Our ape ancestors probably kissed Neanderthals : Short Wave : NPR

How far back in evolutionary history does kissing go?

Through phylogenetic analysis, an international team of scientists found that kissing was likely present in the ancestor of all apes – which lived 21 million years ago.

Their recent study was published in the journal Evolution and Human Behavior. It defines kissing as nonaggressive mouth-to-mouth contact that does not involve passing food. Many animals kiss, especially primates.

“If you think about the fact that humans and our closest living relatives, chimpanzees and bonobos all kiss, it makes sense that the common ancestor of those three species kisses as well,” says Matilda Brindle, lead author and an evolutionary biologist at the University of Oxford.

Tracking back through evolutionary time, Brindle’s team treated kissing as a “trait” and mapped it onto the evolutionary tree of primates. To determine which primates kissed and which did not, they read a lot of scientific literature – and watched a lot of video footage of apes locking lips. “There’s a lot about bonobo tongues going on. That’s not even the worst of it,” Brindle joked.

In constructing the Neanderthal tip of the kissing family tree, Brindle’s team discovered another spicy detail: clues that Neanderthals likely kissed each other – and kissed the ape ancestors of humans.

Most humans of non-African descent have a very small amount of Neanderthal DNA, and it’s widely established that our human ancestors and Neanderthals had occasional sexual encounters. This kissing study gives us even more insight into those relations.

Interested in stories about human evolution? Email us your question at [email protected].

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This episode was produced by Berly McCoy and Kai McNamee. It was edited by Rebecca Ramirez and Christopher Intagliata. Tyler Jones checked the facts. Simon Laslo-Janssen and Damian Herring were the audio engineers.