🔗 Share this article Ancient Hominins and Early Humans May Have Engaging in Intimate Contact, Researchers Suggest Among seabirds to polar bears, chimpanzees to great apes, certain species appear to kiss. Now, scientists propose that ancient hominins also engaged in this behavior – and possibly locked lips with modern humans. Common Microbial Evidence It is not the first time experts have suggested ancient relatives and early modern humans were closely connected. In previous studies, researchers have discovered modern people and their thick-browed cousins 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 concept aligned with studies that has found humans of non-African ancestry contain Neanderthal DNA in their genome, revealing genetic mixing was at play. Intimate Interpretation "This offers a different spin on ancient interactions," the lead researcher commented. Publishing in the journal Evolution and Human Behavior, the researcher and her team report how, to explore the evolutionary origins of kissing, they first had to come up with a description that was not restricted by how people smooch. Defining Intimate Contact "Previously there were some efforts to describe a intimate act, but it's very much been focused on humans, which means that basically other animals do not engage in this. Now we understand that they probably do, it may appear different from what our intimate contact looks like," said the evolutionary biologist. However, she said some actions that resembled intimate contact were something rather different – such as the processing and food sharing, or "kiss-fighting", seen in fish called French grunts. Consequently the team came up with a definition of kissing based on social behaviors involving directed mouth-to-mouth contact with a member of the same species, with some motion of the mouth but no transfer of nutrition. Study Methods The lead researcher explained they concentrated on reports of intimate behavior in non-human species from Africa and Asia, including primates, chimpanzees and orangutans, and employed digital recordings to confirm the observations. The researchers then integrated this information with information on the evolutionary relationships between living and ancient species of such primates. Historical Timeline Researchers say the findings suggest intimate contact developed approximately 21.5m and 16.9m years ago in the ancestors of the large apes. The position of Neanderthals on this evolutionary lineage suggests it is probable they, too, indulged in a kiss, the researchers conclude. But the behavior might not have been limited to their specific group. "The fact that humans engage intimately, the reality that we now have demonstrated that ancient relatives very likely engaged, suggests that the both groups are probably did kissed," Brindle added. Evolutionary Significance Although the scientific reasoning is debated, the expert said kissing could be employed in sexual contexts to potentially increase reproductive success or assist in selecting between partners, while it might help reinforce bonding when used in a non-sexual manner. A separate researcher in the activities of great apes said that as kissing behavior was seen in a wide range of apes it made sense its origins extend far into our evolutionary past, and an analysis of various types of intimate behavior among a broader range of species might extend its beginnings back even earlier still. "Things that we consider as signatures of our species, like kissing, are not exclusive to us if we look closely at other animals," he said. Social Elements An archaeology expert explained that kissing had a cultural element as it was not common to all societies. "Nonetheless, as people we thrive or fail on the strength of our emotional bonds, and methods of encouraging trust and intimacy will have been important for millions of years," she said. "It might be an concept that appears a bit incongruous to our misplaced ideas of a supposedly aggressive and aggressive past, but really it ought to be expected that ancient hominins – and even them and our human ancestors together – kissed."