When we think of kissing, we usually imagine romance, affection, or playful intimacy. But have you ever wondered when kissing first evolved—and whether our ancient relatives, the Neanderthals, shared this behavior? A fascinating new study suggests that the roots of kissing go back millions of years, and yes, Neanderthals may have been part of the story.
Defining What Counts as a Kiss
Researchers began by carefully defining kissing in a way that applies across species. They excluded behaviors that only look like kissing, such as:
- Premastication: primates feeding offspring by chewing food and passing it mouth-to-mouth.
- Trophallaxis: ants exchanging food and fluids mouth-to-mouth (sometimes even mouth-to-anus).
- Kiss-fighting: tropical fish locking lips as a dominance display.
Instead, the team defined kissing as nonaggressive, directed, mouth-to-mouth contact between members of the same species that does not involve food transfer. By this definition, many animals—from polar bears to prairie dogs—engage in kissing-like behavior.
Kissing Among Primates and Apes
The researchers analyzed scientific records of monkeys and apes across Africa, Asia, and Europe. They found that:
- Several monkey species and most apes kiss.
- Bonobos are especially sensual, often engaging in prolonged tongue-to-tongue interaction.
- Other apes kiss during foreplay or sex, but also in affectionate contexts like mother-infant bonding or reconciliation.
- Eastern gorillas and small apes (gibbons, siamangs) appear to be exceptions, showing little evidence of kissing.
This suggests that the ancestors of large apes were already kissing 21.5–16.9 million years ago.
Did Neanderthals Kiss Humans?
The study also explored Neanderthals, who lived alongside early modern humans. Evidence shows that humans and Neanderthals shared an oral microbe long after their evolutionary split. The most likely explanation? Saliva exchange—possibly through kissing.
While food sharing could also explain this, genetic evidence reveals that most people of non-African descent carry Neanderthal DNA. Combined with the new findings, this paints a vivid picture: humans and Neanderthals may well have exchanged kisses along with genes.
Why This Matters
Kissing is more than a cultural practice—it has deep evolutionary roots. It likely served multiple purposes:
- Strengthening social bonds.
- Facilitating sexual intimacy.
- Transmitting microbes that shaped immune systems.
Though kissing doesn’t fossilize, the evidence strongly suggests that our ancestors—and even Neanderthals—were no strangers to a smooch.
Source: Phys.org – When did kissing evolve? Did humans and Neanderthals smooch?
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