If you believe kissing is purely a human expression of romance, a new evolutionary study says otherwise. According to researchers, the first kiss took place between the ancestors of ancient apes in Africa around 16.9 to 21.5 million years ago, long before modern humans existed.
The study suggests that kissing should be viewed not just as affection, but as an evolutionary behaviour — a risky mouth-to-mouth exchange that began among great apes and possibly even Neanderthals.
Why Did Kissing Begin?
Instead of asking “What does a kiss mean?”, the research team examined a deeper question:
Why did this strange, germ-sharing behaviour evolve in the first place?
Scientists from the University of Oxford, University College London, and the Florida Institute of Technology attempted to define kissing across species, separating it from emotional or cultural meanings.
Their definition:
“Kissing is non-aggressive mouth-to-mouth contact within a species, involving some lip movement and no food exchange.”
This excludes behaviour such as food sharing, aggressive “kiss-fighting,” or a dog licking a person’s face — but includes everything from gentle ape kisses to passionate human kissing.
Kissing Exists Beyond Humans and Apes
Using this definition, researchers found that several species engage in kissing-like behaviour, including:
- Ants
- Certain birds
- Polar bears
However, most documented cases were found in primates, especially great apes.
Did Neanderthals Kiss Before Humans?
Researchers analysed decades of field observations and video records, mapping the behaviour onto a primate evolutionary family tree. Statistical analysis suggests that lip-to-lip contact existed long before Homo sapiens evolved.
The behaviour likely developed among chimpanzees, bonobos, and orangutans, the close evolutionary relatives of humans.
The study also proposes there is an 84% probability that Neanderthals were kissing before or alongside early humans. It is even possible that Neanderthals and modern humans exchanged kissing behaviour during the period when both species coexisted.
Conclusion
The findings suggest that kissing is not a recent cultural invention, but an ancient biological behaviour inherited from our primate ancestors — one that evolved millions of years before humans appeared.
In short, humans didn’t create the kiss — we inherited it.