They say the prettiest girls make men's mouths water - and now scientific research suggests that it is true.
A study has revealed that male saliva undergoes dramatic changes during small talk with attractive young women.
It suggests they almost start drooling during the briefest of flirtations with members of the opposite sex.
And the more they try to impress, the more their saliva gives them away.
Experts at the University of Chicago in America set out to test male hormonal reactions. College students who took part in the study, all of whom were heterosexual, were asked to make small talk with a young man or a young woman.
The participants, most of whom were in their early twenties, provided saliva samples before and after the encounter.
Results reveal that after just five minutes talking to young women, men's saliva undergoes significant changes.
While little or no change was noted in the saliva of those paired with other males, those paired with young women produced saliva containing high levels of the male sex hormone testosterone.
The most dramatic changes were noted in men who appeared to be trying to impress. Dr James Roney, of the Institute for Mind and Biology at the University of Chicago, who led the research, said: "I would not say that the men were actually drooling but there were significant changes to their saliva. After these conversations with the women, they showed a major testosterone increase.
"The degree of change was associated with the extent to which the girls thought they were interested in them as romantic partners or trying to show off."
The study participants were quizzed about how physically attractive they found the woman they talked to, using such categories as 'sexy' and 'cute'.
Following the five-minute sessions, the women were asked detailed questions about the men's behaviour, focusing on how interested and engaged they seemed, and whether or not they appeared to be trying to impress.
The women involved in the study were not professional models or exceptionally good-looking - suggesting that many women may have the power to make men's mouths water.
In their research paper, published in the latest edition of the journal Evolution And Human Behaviour, the American team describes the process as a 'courtship response'.
It is thought that when men find women attractive, their brains send messages to the pituitary gland, triggering production of testosterone. Changes in the level of the hormone is easiest to test in saliva.
Read more: http://www.dailymail.co.uk/health/article-201319/Pretty-women-make-mans-mouth-water.html#ixzz2ZAY9uJyI
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