🔗 Share this article

From Galápagos albatrosses to Arctic mammals, primates to great apes, certain species appear to kiss. Now, researchers suggest that ancient hominins also engaged in this behavior – and possibly locked lips with modern humans.

Shared Oral Evidence

It is not the first time scientists have proposed Neanderthals and early modern humans were intimately acquainted. Among earlier research, scientists have discovered modern people and their thick-browed cousins possessed the identical oral bacteria for hundreds of thousands of years after the evolutionary divergence, implying they exchanged oral fluids.

"Probably they were engaging in intimate contact," she said, adding that the concept aligned with research that has found people of non-African ancestry contain ancient genetic material in their genome, demonstrating interbreeding was at play.

Intimate Interpretation

"It certainly puts a more romantic perspective on ancient interactions," Brindle commented.

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

Describing Kissing

"There have been some previous attempts to describe a kiss, but it's very much been human-centric, which means that essentially other animals don't kiss. Currently we know that they probably do, it might just not look from what our intimate contact looks like," explained Brindle.

Nonetheless, she said some actions that looked like kissing were something rather different – such as the chewing and food sharing, or "kiss-fighting", seen in fish known as certain marine animals.

Consequently the research group developed a description of kissing based on friendly interactions involving directed oral interaction with a individual of the same species, with some motion of the mouth but absence of food.

Study Approach

Brindle explained they concentrated on accounts of intimate behavior in primates from the African continent and Asia, including primates, chimpanzees and great apes, and used digital recordings to confirm the reports.

Scientists then integrated this information with details on the genetic connections between extant and extinct species of such animals.

Historical Timeline

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

Placement of ancient hominins on this family tree means it is likely they, too, engaged in a kiss, the researchers conclude. But the behavior might not have been confined to their specific group.

"The fact that modern people kiss, the reality that we now have shown that ancient relatives very likely kissed, indicates that the two [species] are also likely to have engage," Brindle added.

Biological Importance

While the scientific reasoning is discussed, the expert said kissing could be employed in reproductive situations to possibly enhance mating outcomes or assist in selecting between mates, while it could assist strengthen connections when practiced in a non-sexual manner.

Another expert in the activities of great apes commented that as intimate contact was observed in a broad spectrum of primates it made sense its origins extend far into our evolutionary past, and an analysis of different forms of intimate behavior among a wider variety of animals might push its beginnings back further still.

"Things that we think of as characteristics of our species, like kissing, are not exclusive to us if we look closely at different species," the expert noted.

Cultural Aspects

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 strength of our relationships, and ways of promoting trust and intimacy will have been significant for eons," the professor stated. "It might be an image that seems a bit incongruous to our incorrect assumptions of a rather ruthless and ancient history, but actually it ought to be no surprise that Neanderthals – and including them and our own species collectively – kissed."