Neanderthals and Early Humans May Have Engaging in Intimate Contact, Scientists Suggest

Among seabirds to Arctic mammals, chimpanzees to great apes, certain species engage in mouth-to-mouth contact. Currently, researchers propose that Neanderthals also engaged in this behavior – and possibly exchanged kisses with early Homo sapiens.

Common Microbial Clues

It is not the first time scientists have suggested Neanderthals and Homo sapiens were closely connected. In earlier research, scientists have discovered humans and their Neanderthal relatives possessed the identical oral bacteria for hundreds of thousands of years after the evolutionary divergence, implying they swapped saliva.

"Likely they were engaging in intimate contact," the researcher noted, explaining that the idea aligned with studies that has found people of non-African ancestry have bits of ancient genetic material in their genetic makeup, demonstrating genetic mixing was at play.

Intimate Interpretation

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

Writing in the publication a scientific periodical, the researcher and her team detail how, to investigate the historical roots of kissing, they first had to come up with a description that was not limited to how people kiss.

Describing Kissing

"There have been some efforts to define a kiss, but it's largely focused on humans, which implies that essentially other animals do not engage in this. Now we understand that they likely engage, it might just not look from what our intimate contact resembles," explained the evolutionary biologist.

Nonetheless, she noted some behaviors that looked like intimate contact were distinct activities – such as the processing and food sharing, or "kiss-fighting", seen in fish called French grunts.

Consequently the team came up with a definition of intimate contact centered around social behaviors involving directed oral interaction with a member of the same species, with some movement of the mouth but absence of food.

Research Approach

The lead researcher explained they concentrated on accounts of kissing in primates from Africa and Asia, including bonobos, apes and orangutans, and employed online videos to confirm the observations.

Scientists then combined this information with information on the evolutionary relationships between living and ancient types of such primates.

Historical Origins

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

The position of ancient hominins on this family tree suggests it is probable they, too, indulged in a kiss, the researchers conclude. But the behavior may not have been limited to their specific group.

"Reality that humans kiss, the reality that we currently have shown that Neanderthals very likely engaged, indicates that the both groups are also likely to have engage," the researcher noted.

Biological Significance

Although the evolutionary explanation is debated, Brindle said kissing could be used in reproductive situations to possibly increase reproductive success or assist in selecting between mates, while it might help reinforce bonding when used in a platonic way.

A separate researcher in the activities of primates said that as kissing behavior was seen in a wide range of primates it was logical its origins extend far into our ancient history, and an analysis of various types of intimate behavior among a wider variety of species might push its beginnings back further still.

"Behaviors that we consider as signatures of our species, like intimate contact, are not unique to us if we examine carefully at other animals," he said.

Cultural Elements

Another professor said that kissing had a social component as it was not common to all societies.

"However, as humans we succeed or struggle on the quality of our relationships, and methods of promoting trust and intimacy will have been important for millions of years," the professor stated. "This could represent an image that seems a bit contradictory to our misplaced ideas of a rather ruthless and ancient history, but actually it ought to be no surprise that ancient hominins – and even them and our own species collectively – engaged intimately."