QuestionAre humans meant to be monogamous?
Hopes&Fears answers questions with the help of people who know what they’re talking about. Today, we ask psychology, biology, and sexuality experts whether humans are wired to stay together.
We live in an age of abundant dating apps and short attention spans, of Dan Savage columns, and new sexual frontiers like "monogamish" and polyamory. Recently, Vanity Fair devoted a hotly-debated exposé to the deletrious effects of hookup culture, with author Nancy Jo Sales calling the widespread frustration and disenchantment precipitated by Tinder and its ilk the "dating apocalypse."
All of this begs the question: is finding a "soulmate" or "true love" still a thing? Are humans actually designed to pair up for life? If not, then why are we still so compelled toward it? Is it biology and genetics, or culture and society? The debate rages on: studies come out and refute one another, books are written and reviewed, experts are cited and dismissed. We tracked down psychologists, biologists, and family and sexuality experts for the answer.
Christopher Ryan, Ph.D.
Author, Sex at Dawn: How we Mate, Why we Stray, and What it Means for Modern Relationships
These are slippery terms. What does "meant to be" mean? What about "monogamous"? I'll assume they mean "evolved to be" and "long-term sexually monogamous" (as opposed to socially monogamous, for example). In that case, it's clear that Homo sapiens did not evolve as a monogamous species. We are very unusual among mammals in our proclivity for a wide range of non-reproductive sexual practices. We have sex hundreds of times for every baby conceived, whereas most mammals sport a ratio closer to a dozen-to-one. We have sex when the female isn't even ovulating—or with no female even involved! That's not typical of mammals. Our bodies, our fantasies, and the fact that we have so many strict regulations around sexual behavior all indicate the depth of our passion for novelty. And why shouldn't we be attracted to novelty in our sexual lives, when we consider the same appetites to be indicative of intelligence when applied to music, travel, food, languages, art, etc.?
Why do I think we are monogamous? I don't. When we can get away with it, vanishingly few of us restrict ourselves to a single sexual partner over a lifetime. Having only one lover at a time isn't monogamy—it's closer to serial polygyny. Some cultures demand sexual monogamy, but they need to resort to horrible punishments to enforce these brutal, anti-human laws—a clear indication of just how strong our sexual appetites are. No animal needs to be stoned to death to do what comes naturally.
Infidelity by the numbers
of men have thought about cheating on their partners
of women have had the same thought
of men claim to have never thought about cheating on their partners
of women claim the same
of men admitted to actually cheating on a partner
of women admitted the same
Professor of History and Family Studies, Evergreen Stage College; Director of Research and Public Education, the Council of Contemporary Families; author, The Way We Never Were: American Families and the Nostalgia Trap
I don't think that humans are meant to be monogamous or polygamous. We have impulses toward both, and how we handle those depends upon our social settings, cultural traditions, personal values, and individual problem-solving techniques.
In some societies, wealthier or more powerful men take several wives. In others, a woman may be married to more than one man. Some are fairly lax about discreet extramarital affairs, even though marriage may be confined to two people. Jealousy is always a potential problem, but many societies frown upon it, considering it unseemly. Among the Bari of Venezuela, any man who sleeps with a woman when she is pregnant is considered to be a joint father, obligated to offer part of whatever he hunts or catches to the child after birth. The men take their obligations so seriously that a child whose mother sleeps with someone other than her husband is more likely to be well-nourished than one whose mother was "faithful."
Some societies impose monogamy on women, but allow men to have more than one wife, to take mistresses or concubines, and/or engage in adulterous affairs. This is usually associated with male dominant, kinship-based cultures where the inheritance of property and social status makes elites very concerned about protecting the "purity" of their bloodline. In the late 19th century, despite upholding an ideology of monogamy, so many men in Europe and America visited prostitutes that there was an epidemic of venereal disease among "respectable" middle-class wives.
By contrast, modern Americans have much higher expectations for mutual fidelity than was common through most of history, although we are also very accepting of premarital sex and divorce. Today, we are trying to figure out how to combine long-term romantic relationships with the plethora of opportunities for other forms of sexual or romantic entanglement, and different people are making different choices. The point is that we do have choices about our sexual behavior—and whatever we end up choosing, it's always going to take work to make the best of them.
Top five reasons people cheat
They feel flattered by the attention
They feel emotionally deprived in their relationship
They are dissatisfied with their sex lives
They enjoy the thrill
They are unable to commit to one partner
Elisabeth Sheff, Ph.D.
Educational consultant and expert witness for sexual and gender minorities; author, The Polyamorists Next Door: Inside Multiple-Partner Relationships and Families
I'm not sure if there is any intention behind it, but monogamy certainly is not "natural" in that it does not seem to be effortless for anyone. Things that are "natural" for people—like breathing, blinking, and wanting to protect our children—do not need nearly so many social strictures to keep them in place. Monogamy, or any form of sexual exclusivity, however, has many rules and laws governing it.
Rather than the naturalness of monogamy, the fact that cultures around the world and across time have created hundreds or thousands of protocols and punishments to patrol and enforce sexual exclusivity (especially for women) indicates that it is socially constructed and not something humans will do "naturally" without external intervention. If humans didn't crave a variety of sexual experiences with new partners, then cultures would not have to work so hard to keep people from having sex with someone who is not their spouse.
While researching consensual non-monogamy, I found that many (or maybe even most) people seem to want to be able to have multiple lovers themselves, and want those lovers to be monogamous with them. Basically, it seems more natural for humans to want a personal harem, so each of us get to enjoy sexual variety, but insist on sexual exclusivity for our lovers, so we don't have to deal with jealousy.
