Human Monogamy: Origins, Naturalness, and Evolution


In the realm of human behavior, few questions have puzzled historians, biologists, and anthropologists as persistently as the one we explore today: “Are humans monogamous by nature?” While the trajectory of human monogamy’s evolution follows a discernible path, the enigma lies in deciphering why humans are monogamous. In the vast spectrum of the animal kingdom, monogamy is a rare occurrence, making its presence among humans all the more intriguing. The quandary extends to the timeline of when humans embraced monogamy, as it coexisted with polygamy for an extended period, rendering its origins elusive. This article delves into this perplexing topic, examining various hypotheses that shed light on the rise of human monogamy.

Monogamy Is Not ‘Natural’ In Humans Like in Geese

A schematic showing the monogamy relationship.
A schematic showing the monogamy relationship. Source: Wikimedia Commons

The debate on whether monogamy is inherent in human biology revolves around the concept of “naturalness.” Pepper Schwartz, a sociology professor at the University of Washington, challenges the notion that humans are inherently monogamous. She draws a comparison with geese, truly monogamous animals that never seek new mates, even when their partner is lost. In contrast, many humans explore alternative or additional partners, questioning the innate naturalness of monogamy. This raises the broader question of what constitutes “natural” behavior in the complex tapestry of human actions, as even reading, using toilet paper, or skydiving can be considered unnatural.

The Enigmatic Origins of Human Monogamy

Polygamy painting from Edward Williams the Elder.
Polygamy painting from Edward Williams the Elder. Source: Wikimedia Commons

Despite numerous theories, the question of why humans practice monogamy remains unanswered due to the absence of a definitive consensus. Multiple plausible theories attempt to elucidate the origins of monogamy. Some propose that the spread of diseases transmitted by humans forced the adoption of monogamy as a means of disease prevention. Others suggest a genetic instinct in fathers to protect their offspring motivated monogamous behaviors. Historians highlight the role of marriage in safeguarding wealth and status, while biologists question the practice’s naturalness, citing its rarity among mammals.

The Biological Conundrum of Monogamy

Doctor Dieter Lukas from the University of Cambridge describes monogamy as an “evolutionary puzzle.” From a strict biological standpoint, monogamy offers no inherent advantages. Male mammals theoretically could produce more offspring by forgoing monogamy and mating with multiple females. Lukas posits that monogamy may have evolved when females “spread out,” making it challenging for males to compete for mating opportunities. In such scenarios, it becomes advantageous for males to commit to a single female to ensure their reproductive success, though the mystery of why humans specifically adopted this remains unsolved.

Disease as a Catalyst for Monogamy

Canadian scientists propose that monogamy gained prevalence as societies grew larger, leading to increased disease transmission. A mathematical study conducted at the University of Waterloo revealed that larger societies correlated with a higher prevalence of sexually transmitted diseases. The pressure to prevent the spread of STDs, coupled with the infertility effects of certain diseases like syphilis and Chlamydia, could have driven the shift toward monogamy.

Monogamy: The Unconventional Choice

Monogamy remains a rare phenomenon in the mammalian world, with only three to five percent of mammals practicing it out of 5,000 species. Among humans, the picture is complex, as only 17 percent of cultures strictly adhere to monogamy, while most societies embrace a mix of marriage types, including monogamy and polygamy. This diversity underscores the intricate nature of human relationships and challenges the perception of monogamy as a one-size-fits-all practice.

Infanticide and Male Commitment

Arab with Three Wives and Two Servants.
Arab with Three Wives and Two Servants. Source: Wikimedia Commons

Another intriguing theory suggests that males embraced monogamy to protect their offspring from harm or elimination by rival males. When a mother nurses, she is less likely to mate, potentially reducing a male’s mating opportunities. In response, males began safeguarding their genetic line and assisting in raising offspring to ensure their reproductive success. This complex balancing act may have contributed to the emergence of monogamy.

The Duality of Human Nature: Polygamy and Monogamy

E E Smith, writing for Psychology Today, contends that humans carry the biological imprint of polygamy alongside their practice of monogamy. Despite its apparent unnaturalness, monogamy remains a prevalent choice for humans. Professor David Barash suggests that humans intentionally engage in complex activities, much like playing the violin, indicating a willingness to navigate the challenges posed by monogamy over the potential problems associated with polygamy, such as disease and a lack of commitment.

The Evolution of Monogamy in Recent Millennia

While the concept of monogamy developed over millions of years, its manifestation as we know it today emerged relatively recently. Scientists like Kit Opie are still working to unravel the specific factors that led to monogamy in humans. Meanwhile, other primates continue to practice polygamy, emphasizing the distinctiveness of human monogamy in the animal kingdom.

Monogamy: A Catalyst for Fatherhood

Although monogamy may not be the cause of human monogamous behavior, it is closely linked to the emergence of committed fatherhood. Male commitment to protecting offspring and ensuring their survival increases the likelihood of offspring thriving. This commitment involves nurturing, grooming, and safeguarding offspring, ultimately enhancing their chances of survival.

Monogamy’s Impact on Brain Size

Monogamy’s influence extends beyond behavior to physiology. Opie theorizes that monogamy may have contributed to the development of larger human brains. As males committed to providing food for their offspring to ensure their survival, this steady source of protein could have driven the evolution of larger brains. This adaptation may have been crucial for early humans as they evolved into more social beings.

From Solitude to Society: The Evolution of Monogamy and Polygamy

Before the adoption of monogamy and polygamy, early primates led solitary lives, coming together only for mating purposes approximately 75 million years ago. These solitary origins evolved into the societal urges that drove the transition to group living, eventually leading to the emergence of both monogamy and polygamy.


The question of whether humans are inherently monogamous remains a subject of intrigue and debate among scholars from various disciplines. While no single theory offers a definitive answer, the diverse hypotheses presented here shed light on the complex factors that likely contributed to the rise of monogamy in humans. This enigmatic aspect of human behavior continues to captivate our curiosity, reminding us of the intricate tapestry of our evolutionary journey.

Is monogamy truly natural for humans?

The naturalness of monogamy in humans is a subject of debate. Some argue that it is not inherently natural, while others believe it is a societal construct.

Why is monogamy so rare in the animal kingdom?

Monogamy is rare among animals because it often offers no inherent biological advantages, and in many cases, mating with multiple partners can lead to more offspring.

Did disease play a role in the emergence of human monogamy?

Some theories suggest that disease pressure may have contributed to the adoption of monogamy as a means of preventing the spread of sexually transmitted diseases.

What is the connection between monogamy and committed fatherhood?

Monogamy can lead to committed fatherhood, as males are more likely to invest in raising and protecting their offspring when they have a single, long-term mate.

How did monogamy impact the evolution of human brain size?

Monogamy may have contributed to the development of larger human brains as it provided a stable source of protein, supporting the cognitive evolution of early humans.

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