Neanderthals and Early Humans Were Likely Engaging in Intimate Contact, Scientists Suggest
Among Galápagos albatrosses to Arctic mammals, primates to orangutans, various animals appear to kiss. Currently, scientists propose that Neanderthals also engaged in this behavior – and possibly locked lips with modern humans.
Common Microbial Clues
This isn't the initial instance experts have proposed ancient relatives and early modern humans were closely connected. In earlier research, scientists have discovered humans and their Neanderthal relatives possessed the same mouth microbe for millions of years after the evolutionary divergence, implying they exchanged oral fluids.
"Likely they were engaging in intimate contact," she said, explaining that the idea aligned with studies that has revealed people of certain genetic backgrounds contain Neanderthal DNA in their genome, revealing interbreeding was at play.
Romantic Spin
"It certainly puts a more romantic perspective on human-Neanderthal relations," the lead researcher commented.
Publishing in the publication a scientific periodical, Brindle and colleagues detail how, to investigate the historical roots of intimate contact, they first had to develop a description that was not restricted by how humans kiss.
Describing Intimate Contact
"Previously there were some efforts to define a intimate act, but it's largely human-centric, which implies that essentially non-human species don't kiss. Currently we know that they likely engage, it might just not look from what human kissing looks like," explained Brindle.
Nonetheless, she noted some behaviors that resembled kissing 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 centered around friendly interactions involving directed oral interaction with a individual of the same species, with some motion of the mouth but absence of nutrition.
Research Approach
The lead researcher said they concentrated on reports of kissing in primates from the African continent and Asia, including bonobos, chimpanzees and orangutans, and employed digital recordings to verify the reports.
Scientists then integrated this information with details on the evolutionary relationships between living and extinct types of such primates.
Historical Origins
The team say the results suggest intimate contact developed approximately 21.5 million and 16.9 million years ago in the ancestors of the great primates.
Placement of ancient hominins on this evolutionary lineage means it is probable they, too, indulged in a kiss, the researchers conclude. But the behavior might not have been confined to their own species.
"The fact that modern people kiss, the reality that we now have shown that ancient relatives very likely kissed, indicates that the two [species] are also likely to have kissed," Brindle noted.
Biological Importance
Although the scientific reasoning is debated, the expert explained kissing could be used in sexual contexts to potentially enhance reproductive success or help choose between mates, while it could assist reinforce bonding when practiced in a platonic way.
Another expert in the behavior of primates commented that as intimate contact was seen in a broad spectrum of primates it made sense its roots lie deep in our ancient history, and an analysis of various types of intimate behavior among a wider variety of species might extend its origins back further still.
"Behaviors that we consider as characteristics of our species, like intimate contact, are not exclusive to us if we examine carefully at other animals," the expert noted.
Cultural Aspects
An archaeology expert said that kissing had a cultural element as it was not common to all societies.
"However, as people we thrive or fail on the strength of our relationships, and methods of encouraging trust and closeness will have been important for millions of years," she said. "It might be an concept that seems a bit incongruous to our incorrect assumptions of a rather ruthless and aggressive past, but really it ought to be no surprise that Neanderthals – and even Neanderthals and our own species collectively – engaged intimately."
