Overview
- Published in Evolution and Human Behavior, the study defines a kiss as non‑aggressive mouth‑to‑mouth contact without food transfer.
- Comparative observations across primates document kissing in chimpanzees, bonobos, orangutans and some gorillas, with models dating the origin to roughly 21.5–16.9 million years ago.
- The analysis infers that Neanderthals probably kissed, and it considers kissing between Neanderthals and modern humans plausible given genetic admixture and shared oral‑microbiome evidence.
- Authors outline possible functions that include mate assessment, sexual foreplay, social bonding and reconciliation, while stressing that no single adaptive purpose is confirmed.
- Researchers note sparse data beyond great apes and heavy reliance on captive or sanctuary observations, urge more studies in wild populations, and point out that romantic kissing is documented in about 46% of human cultures.