🔗 Share this article

From seabirds to Arctic mammals, chimpanzees to great apes, various animals appear to kiss. Now, scientists propose that ancient hominins also engaged in this behavior – and might even have exchanged kisses with early Homo sapiens.

Common Oral Evidence

This isn't the initial instance experts have proposed ancient relatives and early modern humans were intimately acquainted. In earlier research, scientists have discovered modern people and their Neanderthal relatives possessed the same mouth microbe for hundreds of thousands of years after the two species split, implying they exchanged oral fluids.

"Likely they were kissing," the researcher noted, adding that the concept chimed with research that has revealed humans of certain genetic backgrounds contain Neanderthal DNA in their genome, demonstrating interbreeding was occurring.

Intimate Spin

"It certainly puts a different perspective on human-Neanderthal relations," the lead researcher commented.

Publishing in the publication a scientific periodical, the researcher and colleagues detail how, to explore the historical roots of intimate contact, they first had to come up with a description that was not limited to how people kiss.

Defining Intimate Contact

"Previously there were some previous attempts to describe a kiss, but it's largely human-centric, which means that basically non-human species do not engage in this. Now we know that they likely engage, it might just not look from what our intimate contact resembles," explained Brindle.

However, she said some actions that resembled kissing were something rather different – such as the processing and transfer of food, or "mouth contact", observed in aquatic species known as French grunts.

As a result the research group developed a description of kissing based on friendly interactions involving directed oral interaction with a member of the same species, with some movement of the oral area but absence of nutrition.

Study Approach

The lead researcher said they concentrated on accounts of intimate behavior in non-human species from the African continent and Asia, including primates, chimpanzees and orangutans, and employed digital recordings to confirm the observations.

The researchers then combined this information with details on the evolutionary relationships between extant and extinct types of such animals.

Historical Origins

Researchers say the results indicate kissing evolved approximately 21.5 million and 16.9m years ago in the predecessors of the large apes.

Placement of Neanderthals on this family tree means it is likely they, too, indulged in a kiss, the researchers conclude. But the activity may not have been confined to their own species.

"Reality that humans kiss, the fact that we currently have shown that Neanderthals very likely kissed, suggests that the both groups are probably did engage," the researcher added.

Biological Significance

While the scientific reasoning is discussed, the expert said intimate contact could be employed in sexual contexts to possibly enhance mating outcomes or assist in selecting between partners, while it could assist reinforce bonding when practiced in a platonic way.

Another expert in the activities of primates said that as intimate contact was observed in a broad spectrum of primates it made sense its origins extend far into our ancient history, and an examination of different forms of kissing among a broader range of animals might extend its origins back further still.

"Things that we think of as signatures of our species, like intimate contact, are not unique to us if we examine carefully at different species," he said.

Cultural Aspects

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

"However, as humans we thrive or fail on the strength of our relationships, and ways of encouraging trust and closeness will have been significant for eons," she said. "This could represent an image that seems a bit incongruous to our incorrect assumptions of a rather ruthless and aggressive past, but really it ought to be expected that Neanderthals – and even Neanderthals and our human ancestors together – kissed."