Blokes given a blast of the love hormone oxytocin are more likely to become more ethnocentric.
Oxytocin-snorting Dutch men were given a moral dilemma to solve where they would save five lives from a runaway train by sacrificing one life.
When they did, they always chose to save Dutch people over Arabs and Germans. Those who were not given a blast of Oxytocin were a lot less bigoted in their selection.
Social psychologist Carsten De Dreu of the University of Amsterdam said that the earlier research into oxytocin showed it to be a neurological system that survived evolution would make people indiscriminately loving toward others.
However, in a report to the Proceedings of the National Academy of Sciences he said that it is clear that it has a downside of discrimination against people who are not part of your group.
Oxytocin is a hormone made in the brain and some reproductive organs. The body releases the biggest doses of it into the bloodstream during cuddling. It is supposed to dampen fight-or-flight instincts and calm down organs.
However it means that loving feelings tend to be exclusive to those who are similar to us. Anyone else can be eliminated.