Oxytocin, a hormone involved in labor and lactation, has now been found to engender trust. The Swiss study, appearing in this week’s Nature, was summarized in the New York Times:

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In the study, the participants played an investment game with anonymous partners. Those who were given oxytocin invested more money with the partners than did those who did not receive the hormone, the researchers found…

Neuroscientists, including the Swiss researchers, argue that oxytocin is not so much a trust serum as a kind of brain messenger that primes animals to overcome their natural aversion to others. It allows for what they call “approach behavior,” that push to walk up and to a stranger and say hello.

This may be an especially important ability in people with autism. Whether oxytocin or other hormones could affect such behavior is unclear, but the oxytocin study suggests it is worth investigating…

The prospect of used-car dealerships infusing the air with oxytocin to increase sales is also far-fetched, Dr. Fehr said. “The half-life of oxytocin in the air (in a spray) is just two or three minutes,” he said. “Thus you would have to administer a permanent rainfall of it. This looks impossible to me.”

If you had asked me to guess which hormone encouraged trust, I wouldn’t have put oxytocin high up on the list (but I unquestioningly believe these findings).

Oxytocin nasal sprays (like syntocinon, pictured above) are used to encourage milk let-down in nursing mothers. In some animals, new moms given oxytocin blockers don’t nurture their young at all. Maybe that’s where this line of thinking began: isn’t love based on trust?

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