Ancient Hominins and Modern Humans Were Likely Kissing, Scientists Suggest
From Galápagos albatrosses to polar bears, primates to great apes, certain species appear to kiss. Now, scientists suggest that Neanderthals also engaged in this behavior – and possibly exchanged kisses with early Homo sapiens.
Shared Microbial Clues
It is not the first time scientists have suggested Neanderthals and early modern humans were closely connected. Among earlier research, scientists have found humans and their Neanderthal relatives shared the identical oral bacteria for millions of years after the two species split, implying they exchanged oral fluids.
"Probably they were kissing," the researcher noted, adding that the idea aligned with research that has found people of certain genetic backgrounds contain ancient genetic material in their genome, demonstrating genetic mixing was occurring.
Romantic Spin
"It certainly puts a different perspective on human-Neanderthal relations," the lead researcher said.
Writing in the journal a scientific periodical, Brindle and colleagues report how, to investigate the evolutionary origins of kissing, they first had to come up with a definition that was not restricted by how people smooch.
Defining Kissing
"There have been some previous attempts to define a kiss, but it's largely focused on humans, which implies that essentially non-human species don't kiss. Now we understand that they probably do, it might just not look from what human kissing resembles," said Brindle.
Nonetheless, she noted some behaviors that looked like kissing were distinct activities – such as the chewing and food sharing, or "kiss-fighting", seen in fish called French grunts.
Consequently the team came up with a description of kissing based on friendly interactions involving directed mouth-to-mouth contact with a member of the same species, with some motion of the oral area but no transfer of food.
Study Approach
Brindle explained they concentrated on reports of intimate behavior in non-human species from Africa and Asian regions, including primates, apes and great apes, and used online videos to verify the reports.
Scientists then combined this data with details on the genetic connections between living and ancient types of such animals.
Evolutionary Origins
The team propose the findings suggest kissing developed approximately 21.5m and 16.9 million years ago in the ancestors of the great primates.
Placement of ancient hominins on this family tree suggests it is probable they, too, engaged in a kiss, the researchers conclude. But the activity might not have been confined to their own species.
"Reality that humans engage intimately, the reality that we currently have demonstrated that ancient relatives very likely kissed, indicates that the both groups are also likely to have engage," the researcher noted.
Evolutionary Significance
While the scientific reasoning is discussed, the expert explained kissing could be used in reproductive situations to possibly enhance mating outcomes or help choose between partners, while it could assist strengthen connections when used in a platonic way.
Another expert in the behavior of primates said that as intimate contact 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 intimate behavior among a wider variety of animals might push its origins back further still.
"Things that we think of as signatures of human life, like intimate contact, are not unique to us if we examine carefully at different species," he said.
Social Aspects
Another professor said that intimate contact had a cultural element as it was not universal to all human groups.
"Nonetheless, as people we thrive or fail on the quality of our emotional bonds, and methods of encouraging trust and intimacy will have been important for millions of years," she said. "It might be an image that appears a bit contradictory to our misplaced ideas of a supposedly aggressive and aggressive past, but actually it should be expected that ancient hominins – and even Neanderthals and our human ancestors collectively – kissed."