When did people start kissing: In most cultures, they actually haven't yet

Although some gestures of affection have probably been present throughout human history, the kiss is not among them. Expressing love by passionately connecting the lips is a fairly new thing in the evolutionary history of humans, according to research conducted by scientists from the Kinsey Institute at Indiana University along with colleagues from the University of Nevada, Las Vegas.

A passionate kiss isn't even a universally accepted practice, and some cultures even consider it extremely "disgusting," writes National Geographic. According to this, as its authors claim, the first major study on "romantic-sexual" kissing, only 46 percent of the 168 cultures examined show a passionate kiss as part of social history.

For example, Middle Eastern and European cultures adopted this way of kissing, while sub-Saharan Africans and Amazonian hunter-gatherer communities did not. Vilijem Jankovjak, the author of this research, assumes that kissing may be "related to increased leisure". In socially stratified communities, when the elites began to apply it, the masses began to imitate them.

"The combined court system is ubiquitous in human history," he says. "And people seemed to really like kissing once they discovered it."