new study shows first scientific link between genes and monogamy

Urge to Stray Is in Men’s DNA

September 03, 2008 08:52 AM
by Cara McDonough
New study shows first scientific link between genes and monogamy, igniting debate over whether people should be able to conduct genetic tests on potential mates.

Programmed to Cheat?

The new study, conducted at the Karolinska Institute in Stockholm, concludes that men who lack a particular variant of a gene associated with brain activity are less likely to cheat, illustrating the first direct scientific link between genes and monogamy.

Men who have the gene variant, or allele—which regulates the activity of a hormone called vasopressin—have higher rates of marital discord and divorce, The Washington Post reports. And men with two copies of the allele are even more likely to stray from partners or spouses than those with one copy, who are still more likely to cheat than those with none at all. The gene variant was found in two of every five men.

But should the information be used in determining a mate or dealing with marital issues? Helen Fisher, a biological anthropologist who studies romantic love at Rutgers University, said to The Washington Post that knowing his genetic makeup might help a man make the right decision when he feels the urge to stray: “You can say, ‘Oh, it is just my DNA, and I am going to ignore it,’” Fisher said.

The presence of the gene also seems to be able to predict how women describe their relationship with those men. “Women married to men who carry one or two copies of (the gene) were, on average, less satisfied with their relationship than women married to men who didn’t carry it,” said Hasse Walum, who led the study, to the Daily Telegraph.
The study, published in the Proceedings of the National Academy of Sciences, focused on 1,000 heterosexual couples and showed that about 15 percent of the men who did not have the vasopressin allele reported “serious marital discord” in the past year, compared with 34 percent of the men with two copies of the allele, who reported the same thing.

Background: Monogamy and vasopressin

The new research out of Sweden builds on past research that studied vasopressin receptors in voles.

In a study conducted in 2004, scientists noticed that the “promiscuous meadow vole” had fewer of the vasopressin receptors in the brains, and then gave the animals extra receptors and studied the result, the BBC reported. After the gene was introduced “the former playboys reformed their ways.” The voles became interested in mating with only one female, even when tempted by other female voles.

The exact link between vasopressin and monogamy was unclear, but scientists attempted to explain the phenomenon.

“We think what happens is when the voles mate, vasopressin activates the reward centre, and it really makes the animals pay attention to who they are mating with,” said study co-author Larry Young, from Emory University, to the BBC. “It makes the voles think, ‘when I’m with this partner I feel good’. And from then on, they want to spend their time with that particular partner.”

Related Topics: Infidelity and the genetics of romantic love

When New York Gov. Eliot Spitzer admitted to an affair with a prostitute in March before resigning, and his replacement, Gov. David Paterson, admitted to an extramarital affair as well, the media questioned whether an “infidelity epidemic” was to blame, findingDulcinea reported.

Some experts said that while there may be no modern epidemic, males may be more tempted to stray than females from an evolutionary psychology perspective because, theoretically, men can father hundreds of children, whereas women are limited in reproduction.

But while men often get the bad reputation, women—including mothers—admit to straying, too. In May, 34 percent of married moms admitted to being in the midst of, or having, an affair, according to an AOL Body and Cookie magazine survey.

Whether men or women are at the center of the debate, scientists have pondered the link between genes and romantic love for some time. New studies suggest that picking a mate may involve more than just true love.

A Stanford University study released in August, for example, showed that “selective pressure” may come into play in groups of men fighting for land and other winnings—meaning that, throughout history, the most aggressive men may have been favored with genetic or cultural traits, giving them an advantage to prosper and multiply.

Regarding relationships, the research showed that aggressive men may, from an evolutionary standpoint, actually be more attractive to potential female mates.

Most Recent Beyond The Headlines