Neanderthals and Early Humans Were Likely Kissing, Researchers Suggest

Among Galápagos albatrosses to Arctic mammals, primates to orangutans, certain species engage in mouth-to-mouth contact. Now, researchers suggest that ancient hominins did it too – and possibly exchanged kisses with early Homo sapiens.

Shared Microbial Evidence

This isn't the initial instance experts have suggested Neanderthals and Homo sapiens were intimately acquainted. Among earlier research, scientists have discovered humans and their thick-browed cousins shared the same mouth microbe for millions of years after the two species split, implying they swapped saliva.

"Likely they were kissing," the researcher noted, adding that the idea chimed with studies that has revealed people of non-African ancestry contain Neanderthal DNA in their genetic makeup, demonstrating interbreeding was occurring.

Intimate Interpretation

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

Publishing in the publication Evolution and Human Behavior, the researcher and her team detail how, to investigate the historical roots of intimate contact, they first had to come up with a definition that was not restricted by how people kiss.

Describing Kissing

"There have been some efforts to define a intimate act, but it's largely focused on humans, which means that basically non-human species do not engage in this. Now we understand that they likely engage, it might just not look from what our intimate contact looks like," said Brindle.

Nonetheless, she said some behaviors that looked like kissing were something rather different – such as the chewing and food sharing, or "kiss-fighting", seen in aquatic species called French grunts.

Consequently the research group developed a definition of intimate contact centered around social behaviors involving directed mouth-to-mouth contact with a individual of the same species, with some movement of the mouth but no transfer of food.

Study Methods

The lead researcher said they concentrated on accounts of kissing in primates from Africa and Asia, including primates, apes and orangutans, and used digital recordings to confirm the observations.

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

Historical Origins

Researchers say the results suggest kissing developed somewhere between 21.5m and 16.9 million years ago in the ancestors of the great primates.

The position of Neanderthals on this family tree means it is probable they, too, indulged in a kiss, the researchers say. But the activity may not have been limited to their specific group.

"Reality that humans engage intimately, the reality that we currently have shown that Neanderthals probably engaged, indicates that the two [species] are also likely to have kissed," the researcher noted.

Biological Importance

Although the evolutionary explanation is debated, the expert explained kissing could be employed in reproductive situations to possibly increase reproductive success or assist in selecting between mates, while it could assist reinforce bonding when used in a platonic way.

A separate researcher in the activities of primates commented that as kissing behavior was observed in a wide range of primates it made sense its origins extend far into our evolutionary past, and an analysis of different forms of intimate behavior among a broader range of animals might extend its origins back further still.

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

Social Aspects

Another professor explained that kissing had a social component as it was not universal to all human groups.

"However, as people we thrive or fail on the strength of our relationships, and methods of promoting trust and closeness will have been significant for millions of years," she said. "It might be an image that seems a bit incongruous to our incorrect assumptions of a rather ruthless and ancient history, but actually it should be no surprise that Neanderthals – and even them and our own species collectively – kissed."