Ancient Hominins and Modern Humans May Have Engaging in Intimate Contact, Researchers Suggest

From seabirds to Arctic mammals, primates to great apes, certain species engage in mouth-to-mouth contact. Now, scientists propose that Neanderthals also engaged in this behavior – and might even have exchanged kisses with early Homo sapiens.

Shared Microbial Clues

It is not the first time scientists have proposed Neanderthals and early modern humans were closely connected. In previous studies, researchers have discovered modern people and their Neanderthal relatives possessed the same mouth microbe for millions of years after the two species split, suggesting they exchanged oral fluids.

"Probably they were engaging in intimate contact," she said, adding that the idea chimed with research that has revealed people of certain genetic backgrounds contain Neanderthal DNA in their genome, revealing interbreeding was at play.

Intimate Spin

"It certainly puts a different perspective on human-Neanderthal relations," Brindle said.

Publishing in the journal a scientific periodical, Brindle and her team report how, to explore the historical roots of intimate contact, they first had to come up with a description that was not limited to how people smooch.

Describing Intimate Contact

"Previously there were some efforts to define a kiss, but it's very much been focused on humans, which means 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 said some behaviors that looked like intimate contact were something rather different – such as the chewing and transfer of food, or "kiss-fighting", seen in fish known as certain marine animals.

Consequently the research group came up with a definition of intimate contact based on friendly interactions involving directed mouth-to-mouth contact with a individual of the same species, with some movement of the mouth but absence of food.

Research Approach

The lead researcher explained they focused on reports of kissing in primates from Africa and Asia, including primates, chimpanzees and great apes, and used online videos to confirm the observations.

Scientists then combined this data with information on the genetic connections between extant and extinct species of such animals.

Evolutionary Origins

The team propose the results indicate kissing evolved approximately 21.5m and 16.9m years ago in the ancestors of the large apes.

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

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

Evolutionary Importance

While the scientific reasoning is debated, the expert said kissing could be employed in reproductive situations to potentially increase reproductive success or assist in selecting between partners, while it could assist reinforce bonding when practiced in a non-sexual manner.

Another expert in the activities of primates commented that as intimate contact was seen in a broad spectrum of apes it made sense its origins lie deep in our evolutionary past, and an examination of various types of kissing among a wider variety of species might extend its beginnings back even earlier still.

"Behaviors that we think of as characteristics of our species, like kissing, are not exclusive to us if we look closely at different species," he said.

Cultural Elements

An archaeology expert said that intimate contact had a social component as it was not universal to all societies.

"However, as humans we thrive or fail on the quality of our relationships, and ways of promoting trust and closeness will have been significant for eons," she said. "This could represent an image that seems a bit incongruous to our incorrect assumptions of a rather ruthless and ancient history, but actually it ought to be expected that ancient hominins – and including them and our own species collectively – engaged intimately."