🔗 Share this article Ancient Hominins and Modern Humans Were Likely Engaging in Intimate Contact, Researchers Suggest From seabirds to Arctic mammals, chimpanzees to great apes, various animals appear to kiss. Currently, researchers suggest that Neanderthals did it too – and might even have exchanged kisses with modern humans. Shared Oral Clues This isn't the initial instance experts have proposed ancient relatives and Homo sapiens were closely connected. Among previous studies, scientists have discovered modern people and their thick-browed cousins shared the identical oral bacteria for millions of years after the two species split, suggesting they swapped saliva. "Probably they were engaging in intimate contact," the researcher noted, explaining that the idea chimed with research that has found people of non-African ancestry have bits of Neanderthal DNA in their genetic makeup, demonstrating interbreeding was at play. Romantic Interpretation "This offers a more romantic perspective on human-Neanderthal relations," the lead researcher commented. Writing in the publication Evolution and Human Behavior, Brindle and colleagues detail how, to investigate the historical roots of kissing, they first had to develop a definition that was not restricted by how people kiss. Defining Kissing "There have been some efforts to define a kiss, but it's very much been focused on humans, which means that essentially non-human species don't kiss. Now we know that they probably do, it may appear different from what human kissing resembles," explained Brindle. However, she noted some behaviors that looked like kissing were something rather different – such as the chewing and food sharing, or "mouth contact", observed in aquatic species called French grunts. Consequently the research group came up with a definition of intimate contact centered around friendly interactions involving intentional oral interaction with a individual of the same species, with some motion of the oral area but absence of nutrition. Study Methods The lead researcher said they focused on accounts of kissing in non-human species from the African continent and Asia, including bonobos, chimpanzees and orangutans, and employed online videos to verify the reports. The researchers then integrated this information with information on the evolutionary relationships between extant and ancient types of such animals. Historical Timeline Researchers say the results indicate kissing developed approximately 21.5 million and 16.9m years ago in the predecessors of the large apes. Placement of ancient hominins on this family tree means it is probable they, too, engaged in a intimate act, the scientists say. But the behavior may not have been confined to their own species. "The fact that humans kiss, the reality that we currently have shown that ancient relatives probably kissed, suggests that the two [species] are probably did engage," the researcher noted. Evolutionary Importance While the evolutionary explanation is discussed, the expert explained intimate contact could be employed in reproductive situations to potentially increase reproductive success or help choose between mates, while it could assist strengthen connections when used in a platonic way. A separate researcher in the behavior of great apes commented that as intimate contact was observed in a wide range of apes it made sense its roots extend far into our ancient history, and an analysis of different forms of kissing among a broader range of species might push its origins back even earlier still. "Things that we consider as characteristics of our species, like intimate contact, are not unique to us if we examine carefully at different species," the expert noted. Cultural Elements Another professor explained that intimate contact had a social component as it was not universal to all societies. "Nonetheless, as people we succeed or struggle on the strength of our emotional bonds, and ways of promoting trust and closeness will have been significant for millions of years," she said. "This could represent an image that appears a bit contradictory to our incorrect assumptions of a rather ruthless and aggressive past, but actually it ought to be expected that ancient hominins – and including Neanderthals and our human ancestors together – kissed."