Overview
- Researchers from the University of Oxford and Florida Institute of Technology report findings in Evolution and Human Behavior that reconstruct the evolutionary history of kissing across primates.
- Kissing was operationally defined as non-aggressive, mouth-to-mouth contact without food transfer to allow consistent comparison across species.
- The team mapped documented behavior in Afro‑Eurasian primates—including chimpanzees, bonobos, and orangutans—and treated kissing as a trait on the primate family tree.
- Bayesian phylogenetic models run 10 million times estimate the behavior arose in the ancestor of large apes roughly 21.5–16.9 million years ago, with a high inferred probability for Neanderthal kissing consistent with evidence of shared oral microbes and interbreeding.
- The authors emphasize limited behavioral data outside great apes, note that kissing is recorded in about 46% of human cultures, and present the framework to guide future tests of proposed functions such as mate assessment or social bonding.