Ancient Hominins and Modern Humans May Have Engaging in Intimate Contact, Researchers Propose

From seabirds to polar bears, chimpanzees to great apes, various animals appear to kiss. Currently, researchers suggest that Neanderthals did it too – and possibly exchanged kisses with early Homo sapiens.

Common Microbial Evidence

This isn't the initial instance experts have suggested Neanderthals and Homo sapiens were intimately acquainted. Among earlier research, scientists have found humans and their Neanderthal relatives possessed the same mouth microbe for millions of years after the evolutionary divergence, implying they exchanged oral fluids.

"Likely they were engaging in intimate contact," she said, adding that the concept aligned with studies that has revealed people of non-African ancestry contain ancient genetic material in their genetic makeup, revealing interbreeding was at play.

Intimate Spin

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

Publishing in the journal a scientific periodical, Brindle and her team report how, to explore the historical roots of intimate contact, they first had to come up with a description that was not limited to how humans smooch.

Defining Kissing

"Previously there were some previous attempts to define a kiss, but it's very much been human-centric, which implies that essentially other animals don't kiss. Now we know that they probably do, it may appear different from what human kissing resembles," explained Brindle.

However, she said some behaviors that looked like intimate contact were distinct activities – such as the processing and transfer of food, or "kiss-fighting", seen in fish known as French grunts.

As a result the team developed a description of intimate contact based on friendly interactions involving intentional oral interaction with a individual of the identical group, with some movement of the oral area but absence of nutrition.

Research Approach

Brindle said they concentrated on reports of intimate behavior in primates from the African continent and Asian regions, including primates, apes and great apes, and used digital recordings to confirm the observations.

The researchers then combined this data with information on the evolutionary relationships between extant and extinct species of such primates.

Historical Origins

Researchers say the results indicate intimate contact evolved approximately 21.5m and 16.9m years ago in the ancestors of the large apes.

The position of Neanderthals on this evolutionary lineage means it is likely they, too, indulged in a intimate act, the researchers conclude. But the behavior may not have been limited to their specific group.

"The fact that humans engage intimately, the fact that we now have demonstrated that Neanderthals probably engaged, suggests that the both groups are probably did kissed," the researcher added.

Biological Importance

While the evolutionary explanation is debated, Brindle explained intimate contact could be used in sexual contexts to possibly enhance mating outcomes or assist in selecting between partners, while it could assist strengthen connections when practiced in a non-sexual manner.

A separate researcher in the activities of great apes said that as kissing behavior was observed in a wide range of primates it made sense its roots extend far into our ancient history, and an examination of different forms of kissing among a broader range of species might extend its origins back even earlier still.

"Behaviors that we consider as signatures of our species, like kissing, are not exclusive to us if we examine carefully at other animals," he said.

Cultural Elements

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

"Nonetheless, as humans we succeed or struggle on the quality of our emotional bonds, and methods of promoting confidence and closeness will have been important for eons," she said. "It might be an image that seems a bit incongruous to our incorrect assumptions of a supposedly aggressive and ancient history, but actually it ought to be expected that Neanderthals – and even them and our human ancestors together – kissed."