The essence of trust - a catalyst of all friendship, trade and democracy - is a neurochemical that can be distilled in a nasal spray and used to ease the natural suspicion of strangers, researchers reported yesterday.
The discovery is the first direct evidence that a hormone called oxytocin, which evolved 100 million years ago to aid mating among fish and breast feeding among mammals, also promotes trust between humans, the scientists said.
The finding arises from a new wave of brain research designed to deconstruct how people make decisions, by investigating neural impulses that dart beneath the surface of self-awareness.
In an experiment published in the current edition of the journal Nature, researchers at the University of Zurich in Switzerland and Claremont Graduate University in California determined that people who inhaled two puffs of an oxytocin nasal spray were measurably more likely to risk all their money with a stranger, without consciously knowing why.
"If I increase your level of oxytocin, I can induce you to overcome your anxiety in trusting a stranger," said Paul J. Zak, director of Claremont's center for neuroeconomic studies and a co-author of the research paper. "It is a [biochemical] signal we induce unknowingly all the time by looking people in the eye or shaking someone by the hand."
Although the researchers set up their experiment to test the effects of oxytocin on financial decisions, they believe the hormone is the keystone of a normal social life.
Trust is as crucial in love and diplomacy as in finance. Social phobias, which hinge on the inability to trust other people, are the third most common mental health problem.
"My conjecture is that it applies broadly to all kinds of social interactions where your trust could be abused," said Zurich economist Ernst Fehr, the senior member of the research team.
The finding is an important advance in understanding the biology of human behavior, two independent experts said.
"Oxytocin enhanced trust," said University of Iowa neuroscientist Antonio Damasio. "The finding has powerful implications for understanding the brain. Remove trust, and you compromise love, friendship, trade and leadership."
Dartmouth College neuroscientist Michael S. Gazzaniga, a member of the President's Council on Bioethics and author of The Ethical Brain, said the researchers had laid "the foundation for a lot of new work on the human condition."
At the least, the insight into the role of oxytocin suggests new ways to study and treat mental conditions in which people trust too readily, such as Williams syndrome, or are too suspicious, such as clinical paranoia, the two experts said.
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