Researchers Trace the Origins of Kissing to Great Apes 21.5 Million Years Ago

Overview

• The study, published in Evolution and Human Behaviour, estimates the gesture arose in the common ancestor of great apes roughly 21.5 million years ago.
• Authors define a kiss as non‑aggressive mouth‑to‑mouth contact with lip movement and no transfer of food to enable cross‑species comparisons.
• Reports of analogous behaviours meeting this definition were documented in wolves, prairie dogs, polar bears and albatrosses alongside primates.
• Drawing on prior findings of shared oral microbes, the team infers Neanderthals likely kissed and may have exchanged saliva with modern humans.
• Lead author Matilda Brindle of the University of Oxford notes the function of kissing remains unresolved, with hypotheses ranging from hygiene origins to partner assessment and a call for further research.