Overview
- The peer-reviewed paper in Evolution and Human Behavior reconstructs kissing as an ancestral trait of large apes dating to roughly 21.5–16.9 million years ago.
- The team defined kissing as non-aggressive, mouth-to-mouth contact without food transfer and treated it as a trait mapped across the primate family tree.
- Bayesian models were run 10 million times, producing estimates that the behavior was retained in most surviving great apes, with observations in chimpanzees, bonobos and orangutans.
- The study reports Neanderthals likely kissed, and prior evidence of shared oral microbes and interbreeding supports the probability of kissing between Neanderthals and Homo sapiens.
- Authors highlight limited behavioral data beyond great apes and note kissing appears in about 46% of human cultures, calling for systematic observations to test competing functional hypotheses.