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Research assistant sends sex hormones soaring

November 3, 2003 By Helen Pearson This article courtesy of Nature News.

A wink and a nod flood men's saliva with testosterone.

Boy meets girl. Boy's sex hormone goes through the roof, finds a new study of lab-based flirting.

James Roney and his team at the University of Chicago paid 18-36-year-old students $10 to come into the lab under the pretence of simply testing their saliva chemistry. Unbeknownst to the men, the scientists staged a five-minute chat with a twentysomething female research assistant.

This brief brush set the men's hormones surging: testosterone levels in their spit shot up around 30%. And the higher a man's hormone soared, the more the female research assistant judged that he was out to impress - by talking about himself, for example1.

Because testosterone levels are linked to libido, the surge may seem predictable - but no one has taken such measurements before, says Peter Ellison of Harvard University, in Cambridge, Massachusetts, who studies how hormones affect our behaviour. "There's been a lot of anecdotal wisdom," he says.

A testosterone flood in the brain may partly drive men's swagger, says Ellison. It might, for example, make them bolder or brasher - immediately or in the long term. Similar testosterone spikes occur in animals, triggering courtship or aggressive behaviour.

There is one alternative explanation for the reaction of the more bashful male guinea pigs. "It's possible that some of those were having a stress response," Roney says.

Trouble and strife

In men, background testosterone levels peak during late adolescence or early twenties - after which "it's all downhill", says Ellison. Researchers are increasingly interested in understanding how changing intensities of this and other hormones are linked to our brain and behaviour.

It's possible that some of those men are having a stress response
James Roney
University of Chicago

In one study, Ellison found that men who are married or in long-term relationships have lower testosterone levels than those still playing the field. But it's not yet clear whether marriage drives testosterone down, he says, or if low-testosterone men are more likely to get married.


  1. Roney, J. R., Mahler, S. V. & Maestripieri, D. Behavioral and hormonal responses of men to brief interactions with women. Evolution and Human Behavior, 24, 365 - 375, doi:10.1016/S1090-5138(03)00053-9 (2003).


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