Neanderthals and Early Humans May Have Kissing, Scientists Suggest

From seabirds to polar bears, primates to orangutans, various animals appear to kiss. Now, researchers propose that Neanderthals did it too – and possibly exchanged kisses with modern humans.

Shared Microbial Evidence

This isn't the initial instance experts have proposed Neanderthals and early modern humans were intimately acquainted. In earlier research, researchers have found humans and their Neanderthal relatives possessed the identical oral bacteria for hundreds of thousands of years after the two species split, suggesting they exchanged oral fluids.

"Probably they were kissing," she said, explaining that the concept aligned with research that has revealed people of certain genetic backgrounds contain ancient genetic material in their genetic makeup, demonstrating genetic mixing was occurring.

Intimate Interpretation

"This offers a more romantic perspective on ancient interactions," the lead researcher said.

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

Describing Intimate Contact

"There have been some efforts to define a kiss, but it's largely focused on humans, which implies that essentially other animals do not engage in this. Currently we understand that they probably do, it may appear different from what our intimate contact looks like," said Brindle.

Nonetheless, she noted some actions that looked like intimate contact were something rather different – such as the chewing and food sharing, or "mouth contact", observed in aquatic species called French grunts.

Consequently the research group came up with a definition of kissing centered around social behaviors involving intentional mouth-to-mouth contact with a individual of the same species, with some movement of the mouth but absence of nutrition.

Research Methods

Brindle explained they concentrated on accounts of intimate behavior in primates from the African continent and Asian regions, including primates, chimpanzees and great apes, and used online videos to verify the observations.

Scientists then combined this data with details on the evolutionary relationships between extant and extinct species of such primates.

Historical Origins

Researchers propose the results indicate kissing evolved approximately 21.5 million and 16.9m years ago in the ancestors of the great primates.

The position of Neanderthals on this evolutionary lineage suggests it is likely they, too, engaged in a kiss, the scientists say. But the behavior may not have been confined to their specific group.

"The fact that humans engage intimately, the fact that we currently have shown that ancient relatives very likely kissed, indicates that the two [species] are also likely to have kissed," Brindle noted.

Biological Importance

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

A separate researcher in the activities of primates said that as kissing behavior was observed in a wide range of apes it made sense its origins lie deep in our evolutionary past, and an analysis of various types of intimate behavior among a broader range of animals might push its beginnings back even earlier still.

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

Cultural Aspects

An archaeology expert said that kissing had a cultural element as it was not universal to all societies.

"Nonetheless, as people we succeed or struggle on the strength of our relationships, and ways of promoting confidence and intimacy will have been significant for eons," she said. "This could represent an concept that appears a bit contradictory to our misplaced ideas of a rather ruthless and aggressive past, but actually it ought to be expected that ancient hominins – and even them and our own species collectively – kissed."