Is Monogamy Natural?

Monogamous relationships are commonly depicted as the norm in American media, movies, and TV shows, and many people may prefer monogamy when it comes to their romantic relationships. However, there has been a growing interest in non-monogamous relationships in recent years, which can raise the question: is monogamy natural? This question may seem pertinent if you are considering exploring other relationship structures.

Whether monogamy is natural can be a complex question, and in trying to answer it, it can be helpful to consider the prevalence of monogamy in nature and the history of monogamy for humans. However, determining whether monogamy seems right to you can be a different question—often significantly related to your thoughts, feelings, and preferences.

What is monogamy?

The word “monogamy” is used to refer to a relationship, usually a romantic or sexual relationship, between two people in which both partners agree to be romantically, sexually, and emotionally intimate only with each other. The word stems from the Greek roots “monos,” meaning “single,” and “gamos,” meaning “marriage.” Still, the term monogamy is typically used today to refer to all kinds of romantic relationships, not just marriages. 

On the flip side are consensual, non-monogamous relationships, which can come in many forms. “Polygamy” typically refers to marriage to more than one person at a time. At the same time, “polyamory” is typically used to describe other forms of intimate relationships that involve multiple partners who may or may not be married. Other examples of consensual, non-monogamous relationships include open relationships and swinging. 

Monogamy in nature

Monogamy in animals can be broken down into two subsets of monogamous relationships, including: 

• Genetic monogamy, in which a female member and a male member of a species procreate and produce offspring with only each other.
• Social monogamy, in which a female member and a male member of a species cohabitate with only each other.

These two subsets are not always (or even often) mutually exclusive. A female animal and a male animal might be socially monogamous but may still have sexual intercourse with other members of their species. In addition, if an animal pair is socially monogamous, both the female and the male will care for the children of the female member of the couple, even if the children are not the biological offspring of the male partner. 

Social monogamy seems more common than genetic monogamy in the animal kingdom, meaning that many animals may live in bonded relationships but participate in a mating system outside of those relationships. 

Prevalence of monogamy in animals

Genetic and social monogamy are extremely rare in fish and amphibian animal species. Monogamy in both forms occurs more often in mammals but is still relatively uncommon. One study found that less than 10% of mammals practice social monogamy, and social monogamy occurs more frequently in some mammalian orders, such as primates, in which it is around 29%. In contrast, monogamy is quite common in birds. Roughly 90% of birds are socially monogamous; some species, such as geese, even form life-long monogamous pairs. 

Various theories exist about why social monogamy developed among some animal species. Practicing social monogamy may give an animal species a survival advantage. This benefit may be due to the increased likelihood of offspring living to adulthood if more than one adult member of the species is involved in protecting, feeding, and raising children. 

Sexual dimorphism

One trait that is commonly viewed as a predictor of an animal species’ preference toward monogamy or rejection of monogamy is called sexual dimorphism. Essentially, the more physical differences between female and male members of a species, the more likely that species is not to practice genetic or social monogamy. 

Meanwhile, reduced sexual dimorphism is common in animals practicing monogamy. This phenomenon can be demonstrated by comparing geese, which appear identical regardless of sex and practice lifelong monogamy, to peacocks, whose male species members have distinctive, eye-catching tail feathers they use in mating rituals. In contrast, female peacocks have fewer feathers in more subdued colors and are easily differentiated from the males. Peacocks are neither genetically nor socially monogamous. 

Monogamy in the human species

So, what does nature tell us about monogamy in the human species? Human males and human females are not physically distinct enough to fall under the label of exaggerated sexual dimorphism, suggesting our species may lean more towards monogamy. However, it is possible for species without exaggerated sexual dimorphism to not practice monogamy. 

Research indicates that human paternal investment—the involvement of human fathers in raising their biological children—reduces the risk of mortality in human children and infants. However, the evidence is still indecisive on whether this is a sufficient motivator for human social monogamy. 

It may be helpful to look at relationship structures throughout human societies' history to understand how monogamy evolved. 

Monogamy in human history

Monogamy has not always been the norm for humans—and in fact, it still isn’t today in some cultures and regions where polygamy is practiced and normalized. Some early human societies practiced polygamy, with many kings and pharaohs taking multiple women as wives. The Church of Jesus Christ of Latter-Day Saints, better known as the Mormon Church, practiced polygamy until the religion’s leadership renounced the practice more than a century ago. Some sects of the church, including the Fundamentalist Church of Jesus Christ of Latter-Day Saints, still maintain the practice to this day.

Even in cultures where monogamy is considered the norm, lifelong monogamy is often not the standard in practice. High divorce rates mean many people have multiple marriages throughout their life. More and more people are marrying later in life than previous generations, so they may have experienced various partners before committing to just one for their foreseeable future and may have children before entering into a marriage. Even within monogamous relationships, extramarital affairs and cheating on partners can lead to a lack of faithful monogamy. 

Exploring your relationship needs

Human sexuality is understood to be complex, and the complicated relationships humans have with each other can add additional layers to the question of whether monogamy is “natural” or whether it is a social construct many people have implicitly agreed to uphold. Regardless of societal attitudes, historical precedents, and evolutionary motivations, it may be more helpful to consider not whether monogamy is natural but whether monogamy is the right choice for you. 

Determining what you want from romantic and sexual relationships can lead to a more profound self-understanding and more fulfilling relationships, but it can sometimes be a complicated process to undertake on your own. A trained and licensed therapist can help you process your thoughts toward monogamy in relationships and explore whether monogamy is a natural fit. Talking about relationships and sexual preferences can sometimes be perceived as vulnerable and uncomfortable. However, with online therapy through a platform like BetterHelp, you can speak to a therapist from the comfort of your home. 

Research indicates that attending therapy online can effectively address various concerns, including relationship concerns. For instance, one such study examined the effectiveness of an online couples therapy program. The online program effectively " improved relationship and individual functioning.” Online therapy can help you explore your thoughts and feelings surrounding relationships as an individual and help you and your partner find ways to improve your relationship as a couple. This type of treatment could be helpful if you are examining your thoughts on monogamy, or if you and your partner want support in exploring a different relationship structure.