The chemistry of kissing

When lips meet the hormones surge, and mmmm!

In an unromantic and untimely move, days before Valentine’s Day, scientists have just discovered that it’s not just love that makes a kiss feel delicious and exciting.

In 2007, a team of British scientists led the way in kissing research when they measured the brain and heart activity sparked by passionate clinches, but found it was less intense that the stimulation produced by eating chocolate.

The new American study conducted by Wendy Hill, professor of psychology at Lafayette College, Pennsylvania, found that sensations of delight during a passionate smooch are produced by a complex series of chemical processes.

Furthermore the study, reported in today's Telegraph, showed that while, for men, that process is triggered at the mere touch of lips, women need a little atmosphere thrown in to achieve the same chemical high.

For women to experience the same high as men they need additional features such as a romantic environment, dimmed lights and mood music.

Hill began the research to find out why the physical activity of rubbing lips with the lips of another can provide such a rewarding emotional response.

Her team used 15 couples as guinea pigs and tested the levels of two hormones, cortisol and oxytocin, before and after they held hands and again before and after they kissed.

In all 30 people — men and women — they found that kissing reduced the levels of the stress hormone, cortisol. But contrary to expectations, the levels of oxytocin, a hormone that aids social bonding, remained unchanged in the women and only rose among the men.

Hill’s team of scientists were worried that the emphatically unromantic vibe of the university health centre where the original research was carried out might have affected the results.

So they repeated the tests in more intimate settings, to see if the women's hormonal surge would be any different. And they were significantly higher.

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