Neanderthals and Early Humans May Have Engaging in Intimate Contact, Researchers Suggest

From Galápagos albatrosses to Arctic mammals, chimpanzees to orangutans, certain species engage in mouth-to-mouth contact. Currently, researchers propose that Neanderthals also engaged in this behavior – and possibly locked lips with early Homo sapiens.

Common Oral Clues

This isn't the initial instance experts have proposed ancient relatives and Homo sapiens were closely connected. In previous studies, researchers have found modern people and their thick-browed cousins shared the same mouth microbe for hundreds of thousands of years after the two species split, implying they exchanged oral fluids.

"Likely 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 genetic makeup, revealing interbreeding was occurring.

Intimate Spin

"This offers a different spin on ancient interactions," Brindle commented.

Publishing in the journal Evolution and Human Behavior, the researcher and her team report how, to investigate the evolutionary origins of kissing, they first had to develop a definition that was not restricted by how people smooch.

Defining Intimate Contact

"Previously there were some previous attempts to describe a intimate act, but it's largely focused on humans, which implies that essentially non-human species don't kiss. Now we know that they probably do, it may appear different from what human kissing resembles," said the evolutionary biologist.

However, she said some behaviors that resembled kissing were distinct activities – such as the chewing and transfer of food, or "mouth contact", observed in aquatic species known as certain marine animals.

Consequently the team came up with a definition of intimate contact based on friendly interactions involving intentional oral interaction with a member of the identical group, with some movement of the mouth but absence of food.

Research Approach

The lead researcher said they concentrated on accounts of intimate behavior in non-human species from Africa and Asian regions, including primates, apes and great apes, and used digital recordings to confirm the observations.

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

Historical Timeline

Researchers propose the results suggest kissing developed approximately 21.5m and 16.9m years ago in the ancestors of the large apes.

Placement of ancient hominins on this evolutionary lineage suggests it is probable they, too, indulged in a intimate act, the researchers say. But the behavior might not have been confined to their specific group.

"The fact that humans kiss, the fact that we currently have demonstrated that Neanderthals probably kissed, suggests that the both groups are probably did engage," Brindle added.

Evolutionary Importance

While the scientific reasoning is discussed, the expert explained kissing could be employed in sexual contexts to potentially enhance mating outcomes or assist in selecting between partners, while it could assist reinforce bonding when used in a non-sexual manner.

Another expert in the activities of primates commented that as kissing behavior was seen in a broad spectrum of apes it was logical its roots extend far into our ancient history, and an examination of different forms of intimate behavior among a wider variety of animals might extend its beginnings back further still.

"Things that we consider as characteristics of our species, like intimate contact, are not exclusive to us if we look closely at other animals," he said.

Social Aspects

Another professor said that intimate contact had a cultural element as it was not universal to all human groups.

"However, as humans we succeed or struggle on the quality of our emotional bonds, and methods of promoting confidence and intimacy will have been significant for eons," the professor stated. "This could represent an concept that seems a bit incongruous to our misplaced ideas of a rather ruthless and ancient history, but really it should be no surprise that ancient hominins – and including Neanderthals and our own species collectively – engaged intimately."