Sex, Love and DNA
Wouldn’t it be great if we could do away with dating and failed relationships merely by doing a DNA cheek swab? It sounds simple and pain free, doesn’t it? In our cells lurk genetic markers that just might indicate who is an ideal spouse and who is an utter cad.
My guest today, Peter Schattner, is an award-winning scientist, educator and writer with 30 years experience in molecular biology, genetics, biomedical instrumentation and physics. He is the author of numerous research articles, scientific reviews and a textbook. Sex, Love and DNA is his first book for nonscientists. In his post below, Peter will explain a bit about research being done in this field and whether single people everywhere need to run out to take a DNA test.
Peter Schattner: How much would you pay to find out your partner’s genetic predisposition to kindness or to marital fidelity?
Unfortunately, deciphering the biological origins of human traits such as love or marital fidelity is not easy; our behavior is influenced by our individual experiences, something that can’t be measured by a genetic test. So in order to learn more about human love, scientists instead often study animals, hoping to get clues about how biology affects the experience of love in humans as well.
No animals have taught us more about loving behavior than small rodents called voles. Voles look a lot like mice, and in some places are referred to as field mice or meadow mice. Over 150 species of vole are described in the scientific literature. The DNA sequences of the species are similar, and so are their appearance and behavior.
But vole species also have striking differences, especially regarding what we might describe as feelings of love. In most vole species, the males are not exactly model lovers. Most male voles – such as male montane voles – are promiscuous, and after mating, they lose interest in their partners and move on in search of their next romantic conquest. These solitary creatures rarely make long-term associations even with other male voles. And certainly, they aren’t interested in wasting their time taking care of little vole pups (These are typical male behaviors in many species by the way, which may not surprise human females!).
Not all voles behave this way, however. Prairie voles, for instance, are very loving. Male and female prairie voles form long-term pair-bonds, and once pair-bonded, show little interest in new romantic partners. What could be the reason for this difference?
As montane voles and prairie voles already differ in social behavior at birth, their differences regarding pair-bonding and pup rearing likely reflect innate biological differences. Scientists focused on the voles’ sex hormones, including one called vasopressin, in their efforts to understand the differences between these two species.
To test vasopressin’s influence on voles, scientists injected male prairie voles with vasopressin. Now as I’ve mentioned, after mating, male prairie voles are devoted partners. Despite this fact (or perhaps because of it), male prairie voles take a while before selecting a female partner. Nevertheless, if a male prairie vole is injected with vasopressin, it’s as if he’s been shot by Cupid’s arrow. The next time he comes in contact with a female, the vole will act as if he has already bonded with her, even if they have never mated. Apparently, for male prairie voles, a shot of vasopressin has as big an impact on the psyche as sex.
The observation that hormones such as vasopressin affect pair-bonding and nurturing behavior in rodents raised the question whether they also influence human behavior. To explore this idea, a team of Swedish scientists tested whether people with an unusual genetic variant in a vasopressin-detecting protein might display different pair-bonding behavior. In their widely cited study, published in 2008, approximately 1000 human volunteers filled out questionnaires assessing their “pair-bonding status.” The Swedish study reported “statistically significant” correlations between self-reported pair-bonding history and gene variants in men, though the difference in the pair-bonding behavior between the two groups of men was actually quite small.
Nevertheless, the Swedish team’s results were intriguing enough to influence the world of 21st-century matchmaking. So many people want information on their perfect mate, that several companies have proposed genetic testing to find a better “match”. Although Genesis Biolabs went out of business in 2012, other companies – such as ScientificMatch.com, GenePartner.com, BasisNote.com and Chemistry.com have had more commercial success.
That said, the existence of these companies shouldn’t be construed as evidence that DNA-based matchmaking is actually useful. In the words of Larry Young of Emory University: “I do not believe that any service that claims to use genetic information, or any estimation of neurochemistry (based on personality or genotype) [to find a perfect romantic match] has any basis in reality.” And Professor Young is as likely to know as anyone; after all, it was his laboratory that carried out the key experiments on hormones and pair-bonding in voles in the first place.
This essay is adapted from the chapter “What is Love?” from Peter Schattner’s recent book Sex, Love and DNA. Other book chapters explore how our biology affects our intelligence, athletic ability, sexuality, emotions and a wide range of other fundamental human traits. To read an excerpt please go to: Excerpt.