Men in committed relationships choose to keep a greater distance between themselves and an unknown woman they find attractive when given the hormone oxytocin, according to new research in the November 14 issue of The Journal of Neuroscience. The findings suggest oxytocin may help promote fidelity within monogamous relationships.
Oxytocin plays a vital role in triggering childbirth and facilitating nursing. 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. Additionally, previous studies have shown oxytocin increases trust among people. However, scientists had yet to determine what, if any, role oxytocin played in maintaining monogamous human relationships.
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."
"Because oxytocin is known to increase trust in people, we expected men under the influence of the hormone to allow the female experimenter to come even closer, but the direct opposite happened," Hurlemann said. 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 effect of oxytocin on the monogamous men was the same regardless of whether the female experimenter maintained eye contact or averted her gaze, or if the men were the ones approaching or withdrawing from the experimenter. Oxytocin also had no effect on the men's attitude toward the female experimenter — both those who received the oxytocin and the placebo rated the female experimenter as being equally attractive.
In a separate experiment, the researchers found oxytocin had no effect on the distance men kept between themselves and a male experimenter.
"In monogamous prairie voles, we know that oxytocin plays an important role in the formation of the pair bond," said Larry Young, PhD, an expert on oxytocin at Emory University who was not involved in the study. "This study suggests that the general role of oxytocin in promoting monogamous behavior is conserved from rodents to man."
Society for Neuroscience: http://www.sfn.org
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
An innate ability some people have to manipulate their vocal frequency could be the key to sounding charismatic, according to new research.
Time-lapse imagery of scavengers tucking in proves that dead jellyfish aren't unpalatable after all, so can return nutrients to the sea's food webs
When bird pairs break up females often lay more eggs with a new partner, but the split can be disastrous for the male of the species
Spontaneous gene mutations, not ones inherited from parents, increase a child's risk of autism, scientists say. By comparing genes within families they've identified more than 100 suspects.
Slovenian archaeologist Ivan prajc is behind discovery of three significant ruins in the remote jungles of the Yucatán peninsula
Every year, Nikon selects the most artful, scientifically enlightening and skillfully produced images from thousands of submissions for its Small World microscope photography contest. Tomorrow, another set of impressive winners will be announced for the contest’s 40th year.
Seaview divers routinely cover 2 kilometers in a dive and generate 3,000 panoramic images in a day. Only a fraction of the best are uploaded to Google Street View.
Meeting sharks can be a moving experience, says photographer Jean-Marie Ghislain, who works to educate people on the plight of sharks around the world
From kraken to mermaids, some monsters are real—if you know how to look for them
Australia's Academy of Science says a government draft plan to protect the Great Barrier Reef will not prevent its decline.