Neanderthals and Early Humans Were Likely Kissing, Scientists Propose
Among seabirds to polar bears, primates to great apes, various animals engage in mouth-to-mouth contact. Currently, scientists propose that ancient hominins also engaged in this behavior – and possibly exchanged kisses with early Homo sapiens.
Common Oral Clues
This isn't the initial instance scientists have suggested Neanderthals and early modern humans were closely connected. In earlier research, scientists have found humans and their thick-browed cousins shared the same mouth microbe for millions of years after the evolutionary divergence, suggesting they swapped saliva.
"Probably they were kissing," she said, explaining that the idea aligned with studies that has revealed humans of certain genetic backgrounds have bits of Neanderthal DNA in their genome, demonstrating genetic mixing was at play.
Intimate Interpretation
"It certainly puts a more romantic spin on ancient interactions," the lead researcher said.
Publishing in the journal Evolution and Human Behavior, Brindle and colleagues report how, to investigate the historical roots 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 efforts to define a kiss, but it's largely human-centric, which means that basically non-human species do not engage in this. Currently we understand that they likely engage, it may appear different from what human kissing looks like," explained Brindle.
Nonetheless, she said some actions that looked like intimate contact were distinct activities – such as the processing and food sharing, or "kiss-fighting", observed in fish called certain marine animals.
As a result the team developed a description of kissing based on friendly interactions involving intentional oral interaction with a member of the same species, with some motion of the oral area but absence of food.
Study Approach
Brindle explained they concentrated on accounts of intimate behavior in non-human species from Africa and Asia, including primates, chimpanzees and orangutans, and used digital recordings to confirm the observations.
The researchers then integrated this data with details on the evolutionary relationships between extant and ancient types of such animals.
Evolutionary Origins
The team propose the findings suggest intimate contact developed approximately 21.5m and 16.9m years ago in the predecessors of the large apes.
Placement of ancient hominins on this evolutionary lineage means it is likely they, too, engaged in a intimate act, the scientists say. But the behavior may not have been confined to their specific group.
"Reality that modern people engage intimately, the reality that we now have shown that Neanderthals probably engaged, suggests that the two [species] are also likely to have kissed," the researcher added.
Biological Significance
Although the evolutionary explanation is debated, the expert explained kissing could be employed in reproductive situations to possibly enhance reproductive success or assist in selecting between mates, while it could assist reinforce bonding when practiced in a platonic way.
Another expert in the behavior of primates said that as kissing behavior was seen in a broad spectrum of apes it was logical its roots extend far into our evolutionary past, and an examination of various types of intimate behavior among a broader range of animals might push its origins back even earlier still.
"Behaviors that we consider as signatures of human life, like kissing, are not exclusive to us if we examine carefully at different species," the expert noted.
Social Aspects
Another professor said that intimate contact had a social component as it was not universal to all human groups.
"However, as humans we thrive or fail on the strength of our emotional bonds, and methods of promoting confidence and closeness will have been important for millions of years," the professor stated. "It might be an image that appears a bit contradictory to our misplaced ideas of a rather ruthless and aggressive past, but actually it should be no surprise that Neanderthals – and including Neanderthals and our human ancestors collectively – kissed."
