Neanderthals and Early Humans May Have Kissing, Researchers Suggest

Among seabirds to Arctic mammals, chimpanzees to great apes, various animals appear to kiss. Currently, researchers propose that Neanderthals also engaged in this behavior – and possibly locked lips with early Homo sapiens.

Common Oral Clues

This isn't the initial instance scientists have proposed Neanderthals 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 idea chimed with research that has found humans of certain genetic backgrounds contain ancient genetic material in their genome, revealing genetic mixing was occurring.

Romantic Interpretation

"It certainly puts a more romantic spin on human-Neanderthal relations," Brindle commented.

Writing in the publication a scientific periodical, the researcher and colleagues report how, to investigate the historical roots of intimate contact, they first had to come up with a description that was not restricted by how people smooch.

Defining Intimate Contact

"There have been some efforts to describe a intimate act, but it's largely human-centric, which means that essentially other animals do not engage in this. Now we understand that they probably do, it might just not look from what our intimate contact resembles," explained Brindle.

Nonetheless, she noted some actions that resembled kissing were something rather different – such as the processing and food sharing, or "kiss-fighting", seen in aquatic species called certain marine animals.

Consequently the research group came up with a description of kissing centered around friendly interactions involving intentional oral interaction with a individual of the same species, with some motion of the mouth but no transfer of food.

Study Methods

The lead researcher said they focused on reports of intimate behavior in non-human species from the African continent and Asia, including bonobos, chimpanzees and great apes, and used online videos to verify the observations.

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

Historical Timeline

The team propose the findings suggest intimate contact evolved approximately 21.5m and 16.9m years ago in the predecessors of the large apes.

The position of ancient hominins on this evolutionary lineage means it is probable they, too, engaged in a intimate act, the scientists say. But the behavior might not have been limited to their own species.

"The fact that humans engage intimately, the reality that we currently have shown that ancient relatives very likely kissed, suggests that the two [species] are also likely to have engage," Brindle added.

Evolutionary Significance

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

Another expert in the activities of great apes commented that as intimate contact was observed in a wide range of apes it made sense its roots extend far into our evolutionary past, and an examination of various types of kissing among a broader range of species might push its origins back even earlier still.

"Behaviors that we consider as signatures of human life, like intimate contact, are not unique to us if we look closely at other animals," the expert noted.

Cultural Aspects

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

"However, as humans we succeed or struggle on the strength of our relationships, and methods of promoting trust and intimacy will have been significant for eons," the professor stated. "It might be an image that appears a bit contradictory to our incorrect assumptions of a rather ruthless and ancient history, but actually it should be no surprise that Neanderthals – and even Neanderthals and our human ancestors together – kissed."