Neanderthals and Modern Humans Were Likely Kissing, Researchers Propose
Among Galápagos albatrosses to polar bears, primates to great apes, various animals engage in mouth-to-mouth contact. Now, scientists suggest that Neanderthals did it too – and possibly exchanged kisses with modern humans.
Shared Microbial Evidence
This isn't the initial instance experts have proposed ancient relatives and early modern humans were closely connected. In previous studies, scientists have found humans and their Neanderthal relatives shared the same mouth microbe for millions of years after the evolutionary divergence, implying they swapped saliva.
"Likely they were kissing," the researcher noted, explaining that the idea chimed with research that has revealed people of non-African ancestry contain ancient genetic material in their genetic makeup, demonstrating interbreeding was occurring.
Intimate Spin
"It certainly puts a different perspective on human-Neanderthal relations," Brindle said.
Publishing in the publication a scientific periodical, the researcher and colleagues report how, to explore the evolutionary origins of intimate contact, they first had to develop a definition that was not limited to how humans smooch.
Describing Intimate Contact
"Previously there were some previous attempts to define a kiss, but it's largely focused on humans, which means that essentially non-human species don't kiss. Now we know that they likely engage, it may appear different from what human kissing resembles," said the evolutionary biologist.
However, she said some actions that resembled kissing were something rather different – such as the chewing and transfer of food, or "kiss-fighting", observed in aquatic species called French grunts.
As a result the research group developed a definition of intimate contact based on friendly interactions involving directed mouth-to-mouth contact with a individual of the same species, with some movement of the mouth but no transfer of food.
Study Approach
The lead researcher said they focused on accounts of intimate behavior in primates from Africa 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 living and ancient species of such primates.
Historical Origins
Researchers say the results suggest kissing developed approximately 21.5 million and 16.9m years ago in the predecessors of the great primates.
Placement of Neanderthals on this evolutionary lineage means it is probable they, too, engaged in a kiss, the researchers conclude. But the activity may not have been limited to their own species.
"Reality that modern people engage intimately, the reality that we now have demonstrated that Neanderthals probably engaged, indicates that the two [species] are also likely to have engage," Brindle added.
Biological Importance
Although the scientific reasoning is debated, Brindle explained kissing could be employed in sexual contexts to potentially enhance reproductive success or assist in selecting between partners, while it might help strengthen connections when practiced in a platonic way.
Another expert in the behavior of great apes commented that as intimate contact was seen in a broad spectrum of primates it was logical its origins extend far into our evolutionary past, and an examination of different forms of intimate behavior among a broader range of animals might push its origins back further still.
"Behaviors that we think of as characteristics of our species, like intimate contact, are not unique to us if we look closely at other animals," he said.
Social Elements
An archaeology expert explained that intimate contact had a social component as it was not common to all human groups.
"However, as humans we succeed or struggle on the quality of our emotional bonds, and methods of promoting trust and closeness will have been significant for eons," she said. "This could represent an image that seems a bit incongruous to our incorrect assumptions of a supposedly aggressive and ancient history, but actually it ought to be no surprise that Neanderthals – and including Neanderthals and our human ancestors together – kissed."
