Among seabirds to polar bears, chimpanzees to great apes, various animals engage in mouth-to-mouth contact. Now, researchers propose that Neanderthals did it too – and possibly exchanged kisses with modern humans.
It is not the first time experts have proposed ancient relatives and Homo sapiens were intimately acquainted. In previous studies, researchers have found modern people and their Neanderthal relatives shared the identical oral bacteria for millions of years after the two species split, implying they swapped saliva.
"Likely they were kissing," the researcher noted, adding that the concept chimed with research that has revealed humans of non-African ancestry have bits of Neanderthal DNA in their genome, revealing genetic mixing was at play.
"This offers a more romantic perspective on ancient interactions," the lead researcher said.
Publishing in the journal a scientific periodical, the researcher and her team report how, to explore the evolutionary origins of intimate contact, they first had to come up with a description that was not limited to how people kiss.
"Previously there were some previous attempts to describe a kiss, 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 human kissing looks like," said Brindle.
Nonetheless, she said some behaviors that looked like intimate contact were distinct activities – such as the chewing and food sharing, or "kiss-fighting", seen in fish called French grunts.
As a result the research group came up with a definition of kissing based on social behaviors involving directed mouth-to-mouth contact with a member of the identical group, with some movement of the oral area but no transfer of nutrition.
The lead researcher said they focused on reports of kissing in non-human species from the African continent and Asian regions, including primates, chimpanzees and orangutans, and employed digital recordings to verify the observations.
Scientists then integrated this information with information on the evolutionary relationships between living and extinct types of such primates.
Researchers propose the findings indicate intimate contact developed approximately 21.5m and 16.9 million years ago in the ancestors of the great primates.
Placement of Neanderthals on this evolutionary lineage suggests it is likely they, too, indulged in a intimate act, the scientists conclude. But the behavior might not have been limited to their own species.
"The fact that humans engage intimately, the reality that we currently have demonstrated that Neanderthals very likely engaged, suggests that the both groups are probably did kissed," Brindle added.
Although the scientific reasoning is discussed, Brindle explained intimate contact could be employed in reproductive situations to potentially increase reproductive success or help choose 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 intimate contact was observed in a wide range of primates it was logical its roots lie deep in our evolutionary past, and an analysis of various types of intimate behavior among a wider variety of animals might extend its beginnings back further still.
"Things that we think of as characteristics of human life, like kissing, are not unique to us if we examine carefully at other animals," the expert noted.
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 relationships, and ways of promoting trust and closeness will have been important for eons," the professor stated. "This could represent an concept that seems a bit contradictory to our misplaced ideas of a supposedly aggressive and ancient history, but really it should be no surprise that Neanderthals – and including Neanderthals and our own species together – engaged intimately."
Elara is a financial strategist with over a decade of experience in wealth management and entrepreneurship.
