Neanderthals and Modern Humans May Have Kissing, Scientists Suggest

Among seabirds to Arctic mammals, chimpanzees to orangutans, certain species 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 Clues

It is not the first time experts have proposed ancient relatives and early modern humans were closely connected. In previous studies, researchers 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 swapped saliva.

"Probably they were engaging in intimate contact," the researcher noted, adding that the idea chimed with research that has found people of certain genetic backgrounds contain ancient genetic material in their genome, revealing interbreeding was at play.

Intimate Spin

"It certainly puts a different perspective on human-Neanderthal relations," Brindle said.

Publishing in the journal a scientific periodical, the researcher and colleagues report how, to explore the historical roots of kissing, they first had to come up with a definition that was not restricted by how people smooch.

Describing Intimate Contact

"Previously there were some efforts to define a intimate act, but it's very much been human-centric, which implies that essentially non-human species don't kiss. Now we understand that they likely engage, it may appear different from what human kissing resembles," said Brindle.

Nonetheless, she said some actions that looked like intimate contact were distinct activities – such as the processing and transfer of food, or "mouth contact", observed in aquatic species known as French grunts.

Consequently the team came up with a description of kissing based on friendly interactions involving directed mouth-to-mouth contact with a individual of the same species, with some motion of the mouth but no transfer of nutrition.

Research Approach

The lead researcher said they concentrated on reports of kissing in non-human species from Africa and Asia, including bonobos, apes and great apes, and employed digital recordings to confirm the observations.

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

Evolutionary Origins

The team propose the findings suggest intimate contact developed approximately 21.5 million and 16.9 million years ago in the ancestors of the great primates.

The position of ancient hominins on this family tree suggests it is probable they, too, engaged in a kiss, the researchers conclude. But the behavior might not have been confined to their own species.

"Reality that modern people engage intimately, the reality that we now have demonstrated that Neanderthals very likely engaged, suggests that the two [species] are also likely to have engage," the researcher added.

Evolutionary Significance

Although the scientific reasoning is debated, Brindle said intimate contact could be used in reproductive situations to possibly enhance reproductive success or help choose between partners, while it might help strengthen connections when practiced in a platonic way.

A separate researcher in the behavior of primates commented that as intimate contact was seen in a wide range of primates it was logical its origins extend far into our ancient history, and an examination of various types of kissing among a broader range of species might push its origins back further still.

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

Social Elements

An archaeology expert explained that kissing had a social component as it was not universal to all societies.

"Nonetheless, as people we succeed or struggle on the strength of our emotional bonds, and methods of promoting trust and intimacy will have been important for eons," the professor stated. "It might be an image that seems a bit contradictory to our misplaced ideas of a rather ruthless and aggressive past, but actually it should be no surprise that Neanderthals – and including Neanderthals and our human ancestors collectively – engaged intimately."