From The National Geographic:
Scientists have discovered that the hormone oxytocin, when sniffed, makes people more prone to trust others to look after their money. To test the trusting effect of oxytocin, the researchers studied people who played an investment game. In the game, participants would choose how much money to hand over to a trustee. Investors were far more trusting after inhaling the hormone, researchers found. “This is the first study that can describe the underlying biological mechanism of trust in humans,” said Markus Heinrichs, a clinical psychologist at the University of Zurich in Switzerland. Heinrichs co-authored the study, which will appear tomorrow in the journal Nature.
The findings have important implications for the study of conditions in which trust is diminished (as in the mental disorder autism) or augmented. Ongoing research suggests that inhaling oxytocin may help reduce anxiety in people with social phobia, for example, and help them to interact better with others.
More here.