Pucker up, its Kissing Day, a day to celebrate all aspects of the age-old art of kissing.

Of course kissing is not just an art, so given that this blog has a bit of a science leaning, lets discuss the science of kissing, or philematology (my new word for the day!).

Philematology tells us that kissing not only activates and stimulates large parts of the brain, it also releases chemicals that reduce stress. Furthermore, the human lips apparently have the thinnest layer of skin on the body, and are more densely populated with sensory neurons than any other bodily region.

Kissing is good for you – it’s a scientific fact, ask any philematologist!
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In a study on the chemical impact of kissing, Neuroscience Professor Wendy Hill from Lafayette College, Easton, Pennsylvania, studied 15 romantically involved couples before and after kissing and holding hands for 15 minutes. Their levels of oxytocin (a feel-good, ‘social bonding hormone’) and cortisol (a ‘stress hormone’) were measured before and after the kissing session. It was found that cortisol levels decreased in all subjects, while oxytocin levels increased in the men and decreased in the women. The oxytocin reduction in the women was quite a surprising result, but may have had to do with the fact that the experiment was conducted in an “unromantic” student health center, which may have had more of an inhibiting effect on the women than the men (who, lets face it, are normally not too fussed by their surroundings!).

In another project, this time by anthropologist Helen Fisher from Rutgers University in New Brunswick, New Jersey, a number of brain imaging studies were conducted to see how the brain reacts to kissing. Fisher believes kissing activates different chemicals that stimulate different regions of the brain, and more specifically different “primary brain systems”, involved in the human mating and reproduction process. The first of these systems is sex drive, primarily testosterone driven, which drives people to find a mate, or even multiple mates. The second, romantic love, motivates people to gravitate towards a particular mate, and the third, attachment, helps couples stay together so they can rear children. Kissing is considered to have beneficial effects on all these systems.

Fisher furthermore says that kissing is, at a basic level, about exchange of saliva. Men tend to be sloppier kissers, because this lets them transfer more testosterone to stimulate their partners’ sex drive. She also speculates that men might be able to assess a woman’s fertility by subconsciously analysing the levels of estrogen and other hormones in her saliva (but that sounds a bit like science fiction to me).

According to neuroendocrinologist Sarah Woodley, another important chemical that may be present in saliva is androstadienone, a mood-enhancing steroid that also plays a role in helping you focus. “It may not be a sex attractant, but it plays a role in enhancing responsiveness to other stimuli. It makes them feel better”, she explained.

So what to do with all this philematological knowledge? Well, the best advice on Kissing Day is probably to just put it all out of your mind and enjoy what the day has to offer. Just do it – you don’t want all this science to spoil the fun!

(Source: Chemical attraction: The science of kissing.)


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