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Frist Kiss May Date Back 21 Million Years, Study Suggests
OXFORD, UK – November 19, 2025 - A groundbreaking study from the University of Oxford suggests that kissing, as a non-aggressive mouth-to-mouth behavior, may have originated with our great ape ancestors as far back as 21 million years ago. Published Wednesday in the journal Evolution and Human Behaviour, the research offers the first comprehensive look at the evolutionary history of this intimate act.
The findings challenge previous assumptions about the origins of kissing,positioning it not as a recent cultural development,but as an ancient behavioral trait deeply rooted in primate history. Researchers believe the practice was present in the common ancestor of all great apes - including humans, chimpanzees, bonobos, and orangutans - and has persisted through millions of years of evolution. The study also indicates Neanderthals likely engaged in kissing, having coexisted with Homo Sapiens until approximately 40,000 BCE.
Researchers defined kissing as “non-aggressive mouth-to-mouth contact that does not involve food transfer.” They compiled data on primate species known to kiss, then used a statistical approach based on the primate phylogenetic tree to estimate the likelihood of the behavior in their ancestors.
“Kissing has been maintained throughout evolution and is still present in most great apes,” the researchers concluded.
“By integrating evolutionary biology with behavioral data, we are able to draw informed conclusions about behavioral traits that do not fossilize, such as kissing,” explained Stuart West, co-author and professor of evolutionary biology at Oxford. The study opens new avenues for understanding the biological basis of human social behavior and the deep history of connection between primates.
