🔗 Share this article

Among seabirds to Arctic mammals, primates to great apes, certain species appear to kiss. Currently, scientists suggest that Neanderthals did it too – and might even have locked lips with early Homo sapiens.

Shared Microbial Clues

It is not the first time scientists have proposed ancient relatives and early modern humans were closely connected. Among earlier research, researchers have found humans and their Neanderthal relatives possessed the identical oral bacteria for hundreds of thousands of years after the two species split, implying they swapped saliva.

"Probably they were engaging in intimate contact," she said, explaining that the idea chimed with research that has found humans of certain genetic backgrounds have bits of ancient genetic material in their genetic makeup, demonstrating genetic mixing was at play.

Romantic Interpretation

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

Publishing in the publication a scientific periodical, Brindle and her team detail how, to explore the historical roots of intimate contact, they first had to come up with a description that was not restricted by how humans kiss.

Describing Kissing

"There have been some previous attempts to define a intimate act, but it's very much been focused on humans, which means that basically other animals don't kiss. Now we know that they likely engage, it might just not look from what our intimate contact resembles," explained the evolutionary biologist.

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

Consequently the team developed a definition of kissing centered around friendly interactions involving intentional oral interaction with a individual of the same species, with some motion of the oral area but no transfer of food.

Research Approach

The lead researcher explained they focused on accounts of kissing in primates from the African continent and Asian regions, including primates, chimpanzees and great apes, and employed online videos to confirm the reports.

The researchers then combined this data with details on the evolutionary relationships between living and ancient types of such primates.

Historical Origins

Researchers propose the results suggest intimate contact developed somewhere between 21.5m and 16.9 million years ago in the predecessors of the large apes.

Placement of Neanderthals on this evolutionary lineage means it is likely they, too, indulged in a intimate act, the scientists conclude. But the activity may not have been confined to their specific group.

"The fact that modern people engage intimately, the fact that we now have demonstrated that ancient relatives probably engaged, suggests that the two [species] are probably did kissed," the researcher noted.

Evolutionary Importance

While the evolutionary explanation is discussed, the expert said kissing could be employed in reproductive situations to potentially enhance reproductive success or assist in selecting between partners, while it might help reinforce bonding when used in a non-sexual manner.

A separate researcher in the behavior of primates commented that as kissing behavior was seen in a broad spectrum of apes it was logical its roots lie deep in our ancient history, and an analysis of various types of kissing among a broader range of animals might extend its beginnings back further still.

"Behaviors that we consider as characteristics of human life, like intimate contact, are not unique to us if we examine carefully at other animals," the expert noted.

Cultural Elements

An archaeology expert explained that kissing had a social component as it was not common to all societies.

"However, as people we thrive or fail on the quality of our relationships, and ways of encouraging trust and intimacy will have been important for eons," she said. "This could represent an concept that seems a bit incongruous to our incorrect assumptions of a supposedly aggressive and aggressive past, but actually it should be expected that ancient hominins – and even Neanderthals and our own species together – engaged intimately."