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This article was published 11/2/2011 (2170 days ago), so information in it may no longer be current.
The Science of Kissing
What Our Lips Are Telling Us
By Sheril Kirshenbaum
Grand Central Publishing, 246 pages, $22.50
Chances are that at least one kiss is etched among your deepest memories. With input from all five senses, a torrent of hormones, and high emotional stakes, our brains are rarely more active than during a kiss.
As we near Valentine's Day, University of Texas researcher Sheril Kirshenbaum gives us even more to think about before, during and after this popular pastime in her book The Science of Kissing.
With a tone that is lighthearted but never unprofessional, scholarly but not sterile, she takes a short trip through the origins, physiology and future of osculation.
Readers who are concerned that too much science will unweave the rainbow needn't worry. While it is traditionally poets' territory, a little rational understanding enhances rather than undermines the wonder and romance of the kiss.
Why take kissing so seriously? At first sidelong glance, it appears a silly custom: swapping saliva and bacteria, without an obvious purpose.
Yet, kissing is near-ubiquitous today, alluring and mysterious, with enormous cultural significance, an event that can begin, sustain -- or sometimes stop short -- our most important relationships.
As a field of research, kissing is beginning to receive greater academic attention. Evolution, history, anthropology and medicine can all shed light on when and why we kiss.
Within our own culture, Kirshenbaum notes that kissing "is better advertised than Coca-Cola" so it's easy to assume that the behaviour is universal. However, people throughout history have kissed in different ways and for different reasons, or sometimes not at all.
Kissing makes its first documented appearance in India, around 1500 BC. Centuries later India gave us the Vatsyayana Kama Sutra, which, among its varied subject matter, includes an entire chapter on kissing.
The Old and New Testaments are peppered with kisses, including kisses of deception, of betrayal and of peace, not to mention the racier sort in the Song of Solomon.
Today, kissing customs vary from one country to another. The French are famous for their signature style, which they call a "soul kiss," but a quick kiss on the cheek is a common greeting between friends and family in France, throughout much of Europe and Latin America.
In Turkey, people share friendly cheek kisses with their own gender but never the other, while kissing in public is reportedly frowned upon in Finland, Thailand and India.
All this variation across time and space is fodder for one of the great kissing debates: genetic or cultural? Kirshenbaum plays the referee, giving arguments from both sides.
If we evolved to kiss, why did European visitors to the Pacific island of Mangaia find its inhabitants innocent of mouth-to-mouth kissing, despite being the most sexually active culture in recorded history?
On the other hand, cultures that do not kiss invariably have some form of "substitute" like sniffing or rubbing noses.
Many members of the animal kingdom, from apes to cats to porcupines, exhibit kissing-like behaviour. Then, there is man's best friend: "If it's a noun," Kirshenbaum writes, "chances are a dog will lick it."
Different forms of animal "kissing" serve to establish hierarchy, build trust, sample taste or scent, groom, soothe, or to pass along regurgitated food. There is no one reason that animals kiss, and no one reason that we do.
Certainly, kissing can profoundly affect our bodies. During a passionate kiss, our facial muscles work in concert, our cranial nerves light up with new sensory data, while our cheeks flush and our pulse quickens.
Kissing releases a myriad of hormones and neurotransmitters, including dopamine, an energizing drug that leads to feelings of euphoria, anticipation, lost appetite, and sometimes even obsessive or addictive behaviour.
Because dopamine is unleashed by new and exciting experiences, the effect wanes as two people grow accustomed to one another. The desire to recapture that euphoria is certainly a culprit in many extramarital affairs.
Luckily, there are other hormones at work helping to foster long-term attachment, and chief among them is oxytocin (not to be confused with OxyContin). Oxytocin is a potent substance credited with sustaining the parent-child bond and keeping the love alive between happily married couples.
As kissing reliably produces oxytocin (and sex even more so), it is not merely an outward sign of a healthy relationship. By kissing often, couples can literally make it easier and more enjoyable to stay together.
Kirshenbaum also gives some good reasons to hold back from a kiss. On the emotional side, an ill-timed kiss, when the mood is wrong, can extinguish rather than ignite a relationship.
Moreover, kissing can spread mononucleosis, Type 1 herpes, meningitis, strep throat and a host of other maladies, so your partner ought to be worth the risk.
Kissing may be unhygienic and not strictly necessary for procreation, but it has withstood every attempt at eradication, and shows no sign of going out of style.
The Science of Kissing covers extensive ground, and will likely leave readers wanting more detail. Still, it shows how much there is to learn about the subject, and how much still belongs to wonder and mystery.
Paul Klassen is an engineer who writes, and lives with his wife, in Winnipeg.