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

From seabirds to polar bears, chimpanzees to orangutans, various animals engage in mouth-to-mouth contact. Currently, researchers suggest that ancient hominins did it too – and possibly locked lips with early Homo sapiens.

Shared Microbial Clues

It is not the first time experts have suggested ancient relatives and early modern humans were intimately acquainted. In previous studies, researchers have found modern people and their thick-browed cousins shared the same mouth microbe for hundreds of thousands of years after the evolutionary divergence, implying they exchanged oral fluids.

"Likely they were engaging in intimate contact," she said, adding that the idea chimed with research that has revealed humans of certain genetic backgrounds have bits of Neanderthal DNA in their genetic makeup, revealing interbreeding was occurring.

Romantic Interpretation

"This offers a more romantic spin on ancient interactions," Brindle said.

Writing in the publication a scientific periodical, the researcher and colleagues report how, to explore the evolutionary origins of intimate contact, they first had to come up with a description that was not restricted by how humans smooch.

Describing Intimate Contact

"Previously there were some previous attempts to describe a kiss, but it's very much been human-centric, which implies that basically non-human species don't kiss. Currently we understand that they probably do, it may appear different from what human kissing looks like," explained the evolutionary biologist.

However, she said some behaviors that resembled kissing were distinct activities – such as the processing and food sharing, or "kiss-fighting", seen in aquatic species called French grunts.

As a result the team developed a definition of kissing based on social behaviors involving directed mouth-to-mouth contact with a member of the same species, with some motion of the mouth but no transfer of nutrition.

Study Approach

The lead researcher said they focused on accounts of intimate behavior in primates from Africa and Asian regions, including bonobos, chimpanzees and great apes, and used digital recordings to verify the observations.

Scientists then integrated this data with details on the evolutionary relationships between living and ancient types of such animals.

Historical Timeline

Researchers say the results indicate intimate contact developed somewhere between 21.5m and 16.9 million years ago in the ancestors of the great primates.

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

"The fact that humans engage intimately, the fact that we currently have shown that Neanderthals very likely kissed, indicates that the both groups are probably did kissed," the researcher noted.

Biological Significance

Although the scientific reasoning is discussed, Brindle explained intimate contact could be employed in reproductive situations to possibly enhance mating outcomes or help choose between partners, while it might help strengthen connections when used in a platonic way.

A separate researcher in the activities of great apes commented that as kissing behavior was seen in a broad spectrum of apes it made sense its roots lie deep in our ancient history, and an analysis of different forms of intimate behavior among a wider variety of species might extend its origins back further still.

"Behaviors that we think of as signatures of our species, like kissing, are not exclusive to us if we examine carefully at different species," the expert noted.

Cultural Aspects

Another professor explained that kissing had a social component as it was not common to all human groups.

"Nonetheless, as humans we thrive or fail on the quality of our emotional bonds, and ways of promoting confidence and closeness will have been significant for millions of years," the professor stated. "This could represent an concept that appears a bit contradictory to our misplaced ideas of a rather ruthless and aggressive past, but really it ought to be expected that Neanderthals – and even Neanderthals and our human ancestors collectively – engaged intimately."