Ancient Hominins and Early Humans Were Likely Engaging in Intimate Contact, Scientists Propose

Among seabirds to Arctic mammals, chimpanzees to great apes, certain species engage in mouth-to-mouth contact. Now, scientists propose that Neanderthals did it too – and possibly locked lips with modern humans.

Shared Microbial Evidence

It is not the first time scientists have proposed Neanderthals and Homo sapiens were intimately acquainted. Among earlier research, scientists have discovered modern people and their thick-browed cousins possessed the same mouth microbe for millions of years after the two species split, implying they swapped saliva.

"Probably they were kissing," the researcher noted, explaining that the concept chimed with studies that has revealed people of non-African ancestry contain ancient genetic material in their genome, demonstrating genetic mixing was occurring.

Romantic Spin

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

Writing in the publication Evolution and Human Behavior, the researcher and her team report how, to investigate the historical roots of intimate contact, they first had to come up with a description that was not limited to how humans smooch.

Describing Intimate Contact

"There have been some previous attempts to describe a kiss, but it's very much been human-centric, which means that basically other animals do not engage in this. Now we understand that they probably do, it may appear different from what human kissing looks like," explained Brindle.

Nonetheless, she noted some actions that looked like intimate contact were something rather different – such as the chewing and food sharing, or "mouth contact", seen in fish called French grunts.

Consequently the team came up with a description of intimate contact centered around friendly interactions involving intentional mouth-to-mouth contact with a individual of the identical group, with some movement of the mouth but absence of nutrition.

Study Approach

The lead researcher explained they focused on accounts of intimate behavior in primates from Africa and Asian regions, including bonobos, apes and orangutans, and employed digital recordings to confirm the observations.

The researchers then combined this information with details on the genetic connections between living and ancient species of such primates.

Historical Timeline

Researchers propose the findings indicate kissing developed approximately 21.5m and 16.9 million years ago in the predecessors of the large apes.

Placement of ancient hominins on this evolutionary lineage means it is probable they, too, engaged in a kiss, the scientists conclude. But the activity may not have been confined to their specific group.

"The fact that modern people kiss, the fact that we currently have demonstrated that Neanderthals very likely kissed, suggests that the both groups are probably did engage," Brindle added.

Evolutionary Importance

While the evolutionary explanation is debated, Brindle explained intimate contact could be employed in sexual contexts to potentially increase reproductive success or assist in selecting between partners, while it might help reinforce bonding when used in a platonic way.

Another expert in the behavior of great apes commented that as kissing behavior was observed in a wide range 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 species might push its beginnings back further still.

"Behaviors that we consider as characteristics of human life, like intimate contact, are not exclusive to us if we look closely at different species," he said.

Cultural Aspects

An archaeology expert explained that intimate contact had a cultural element as it was not universal to all societies.

"However, as humans we thrive or fail on the strength of our emotional bonds, and methods of promoting confidence and intimacy will have been significant for millions of years," the professor stated. "This could represent an concept that seems a bit incongruous to our misplaced ideas of a supposedly aggressive and ancient history, but actually it should be no surprise that ancient hominins – and including Neanderthals and our own species together – engaged intimately."