🔗 Share this article

From seabirds to Arctic mammals, chimpanzees to orangutans, various animals engage in mouth-to-mouth contact. Now, scientists suggest that Neanderthals also engaged in this behavior – and might even have locked lips with early Homo sapiens.

Common Oral Evidence

This isn't the initial instance experts have suggested ancient relatives and Homo sapiens were closely connected. In earlier research, researchers have discovered humans and their Neanderthal relatives possessed the identical oral bacteria for hundreds of thousands of years after the evolutionary divergence, suggesting they exchanged oral fluids.

"Probably they were engaging in intimate contact," she said, explaining that the idea chimed with studies that has found people of non-African ancestry contain ancient genetic material in their genome, demonstrating genetic mixing was occurring.

Romantic Interpretation

"It certainly puts a more romantic spin on ancient interactions," the lead researcher commented.

Writing in the journal a scientific periodical, Brindle and her team detail how, to explore the evolutionary origins of kissing, they first had to come up with a description that was not restricted by how people kiss.

Describing Kissing

"There have been some previous attempts to describe a kiss, but it's largely focused on humans, which implies that essentially non-human species do not engage in this. Currently we understand that they probably do, it might just not look from what human kissing looks like," explained the evolutionary biologist.

However, she said some behaviors that looked like intimate contact were something rather different – such as the chewing and food sharing, or "mouth contact", seen in fish called French grunts.

Consequently the team came up with a definition of intimate contact centered around friendly interactions involving intentional oral interaction with a individual of the same species, with some movement of the oral area but absence of nutrition.

Research Methods

The lead researcher explained they concentrated on accounts of kissing in primates from the African continent and Asian regions, including bonobos, apes and orangutans, and employed digital recordings to verify the observations.

The researchers then integrated this data with information on the genetic connections between extant and extinct species of such primates.

Evolutionary Origins

The team propose the results suggest kissing developed approximately 21.5 million and 16.9m years ago in the ancestors of the large apes.

The position of ancient hominins on this family tree means it is probable they, too, engaged in a intimate act, the scientists say. But the activity may not have been limited to their specific group.

"The fact that humans kiss, the fact that we currently have shown that ancient relatives probably engaged, indicates that the two [species] are probably did kissed," the researcher noted.

Evolutionary Importance

Although the scientific reasoning is discussed, the expert said kissing could be employed in reproductive situations to potentially increase mating outcomes or help choose between partners, while it might help strengthen connections when practiced in a non-sexual manner.

A separate researcher in the activities of primates said that as intimate contact was seen in a broad spectrum of apes it was logical its roots extend far into our evolutionary past, and an analysis of various types of intimate behavior among a broader range of animals might extend its beginnings back even earlier still.

"Behaviors that we think of as characteristics of our species, like kissing, are not unique to us if we look closely at other animals," the expert noted.

Social Elements

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

"Nonetheless, as people we succeed or struggle on the quality of our emotional bonds, and ways of encouraging confidence and intimacy will have been significant for millions of years," she said. "This could represent an image that seems a bit incongruous to our misplaced ideas of a supposedly aggressive and ancient history, but actually it should be no surprise that ancient hominins – and including them and our own species collectively – engaged intimately."