Is Monogamy Natural?

(Humphrey Bogart): A man takes a drop too much once in a while, it’s only human nature.
 (Katherine Hepburn): Nature, Mr. Allnut, is what we are put in this world to rise above.
~ The African Queen (1951)

Which is more natural for human beings, monogamy1 or polygamy? If one is more natural, does that make it preferable?

Most documented human societies, about 85%, have been polygamous. This almost always involves polygyny, men having multiple wives. Polyandry, wives having multiple husbands and polyamory, having more than one consensual, intimate relationship at the same time, are far less common. Even in so-called monogamous cultures people have affairs, and they often engage in serial monogamy, the custom of having multiple, consecutive sexual relationships but not more than one at a time. Perhaps humans are naturally polygamous.

Yet there are examples in nature of mostly monogamous relationships: lar gibbons, mute swans, Malagasy giant rats, waved albatrosses, California mouses, black vultures, shingleback skinks, sandhill cranes, prairie voles, convict cichlids, some African antelopes, and … humans. Humans are capable of long-term, happy, monogamous relationships, just as they are capable of having polygamous ones.

So it is hard to say whether monogamy or polygamy is more natural. It might be like asking whether it is more natural to speak English or German. Humans are wired to learn language just as they naturally crave contact with others, but culture largely determines the language they learn and the forms of their relationships.  Nature doesn’t determine which language or relationship is best. And even if one is more natural than the other that doesn’t make it better. Some natural things are good, but some are bad—like smallpox!

Moreover, humans have both long-term and short-term mating strategies. We associate long-term mating strategies with monogamy. These strategies value commitment, gene quality, economic prospects and parenting skills. We associate short-term mating strategies with polygamy. These strategies value physical attractiveness, sex appeal, and sexual experience. But nature doesn’t decree which types of relationships are morally or biologically better.

Regarding the origins of monogamy the situation is straightforward:

The genetic evidence for the evolution of monogamy in humans is more complex but much more straightforward. While female effective population size (the number of individuals successfully producing offspring thus contributing to the gene pool), as indicated by mitochondrial-DNA evidence, increased around the time of human (not hominid) expansion out of Africa about 80,000–100,000 years ago, male effective population size, as indicated by Y-chromosome evidence, did not increase until the advent of agriculture 18,000 years ago. This means that before 18 000 years ago, many females would be reproducing with the same few males.[36]

This strongly suggests that monogamy is a cultural imperative, not a biological one. And the modern world favors monogamy—polygamy is illegal in the entire developed world.  Why the transition from polygamy to monogamy? The main reason is that polygyny is detrimental to society. It creates an incentive for men to take many wives, leaving other men without wives—and men without mates cause problems. In polygynous societies levels of crime, violence, poverty and gender inequality are greater than in monogamous ones as a recent study at the University of British Columbia confirmed:

… monogamy’s main cultural evolutionary advantage over polygyny is the more egalitarian distribution of women, which reduces male competition and social problems. By shifting male efforts from seeking wives to paternal investment, institutionalized monogamy increases long-term planning, economic productivity, savings and child investment …

Monogamous marriage also results in significant improvements in child welfare, including lower rates of child neglect, abuse, accidental death, homicide and intra-household conflict, the study finds. These benefits result from greater levels of parental investment, smaller households, and increased direct “blood relatedness” in monogamous family households …

… By decreasing competition for younger and younger brides, monogamous marriage increases the age of first marriage for females, decreases the spousal age gap and elevates female influence in household decisions which decreases total fertility and increases gender equality.

It seems that we should favor the wisdom of culture over our genetic lease. Still, you might object. “Even if it’s in society’s interests to have stable monogamous unions that doesn’t mean it’s in mine. I like polygamous or polyandrous relationships.” It is hard to give a knockdown argument against this. If all involved parties are happier in such relationships, and the effects on society are limited, then so be it.

I can only speak for myself by echoing the words of that great freethinker Voltaire:

As I had now seen all that was beautiful on earth, I resolved for the future to see nothing but my own home; I took a wife, and soon suspected that she deceived me; but notwithstanding this doubt, I still found that of all conditions of life this was much the happiest.2


1. I am referring to marital monogamy, marriages of two people only, and social monogamy, two partners living together, having sex together, and cooperating in acquiring basic resources.

2. Voltaire, The Travels of Scarmentado.

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4 thoughts on “Is Monogamy Natural?

  1. Very interesting! I see many benefits of our shift from polygyny to monogomy in society. In addition to the more equal distribution of women and more gender equality, I think people feel safer and more secure in mongomous relationships. They provide security and comfort—-someone you can count on during difficult times. When you are a child, you have your parents. When you grow older, you have a mate. It is important to have one person who can truly listen, support, and love you no matter what. Some may argue that this bond could get diluted in a polygamous or polyamorous relationship.

    In addition, there is another struggle with non-monogomous relationships—the jealousy component. I’m not sure if humans are naturally wired to be jealous, but perhaps we are. When we see a friend with a great job or great house for example, there is usually a small part of us that is jealous of their success (assuming those aspects are our lives are unfulfilled). I think the same goes for relationships, except it is multiplied when you have deep attachments with that person.

    Anyway, great post! I enjoyed it

  2. Both are natural human conditions. Which is more effective for any given society depends on the economics and circumstances of that society. In places where there is an over supply of women due to such things as war, polygamy is more common and encouraged. Places were there is a more equal distribution of men and women tend toward monogamy or at least serial monogamy.

  3. Been thinking this,exact thing all last week, but Lang these lines: Are we as humans hard wired for monogamy or polygamy and do those wires originate in or correlate with the Relptilain brain, the mammalian and the neocortex, only to find that these divisions of the brain are getting diluted 🙁 anyway…still looking for physiological basis for pair bonding

  4. I think it’s nearly impossible to say what’s “natural” for humans. Nature seems to have little to do with a being with as advanced a brain as we humans have, and with the ability to reason, plan, argue, create, and even manipulate emotions, both our own and those of others. This is purely anecdotal, of course, but in my own case, monogamy has many benefits, and at my age reproduction and even sexual fulfillment are least among them. My wife and I have spent a lifetime strategizing our retirement together. We got together for the sex, stayed together for the kids, and are growing old together for the security (which seems about right among friends in our age group.)

    This doesn’t mean the 19-year-old babe who works for me isn’t attractive on a purely physical level, or that I don’t have moments of “Hmm, I wonder … ?” when another woman flirts. But in my situation, and in the situations of most people my age, Rose Sayer is right — we rise above “nature” because it’s more than just a survival strategy, it’s an enjoyment-of-life strategy.

    Were I, on the other hand, to break off my marriage in pursuit of more carnal (more “natural”) pleasures, I would lose the home we’ve spent decades building and perfecting, and I would lose much more than half of the retirement income we’re counting on. Even more importantly, I would lose friendships and family and all manner of personal contact that makes life rewarding.

    So, in the end, monogamy is neither natural nor unnatural; it is a conscious decision I’ve made, and I make whatever adjustment I need to make in life (drink less, stop smoking, exercise, watch the occasional “chick flick,” tolerate a lapdog, etc.) to enjoy the life that being married to this particular woman brings me. It is my brain that allows me to debate the trade-offs and arrive at a satisfying and fulfilling conclusion.

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