🔗 Share this article Ancient Hominins and Early Humans Were Likely Kissing, Researchers Propose Among Galápagos albatrosses to Arctic mammals, chimpanzees to orangutans, various animals appear to kiss. Now, researchers suggest that ancient hominins did it too – and possibly exchanged kisses with modern humans. Common Microbial Clues This isn't the initial instance experts have suggested Neanderthals and early modern humans were intimately acquainted. Among previous studies, scientists have discovered modern people and their thick-browed cousins possessed the same mouth microbe for hundreds of thousands of years after the evolutionary divergence, implying they exchanged oral fluids. "Likely they were engaging in intimate contact," the researcher noted, adding that the concept chimed with research that has revealed people of certain genetic backgrounds contain ancient genetic material in their genome, revealing interbreeding was occurring. Romantic Interpretation "It certainly puts a more romantic spin on ancient interactions," Brindle commented. Writing in the publication Evolution and Human Behavior, Brindle and colleagues detail how, to explore the evolutionary origins of intimate contact, they first had to come up with a description that was not limited to how humans kiss. Describing Kissing "There have been some previous attempts to describe a intimate act, but it's largely focused on humans, which implies that essentially non-human species don't kiss. Now we understand that they likely engage, it might just not look from what our intimate contact looks like," said Brindle. However, she noted some behaviors that resembled intimate contact were distinct activities – such as the processing and transfer of food, or "mouth contact", observed in fish known as certain marine animals. As a result the team developed a description of intimate contact centered around social behaviors involving directed mouth-to-mouth contact with a individual of the identical group, with some movement of the oral area but no transfer of nutrition. Research Methods The lead researcher explained they focused on accounts of intimate behavior in primates from the African continent and Asia, including bonobos, chimpanzees and orangutans, and employed digital recordings to confirm the observations. Scientists then combined this information with details on the evolutionary relationships between extant and extinct species of such primates. Evolutionary Timeline The team say the findings suggest kissing developed somewhere between 21.5m and 16.9 million years ago in the ancestors of the great primates. The position of Neanderthals on this family tree suggests it is probable they, too, engaged in a kiss, the researchers conclude. But the behavior may not have been confined to their specific group. "The fact that modern people kiss, the fact that we now have demonstrated that Neanderthals probably kissed, suggests that the two [species] are also likely to have kissed," the researcher noted. Biological Significance Although the scientific reasoning is debated, Brindle said intimate contact could be employed in reproductive situations to possibly increase reproductive success or help choose between partners, while it could assist strengthen connections when used in a platonic way. A separate researcher in the activities of primates commented that as kissing behavior was seen in a wide range of apes it was logical its origins extend far into our evolutionary past, and an analysis of various types of kissing among a broader range of species might extend its origins back further still. "Behaviors that we consider as characteristics of our species, like kissing, are not unique to us if we look closely at different species," he said. Social Aspects An archaeology expert explained that kissing had a social component as it was not common to all human groups. "Nonetheless, as humans we thrive or fail on the strength of our emotional bonds, and ways of encouraging trust and intimacy will have been important for eons," she said. "It might be an image that seems a bit contradictory to our misplaced ideas of a rather ruthless and aggressive past, but really it should be no surprise that ancient hominins – and even them and our human ancestors collectively – kissed."