Is There a Monogamy Gene?

A recent scientific study of Swedish twin brothers suggests that there may be a genetic component the ability of men to be monogamous and how strongly they bond with their mates.

The gene involved modulates the hormone vasopressin.

"Our main finding was an association between a variant of the vasopressin receptor 1a gene and how strong bonds men reported they had to their partners," said lead researcher Hasse Walum, of the department of medical epidemiology and biostatistics at the Karolinska Institute in Stockholm. "Men carrying this variant scored on average lower on a scale measuring the strength of the bond compared to men not carrying this variant."

This study was begun in response to results from a similar study with voles. "Studies in voles have shown that the hormone vasopressin is released in the brain of males during mating," Walum said.

The more vasopressin in the brain, the more male voles wanted to remain with the female after copulation is over, the study showed . This effect was more pronounced in monogamous voles.

Of course, voles and humans are quite different, so the research team focused the vasopressin 1a gene, which is shared by both species. Variations in this gene strongly influenced vasopressin activity in the male vole, so researchers wondered if it might be the same for men.

The research team looked for variants of the vasopressin 1a gene among the 552 pairs of male twins that participated in the study. All the men were currently in a relationship that had lasted at least five years, with 18 percent being unmarried. The men were given psychological tests that measured their ability to bond and commit.

They found that men with a certain allele of the vasopressin 1a gene, called 334, tended to score markedly low on the Partner Bonding Scale, which is a psychological test. They were also less likely to be married than men with another form of the gene. Carrying two copies of the 334 allele doubled the odds that the men had undergone some sort of marital crisis.

Dr. John Lucas, clinical associate professor of psychiatry at Weill Cornell Medical College said that the findings made sense to him, as genes help drive much of human behavior, including mate bonding.

He pointed out, however, that this gene wasn't the only factor involved that influence a man's ability to form bonds and/or be monogamous.

"It's unlikely to be a single gene—it's likely to be multiple genes that are expressed incompletely and interact with the environment," said Lucas. He said that inborn temperament, which is likely hard wired by our individual genetic makeup, and interacts through time with our environment through training and experience, forms our personalities. Personality, in turn, involves the ability to commit.

Walum also noted that the finding would likely not be applicable to women, since vasopressin appears to be tied to social bonding in males, but not females. Further studies focusing on females would be needed to indicate what affects the ability to commit for women.

He also stated that the results of this study would not be sufficient to predict future behavior in any given man.

For me, personally, monogamy is a bad fit that has always felt unnatural. And through experience and observation, I've come to the conclusion that some people naturally have an easier time living monogamously than others. it's quite interesting to find that medical studies that back up what I've always known instinctively.

I think a follow-up study should be conducted to see why the variation in alleles exists, as it apparently serves a biological purpose that would indicate that a variation in mating strategies, rather than monogamy for everyone without exception, is beneficial to the human race.

Thoughts?