Ancient Hominins and Modern Humans Were Likely Engaging in Intimate Contact, Scientists Propose

Among Galápagos albatrosses to Arctic mammals, primates to orangutans, certain species appear to kiss. Currently, scientists propose that Neanderthals also engaged in this behavior – and possibly exchanged kisses with modern humans.

Common Oral Evidence

This isn't the initial instance scientists have suggested Neanderthals and early modern humans were closely connected. Among earlier research, scientists have found humans and their Neanderthal relatives possessed the same mouth microbe for millions of years after the evolutionary divergence, suggesting they exchanged oral fluids.

"Likely they were engaging in intimate contact," the researcher noted, explaining that the idea chimed with studies that has found humans of non-African ancestry contain Neanderthal DNA in their genome, revealing interbreeding was occurring.

Romantic Interpretation

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

Publishing in the publication a scientific periodical, Brindle and her team report how, to explore the historical roots of intimate contact, they first had to develop a definition that was not limited to how people smooch.

Defining Kissing

"There have been some efforts to describe a kiss, but it's largely human-centric, which means that basically other animals don't kiss. Currently we understand that they probably do, it may appear different from what human kissing looks like," explained the evolutionary biologist.

Nonetheless, she noted some actions that resembled intimate contact were something rather different – such as the chewing and food sharing, or "kiss-fighting", observed in fish known as certain marine animals.

Consequently the team developed a definition of intimate contact centered around friendly interactions involving intentional oral interaction with a member of the same species, with some motion of the oral area but no transfer of nutrition.

Research Approach

The lead researcher explained they focused on accounts of intimate behavior in primates from the African continent and Asia, including primates, chimpanzees and orangutans, and employed digital recordings to confirm the observations.

The researchers then integrated this data with information on the evolutionary relationships between extant and ancient species of such animals.

Evolutionary Origins

The team propose the results indicate kissing developed somewhere between 21.5m and 16.9 million years ago in the predecessors of the great primates.

The position of ancient hominins on this evolutionary lineage suggests it is probable they, too, indulged in a intimate act, the researchers say. But the behavior may not have been limited to their own species.

"Reality that humans engage intimately, the reality that we currently have shown that Neanderthals very likely engaged, suggests that the both groups are probably did kissed," the researcher added.

Biological Importance

While the evolutionary explanation is discussed, the expert explained kissing could be employed in sexual contexts to potentially enhance mating outcomes or assist in selecting between mates, while it could assist reinforce bonding when practiced in a platonic way.

A separate researcher in the activities of primates commented that as intimate contact was observed in a wide range of apes it made sense its roots lie deep in our ancient history, and an analysis of different forms of intimate behavior among a broader range of animals might push its origins back further still.

"Behaviors that we think of as characteristics of human life, like intimate contact, are not unique to us if we look closely at different species," the expert noted.

Social Elements

Another professor explained that kissing had a cultural element as it was not common to all human groups.

"However, as humans we succeed or struggle on the quality of our relationships, and methods of encouraging trust and intimacy will have been significant for millions of years," the professor stated. "It might be an image that appears a bit incongruous to our misplaced ideas of a rather ruthless and ancient history, but actually it should be expected that ancient hominins – and even them and our own species together – kissed."