Diehard romantic: Henry Gibbons describes the kiss as "the anatomical juxtaposition of two orbicularis oris muscles in a state of contraction".
Credit: Corbis
There is some evidence that some cultures never engaged in the practice. The indigenous inhabitants of the island of Mangaia in the South Pacific, for example, were enthusiastic lovers but knew nothing of kissing until the 1700s, when Europeans arrived.
The same was true of Australian aborigines and of tribes in sub-Saharan Africa. As recently as 1990, an editorial in the Beijing Workers' Daily declared that kissing "is a vulgar practice which is all too suggestive of cannibalism". Today in China, kissing is common, but not among older people.
So if kissing isn't genetic, what possessed people to get so intimate with each other's faces? "The smell", says Bryant. He thinks kissing began as a way of screening potential partners by scent.
So the original kiss might have been something like the Polynesian or Eskimo kiss, in which lips are left out and noses are rubbed across the face. This provides kissers with the chance to inhale the odour emanating from scent glands on the cheeks.
"Through the roof with euphoria"
The idea makes sense because your smell can reveal a surprising amount about a potential partner (see Sexual Chemistry 101, Cosmos Online). But whether it's entirely cultural or has an innate component, there's a much simpler explanation for our love affair with the kiss.
"Apart from fingertips and genitals, the lips are as well supplied with nerve endings as any part of the body, so that makes them particularly sensitive," says Glenn Wilson. And when you fall in love, the brain's reward system is triggered, so if you lock lips "you go through the roof with euphoria," adds Rutgers University's Fisher.
Key to the reward system is the neurotransmitter dopamine. It's responsible for those crazy feelings you experience when you're swept off your feet: the elation, the craving and obsessive thoughts. As Fisher points out: "The part of your brain that becomes active when you look at a photograph of your sweetheart is exactly the same region that becomes active when you feel the rush of cocaine. So it's no surprise a kiss can be such an overwhelming experience."
So next time you're leaning in for the pash, close your eyes and think of science. You might even be doing something that's good for your health. "The brain likes stimulation," says Fisher. "I think if you kiss the right person, it's wonderful for you."
Erica Harrison is a freelance science writer and photographer based in Sydney.
In one of the many
In one of the many discussions I had with my grandmother she told me that in her days, she only kissed my grandfather twice: one time at the beginning of their relationship and the second and last time was when they got married.
thats sad
thats sad