Neanderthals and Modern Humans May Have Engaging in Intimate Contact, Scientists Suggest

From seabirds to polar bears, chimpanzees to great apes, certain species appear to kiss. Currently, scientists propose that Neanderthals did it too – and possibly exchanged kisses with early Homo sapiens.

Shared Microbial Evidence

It is not the first time scientists have proposed ancient relatives and early modern humans were closely connected. Among earlier research, researchers have found 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 engaging in intimate contact," the researcher noted, adding that the concept aligned with research that has revealed people of certain genetic backgrounds contain Neanderthal DNA in their genetic makeup, demonstrating interbreeding was at play.

Romantic Interpretation

"It certainly puts a different perspective on ancient interactions," the lead researcher said.

Writing in the journal Evolution and Human Behavior, Brindle and her team report how, to explore the evolutionary origins of kissing, they first had to come up with a description that was not restricted by how humans kiss.

Defining Kissing

"Previously there were some previous attempts to describe a kiss, but it's very much been human-centric, which means that basically other animals do not engage in this. Currently we understand that they likely engage, it may appear different from what human kissing resembles," said Brindle.

However, she said some behaviors that resembled kissing were distinct activities – such as the chewing and food sharing, or "mouth contact", seen in fish known as French grunts.

Consequently the team came up with a definition of intimate contact based on social behaviors involving directed oral interaction with a individual of the same species, with some motion of the oral area but absence of nutrition.

Study Approach

The lead researcher explained they concentrated on reports of kissing in non-human species from Africa and Asian regions, including bonobos, apes and orangutans, and employed online videos to verify the observations.

Scientists then integrated this information with information on the genetic connections between living and ancient species of such animals.

Historical Timeline

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

The position of ancient hominins on this family tree means it is likely they, too, engaged in a kiss, the scientists conclude. But the behavior might not have been confined to their own species.

"The fact that humans kiss, the fact that we currently have shown that ancient relatives probably kissed, indicates that the both groups are also likely to have engage," Brindle added.

Biological Importance

While the scientific reasoning is debated, Brindle said intimate contact could be employed in sexual contexts to potentially enhance reproductive success or help choose between mates, while it might help reinforce bonding when used in a platonic way.

A separate researcher in the activities of primates said that as kissing behavior was seen in a wide range of primates it was logical its origins extend far into our ancient history, and an analysis of different forms of kissing among a wider variety of species might extend its beginnings back further still.

"Behaviors that we consider as signatures of our species, like intimate contact, are not unique to us if we examine carefully at other animals," he said.

Social Elements

An archaeology expert said that kissing had a cultural element as it was not common to all human groups.

"However, as people we thrive or fail on the quality of our relationships, and methods of promoting confidence 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 ancient history, but actually it ought to be expected that Neanderthals – and including them and our human ancestors together – kissed."