🔗 Share this article Ancient Hominins and Modern Humans Were Likely Engaging in Intimate Contact, Researchers Suggest From seabirds to polar bears, primates to orangutans, various animals appear to kiss. Now, researchers suggest that ancient hominins did it too – and might even have locked lips with modern humans. Shared Microbial Evidence This isn't the initial instance scientists have proposed ancient relatives and early modern humans were intimately acquainted. In previous studies, scientists have found humans and their thick-browed cousins shared the same mouth microbe for millions of years after the evolutionary divergence, suggesting they swapped saliva. "Likely they were engaging in intimate contact," the researcher noted, explaining that the idea aligned with studies that has revealed people of non-African ancestry have bits of ancient genetic material in their genetic makeup, demonstrating interbreeding was at play. Romantic Spin "It certainly puts a more romantic spin on human-Neanderthal relations," Brindle commented. Writing in the publication Evolution and Human Behavior, the researcher and her team report how, to investigate the evolutionary origins of intimate contact, they first had to develop a definition that was not limited to how people kiss. Defining Intimate Contact "There have been some previous attempts to describe a intimate act, but it's very much been human-centric, which implies that basically non-human species don't kiss. Currently we know that they likely engage, it might just not look from what human kissing looks like," said Brindle. Nonetheless, she noted some actions that looked like intimate contact were distinct activities – such as the processing and food sharing, or "kiss-fighting", seen in fish known as French grunts. As a result the research group came up with a definition of intimate contact based on social behaviors involving directed mouth-to-mouth contact with a individual of the identical group, with some motion of the mouth but absence of food. Research Methods The lead researcher said they concentrated on reports of kissing in primates from Africa and Asian regions, including bonobos, chimpanzees and orangutans, and employed online videos to verify the observations. Scientists then integrated this information with details on the evolutionary relationships between living and ancient types of such primates. Historical Origins Researchers say the findings indicate kissing developed somewhere between 21.5m and 16.9 million years ago in the ancestors of the large apes. The position of Neanderthals on this family tree means it is probable they, too, engaged in a kiss, the scientists say. But the activity may not have been confined to their own species. "Reality that humans kiss, the fact that we currently have shown that Neanderthals very likely engaged, suggests that the two [species] are also likely to have engage," Brindle added. Evolutionary Significance Although the scientific reasoning is discussed, the expert explained kissing could be employed in reproductive situations to potentially enhance reproductive success or help choose between mates, while it could assist reinforce bonding when used in a platonic way. A separate researcher in the behavior of great apes said that as kissing behavior was observed in a broad spectrum of apes it made sense its origins extend far into our ancient history, and an analysis of various types of kissing among a wider variety of animals might extend its beginnings back further still. "Behaviors that we think of as signatures of our species, like kissing, are not unique to us if we look closely at other animals," the expert noted. Social Elements Another professor said that intimate contact had a cultural element as it was not common to all human groups. "Nonetheless, as people we thrive or fail on the quality of our relationships, and ways of promoting confidence and closeness will have been important for eons," the professor stated. "It might be an concept that seems a bit incongruous to our misplaced ideas of a supposedly aggressive and ancient history, but really it should be no surprise that ancient hominins – and including them and our human ancestors together – kissed."