something uniquely human—the vast, complex social networks in which we live.
By mating with more than one male over the course of her lifetime, a female gains higher genetic variation among her offspring. The benefits of monogamy, which are shared parental care and territorial resources, are maintained by having only one mate at a time, or by concealing extra-pair partnerships.
Monogamy does exist in nature, as, of course, do females who seek out multiple partners. But nature does seem to push things in the direction of polygyny on our branch of the evolutionary tree. Among mammals, just 9 percent of species are monogamous; among primates, just 29 percent are.
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 ...
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.
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. But, Buss argues, promiscuity is not a universal phenomenon; lifelong relationships can and do work for many people.
Socially imposed monogamy was first established in ancient Greece and Rome (even if sexual infidelity with concubines and slaves was largely tolerated).
There is little doubt that the “natural” mating system for human beings is polygamy, which includes two different reproductive arrangements: polygyny and polyandry. In polygyny, one man mates with more than one woman, a “harem” as traditionally understood. In polyandry, one woman mates with more than one man.
Denisovans are close relatives of both modern humans and Neanderthals, and likely diverged from these lineages around 300,000 to 400,000 years ago; they are more closely related to Neanderthals than to modern humans.
Neandertals and anatomically modern humans overlapped geographically for a period of over 30,000 years following human migration out of Africa. During this period, Neandertals and humans interbred, as evidenced by Neandertal portions of the genome carried by non-African individuals today.
Most of us have some Neanderthal genes, study finds. The study uncovered the first solid genetic evidence that "modern" humans—or Homo sapiens—interbred with their Neanderthal neighbors, who mysteriously died out about 30,000 years ago.
The Talmud interprets this as a requirement for a man to provide food and clothing to, and have sex with, each of his wives, even if he only has one. As a polygynous society, the Israelites did not have any laws which imposed monogamy on men.
Fourth-century Roman law forbade Jews to contract plural marriages. A synod convened by Gershom ben Judah around 1000 CE banned polygamy among Ashkenazi and Sephardic Jews.
Bible Gateway 1 Corinthians 7 :: NIV. But since there is so much immorality, each man should have his own wife, and each woman her own husband. The husband should fulfill his marital duty to his wife, and likewise the wife to her husband.
Modern culture tells us that each person has their “one,” a perfect partner to share the rest of their lives with. Although polygamy is practiced in various cultures, humans still tend toward monogamy. But this was not always the norm among our ancestors.
In many cases, monogamy can be justified on grounds of practicality, specialness, or jealousy. There have been many assumptions in the philosophy of love and sex, not to men- tion popular culture, that monogamy is the only possible form of romantic love or at least the most ethical sexual and romantic practice.
Probably the biggest factor in why it is hard to remain monogamous is that there are several drives built into us that contribute to reproduction, but they do not work in unison. First up is simple lust.
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.
The PNAS paper, which analyzed 230 species of primates, concludes that protecting the kids is the greatest benefit of male monogamy. By sticking close to his mate a male reduces the risk of infanticide.
Probably not. Ethical considerations preclude definitive research on the subject, but it's safe to say that human DNA has become so different from that of other animals that interbreeding would likely be impossible.