November 27th 2013
Ever wondered how some couples maintain a strong bond?
Scientists from the Bonn University Medical Center suggests a neuropeptide hormone called oxytocin, also known as the cuddle drug, that could contribute to romantic bonds in men by enhancing their partner’s attractiveness and reward value compared with other women, thus strengthening monogamy.
Monogamy in the biological realm is not common. The more partners an animal has, the greater likelihood that animal’s genetic material will be passed down to future generations. Why are human beings one of the exceptions to this notion? Published in this week’s issue of Proceedings of the National Academy ofSciences, oxytocin may be responsible for attraction within a loving couple.
"An important role in partner bonding is played by the hormone oxytocin, which is secreted in the brain", says Prof. Dr. René Hurlemann, Executive Senior Physician at the Inpatient and Outpatient Department of Psychiatry and Psychotherapy of the Bonn University Medical Center. The University of Bonn, the Ruhr University of Bochum, and the University of Chengdu (China) have collaborated in order to examine the true effect of oxytocin.
In the first experiment, 20 heterosexual male volunteers in committed relationships of 28 months, on average, were presented pictures of either their female counterparts or other women they did not know.
For the second experiment, the male volunteers used nasal spray to administer either oxytocin or a placebo to their noses and had their brains monitored using a magnetic resonance imaging (MRI) machine. Then, they rated pictures of either their partners or women they knew but were not related to, work colleagues for example. In most cases, the men rated their partners as more attractive and arousing than other women when the men whiffed oxytocin instead of the placebo.
Scientists also found differences in the brain activity when analyzing the MRI data. The pleasure and reward systems lit up in the male volunteers’ brains, when they saw their partner’s faces. "Oxytocin triggers the reward system to activate on the partner's face, the presence of the partner," said study author Dr. Rene Hurlemann, a professor of psychiatry at the University of Bonn, in Germany.
"When the men received oxytocin instead of the placebo, their reward system in the brain when viewing the partner was very active, and they perceived them as more attractive than the other women", says lead author psychologist Dirk Scheele.
"Sexual monogamy is actually quite costly for males, so there must be some form of mechanism binding males and females together, at least for some time. There must be some benefit, and reward is actually the strongest motivation underlying human behavior,” Hurlemann said.
"When you're first becoming intimate, you're releasing lots of dopamine and oxytocin. That's creating that link between the neural systems that are processing your facial cues, your voice and the reward system" of a partner's brain, said Larry Young, a professor of psychiatry at Emory University in Atlanta. Young also added that social bonding can decay when the couple becomes less intimate as time goes on; however; activities that release oxytocin like looking into another person’s eyes, holding hands, kissing, and sex may replenish that social bond.
Hurlemann added, "I think this is the only reason that we do hug and touch each other all the time. I think this is the mechanism that keeps oxytocin levels high in relationships."