Is it natural for humans to be monogamous?

Perhaps this is one of the world’s oldest questions, especially considering that prostitution is considered to be the world’s oldest profession.

For decades researchers have been exploring if humans, by nature, are meant to be monogamous. No one questions that some individuals can successfully practice monogamy. Just as humans are omnivores by design, some people faithfully lead a vegetarian lifestyle.

The real question for scholars is not what people can practice, but what are our natural inclinations. The evidence overwhelmingly suggests that individuals desire multiple sexual partners. Even a casual observation of human behavior suggests that people like entertaining the idea of having sex with someone outside of a committed relationship. If people were naturally inclined to only want to have sex with one person, how do you explain that at least 70 million copies of Fifty Shades of Grey have been purchased and pornography is a multibillion-dollar industry? Certainly, a monogamous mind would not create such a large market for such erotically based works.

The evidence against monogamy does not only involve what happens in our minds, but our bodies reveal cues to our sexual desires as well. Sexual dimorphism – physical size differences between men and women – are a reliable indicator of sexual behavior. In related species where males and females are similar in size, pair-bonding is more common. Larger physical differences between males and females often correspond to less monogamous sexual behavior. A new article in theWall Street Journal does a good job of highlighting the findings of sexual dimorphism as it relates to humans:

“So by these various biological measures, are humans a pair-bonding or a tournament species? Neither. Across populations, men are roughly 10% taller and 20% heavier than women, need 20% more calories and live 6% shorter—more sexually dimorphic than monogamous species, less than polygamous species. Moreover, compared with, say, monogamous gibbons, human males have bigger testes and higher sperm counts…but pale in comparison to polygamous chimps. Measure after measure, it’s the same.

It turns out that we aren’t monogamous or polygamous by nature. As everyone from poets to divorce attorneys can attest, we are by nature a profoundly confused species—somewhere in between.”