Neanderthals and Early Humans Were Likely Kissing, Scientists Propose
Among seabirds to polar bears, chimpanzees to great apes, various animals appear to kiss. Now, scientists suggest that ancient hominins did it too – and might even have exchanged kisses with modern humans.
Shared Microbial Clues
This isn't the initial instance experts have proposed ancient relatives and early modern humans were closely connected. Among earlier research, researchers have discovered humans and their Neanderthal relatives shared the identical oral bacteria for hundreds of thousands of years after the evolutionary divergence, suggesting they exchanged oral fluids.
"Likely they were kissing," she said, explaining that the idea chimed with studies that has revealed people of non-African ancestry contain Neanderthal DNA in their genetic makeup, revealing genetic mixing was occurring.
Romantic Interpretation
"This offers a more romantic perspective on ancient interactions," the lead researcher said.
Publishing in the publication Evolution and Human Behavior, the researcher and colleagues report how, to investigate the historical roots of kissing, they first had to come up with a definition that was not limited to how people smooch.
Defining Intimate Contact
"There have been some previous attempts to define a kiss, but it's largely human-centric, which implies that basically non-human species don't kiss. Now we understand that they probably do, it may appear different from what our intimate contact looks like," explained the evolutionary biologist.
Nonetheless, she noted some actions that resembled intimate contact were distinct activities – such as the processing and transfer of food, or "kiss-fighting", seen in aquatic species called certain marine animals.
Consequently the team came up with a definition of intimate contact centered around social behaviors involving directed oral interaction with a member of the same species, with some movement of the oral area but absence of food.
Study Methods
Brindle said they focused on reports of intimate behavior in non-human species from the African continent and Asian regions, including bonobos, chimpanzees and great apes, and employed digital recordings to verify the reports.
Scientists then integrated this information with information on the genetic connections between extant and extinct types of such primates.
Historical Origins
The team propose the results indicate kissing developed approximately 21.5m and 16.9 million years ago in the predecessors of the great primates.
The position of ancient hominins on this family tree suggests it is probable they, too, indulged in a kiss, the researchers conclude. But the behavior might not have been limited to their specific group.
"Reality that humans engage intimately, the reality that we now have demonstrated that Neanderthals probably kissed, indicates that the both groups are probably did engage," Brindle added.
Biological Significance
While the evolutionary explanation is debated, Brindle said intimate contact could be used in sexual contexts to potentially enhance reproductive success or help choose between mates, while it could assist strengthen connections when used in a platonic way.
A separate researcher in the behavior of great apes said that as kissing behavior was seen in a wide range of apes it was logical its origins lie deep in our ancient history, and an examination of various types of kissing among a wider variety of animals might extend its origins back even earlier still.
"Behaviors that we consider as characteristics of human life, like intimate contact, are not unique to us if we examine carefully at different species," he said.
Cultural Aspects
Another professor said that kissing had a cultural element as it was not universal to all societies.
"However, as people we succeed or struggle on the quality of our emotional bonds, and ways of promoting trust and closeness will have been important for millions of years," she said. "It might be an concept that seems a bit contradictory to our incorrect assumptions of a supposedly aggressive and aggressive past, but actually it should be no surprise that ancient hominins – and even Neanderthals and our own species together – engaged intimately."
