The Origins of Kissing trace Back 20 Million Years to Our Primate Ancestors
AMSTERDAM – A new study suggests the act of kissing isn’t a uniquely human behaviour, but rather a trait inherited from primate ancestors dating back approximately 20 million years. Researchers from Oxford University and the Florida Institute of Technology investigated the evolutionary origins of kissing, a behavior that appears to offer no clear survival advantage and even carries the risk of disease transmission.
The research team noted that kissing - defined as non-aggressive,mouth-to-mouth contact excluding food transfer – is observed across several great ape species,including humans,chimpanzees,bonobos,orangutans,and gorillas. This widespread practice strongly indicated a shared ancestral origin.
To pinpoint when this behavior frist emerged, scientists combined observations of current primate kissing behaviors with data detailing evolutionary relationships between species. They then utilized a modeling approach, running simulations millions of times, to estimate the timeframe.
“Using these two key pieces of data, we employed a modeling approach that allowed us to simulate different evolutionary scenarios,” explained Dr. Matilda Brindle, lead author from Oxford’s Department of Biology. The modeling consistently placed the origin of kissing between 21.5 and 16.9 million years ago. The findings were published in the journal Evolution and Human Behavior.
While the study establishes when kissing likely began,the why remains open to interpretation. Researchers propose several possibilities. Sexual kissing could serve as a method for assessing potential mates, while also functioning as foreplay to increase arousal and the likelihood of successful fertilization. Non-sexual “pecks” may have evolved to facilitate social bonding and navigate complex relationships within primate groups.
Interestingly, the study also suggests that Neanderthals and early humans likely engaged in kissing. Evidence of interbreeding between the two species, coupled with the sharing of oral microbes – indicating saliva exchange – supports this idea, even after their evolutionary paths diverged between 450,000 and 750,000 years ago.
