🔗 Share this article Ancient Hominins and Modern Humans Were Likely Kissing, Researchers Suggest From seabirds to polar bears, primates to great apes, various animals engage in mouth-to-mouth contact. Currently, researchers propose that Neanderthals also engaged in this behavior – and might even have locked lips with modern humans. Shared Oral Evidence It is not the first time experts have suggested ancient relatives and early modern humans were closely connected. Among previous studies, scientists have discovered modern people and their Neanderthal relatives possessed the identical oral bacteria for millions of years after the two species split, implying they swapped saliva. "Probably they were engaging in intimate contact," she said, explaining that the idea aligned with research that has found humans of non-African ancestry have bits of Neanderthal DNA in their genetic makeup, demonstrating genetic mixing was at play. Intimate Spin "It certainly puts a more romantic spin on human-Neanderthal relations," Brindle said. Writing in the publication a scientific periodical, the researcher and her team detail how, to investigate the evolutionary origins of intimate contact, they first had to develop a description that was not limited to how humans kiss. Describing Kissing "There have been some previous attempts to describe a kiss, but it's very much been focused on humans, which means that basically other animals don't kiss. Currently we know that they probably do, it might just not look from what human kissing looks like," said Brindle. Nonetheless, she said some behaviors that resembled kissing were distinct activities – such as the processing and food sharing, or "kiss-fighting", observed in aquatic species called French grunts. Consequently the team developed a definition of intimate contact centered around social behaviors involving directed mouth-to-mouth contact with a member of the same species, with some movement of the mouth but absence of nutrition. Research Approach The lead researcher said they focused on reports of kissing in non-human species from the African continent and Asia, including primates, chimpanzees and great apes, and employed digital recordings to verify the reports. Scientists then integrated this information with information on the genetic connections between extant and ancient species of such animals. Historical Timeline The team propose the findings indicate kissing developed approximately 21.5 million and 16.9 million years ago in the ancestors of the great primates. The position of ancient hominins on this family tree suggests it is probable they, too, indulged in a intimate act, the scientists say. But the activity might not have been limited to their own species. "Reality that humans engage intimately, the fact that we currently have shown that Neanderthals probably kissed, suggests that the two [species] are also likely to have kissed," the researcher noted. Evolutionary Significance While the evolutionary explanation is debated, the expert said intimate contact could be employed in reproductive situations to potentially increase mating outcomes or help choose between mates, while it might help reinforce bonding when practiced in a non-sexual manner. Another expert in the activities of primates commented that as kissing behavior was observed in a broad spectrum of apes it was logical its origins lie deep in our evolutionary past, and an examination of different forms of intimate behavior among a broader range of species might push its beginnings back even earlier still. "Behaviors that we consider as signatures of human life, like intimate contact, are not exclusive to us if we examine carefully at other animals," he said. Cultural Aspects An archaeology expert explained that intimate contact had a social component as it was not universal to all societies. "However, as people we thrive or fail on the strength of our emotional bonds, and ways of promoting trust and intimacy will have been important for eons," she said. "It might be an concept that seems a bit contradictory to our incorrect assumptions of a supposedly aggressive and aggressive past, but really it should be no surprise that ancient hominins – and including them and our own species collectively – kissed."