Kissing may be older than humans: Oxford scientists say it began 21 million years ago and Neanderthals did it too

Picture two ancient apes in a lush African forest, gently pressing their mouths together, not for romance, but as a primal bond. Fast forward 21 million years, and that simple act has changed into the kisses we cherish today. A significant University of Oxford study, published in Evolution and Human Behaviour, used smart statistics to trace kissing's origins to our shared ancestor with great apes about 16.9 to 21.5 million years ago. Neanderthals likely kissed too, with an 84% chance, integrating biology and romance across species. This isn't just cultural fluff; it reflects deep-rooted evolution and challenges the idea that kissing is a modern human habit.Oxford evolutionary biologist Matilda Brindle cracked the kissing code using primate family trees and stats wizardry. She defined it simply: non-aggressive mouth-to-mouth contact, no food swapping. Bonobos smooch sensually; chimps keep it quick and tense. Gorillas and orangutans join the party, too. Bayesian models ran 10 million times traced kissing to 16.9-21.5 million years ago, post-split from gibbons. "This is the first time anyone has taken a broad evolutionary lens to examine kissing," Brindle said. "Our findings add to a growing body of work highlighting the remarkable diversity of sexual behaviours exhibited by our primate cousins." Professor Stuart West, her Oxford co-author, cheered the method: "By integrating evolutionary biology with behavioural data, we're able to make informed inferences about traits that don't fossilise, like kissing."As published in Nature Neanderthals, our strong relatives who disappeared 40,000 years ago, get the kiss of approval. The model indicates an 84.3% chance they kissed. The shared oral microbe *Methanobrevibacter oralis*, which split around 112,000-143,000 years ago, suggests saliva exchange long after our lineages diverged.Neanderthals, our strong relatives who disappeared 40,000 years ago, get the kiss of approval. The model indicates an 84.3% chance they kissed. The shared oral microbe Methanobrevibacter oralis, which split around 112,000-143,000 years ago, suggests saliva exchange long after our lineages diverged.Matilda Brindle, an evolutionary biologist from Oxford University, told NPR, Kissing risks germs but packs perks. It sniffs out mate quality via scents, ramps arousal for baby-making, or stems from mum pre-chewing food for tots; all great apes do it. The details of this sim were explained in an NPR chat by Brindle: "We did something called an evolutionary simulation... Our data suggests that the common ancestor of all large apes was kissing around 21.5 million years ago." While not common today, only among 46% of cultures, kissing is an established fact among our ape relatives, illustrating its evolutionary bedrock nature. Catherine Talbot, co-author of this study from Florida Tech, wrote: "The social norms and contexts are very different... This leads us to wonder if kissing is an evolutionary adaptation or a cultural construct." The study's limitations: "inconclusive data from wild animals, but mostly studies of kissing in captivity." A "proof of concept" for future study, says Brindle.Kissing pops up beyond primates: polar bears, wolves, prairie dogs. Ingrid Bergman's quip fits: "A kiss is a lovely trick designed by nature to stop speech when words become superfluous", 21 million years in the making.This rewrites romance's roots, blending science with that butterflies-in-stomach thrill.