Neanderthals and Modern Humans May Have Kissing, Researchers Suggest

From seabirds to Arctic mammals, primates to great apes, certain species appear to kiss. Now, researchers propose that ancient hominins also engaged in this behavior – and possibly exchanged kisses with early Homo sapiens.

Shared Oral Evidence

This isn't the initial instance scientists have suggested Neanderthals and early modern humans were intimately acquainted. In previous studies, scientists have found modern people and their Neanderthal relatives shared the identical oral bacteria for hundreds of thousands of years after the two species split, implying they exchanged oral fluids.

"Likely they were kissing," she said, adding that the idea aligned with research that has revealed humans of non-African ancestry have bits of ancient genetic material in their genetic makeup, revealing genetic mixing was at play.

Intimate Spin

"This offers a different perspective on ancient interactions," Brindle commented.

Writing in the publication a scientific periodical, Brindle and her team detail how, to explore the historical roots of intimate contact, they first had to develop a description that was not limited to how humans kiss.

Defining Intimate Contact

"Previously there were some efforts to describe a intimate act, but it's largely focused on humans, which implies that basically other animals do not engage in this. Now we understand that they likely engage, it may appear different from what our intimate contact looks like," said the evolutionary biologist.

Nonetheless, she said some actions 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 developed a definition of kissing centered around social behaviors involving intentional mouth-to-mouth contact with a member of the same species, with some movement of the mouth but absence of nutrition.

Study Methods

The lead researcher said they focused on accounts of kissing in primates from Africa and Asia, including bonobos, chimpanzees and great apes, and employed online videos to verify the reports.

The researchers then integrated this information with information on the genetic connections between living and ancient types of such primates.

Evolutionary Origins

Researchers say the results suggest intimate contact evolved approximately 21.5m and 16.9m years ago in the predecessors of the large apes.

Placement of Neanderthals on this evolutionary lineage suggests it is probable they, too, engaged in a kiss, the researchers say. But the activity may not have been confined to their specific group.

"Reality that humans engage intimately, the fact that we now have demonstrated that ancient relatives probably kissed, indicates that the both groups are probably did kissed," the researcher noted.

Evolutionary Significance

Although the scientific reasoning is debated, the expert explained kissing could be employed in sexual contexts to possibly increase reproductive success or assist in selecting between partners, while it could assist reinforce bonding 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 made sense its roots extend far into our ancient history, and an examination of different forms of intimate behavior among a broader range of species might push its beginnings back even earlier still.

"Behaviors that we consider as characteristics of human life, like intimate contact, are not exclusive to us if we examine carefully at other animals," he said.

Social Elements

An archaeology expert said that intimate contact had a social component as it was not common to all human groups.

"Nonetheless, as humans we succeed or struggle on the quality of our relationships, and methods of promoting confidence and intimacy will have been significant for millions of years," the professor stated. "This could represent an image that appears a bit incongruous to our incorrect assumptions of a supposedly aggressive and ancient history, but really it ought to be expected that ancient hominins – and even Neanderthals and our own species collectively – kissed."