Neanderthals and Early Humans Were Likely Kissing, Scientists Propose

Among seabirds to polar bears, chimpanzees to great apes, certain species engage in mouth-to-mouth contact. Now, scientists propose that ancient hominins did it too – and possibly exchanged kisses with early Homo sapiens.

Common Oral Clues

It is not the first time scientists have proposed ancient relatives and Homo sapiens were closely connected. In previous studies, scientists have found humans and their thick-browed cousins shared the same mouth microbe for millions of years after the two species split, suggesting they swapped saliva.

"Probably they were engaging in intimate contact," the researcher noted, adding that the idea chimed with studies that has revealed people of non-African ancestry have bits of ancient genetic material in their genome, demonstrating interbreeding was at play.

Romantic Spin

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

Writing in the journal a scientific periodical, the researcher and colleagues report how, to investigate the evolutionary origins of intimate contact, they first had to come up with a definition that was not limited to how humans smooch.

Describing Intimate Contact

"There have been some previous attempts to define a intimate act, but it's very much been human-centric, which implies that basically 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," said the evolutionary biologist.

However, she said some behaviors that looked like intimate contact were distinct activities – such as the chewing and food sharing, or "mouth contact", seen in aquatic species known as French grunts.

As a result the team came up with a definition of intimate contact based on social behaviors involving intentional oral interaction with a individual of the same species, with some movement of the oral area but no transfer of food.

Study Approach

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

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

Historical Origins

Researchers say the results indicate intimate contact evolved approximately 21.5m and 16.9m years ago in the predecessors of the great primates.

The position of Neanderthals on this family tree means it is probable they, too, indulged in a intimate act, the researchers conclude. But the behavior might not have been limited to their own species.

"The fact that modern people engage intimately, the reality that we currently have demonstrated that ancient relatives very likely kissed, indicates that the both groups are probably did kissed," the researcher noted.

Evolutionary Significance

Although the evolutionary explanation is discussed, the expert explained intimate contact could be used in sexual contexts to potentially enhance mating outcomes or assist in selecting between partners, while it could assist reinforce bonding when practiced in a non-sexual manner.

A separate researcher in the activities of great apes commented that as kissing behavior was seen in a broad spectrum of primates it was logical its origins extend far into our ancient history, and an examination of different forms of kissing among a broader range of animals might push its beginnings back even earlier still.

"Things that we consider as signatures of human life, like kissing, are not unique to us if we examine carefully at different species," the expert noted.

Cultural Aspects

An archaeology expert explained that intimate contact had a cultural element as it was not universal to all human groups.

"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 millions of years," she said. "It might be an concept that seems a bit contradictory to our misplaced ideas of a supposedly aggressive and ancient history, but really it should be expected that ancient hominins – and including Neanderthals and our human ancestors collectively – engaged intimately."