Neanderthals and Early Humans Were Likely Kissing, Scientists Propose

Among Galápagos albatrosses to Arctic mammals, chimpanzees to orangutans, various animals engage in mouth-to-mouth contact. Now, researchers suggest that ancient hominins did it too – and might even have locked lips with early Homo sapiens.

Shared Microbial Evidence

It is not the first time scientists have proposed Neanderthals and Homo sapiens were closely connected. In earlier research, scientists have discovered modern people and their thick-browed cousins possessed the identical oral bacteria for millions of years after the two species split, suggesting they swapped saliva.

"Likely they were engaging in intimate contact," she said, explaining that the concept aligned with research that has revealed humans of certain genetic backgrounds have bits of Neanderthal DNA in their genome, revealing interbreeding was at play.

Romantic Spin

"This offers a more romantic spin on ancient interactions," Brindle commented.

Writing in the publication a scientific periodical, Brindle and her team detail how, to explore the historical roots of kissing, they first had to come up with a definition that was not restricted by how humans kiss.

Describing Kissing

"There have been some efforts to describe a intimate act, but it's very much been human-centric, which means that basically other animals don't kiss. Now we know that they likely engage, it might just not look from what our intimate contact resembles," said Brindle.

Nonetheless, she said some actions that looked like intimate contact were distinct activities – such as the processing and food sharing, or "mouth contact", observed in aquatic species called French grunts.

Consequently the team came up with a description of kissing centered around social behaviors involving directed mouth-to-mouth contact with a individual of the identical group, with some movement of the oral area but no transfer of food.

Research Methods

The lead researcher said they concentrated on reports of kissing in primates from the African continent and Asian regions, including bonobos, chimpanzees and great apes, and employed online videos to confirm the observations.

Scientists then combined this data with information on the evolutionary relationships between extant and extinct species of such primates.

Evolutionary Origins

Researchers propose the results 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 suggests it is probable they, too, engaged in a intimate act, the scientists conclude. But the behavior may not have been confined to their specific group.

"Reality that modern people kiss, the fact that we now have demonstrated that Neanderthals very likely engaged, suggests that the two [species] are probably did kissed," the researcher added.

Biological Importance

Although the scientific reasoning is debated, the expert explained intimate contact could be employed in sexual contexts to potentially increase mating outcomes or assist in selecting between mates, while it could assist reinforce bonding when used in a non-sexual manner.

A separate researcher in the behavior of primates commented that as intimate contact was seen in a wide range of primates it made sense its roots extend far into our evolutionary past, and an analysis of different forms of intimate behavior among a wider variety of species might extend its beginnings back further still.

"Behaviors that we think of as signatures of human life, like intimate contact, are not exclusive to us if we examine carefully at different species," the expert noted.

Social Aspects

An archaeology expert said that kissing had a social component as it was not common to all human groups.

"Nonetheless, as humans we thrive or fail on the quality of our emotional bonds, and ways of encouraging trust 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 incorrect assumptions of a supposedly aggressive and aggressive past, but actually it should be expected that ancient hominins – and including them and our human ancestors collectively – kissed."