Neanderthals and Modern Humans Were Likely Engaging in Intimate Contact, Researchers Propose
From seabirds to Arctic mammals, chimpanzees to orangutans, certain species engage in mouth-to-mouth contact. Currently, scientists suggest that ancient hominins did it too – and might even have exchanged kisses with modern humans.
Common Microbial Clues
It is not the first time scientists have proposed ancient relatives and early modern humans were intimately acquainted. In earlier research, researchers have found humans and their Neanderthal relatives possessed the same mouth microbe for hundreds of thousands of years after the two species split, suggesting they swapped saliva.
"Likely they were kissing," she said, adding that the concept aligned with research that has revealed people of non-African ancestry have bits of Neanderthal DNA in their genome, demonstrating interbreeding was occurring.
Intimate Interpretation
"It certainly puts a different perspective on human-Neanderthal relations," Brindle commented.
Publishing in the journal Evolution and Human Behavior, Brindle and colleagues detail how, to investigate the historical roots of intimate contact, they first had to develop a description that was not limited to how people smooch.
Describing Kissing
"Previously there were some previous attempts to describe a intimate act, but it's largely focused on humans, which means that basically other animals do not engage in this. Now we understand that they likely engage, it may appear different from what our intimate contact resembles," said Brindle.
Nonetheless, she said some actions that resembled kissing were something rather different – such as the chewing and transfer of food, or "mouth contact", seen in aquatic species known as French grunts.
Consequently the research group developed a description of kissing based on social behaviors involving directed oral interaction with a individual of the same species, with some motion of the mouth but no transfer of nutrition.
Study Methods
Brindle explained they focused on accounts of kissing in primates from the African continent and Asia, including primates, chimpanzees and great apes, and used online videos to confirm the reports.
The researchers then combined this data with details on the genetic connections between extant and extinct types of such animals.
Historical Origins
The team propose the results indicate intimate contact evolved somewhere between 21.5 million and 16.9m years ago in the ancestors of the large apes.
Placement of Neanderthals on this evolutionary lineage means it is likely they, too, indulged in a kiss, the researchers say. But the behavior may not have been limited to their own species.
"Reality that humans engage intimately, the fact that we currently have demonstrated that ancient relatives very likely kissed, suggests that the two [species] are also likely to have kissed," Brindle added.
Evolutionary Significance
Although the scientific reasoning is debated, Brindle explained kissing could be used in sexual contexts to potentially increase reproductive success or help choose between mates, while it could assist strengthen connections when practiced in a platonic way.
A separate researcher in the behavior of great apes commented that as kissing behavior was seen in a broad spectrum of apes it made sense its roots extend far into our ancient history, and an examination of various types of kissing among a broader range of animals might push its beginnings back further still.
"Things that we think of as signatures of human life, like kissing, are not unique to us if we examine carefully at other animals," the expert noted.
Cultural Elements
An archaeology expert explained that intimate contact had a cultural element as it was not universal to all societies.
"Nonetheless, as people we thrive or fail on the strength of our relationships, and methods of encouraging confidence and intimacy will have been important for millions of years," the professor stated. "This could represent an image that appears a bit incongruous to our incorrect assumptions of a supposedly aggressive and ancient history, but really it should be expected that ancient hominins – and including them and our own species together – kissed."