Oxytocin is a natural hormone and neurotransmitter produced in the brain's hypothalamus. It plays an important role in the neuroanatomy of intimacy and has been shown to stimulate human bonding -- especially between mates and between parents and children. Now, researchers have shown that same hormone is powerful enough to encourage humans to lie for the benefit of their group members. Previous studies have shown increased levels of oxytocin are associated with greater empathy, lower social anxiety and other pro-social behaviors. The hormone has also been linked with a reduction in fear response, increased interpersonal trust, and a tendency toward defense-related aggression. In this latest study, researchers at the University of Amsterdam gave 60 male participants either a dose of oxytocin or placebo. Participants were then split into teams and challenged to predict coin tosses in order to win money. Aware that they could fudge the results -- dishonestly recording correct prediction -- for the benefit of their group, those given oxytocin at the beginning were more likely to do so. Researchers at Ben-Gurion University of the Negev (BGU), in Israel, collaborated with the Amsterdam researchers in carrying out the study -- which was published this week in the Proceedings of the National Academy of Science. "Our results suggest people are willing to bend ethical rules to help the people close to us, like our team or family," explained Dr. Shaul Shalvi of BGU's Department of Psychology. "Together, these findings fit a functional perspective on morality revealing dishonesty to be plastic and rooted in evolved neurobiological circuitries, and align with work showing that oxytocin shifts the decision-maker's focus from self to group interests." In another recent study in Germany, the same oxytocin nasal spray used in the BGU study was shown to increase the strength of orgasms between couples.