Washington: Men in committed relationships who are given the hormone oxytocin choose to keep distance from attractive women they have just met, according to new research.
The findings suggest oxytocin may help promote fidelity within monogamous relationships.
The hormone, which is produced in a region of the brain called the hypothalamus, is also involved in the formation of social bonds. In humans and other animals, this brain chemical is known to promote bonds between parents and children, and between couples.
In the current study, led by René Hurlemann, MD, PhD, of the University of Bonn, researchers found that men in committed relationships who were given oxytocin kept a greater distance when approaching or being approached by an unknown woman they found attractive compared with those given a placebo. In contrast, oxytocin had no effect on single men.
"Previous animal research in prairie voles identified oxytocin as major key for monogamous fidelity in animals," Hurlemann said. "Here, we provide the first evidence that oxytocin may have a similar role for humans."
Researchers administered oxytocin or placebo via a nasal spray to a group of healthy, heterosexual males. Forty-five minutes later, the men were introduced to a female experimenter that they later described as "attractive."
As the experimenter moved toward or away from the study volunteers, the men were asked to indicate when the experimenter was at an "ideal distance" as well as when the experimenter moved to a distance that felt "slightly uncomfortable."
The researchers found oxytocin led the men in committed relationships, but not those who were single, to keep a greater distance (10-15 cm) between themselves and the woman.
The study was recently published in The Journal of Neuroscience.