Neanderthals and Modern Humans Were Likely Kissing, Researchers Suggest

Among seabirds to Arctic mammals, primates to orangutans, certain species appear to kiss. Currently, scientists propose that Neanderthals did it too – and might even have locked lips with early Homo sapiens.

Shared Microbial Evidence

It is not the first time scientists have suggested Neanderthals and early modern humans were intimately acquainted. In earlier research, scientists have found modern people and their Neanderthal relatives possessed the identical oral bacteria for hundreds of thousands of years after the two species split, implying they swapped saliva.

"Likely they were engaging in intimate contact," she said, adding that the concept chimed with studies that has revealed humans of certain genetic backgrounds contain Neanderthal DNA in their genetic makeup, revealing genetic mixing was at play.

Intimate Interpretation

"It certainly puts a different perspective on ancient interactions," Brindle commented.

Publishing in the journal Evolution and Human Behavior, the researcher and colleagues report how, to investigate the historical roots of kissing, they first had to develop a definition that was not limited to how people kiss.

Describing Kissing

"Previously there were some previous attempts to describe a intimate act, but it's largely focused on humans, which implies that essentially non-human species don't kiss. Currently we understand that they likely engage, it may appear different from what human kissing resembles," said Brindle.

Nonetheless, she noted some behaviors that resembled intimate contact were something rather different – such as the processing and food sharing, or "kiss-fighting", seen in fish called certain marine animals.

As a result the team came up with a definition of kissing centered around social behaviors involving intentional oral interaction with a member of the identical group, with some motion of the mouth but no transfer of food.

Research Methods

The lead researcher explained they concentrated on accounts of kissing in primates from Africa and Asian regions, including primates, chimpanzees and orangutans, and used online videos to verify the reports.

The researchers then integrated this data with information on the evolutionary relationships between extant and ancient species of such primates.

Evolutionary Timeline

The team propose the findings suggest kissing evolved approximately 21.5 million and 16.9m years ago in the predecessors of the large apes.

The position of Neanderthals on this family tree means it is probable they, too, indulged in a intimate act, the researchers conclude. But the behavior may not have been limited to their specific group.

"The fact that modern people engage intimately, the reality that we now have shown that ancient relatives probably engaged, indicates that the two [species] are also likely to have engage," the researcher noted.

Evolutionary Importance

Although the evolutionary explanation is discussed, the expert explained kissing could be employed in reproductive situations to possibly enhance reproductive success or assist in selecting between partners, while it might help strengthen connections when used in a non-sexual manner.

Another expert in the behavior of primates said that as kissing behavior was seen in a broad spectrum of apes it was logical its origins lie deep in our evolutionary past, and an analysis of different forms of kissing among a broader range of species might push its beginnings back even earlier still.

"Things that we consider as signatures of our species, like kissing, are not unique to us if we look closely at other animals," the expert noted.

Cultural Aspects

Another professor explained that intimate contact had a cultural element as it was not universal to all societies.

"However, as humans we succeed or struggle on the quality of our relationships, and methods of encouraging trust and closeness will have been significant for millions of years," the professor stated. "It might be an concept that appears a bit incongruous to our misplaced ideas of a supposedly aggressive and ancient history, but really it ought to be no surprise that ancient hominins – and including Neanderthals and our human ancestors collectively – kissed."