Joshua Foer, writing in The New York Times, reports (among other interesting things):

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." . . .

Vaughn Bryant, an anthropologist at Texas A&M, has traced the first recorded kiss back to India, somewhere around 1500 B.C., when early Vedic scriptures start to mention people "sniffing" with their mouths, and later texts describe lovers "setting mouth to mouth." From there, he hypothesizes, the kiss spread westward when Alexander the Great conquered the Punjab in 326 B.C.

The Romans were inveterate kissers, and along with Latin, the kiss became one of their chief exports. . . .

Thanks to David Tice for the pointer.