Ancient Hominins and Modern Humans Were Likely Engaging in Intimate Contact, Scientists Suggest
Among Galápagos albatrosses to Arctic mammals, chimpanzees to great apes, certain species appear to kiss. Currently, researchers propose that ancient hominins also engaged in this behavior – and might even have exchanged kisses with modern humans.
Shared Microbial Evidence
This isn't the initial instance scientists have proposed ancient relatives and early modern humans were closely connected. In previous studies, scientists have discovered humans and their thick-browed cousins shared the same mouth microbe for hundreds of thousands of years after the two species split, implying they swapped saliva.
"Probably they were engaging in intimate contact," she said, adding that the concept chimed with studies that has found people of non-African ancestry have bits of Neanderthal DNA in their genome, revealing genetic mixing was occurring.
Romantic Spin
"This offers a more romantic perspective on ancient interactions," Brindle commented.
Writing in the journal a scientific periodical, Brindle and colleagues report how, to explore the historical roots of kissing, they first had to come up with a definition that was not restricted by how people kiss.
Describing Kissing
"Previously there were some efforts to describe a kiss, but it's very much been human-centric, which means that essentially other animals don't kiss. Currently we know that they probably do, it might just not look from what our intimate contact resembles," explained the evolutionary biologist.
However, she noted some behaviors that looked like intimate contact were something rather different – such as the processing and food sharing, or "mouth contact", observed in fish called certain marine animals.
As a result the research group came up with a description of intimate contact based on social behaviors involving intentional mouth-to-mouth contact with a member of the identical group, with some motion of the oral area but no transfer of nutrition.
Study Methods
The lead researcher explained they concentrated on reports of kissing in non-human species from the African continent and Asia, including bonobos, chimpanzees and great apes, and employed digital recordings to confirm the observations.
Scientists then combined this data with information on the evolutionary relationships between extant and ancient types of such animals.
Historical Timeline
Researchers say the findings suggest intimate contact evolved approximately 21.5 million and 16.9 million years ago in the predecessors of the large apes.
Placement of Neanderthals on this evolutionary lineage suggests it is probable they, too, engaged in a intimate act, the researchers conclude. But the activity might not have been limited to their own species.
"Reality that humans engage intimately, the reality that we currently have shown that Neanderthals very likely engaged, indicates that the both groups are also likely to have kissed," Brindle added.
Biological Significance
Although the scientific reasoning is debated, the expert explained intimate contact could be employed in reproductive situations to potentially enhance mating outcomes or assist in selecting between mates, while it could assist strengthen connections when practiced in a platonic way.
A separate researcher in the behavior of great apes said that as intimate contact was observed in a broad spectrum of primates it made sense its origins extend far into our ancient history, and an analysis of various types of kissing among a wider variety of animals might extend its beginnings back even earlier still.
"Things that we think of as characteristics of human life, like intimate contact, are not exclusive to us if we examine carefully at different species," the expert noted.
Social Elements
Another professor said that intimate contact had a social component as it was not universal to all societies.
"Nonetheless, as humans we succeed or struggle on the strength of our relationships, and methods of promoting confidence and closeness will have been significant for millions of years," the professor stated. "It might be an image that seems a bit incongruous to our incorrect assumptions of a rather ruthless and aggressive past, but really it ought to be expected that Neanderthals – and including Neanderthals and our human ancestors together – engaged intimately."
