Neanderthals and Early Humans Were Likely Kissing, Scientists Suggest
From Galápagos albatrosses to polar bears, chimpanzees to orangutans, various animals engage in mouth-to-mouth contact. Now, scientists suggest that Neanderthals also engaged in this behavior – and possibly exchanged kisses with early Homo sapiens.
Shared Microbial Clues
This isn't the initial instance experts have suggested Neanderthals and Homo sapiens were closely connected. Among previous studies, researchers have discovered modern people and their thick-browed cousins shared the same mouth microbe for hundreds of thousands of years after the evolutionary divergence, implying they swapped saliva.
"Likely they were engaging in intimate contact," she said, explaining that the idea aligned with research that has found humans of non-African ancestry contain Neanderthal DNA in their genome, demonstrating interbreeding was occurring.
Romantic Interpretation
"It certainly puts a more romantic perspective on human-Neanderthal relations," the lead researcher said.
Writing in the journal Evolution and Human Behavior, Brindle and her team detail how, to explore the evolutionary origins of kissing, they first had to develop a description that was not restricted by how humans smooch.
Defining Intimate Contact
"There have been some previous attempts to describe a intimate act, but it's largely focused on humans, which means that basically other animals don't kiss. Currently we know that they likely engage, it might just not look from what our intimate contact resembles," said Brindle.
However, she noted some behaviors that resembled intimate contact were distinct activities – such as the chewing and food sharing, or "mouth contact", seen in fish known as French grunts.
Consequently the team came up with a description of kissing based on friendly interactions involving intentional mouth-to-mouth contact with a member of the same species, with some movement of the mouth but absence of food.
Study Methods
Brindle explained they focused on accounts of kissing in primates from Africa and Asian regions, including primates, chimpanzees and great apes, and used digital recordings to confirm the observations.
The researchers then combined this data with details on the genetic connections between extant and ancient species of such animals.
Evolutionary Timeline
The team propose the results suggest kissing evolved approximately 21.5 million and 16.9 million years ago in the ancestors of the large apes.
Placement of Neanderthals on this family tree means it is likely they, too, indulged in a intimate act, the scientists conclude. But the activity may not have been limited to their own species.
"The fact that modern people kiss, the reality that we now have demonstrated that ancient relatives very likely kissed, indicates that the two [species] are also likely to have kissed," the researcher added.
Evolutionary Importance
Although the scientific reasoning is debated, Brindle said kissing could be used in reproductive situations to potentially enhance mating outcomes or help choose between partners, while it might help strengthen connections when used in a platonic way.
Another expert in the activities of primates commented that as intimate contact was seen in a broad spectrum of apes it was logical its roots extend far into our evolutionary past, and an analysis of different forms of kissing among a broader range of animals might push its origins back even earlier still.
"Behaviors that we think of as characteristics of human life, like kissing, are not exclusive to us if we look closely at different species," he said.
Social Elements
An archaeology expert explained that kissing had a social component as it was not common to all human groups.
"Nonetheless, as humans we thrive or fail on the strength of our relationships, and ways of encouraging confidence and intimacy will have been significant for eons," she said. "It might be an concept that appears a bit contradictory to our incorrect assumptions of a rather ruthless and ancient history, but actually it ought to be expected that ancient hominins – and including Neanderthals and our own species together – kissed."