Ancient Hominins and Early Humans Were Likely Kissing, Scientists Suggest

Among Galápagos albatrosses to Arctic mammals, primates to great apes, certain species appear to kiss. Currently, researchers suggest that Neanderthals did it too – and might even have exchanged kisses with early Homo sapiens.

Shared Microbial Evidence

It is not the first time scientists have proposed Neanderthals and Homo sapiens were closely connected. Among earlier research, researchers have found modern people and their Neanderthal relatives possessed the same mouth microbe for hundreds of thousands of years after the evolutionary divergence, suggesting they swapped saliva.

"Probably they were engaging in intimate contact," the researcher noted, explaining that the concept chimed with studies that has found humans of non-African ancestry have bits of ancient genetic material in their genetic makeup, revealing interbreeding was occurring.

Romantic Spin

"This offers a more romantic perspective on human-Neanderthal relations," Brindle commented.

Writing in the journal a scientific periodical, the researcher and colleagues report how, to investigate the historical roots of kissing, they first had to develop a description that was not restricted by how humans smooch.

Defining Intimate Contact

"There have been some previous attempts to define a kiss, but it's very much been human-centric, which means that basically non-human species don't kiss. Now we know that they likely engage, it might just not look from what our intimate contact resembles," explained the evolutionary biologist.

However, she noted some actions that resembled kissing were something rather different – such as the processing and transfer of food, or "kiss-fighting", seen in fish known as French grunts.

Consequently the research group developed a definition of intimate contact based on social behaviors involving directed oral interaction with a individual of the same species, with some movement of the oral area but no transfer of nutrition.

Research Methods

Brindle explained they focused on accounts of intimate behavior in non-human species from Africa and Asian regions, including bonobos, apes and orangutans, and employed online videos to verify the observations.

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

Historical Origins

Researchers propose the findings suggest kissing evolved approximately 21.5 million and 16.9m years ago in the predecessors of the great primates.

Placement of Neanderthals on this evolutionary lineage suggests it is likely they, too, engaged in a intimate act, the scientists say. But the activity may not have been limited to their own species.

"Reality that humans kiss, the reality that we currently have shown that Neanderthals very likely engaged, suggests that the two [species] are probably did kissed," Brindle noted.

Biological Significance

While the scientific reasoning is discussed, the expert said kissing could be used in sexual contexts to potentially enhance 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 behavior of primates commented that as intimate contact was seen in a broad spectrum of primates it was logical its roots extend far into our evolutionary past, and an examination of various types of kissing among a broader range of animals might extend its origins back further still.

"Things that we consider as signatures of our species, like intimate contact, are not unique to us if we examine carefully at different species," the expert noted.

Cultural Elements

An archaeology expert explained that intimate contact had a cultural element as it was not common to all human groups.

"However, as people we thrive or fail on the strength of our relationships, and ways of promoting trust and intimacy will have been important for eons," she said. "This could represent an concept that appears a bit incongruous to our incorrect assumptions of a rather ruthless and ancient history, but really it ought to be expected that ancient hominins – and even them and our own species together – kissed."