Overview
- Researchers define kissing as non-aggressive, mouth-to-mouth contact without food transfer and document it in chimpanzees, bonobos, orangutans, and at least one gorilla species.
- The Bayesian phylogenetic reconstruction places the trait’s emergence in the ancestor of large apes between 21.5 and 16.9 million years ago and indicates it persisted in most great apes.
- The study estimates a high likelihood that Neanderthals kissed, with coverage citing an ~84% probability, consistent with evidence of shared oral microbes and known interbreeding with Homo sapiens.
- The work, led by the University of Oxford with Florida Institute of Technology, is published in Evolution and Human Behavior and establishes a standardized framework for recording the behavior across primates.
- Authors note key limits, including sparse data beyond great apes, reliance on many captive observations, and model assumptions, and they emphasize that kissing is documented in only about 46% of human cultures.