In the spirit of Valentine's Day, I submit this fairly interesting column from today's New York Times that discusses exactly how humans came to kiss each other. Is it evolutionary or a social construct? The urge to lock lips is not universal:
All across Africa, the Pacific and the Americas, we find cultures that didn't know about mouth kissing until their first contact with European explorers. And the attraction was not always immediately apparent. Most considered the act of exchanging saliva revolting. Among the Lapps of northern Finland, both sexes would bathe together in a state of complete nudity, but kissing was regarded as beyond the pale.
To this day, public kissing is still seen as indecent in many parts of the world. In 1990, the Beijing-based Workers' Daily advised its readers that 'the invasive Europeans brought the kissing custom to China, but it is regarded as a vulgar practice which is all too suggestive of cannibalism.'
An interesting question, but really irrelevant in the end. Definitely file that under the "if it feels good, do it" category. :)