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.
Monogamy in humans is beneficial because it increases the chances of raising offspring, but it is actually very rare in mammals – less than 10 per cent of mammal species are monogamous, compared with 90 per cent of bird species. Even in primates, where it is more common, only about a quarter of species are monogamous.
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.
Although common in birds, social monogamy, or pair-living, is rare among mammals because internal gestation and lactation in mammals makes it advantageous for males to seek additional mating opportunities.
Among mammals, just 9 percent of species are monogamous; among primates, just 29 percent are. Humans are a diverse lot, but before Western imperialism, 83 percent of indigenous societies were polygynous, 16 percent monogamous, and 1 percent polyandrous (where women have multiple husbands).
In essence, men are only socially monogamous rather than genetically monogamous.
Instead, biological indicators suggest a mating system where both sexes form a long-term pairbond with a single partner (Møller, 2003). And while polygyny was likely present in the human past, as it is across contemporary human societies, the weight of evidence seems to support social monogamy.
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.
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.
If we mean realistic for the species of humans, then the answer clearly is yes. In various cultures around the world people are able to engage in lifelong monogamous relationships.
Monogamy is the concept of having only one partner at a time (sexual and/or romantic). While this is a personal preference and isn't inherently toxic, the idea of toxic monogamy has been defined as monogamous principles of power and control that have been interpreted and practised in unhealthy ways.
“The human mating system is extremely flexible,” Bernard Chapais of the University of Montreal wrote in a recent review in Evolutionary Anthropology. Only 17 percent of human cultures are strictly monogamous.
Many people are not fulfilled in monogamous relationships, and instead pursue other less conventional relationship styles, like polyamory or throuples.
Balance of evidence indicates we are biologically inclined towards monogamy. Science has yet to definitively pronounce on whether humans are naturally monogamous (lifelong male-female breeding pair) or polygamous (single male breeding with more than one female).
Although the Old Testament describes numerous examples of polygamy among devotees to God, most Christian groups have historically rejected the practice of polygamy and have upheld monogamy alone as normative.
But new research is clarifying matters. 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.
REPRODUCTION AND SOCIETY. Humans, like many other terrestrial life forms, reproduce sexually. We, like all other sexual creatures, are subject to instinctive sexual desire triggered by appropriate criteria.
Summary: In cultures that permit men to take multiple wives, the intra-sexual competition that occurs causes greater levels of crime, violence, poverty and gender inequality than in societies that institutionalize and practice monogamous marriage.
But it turns out they were even more promiscuous than we thought. New DNA research has unexpectedly revealed that modern humans (Homo sapiens) mixed, mingled and mated with another archaic human species, the Denisovans, not once but twice—in two different regions of the ancient world.
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).
Ancient Greece and ancient Rome. The ancient Greeks and Romans were monogamous in the sense that men were not allowed to have more than one wife or to cohabit with concubines during marriage.
Benefits include the (relative) certainty of access to the partner's reproductive potential, but the chief disadvantage is that access to other potential partners is strongly diminished, particularly in those cases where males exhibit strong mate-guarding behavior.
More recent field research on a large Canadian sample also found that those in open or polyamorous relationships were just as happy as those in monogamous relationships. The Rubel and Bogaert review reports that most non-monogamous people are just as or more sexually satisfied than monogamists.
Polygyny offers husbands the benefit of allowing them to have more children, may provide them with a larger number of productive workers (where workers are family), and allows them to establish politically useful ties with a greater number of kin groups.