Overview
- Published in Evolution and Human Behavior, the analysis reconstructs kissing in the common ancestor of great apes roughly 21.5 to 16.9 million years ago.
- Researchers defined a kiss as non‑aggressive mouth‑to‑mouth contact without food transfer and mapped primate observations onto the evolutionary tree using computational statistics, including millions of model runs.
- Kissing‑like behavior is reported across many Old World monkeys and in chimpanzees, bonobos, orangutans, and most gorillas, with eastern gorillas noted as an exception.
- The model infers Neandertals likely engaged in kissing, aligning with studies showing shared oral microbes between Neandertals and modern humans, with one report citing an 84% probability.
- Authors note limits on observational data beyond large apes, report documentation in about 46% of human cultures, and leave the adaptive function unresolved despite hypotheses on bonding, assessment, or microbiome exchange.