If you were asked to fall backward into the arms of a stranger, would you trust the other person to catch you? Such a situation, a common exercise in group therapy, is a bit extreme. But every day most people place some degree of trust in individuals they do not know. Unlike other mammals, we humans tend to spend a great deal of time around others who are unfamiliar. Those who live in cities, for instance, regularly navigate through a sea of strangers, deciding to avoid certain individuals but feeling secure that others will, say, give accurate directions to some destination or will, at the very least, refrain from attacking them.
In the past several years, researchers have begun to uncover how the human brain determines when to trust someone. And my colleagues and I have demonstrated that an ancient and simple molecule made in the brain—oxytocin (ox-ee-TOE-sin)—plays a major role in that process. The findings are suggesting new avenues for discovering the causes and treatments of disorders marked by dysfunctions in social interactions.