Kissing the right person can definitely give a sense of wellbeing, but theories abound as to why this might be. We spoke to anthropologist and author Dr Stephen Juan of the University of Sydney to find out more about what's in a kiss.
In passionate kisses, where there is a "wow" factor, the body responds with an adrenaline rush, releasing the feel good chemicals dopamine and phenylethylamine in the brain. The adrenaline speeds the heart rate up, giving that pounding feeling and may cause the body to become sweaty or the cheeks to flush. Women may release oxytocin, a hormone needed for female orgasm. A kiss may also trigger the release of endorphins which stimulate the immune system, adding weight to the argument that people who are in love are generally healthier than those who are not.
The above physical reactions depend, of course, on the emotion behind the kiss. We have to feel attracted to someone, otherwise the kiss will leave us cold. If your senses are ignited by someone and you like the sight, sound and smell of them, then your body is likely to spark a chemical reaction.
Non passionate kisses can, however, make us feel good for other reasons. A baby will enjoy the ticklish sensations and funny sounds of a kiss by someone it loves. A kiss from a close friend or family member will make us feel good as we see it as a sign of love and affection from someone we love. The reason for that sense of well-being is therefore not so much biological, as psychological.
There are many different theories on why we kiss. One is that it relates to times when mothers used to wean their children by chewing their food for them and then passing it into their mouths. Others say it is linked to comforting memories of breastfeeding, or that it is simply learned behaviour picked up from images we see in film, TV and magazines. Several experts argue that kissing is linked to our sense of smell, which can play a major part in physical attraction.
Certainly, the Eskimos' habit of rubbing noses could stem from a desire to get close enough to smell each other's pheromones. North American Indians had a lips to cheek kiss in which no motion or sound was made. In India, there were references in the Karma Sutra to lip-sucking, when the male would suck the female's upper lip and she his lower. There was a period when the "double butterfly" kiss, or eyelash to cheek kiss, was popular.
The romantic, passionate lip kiss is generally thought to originate with the early Greeks and Romans. In fact, when the Europeans first went to the Far East in the 16th century, the Chinese and Japanese were reportedly shocked, horrified and at times amused by the action. Dr Juan puts the recent trend for social kissing in Australia down to our unique blend of different cultures and their habits. The social kiss on the cheek is, he says, a greeting rather than a sign of affection.
While there may be no simple explanation for kissing, it looks as though this universally popular act is with us to stay.