'Love hormone' oxytocin behind monogamous relationships

Researchers have found that oxytocin hormone, which is secreted in the brain and is sometimes referred to as the 'bonding hormone', helps in creating and maintaining monogamy in relationships.

Scientists at the Bonn University Medical Center explained that a biological mechanism was behind the attraction between loving couples: If oxytocin is administered to men and if they are shown pictures of their partner, the hormone stimulates the reward center in the brain, increasing the attractiveness of the partner, and strengthening monogamy.

For research purposes, researchers showed pictures of their female partners to a total of 40 heterosexual men, who were in a permanent relationship, and pictures of other women for comparison.

First a dose of oxytocin was administered to the subjects in a nasal spray, and then a placebo at a later date.

Furthermore, the scientists also studied the brain activity of the subjects with the help of functional magnetic resonance tomography.

Lead author Dirk Scheele said that when the men received oxytocin instead of the placebo, the reward system in their brain when viewing the partner was very active, and they perceived them as more attractive than the other women.

Overall the data showed that oxytocin activates the reward system, thus maintaining the bond between the lovers and promoting monogamy.

The study is published in the Proceedings of the National Academy of Sciences.