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

From Galápagos albatrosses to polar bears, primates to orangutans, certain species engage in mouth-to-mouth contact. Now, researchers propose that ancient hominins did it too – and possibly locked lips with early Homo sapiens.

Common Oral Evidence

This isn't the initial instance scientists have suggested ancient relatives and Homo sapiens were intimately acquainted. Among previous studies, scientists have discovered modern people and their thick-browed cousins shared the identical oral bacteria for millions of years after the evolutionary divergence, implying they exchanged oral fluids.

"Probably they were engaging in intimate contact," she said, adding that the idea chimed with research that has found humans of non-African ancestry have bits of ancient genetic material in their genome, demonstrating interbreeding was occurring.

Intimate Spin

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

Publishing in the publication a scientific periodical, Brindle and colleagues report how, to explore the evolutionary origins of kissing, they first had to come up with a description that was not restricted by how people kiss.

Describing Kissing

"Previously there were some efforts to define a intimate act, but it's largely focused on humans, which means that basically non-human species don't kiss. Now we understand that they probably do, it might just not look from what human kissing resembles," explained Brindle.

Nonetheless, she said some behaviors that looked like kissing were something rather different – such as the chewing and transfer of food, or "kiss-fighting", seen in fish known as French grunts.

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

Study Approach

Brindle explained they concentrated on reports of kissing in non-human species from the African continent and Asia, including primates, chimpanzees and orangutans, and used digital recordings to verify the observations.

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

Historical Timeline

Researchers say the results indicate kissing developed somewhere between 21.5 million and 16.9m years ago in the predecessors of the great primates.

Placement of Neanderthals on this family tree suggests it is probable they, too, indulged in a kiss, the scientists say. But the behavior might not have been confined to their specific group.

"The fact that humans engage intimately, the fact that we currently have shown that ancient relatives very likely kissed, indicates that the both groups are probably did kissed," the researcher added.

Evolutionary Significance

Although the scientific reasoning is discussed, Brindle explained kissing could be used in reproductive situations to potentially enhance reproductive success or assist in selecting between partners, while it could assist reinforce bonding when practiced in a platonic way.

A separate researcher in the behavior 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 different forms of kissing among a wider variety of species might extend its origins back even earlier still.

"Things that we think of as characteristics of our species, like kissing, are not exclusive to us if we examine carefully at different species," he said.

Cultural Aspects

Another professor explained that kissing had a social component as it was not common to all human groups.

"Nonetheless, as people we succeed or struggle on the strength of our relationships, and methods of promoting trust and intimacy will have been significant for eons," she said. "This could represent an concept that seems a bit contradictory to our misplaced ideas of a rather ruthless and ancient history, but actually it ought to be expected that Neanderthals – and even Neanderthals and our human ancestors together – engaged intimately."