Ancient Hominins and Modern Humans Were Likely Engaging in Intimate Contact, Researchers Suggest

From Galápagos albatrosses to polar bears, chimpanzees to great apes, various animals appear to kiss. Now, scientists propose that Neanderthals also engaged in this behavior – and might even have locked lips with early Homo sapiens.

Common Microbial Evidence

This isn't the initial instance scientists have proposed ancient relatives and Homo sapiens were closely connected. In earlier research, researchers have found modern people and their thick-browed cousins possessed the identical oral bacteria for millions of years after the two species split, suggesting they swapped saliva.

"Probably they were kissing," she said, adding that the concept aligned with studies that has found people of non-African ancestry contain Neanderthal DNA in their genome, demonstrating interbreeding was occurring.

Intimate Spin

"This offers a more romantic perspective on human-Neanderthal relations," the lead researcher said.

Writing in the journal a scientific periodical, Brindle and her team report how, to explore the historical roots of kissing, they first had to come up with a definition that was not limited to how people smooch.

Describing Kissing

"There have been some previous attempts to define a intimate act, but it's very much been human-centric, which implies that essentially non-human species do not engage in this. Currently we know that they likely engage, it may appear different from what human kissing looks like," said the evolutionary biologist.

Nonetheless, she noted some actions that resembled kissing were distinct activities – such as the chewing and transfer of food, or "mouth contact", observed in aquatic species called certain marine animals.

Consequently the team came up with a description of kissing centered around friendly interactions involving directed mouth-to-mouth contact with a individual of the identical group, with some movement of the oral area but no transfer of food.

Research Methods

The lead researcher explained they focused on reports of kissing in non-human species from Africa and Asia, including primates, apes and great apes, and employed online videos to confirm the reports.

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

Historical Timeline

Researchers say the results suggest kissing evolved approximately 21.5m and 16.9 million years ago in the predecessors of the large apes.

The position of Neanderthals on this family tree suggests it is probable they, too, indulged in a intimate act, the researchers conclude. But the activity may not have been limited to their own species.

"The fact that humans engage intimately, the reality that we now have shown that ancient relatives probably kissed, indicates that the two [species] are probably did engage," the researcher added.

Biological Importance

While the scientific reasoning is debated, the expert said kissing could be used in sexual contexts to possibly increase reproductive success or help choose between partners, while it could assist strengthen connections when practiced in a platonic way.

A separate researcher in the activities of primates said that as intimate contact was observed in a wide range of primates it was logical its roots lie deep in our evolutionary past, and an analysis of different forms of intimate behavior among a broader range of animals might extend its origins back even earlier still.

"Things that we think of as characteristics of our species, like intimate contact, are not unique to us if we examine carefully at other animals," he said.

Cultural Aspects

An archaeology expert said that intimate contact had a social component as it was not common to all human groups.

"However, as people we succeed or struggle on the quality of our relationships, and ways of promoting confidence and closeness will have been significant for eons," the professor stated. "This could represent an image that appears a bit incongruous to our incorrect assumptions of a supposedly aggressive and ancient history, but really it ought to be no surprise that Neanderthals – and including Neanderthals and our human ancestors together – engaged intimately."