What's in a kiss? Up to 34 facial muscles, a fair amount of saliva, some zippy happy hormones, and a lot of history. Humans have been kissing for millennia, though not all of us. Ten per cent of the world including the San Bushmen of Southern Africa and some New Guinean pygmies still resist the temptation to flex their orbicularis oris muscle, which can pucker lips, as well as their zygomaticus major and minor, depressor labii inferioris and depressor anguli oris, which can pull the lips up and down, and exchange saliva, chewed up food and quite a lot of bacteria, to performs a rather strange activity which has become the unassailable romantic gesture. The San can be forgiven for thinking it weird. One Southern African people, upon seeing this European habit in the 17th century, were recorded as saying, "Look at these people! They suck each other! They eat each other's saliva and dirt!"
Yet kissing has a vast history, geography and physiology. The first recorded reference to humans kissing was in Indian Vedic scrolls dating from 1500 BC. It referred to humans "sniffing" each other with their mouths. By Roman times, kissing had developed enough for a taxonomy to be created; an oscula was a friendly kiss (and gave us osculation, the Latin name for kissing); the basia was a loving kiss and the savia was a deep, passionate kiss, probably with tongues. In the Middle Ages, the Church relied on kissing for ceremony: observants would exchange a holy kiss, until greater segregation of the sexes made this too racy, and they kissed an osculatorium a kissing board instead. Protestants dispensed with kissing altogether. Even so, humans got on with it. We kiss openly, privately, furtively, passionately, chastely, emotionally, ceremonially. As Keith Thomas writes in The Kiss in History, "In 1649, an English observer could write that the kiss was used 'in salutation, subjection, reconciliation...congratulation, approbation, adulation, confederation, but more especially and naturally in token of love." If you think that list still not poetic enough, switch to German, which has 30 words to describe different types of kissing.
And why not? Kissing makes you feel good. It releases oxytocin (which encourages feelings of affection); serotonin (which can regulate mood); dopamine (related to emotions and pleasure); and adrenaline. Lips have the thinnest skin layer on the body, and are packed with sensory neurons. Kissing sparks the neurons to send messages to the brain and body, transmitting pleasure, affection and sensual physical reaction. Some messages end up in the somatosensory cortex, an area of tissue near the front of the brain, which maps out tactile sensations in the body proportionate to how many neurons they have. Unsurprisingly, lips loom large. In the somatosensory cortex, a good kiss gives everyone lips like Angelina Jolie's.
That's not all. A good 15-minute kissing session burns more calories than swimming would (if it's vigorous enough). It can clean your teeth and reduce plaque, because extra saliva is produced. And, according to evolutionary psychologists, it can help you find a good mate. Researchers at the University of Albany in New York State surveyed more than 1,000 students about their kissing habits, with some surprising results: 52.8 per cent of men would have sex without kissing first; 14.6 per cent of women would. Nearly two-thirds of both sexes would change their mind about someone if the kissing was bad. In short, both sides are getting something out of the kiss. Men use kissing as a stepping stone to getting sex (studies of date rape have shown that men feel more entitled to force a woman into sex if they have been kissing her), while women get information about whether the man is a good partner, by judging him on his breath and how he tastes (both of which can carry signs of disease and indicate how healthy he is). We may not have kissed since the dawn of time, but we've made it useful. In evolutionary psychologist language, kissing has become "an evolved courtship ritual".
Not everyone agrees. Desmond Morris was the first to point out that chimpanzees, for example, have a habit of mashing food in their mouths then passing it to their young, mouth to mouth. This, he thought, became kissing. The zoologist Frans de Waal was once snogged by a bonobo. Charles Darwin noted nose-rubbing in some cultures, and thought it was a substitute for a kiss. (Actually, the Inuit, inveterate nose-rubbers, were also exchanging smells; and in classical Egyptian, sn means smell and kiss.) The fact that the majority of us lean to the right when we kiss can also cut both ways. The naturists would believe that it's because it's our natural motor instinct. Nurturists point out that the way most mothers breast-feed means babies have to turn to the right to suckle. Turning to the right, then, means comfort, succour and food.
Nature or nurture? Who cares? A good kiss is an unbeatable exchange of emotion, sensation, pleasure and euphoria. It may even keep you alive: Scientists in the 1980s discovered that men who kissed their wives before they left for work were less likely to crash their cars.
The culture of kissing
The first screen kiss occurred in the 1896 film The Kiss, and was undertaken by the actors John C. Rice and May Irwin. Since then, the popularity of onscreen kisses has gone ever upward. Despite an unwritten rule restricting kiss length to no more than three seconds, Jane Wyman and Regis Tommey kissed for three minutes and five seconds in the 1941 You're in the Army Now, presumably as part of the war effort. The screen kiss was as big a star in Cinema Paradiso when the hero Toto finds a roll of kisses spliced from films by an over-zealous priest as Philippe Noiret. The kiss is now as banal as a handshake in most Hollywood products, but not so in Bollywood, where a standard device to denote kissing used to be to cut the scene to two flowers touching or, more racily, a bee sucking nectar from a flower. Kisses are now more common but remain a sensitive issue: Bollywood megastars Hrithik Roshan and Aishwarya Rai were threatened with court action (later dropped) for allegedly kissing too passionately in the hit film Dhoom 2.
THE KISS AS GREETING
In the UK, it caught on in the 1980s, perhaps from teenagers who had been on French exchanges supposedly of language but actually of kissing greetings. Twenty years on, the affectionate kiss of greeting is as common as chips, though it has brought with it the social awkwardness common to the French, who kiss twice in the north, three times in the south and Belgium and four times in Paris, but only among certain classes. Such confusion means the French have had to perfect the inconspicuous cheek-hover (the Italians make it easier by handshaking first, and pulling you in). Male cheek kissing is still confined to Arabs and Persians, people who have spent too much time in France, Slavs, and some gay men; but give it time. After all, we've had practice: When the Dutch intellectual Erasmus visited London in 1499, he found us shocking. "Wherever you come you are received with a kiss by all; when you take your leave you are dismissed with kisses; you return, kisses are repeated ... Should they meet you anywhere, kisses in abundance; in fine, where you moves there is nothing but kisses."