🔗 Share this article Ancient Hominins and Early Humans Were Likely Kissing, Scientists Propose From seabirds to polar bears, chimpanzees to orangutans, various animals engage in mouth-to-mouth contact. Now, researchers suggest that ancient hominins did it too – and might even have locked lips with modern humans. Shared Microbial Clues It is not the first time experts have suggested ancient relatives and early modern humans were closely connected. Among previous studies, scientists have found modern people and their Neanderthal relatives shared the identical oral bacteria for hundreds of thousands of years after the evolutionary divergence, implying they swapped saliva. "Likely they were engaging in intimate contact," she said, adding that the idea aligned with research that has found people of certain genetic backgrounds contain Neanderthal DNA in their genome, revealing genetic mixing was occurring. Intimate Interpretation "This offers a more romantic perspective on ancient interactions," the lead researcher said. Publishing in the publication Evolution and Human Behavior, the researcher and her team report how, to investigate the evolutionary origins of intimate contact, they first had to develop a description that was not restricted by how people smooch. Describing Kissing "Previously there were some previous attempts to define a kiss, but it's largely focused on humans, which means that basically non-human species do not engage in this. Now we understand that they likely engage, it might just not look from what our intimate contact looks like," explained Brindle. However, she said some behaviors that looked like intimate contact were distinct activities – such as the processing and transfer of food, or "mouth contact", observed in fish called French grunts. As a result the team came up with a description of kissing based on friendly interactions involving directed mouth-to-mouth contact with a individual of the same species, with some motion of the mouth but no transfer of food. Research Methods The lead researcher said they focused on reports of intimate behavior in non-human species from the African continent and Asian regions, including primates, apes and great apes, and used digital recordings to verify the reports. The researchers then integrated this information with details on the genetic connections between extant and extinct types of such animals. Evolutionary Timeline The team propose the findings indicate kissing evolved somewhere between 21.5 million and 16.9 million years ago in the ancestors of the great primates. Placement of ancient hominins on this family tree means it is likely they, too, engaged in a kiss, the researchers conclude. But the activity may not have been confined to their own species. "Reality that humans engage intimately, the fact that we currently have shown that ancient relatives very likely kissed, indicates that the both groups are probably did engage," Brindle added. Evolutionary Significance Although the scientific reasoning is discussed, the expert explained intimate contact could be employed in reproductive situations to possibly increase reproductive success or help choose between mates, while it might help reinforce bonding when practiced in a platonic way. A separate researcher in the activities of primates said that as kissing behavior was seen in a broad spectrum of apes it was logical its roots lie deep in our evolutionary past, and an examination of various types of intimate behavior among a wider variety of species might extend its beginnings back even earlier still. "Behaviors that we think of as characteristics of our species, like intimate contact, are not exclusive to us if we examine carefully at other animals," he said. Social Elements Another professor explained that kissing had a social component as it was not common to all human groups. "However, as people we succeed or struggle on the quality of our emotional bonds, and ways of promoting trust and intimacy will have been important for eons," the professor stated. "It might be an image that appears a bit contradictory to our misplaced ideas of a rather ruthless and aggressive past, but really it ought to be no surprise that ancient hominins – and even Neanderthals and our human ancestors collectively – kissed."