Sex at Dawn

Exploring the evolutionary origins of modern sexuality

A Prairie Vole Companion

Is there a genetic argument for monogamy?

In regard to my previous post, concerning possible evolutionary advantages of culturally enforced sexual monogamy, several readers wrote in to ask about prairie voles. Here's a brief excerpt from our book in which we discuss this. As you'll see, a lot of the "meat" is in the endnotes. That's true of the book in general.

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The prairie vole is another supposed paragon of "natural monogamy." According to one newspaper article, "Prairie voles—squat rodents indigenous to plains and grasslands—are considered to be a near-perfect monogamous species. They form pair bonds that share a nest. Both male and female actively protect each other, their territory, and their young. The male is an active parent and, if one of the pair dies, the survivor does not take a new mate."1

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Considering the vitriol Darwin faced 150 years ago when he dared compare humans to apes, it's striking to note the scraps of comfort contemporary scientists find in equating human sexual behavior with that of the ratlike prairie vole. We who once compared ourselves to angels now see ourselves reflected in this lowly rodent. But C. Sue Carter and Lowell L. Getz, who have studied the biology of monogamy in prairie voles and other species for thirty-five years, are unambiguous: "Sexual exclusivity," they write "is not a feature of [the vole's] monogamy."2 Thomas Insel, director of the National Institute of Mental Health (formerly director of Yerkes Primate Center) and an expert on the prairie vole, says that those in the know have a less exalted view of the prairie vole's monogamy: "They'll sleep with anyone but they'll only sit by their partners."3



1. The San Diego Union-Tribune: "Studies Suggest Monogamy Isn't for the Birds-or Most Creatures," by Scott LaFee, September 4, 2002.
2. "Monogamy and the Prairie Vole," Scientific American online issue, February 2005, pp. 22-27.
3. Things have become a bit more muddled since Insel said that. More recently, Insel and others have been working on trying to discover the hormonal correlations underlying the fidelity or lack thereof among prairie, montane, and meadow voles. As reported in the October 7, 1993 issue of Nature, Insel and his team found that vasopressin, a hormone released during mating, seemed to trigger protective, nest- guarding behavior in some species of male voles, but not others, lead- ing to speculation about "monogamy genes." See http://findarticles .com/p/articles/mi_m1200/is_n22_v144/ai_14642472 for a review.

In 2008, Hasse Walum of the Karolinska Institute in Sweden found that a variation in the gene called RS3 334 seemed to be associated with how easily men bonded emotionally with their partners. Most interestingly, the gene appears to have some association with autism as well. The reference for Walum's paper is Proceedings of the National Academy of Sciences, DOI: 10.1073pnas.0803081105. A news article summarizing the findings is online at article/dn14641-monogamy-gene-found-in-people.html. Another good summary of this research, by Ed Yong, can be found here:

Christopher Ryan, Ph.D., is co-author of Sex at Dawn: The Prehistoric Origins of Modern Sexuality (HarperCollins 2010).


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