🔗 Share this article

From Galápagos albatrosses to polar bears, primates to orangutans, various animals engage in mouth-to-mouth contact. Now, scientists propose that ancient hominins did it too – and might even have locked lips with early Homo sapiens.

Common Microbial Evidence

It is not the first time scientists have suggested Neanderthals and Homo sapiens were closely connected. Among previous studies, scientists have found modern people and their thick-browed cousins shared the identical oral bacteria for millions of years after the two species split, suggesting they swapped saliva.

"Likely they were engaging in intimate contact," the researcher noted, explaining that the concept aligned with research that has found people of non-African ancestry have bits of ancient genetic material in their genetic makeup, demonstrating interbreeding was at play.

Intimate Interpretation

"It certainly puts a more romantic spin on ancient interactions," the lead researcher commented.

Writing in the publication a scientific periodical, the researcher and her team detail how, to investigate the evolutionary origins of kissing, they first had to come up with a definition that was not restricted by how people smooch.

Defining Intimate Contact

"Previously there were some previous attempts to define a intimate act, but it's very much been focused on humans, which means that basically non-human species do not engage in this. Now we understand that they probably do, it may appear different from what human kissing resembles," said the evolutionary biologist.

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

Consequently the research group came up with a description of intimate contact based on friendly interactions involving directed mouth-to-mouth contact with a individual of the same species, with some movement of the mouth but no transfer of nutrition.

Research Methods

The lead researcher said they concentrated on reports of kissing in non-human species from the African continent and Asia, including primates, apes and orangutans, and used digital recordings to confirm the reports.

The researchers then combined this data with information on the genetic connections between extant and ancient types of such primates.

Historical Timeline

The team propose the findings indicate kissing evolved approximately 21.5m and 16.9 million years ago in the predecessors of the large apes.

The position of Neanderthals on this evolutionary lineage suggests it is likely they, too, indulged in a intimate act, the researchers conclude. But the activity might not have been limited to their own species.

"Reality that humans kiss, the fact that we currently have demonstrated that Neanderthals very likely engaged, suggests that the both groups are probably did engage," the researcher added.

Evolutionary Importance

While the evolutionary explanation is discussed, the expert explained kissing could be employed in reproductive situations to potentially enhance mating outcomes or help choose between mates, while it could assist reinforce bonding when used in a platonic way.

Another expert in the activities of primates commented that as intimate contact was observed in a wide range of apes it was logical its roots lie deep in our ancient history, and an analysis of various types of kissing among a wider variety of animals might extend its origins back even earlier still.

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

Social Aspects

An archaeology expert said that kissing had a cultural element as it was not common to all human groups.

"However, as people we thrive or fail on the strength of our emotional bonds, and methods of encouraging trust and intimacy will have been important for millions of years," she said. "It might be an concept that appears a bit contradictory to our incorrect assumptions of a supposedly aggressive and ancient history, but really it should be no surprise that Neanderthals – and including them and our own species together – engaged intimately."