Only 3-5% of mammal species are considered to be monogamous.
David P. Barash
Professor of Psychology, the University of Washington; author, The Myth of Monogamy: Fidelity and Infidelity in Animals and People, Strange Bedfellows: The Surprising Connection Between Sex, Evolution and Monogamy (with Judith Eve Lipton, MD) and Out of Eden: The Surprising Consequences of Polygamy (forthcoming).
I'm often asked whether people are "naturally" monogamous, and similarly, whether monogamy itself is obsolete. The truth is that people aren't naturally monogamous and, indeed, rather than being obsolete, monogamy is relatively recent, and that's much of the problem! What's obsolete is polygamy, which was—and to some extent, still is—the "natural" default system for human beings. Monogamy definitely isn't natural, as attested by much of our biology, including the presence of sexual dimorphism (men being typically larger than women, with substantially more muscle mass) in our species.
In addition, men are significantly more inclined to violence than women, and boys become sexually and socially mature later than girls. All these traits are characteristic of animal species in which one male attempts to mate with multiple females; they are strongly consistent with male-male competition for such opportunities. Beyond this, the anthropology of human polygyny is quite clear, given that before the homogenization of so many traditional societies caused by Western colonialism, roughly 83% of indigenous human groups were preferentially harem-forming. For their part, women are typically less overt in their preference for multiple sexual partners, but they, too, find monogamy more restraining than Victorian stereotypes would suggest. Add this up, and there is no question that a visiting Martian observer would conclude that Homo sapiens is biologically polygamous.
Paradoxically, harem formation was especially hurtful to men, more than to women, since in any harem-forming species with an equal sex ratio, only a minority of men are mated, leaving most excluded and sexually frustrated, in addition to being subject to comparatively high levels of competition, sometimes violent and even lethal. On the other hand, it is clear that women in harem societies are generally poorly treated as well; although they are likely to end up mated to high status men, their actual reproductive success is often reduced by competition among co-wives, not to mention that they are often physically and emotionally abused and restricted by their own romantic and mating choices.
No one knows precisely how and why monogamy became culturally institutionalized, largely in the Western world, from which it has spread. One possibility is that monogamy represented a social exchange whereby powerful polygynists essentially agreed to forego their exclusive access to women, and to share marriage opportunities with otherwise excluded bachelors, in return for a degree of social harmony and relative peace. (From elephant seals to Homo sapiens, bachelor males are socially disruptive.) It is unclear to what extent women were influential in this "agreement," since it can at least be argued that they would be better off as the fourth or even twentieth wife of a very wealthy man than as the only wife of a pauper. In any event, rather than being an old and outmoded institution, it is a biological newcomer for the human species. And herein lies much of the stress associated with monogamy, which is definitely under siege, though not from radical feminism, some sort of home-wrecking homosexual agenda, or rampant, irresponsible pleasure-seeking, but from our biology itself.
Both genders are inclined to seek multiple sexual partners. For men, the underlying evolutionary calculus is obvious: more matings with different women can result in enhanced evolutionary fitness via a larger number of offspring. For women, the predisposing factors are more complex and nuanced, including possibly obtaining better genes for their children, improved access to material resources, prospecting for possible social advancement, and so forth. But for both men and women, the costs of non-monogamy can also be severe, including abandonment of one's children by the cuckolded spouse, as well as social ostracism and even violence. Indeed, for all the liability and strain involved in suppressing our biological inclinations for non-monogamy, the reality is that for human beings, monogamy offers distinct advantages as well. Notable among these is biparental care. In any species experiencing internal fertilization, males, but not females, are stuck with a profound biologically mandated uncertainty: mommy's babies, daddy's maybes. As a result, it is very rare for any species to engage in biparental care unless the males are guaranteed confidence of their genetic relatedness to the offspring, a confidence that monogamy alone can provide. And because human children need so much parental assistance, protection and investment, we, perhaps more than any other animals, are especially benefitted by monogamy (which, incidentally, needn't necessarily involve individuals of two different sexes).
It is important to emphasize that even though monogamy definitely isn't natural to human beings, and therefore isn't easy, it is nonetheless possible, as well as offering some important benefits. Many of humanity's most notable accomplishments—learning to play the violin, speak multiple languages, perform delicate surgery—are equally "unnatural", but are assuredly good. They also, like successful monogamy, require hard work. It is easy to do "what comes naturally"; animals do it all the time! Perhaps what makes human beings special is our ability to do things that are "unnatural," whether those things are obsolete or—like monogamy—are socially imposed and thus new to our evolutionary experience.
Infidelity and morality
of people believe married people having an affair is morally wrong
believe it is morally acceptable
believe it is not a moral issue
Psychotherapist, relationship counselor, educator; author, The Ethical Slut
My personal opinion is that for humans, monogamy is not particularly "natural," and may be beneficial in some circumstances and problematic in others. As to why so many of us think we are supposed to be monogamous, I think that as our society evolved into an urban, job-based society monogamy became important to governments and churches that wished to control populations for their own benefit by instilling lots of guilt and shame about sex, thus making us all feel bad about ourselves when we experience perfectly normal (and delightful!) desires.
What matters to me the most, however, is that we can make many arguments about what is "natural" or "unnatural," but I know from experience that many people learn to create the relationship and sexual lifestyles that they desire, and find a way to fit themselves into the culture while they're at it.
Politically, I support monogamy when it is freely chosen, along with all the other choices about sex and relationships, given the ethical proviso that no harm is done to anyone in the process.
Nancy Jo Sales, "Tinder and the Dawn of the 'Dating Apocalypse'", Vanity Fair