Overview
- Published in Evolution and Human Behavior, the cross-species analysis reconstructs kissing as an ancient trait in the lineage leading to today’s large apes.
- Researchers defined kissing as non-aggressive mouth-to-mouth contact without food transfer to standardize observations across species.
- Using phylogenetic methods run 10 million times, the team estimated the behavior originated roughly 21.5–16.9 million years ago and persisted in most great apes.
- The model assigns about an 84% probability that Neanderthals kissed, aligning with prior evidence of saliva exchange and interbreeding with Homo sapiens.
- Kissing is documented in only about 46% of human cultures, and the authors caution that data beyond great apes are sparse and often from captivity, calling for targeted field studies.