🔗 Share this article

From seabirds to polar bears, chimpanzees to orangutans, certain species engage in mouth-to-mouth contact. Now, researchers propose that Neanderthals did it too – and might even have exchanged kisses with early Homo sapiens.

Shared Oral Evidence

This isn't the initial instance scientists have suggested ancient relatives and Homo sapiens were intimately acquainted. Among earlier research, scientists have discovered humans and their Neanderthal relatives shared the same mouth microbe for millions of years after the two species split, implying they exchanged oral fluids.

"Likely they were engaging in intimate contact," she said, adding that the concept aligned with studies that has revealed people of non-African ancestry contain Neanderthal DNA in their genome, revealing interbreeding was occurring.

Intimate Interpretation

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

Writing in the publication a scientific periodical, the researcher and her team detail how, to investigate the historical roots of kissing, they first had to come up with a description that was not restricted by how humans smooch.

Describing Intimate Contact

"There have been some previous attempts to describe a kiss, but it's very much been human-centric, which means that essentially non-human species 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 noted some actions that looked like intimate contact were something rather different – such as the processing and food sharing, or "mouth contact", observed in fish known as French grunts.

As a result the research group developed a definition of intimate contact centered around friendly interactions involving directed oral interaction with a individual of the identical group, with some motion of the mouth but no transfer of nutrition.

Study Methods

Brindle explained they focused on reports of kissing in non-human species from Africa and Asia, including primates, chimpanzees and great apes, and employed digital recordings to confirm the observations.

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

Historical Timeline

The team say the results indicate intimate contact evolved approximately 21.5m and 16.9 million years ago in the predecessors of the large apes.

The position of ancient hominins on this evolutionary lineage suggests it is likely they, too, engaged in a intimate act, the researchers say. But the activity may not have been limited to their specific group.

"Reality that humans kiss, the fact that we currently have demonstrated that ancient relatives probably kissed, suggests that the both groups are probably did kissed," Brindle noted.

Biological Significance

Although the scientific reasoning is discussed, the expert explained intimate contact could be employed in reproductive situations to potentially enhance reproductive success or help choose between mates, while it could assist strengthen connections when used in a platonic way.

Another expert in the activities of great apes commented that as intimate contact was seen in a broad spectrum of apes it was logical its origins extend far into our evolutionary past, and an analysis of various types of intimate behavior among a wider variety of animals might extend its origins back further still.

"Things that we consider as signatures of our species, like intimate contact, are not exclusive to us if we look closely at other animals," he said.

Social Aspects

Another professor said that intimate contact had a social component as it was not common to all societies.

"Nonetheless, as people we thrive or fail on the strength of our relationships, and methods of encouraging trust and closeness will have been significant for eons," the professor stated. "This could represent an image that appears a bit contradictory to our incorrect assumptions of a supposedly aggressive and ancient history, but actually it ought to be no surprise that Neanderthals – and including Neanderthals and our own species together – engaged intimately."