Overview
- Published in Evolution and Human Behavior, the analysis is the first cross-species reconstruction of kissing’s evolutionary history across primates.
- Kissing was operationally defined as non-aggressive, mouth-to-mouth contact without food transfer, with documented cases in chimpanzees, bonobos and orangutans.
- The team treated kissing as a behavioral trait and ran Bayesian phylogenetic models 10 million times, estimating an origin between 21.5 and 16.9 million years ago that persisted in most great apes.
- The study infers Neanderthals likely kissed, aligning with prior findings of shared oral microbes and genetic admixture between Neanderthals and Homo sapiens.
- Kissing is not universal in humans—documented in about 46% of cultures—and the authors note limits such as sparse data beyond great apes and captive observations, proposing this framework to guide future testing of function hypotheses.