BLOOMINGTON, Ind. -- For generations, passionate kisses immortalized in movies, songs and the arts have served as a thermometer of romantic affection.

But current research has found that not only is romantic kissing not the norm in most cultures, some find it uncomfortable and even flat-out repulsive.

Justin Garcia, research scientist at Kinsey Institute at Indiana University, is the co-author of a new study published in the journal American Anthropologist -- "Is the Romantic-Sexual Kiss a Near Human Universal?" -- that looked at 168 cultures throughout the world to better understand where kissing does and doesn't occur.

Using standard cross-cultural methods, the study found that fewer than half of all cultures surveyed -- 46 percent -- engage in romantic/sexual kissing. Romantic kissing was defined as lip-to-lip contact that may or may not be prolonged.

"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," said Garcia, assistant professor of gender studies in the IU Bloomington College of Arts and Sciences. "This is a real reminder of how Western ethnocentrism can bias the way we think about human behavior."

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.

But there was 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.

The research conducted by Garcia and colleagues 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.

Interest in the study stemmed from renewed attention in the role of close touch and kissing in people's romantic and sexual lives, Garcia said. Recent work on the issue, he said, has made claims about the universality of erotic kissing, some even claiming 90 percent of societies engage in the act.

"However, we realized no one had used standard cross-cultural methods to assess how frequently kissing actually occurs in different societies, but by doing so, we could begin to understand why it might occur in some places and not others," he said.

It is not clear where romantic/sexual kissing evolved from, Garcia said. 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."

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Study co-authors are William Jankowiak, Distinguished Professor of Anthropology, and Shelly Volsche, graduate research assistant in anthropology, both at the University of Nevada, Las Vegas.