Ancient Hominins and Modern Humans Were Likely Engaging in Intimate Contact, Researchers Propose

Among Galápagos albatrosses to polar bears, primates to orangutans, various animals engage in mouth-to-mouth contact. Now, scientists propose that Neanderthals did it too – and might even have exchanged kisses with early Homo sapiens.

Common Oral Evidence

This isn't the initial instance scientists have suggested 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 millions of years after the evolutionary divergence, implying they exchanged oral fluids.

"Probably they were engaging in intimate contact," she said, explaining that the idea chimed with studies that has found humans of certain genetic backgrounds have bits of ancient genetic material in their genome, demonstrating interbreeding was occurring.

Romantic Spin

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

Publishing in the journal Evolution and Human Behavior, the researcher and colleagues detail how, to explore the historical roots of intimate contact, they first had to develop a description that was not restricted by how humans kiss.

Describing Intimate Contact

"There have been some efforts to describe a intimate act, but it's largely human-centric, which implies that basically non-human species do not engage in this. Currently we know that they likely engage, it may appear different from what human kissing looks like," explained Brindle.

However, she noted some behaviors that resembled kissing were something rather different – such as the processing and food sharing, or "mouth contact", seen in aquatic species called certain marine animals.

Consequently the research group came up with a description of intimate contact centered around social behaviors involving intentional mouth-to-mouth contact with a individual of the same species, with some movement of the mouth but absence of food.

Research Approach

Brindle said they focused on accounts of kissing in primates from Africa and Asia, including primates, apes and great apes, and employed online videos to verify the observations.

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

Historical Timeline

Researchers propose the findings suggest intimate contact evolved somewhere between 21.5 million and 16.9 million years ago in the ancestors of the great primates.

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

"The fact that humans engage intimately, the fact that we currently have demonstrated that ancient relatives probably kissed, suggests that the both groups are probably did engage," Brindle added.

Evolutionary Importance

While the evolutionary explanation is debated, the expert said kissing could be employed in reproductive situations to possibly increase reproductive success or help choose between mates, while it might help strengthen connections when used in a non-sexual manner.

Another expert in the behavior of primates said 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 different forms of intimate behavior among a broader range of animals might push its beginnings back further still.

"Things that we think of as characteristics of human life, like kissing, are not unique to us if we look closely at different species," he said.

Social Elements

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

"However, as humans we succeed or struggle on the strength of our relationships, and methods of encouraging confidence and intimacy will have been important for eons," the professor stated. "It might be an image that seems a bit contradictory to our misplaced ideas of a rather ruthless and aggressive past, but really it should be no surprise that ancient hominins – and including them and our human ancestors collectively – engaged intimately."