Ancient Hominins and Modern Humans Were Likely Kissing, Researchers Suggest
Among Galápagos albatrosses to polar bears, chimpanzees to great apes, certain species engage in mouth-to-mouth contact. Now, scientists propose that Neanderthals also engaged in this behavior – and might even have exchanged kisses with modern humans.
Common Oral Clues
This isn't the initial instance experts have suggested Neanderthals and Homo sapiens were intimately acquainted. Among previous studies, researchers have found modern people and their Neanderthal relatives shared the identical oral bacteria for hundreds of thousands of years after the two species split, suggesting they swapped saliva.
"Likely they were kissing," the researcher noted, adding that the idea aligned with research that has found people of certain genetic backgrounds have bits of Neanderthal DNA in their genome, revealing interbreeding was occurring.
Intimate Spin
"This offers a more romantic spin on human-Neanderthal relations," the lead researcher commented.
Publishing in the publication a scientific periodical, Brindle and colleagues detail how, to explore the historical roots of kissing, they first had to develop a definition that was not restricted by how humans smooch.
Describing Kissing
"Previously there were some efforts to describe a intimate act, but it's very much been focused on humans, which implies that essentially other animals do not engage in this. Currently we know that they likely engage, it may appear different from what human kissing resembles," explained Brindle.
However, she noted some behaviors that looked like kissing were distinct activities – such as the chewing and transfer of food, or "kiss-fighting", seen in aquatic species called certain marine animals.
As a result the research group came up with a description of intimate contact based on friendly interactions involving directed mouth-to-mouth contact with a individual of the same species, with some motion of the oral area but absence of nutrition.
Research Methods
The lead researcher said they focused on reports of kissing in non-human species from the African continent and Asia, including primates, apes and orangutans, and employed online videos to verify the reports.
Scientists then integrated this data with details on the genetic connections between extant and ancient types of such animals.
Evolutionary Origins
The team propose the results suggest intimate contact evolved somewhere between 21.5 million and 16.9 million years ago in the ancestors of the great primates.
The position of ancient hominins on this evolutionary lineage suggests it is probable they, too, engaged in a intimate act, the scientists conclude. But the behavior may not have been limited to their own species.
"Reality that modern people kiss, the reality that we currently have demonstrated that ancient relatives probably kissed, suggests that the two [species] are probably did kissed," the researcher added.
Biological Significance
While the scientific reasoning is debated, the expert explained intimate contact could be used in sexual contexts to potentially increase mating outcomes or help choose between partners, while it might help reinforce bonding when used in a platonic way.
Another expert in the behavior of great apes commented that as kissing behavior was seen in a wide range of apes it was logical its origins lie deep in our evolutionary past, and an examination of different forms of kissing among a broader range of species might push its beginnings back even earlier still.
"Things that we think of as signatures of our species, like intimate contact, are not unique to us if we examine carefully at different species," the expert noted.
Cultural Aspects
An archaeology expert 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 methods of promoting confidence and closeness will have been important for eons," the professor stated. "It might be an image that seems a bit contradictory to our incorrect assumptions of a supposedly aggressive and ancient history, but really it ought to be no surprise that ancient hominins – and even them and our human ancestors together – engaged intimately."