Neanderthals and Modern Humans Were Likely Kissing, Researchers Suggest

From Galápagos albatrosses to polar bears, chimpanzees to orangutans, various animals appear to kiss. Now, researchers suggest that ancient hominins also engaged in this behavior – and might even have exchanged kisses with early Homo sapiens.

Common Oral Evidence

This isn't the initial instance experts have suggested Neanderthals and Homo sapiens were closely connected. Among earlier research, researchers have found modern people and their Neanderthal relatives shared the same mouth microbe for hundreds of thousands of years after the two species split, suggesting they exchanged oral fluids.

"Probably they were kissing," the researcher noted, explaining that the concept chimed with studies that has revealed humans of certain genetic backgrounds contain Neanderthal DNA in their genetic makeup, demonstrating genetic mixing was at play.

Intimate Spin

"It certainly puts a different spin on ancient interactions," the lead researcher said.

Publishing in the journal Evolution and Human Behavior, the researcher and colleagues detail how, to investigate the evolutionary origins of intimate contact, they first had to come up with a description that was not restricted by how humans kiss.

Defining Kissing

"Previously there were some previous attempts to define a kiss, but it's largely focused on humans, which means that essentially non-human species do not engage in this. Currently we understand that they likely engage, it might just not look from what human kissing resembles," explained the evolutionary biologist.

However, she said some behaviors that resembled kissing were distinct activities – such as the chewing and transfer of food, or "kiss-fighting", observed in fish called certain marine animals.

Consequently the team came up with a definition of intimate contact based on social behaviors involving intentional mouth-to-mouth contact with a individual of the same species, with some motion of the oral area but absence of nutrition.

Study Methods

Brindle explained they concentrated on accounts of kissing in non-human species from the African continent and Asia, including bonobos, chimpanzees and great apes, and employed digital recordings to confirm the observations.

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

Historical Origins

The team propose the results indicate kissing developed approximately 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 intimate act, the researchers say. But the behavior might not have been limited to their specific group.

"Reality that humans engage intimately, the fact that we now have demonstrated that ancient relatives very likely kissed, indicates that the two [species] are probably did engage," Brindle added.

Evolutionary Importance

Although the evolutionary explanation is debated, the expert explained intimate contact could be used in reproductive situations to possibly increase mating outcomes or help choose between partners, while it might help strengthen connections when used in a platonic way.

Another expert in the activities of primates commented that as intimate contact was seen in a wide range of apes it made sense its roots extend far into our ancient history, and an examination of different forms of kissing among a wider variety of species might extend its beginnings back even earlier still.

"Things that we think of as signatures of human life, like intimate contact, are not exclusive to us if we look closely at other animals," he said.

Social Aspects

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

"Nonetheless, as humans we thrive or fail on the strength of our relationships, and ways of promoting trust and intimacy will have been significant for eons," the professor stated. "It might be an concept that seems a bit incongruous to our misplaced ideas of a supposedly aggressive and aggressive past, but actually it ought to be no surprise that Neanderthals – and including Neanderthals and our human ancestors together – engaged intimately."