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

Among Galápagos albatrosses to polar bears, primates to orangutans, certain species appear to kiss. Currently, researchers propose that Neanderthals also engaged in this behavior – and might even have locked lips with modern humans.

Common Microbial Evidence

This isn't the initial instance experts have suggested Neanderthals and early modern humans were intimately acquainted. Among previous studies, scientists have discovered humans and their Neanderthal relatives possessed the same mouth microbe for hundreds of thousands of years after the two species split, suggesting they swapped saliva.

"Probably they were kissing," she said, adding that the idea chimed with research that has found people of non-African ancestry contain ancient genetic material in their genetic makeup, demonstrating genetic mixing was occurring.

Romantic Spin

"It certainly puts a different spin on human-Neanderthal relations," the lead researcher commented.

Writing in the publication Evolution and Human Behavior, the researcher and her team detail how, to investigate the evolutionary origins of kissing, they first had to develop a description that was not limited to how people smooch.

Defining Intimate Contact

"There have been some previous attempts to describe a kiss, but it's largely focused on humans, which implies that essentially other animals do not engage in this. Currently we understand that they probably do, it might just not look from what our intimate contact resembles," explained Brindle.

Nonetheless, she said some behaviors that looked like intimate contact were distinct activities – such as the processing and transfer of food, or "mouth contact", seen in fish known as certain marine animals.

Consequently the research group developed a description of intimate contact based on social behaviors involving intentional oral interaction with a individual of the same species, with some movement of the mouth but no transfer of food.

Study Methods

Brindle said they concentrated on reports of kissing in primates from the African continent and Asia, including bonobos, apes and orangutans, and used online videos to confirm the observations.

Scientists then integrated this data with information on the evolutionary relationships between living and extinct species of such animals.

Evolutionary Origins

The team say the findings indicate kissing evolved approximately 21.5m and 16.9m years ago in the ancestors of the great primates.

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

"The fact that modern people engage intimately, the reality that we now have demonstrated that Neanderthals very likely engaged, suggests that the both groups are probably did engage," the researcher added.

Evolutionary Significance

Although the evolutionary explanation is discussed, the expert explained kissing could be used in sexual contexts to possibly enhance reproductive success or assist in selecting between mates, while it could assist strengthen connections when used in a platonic way.

Another expert in the behavior of great apes commented that as intimate contact was seen in a wide range of primates it made sense its roots lie deep in our evolutionary past, and an analysis of different forms of kissing among a broader range of species might push its beginnings back further still.

"Behaviors that we consider as characteristics of human life, like kissing, are not unique to us if we examine carefully at different species," the expert noted.

Cultural Elements

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

"However, as people we thrive or fail on the quality of our emotional bonds, and methods of encouraging trust and intimacy will have been important for millions of years," the professor stated. "It might be an image that appears a bit incongruous to our incorrect assumptions of a supposedly aggressive and aggressive past, but actually it ought to be expected that Neanderthals – and including them and our human ancestors together – kissed."