Passionate kisses have immortalized in movies and literature, serving thermometer of romantic affection and occurring at the end of these works to make the audience feel warm and gooey in side. It often signals a happy ending.

However, researchers at Indiana University found that not only is romantic kissing not the norm in most cultures, some find it uncomfortable and even flat-out repulsive.

"We hypothesized that some cultures would either not engage in romantic/sexual kissing, or find it to be a strange display of intimacy, but we were surprised to find that it was a majority of cultures that fell into this category," Justin Garcia, co-author of the study, said in a statement. "This is a real reminder of how Western ethnocentrism can bias the way we think about human behavior."

For the study, researchers looked at 168 cultures throughout the world to better understand where kissing does and doesn't occur.

They found that 46 percent of all cultures surveyed engage in romantic/sexual kissing. Romantic kissing was defined as lip-to-lip contact that may or may not be prolonged. Romantic kissing was most prevalent in the Middle East, where all 10 of the cultures studied engaged in it. In North America, 55 percent of cultures engaged in romantic kissing, along with 70 percent in Europe and 73 percent in Asia.

Researchers found no evidence of romantic kissing in Central America, and no ethnographer working with Sub-Saharan African, New Guinean or Amazonian foragers or horticulturalists reported any evidence of romantic kissing in the populations they studied, according to the research.

Researchers also found a relationship between social complexity and kissing: The more socially complex and stratified a society is, the higher the frequency of romantic kissing.

Garcia said it is not clear where romantic/sexual kissing evolved from. Some animals engage in similar behaviors; chimpanzees, for example, are known to engage in open-mouth kissing.

When it comes to humans kissing, Garcia pointed out that it does serve as a way to learn more about a partner, "whether one feels there is any 'chemistry,' or possibly to assess health via taste and smell, and in some ways to assess compatibility with each other."

"There is likely a biological underpinning to kissing, as it can often involve exchange of pheromones and saliva, and also pathogens -- which might be particularly dangerous in societies without oral hygiene, where kissing may lead to spread of respiratory or other illness," he said. "But this is only in societies that have come to see the erotic kiss as part of their larger romantic and sexual repertoires. How that shift occurs is still an open question for research."

The findings are detailed in the journal American Anthropologist.