Overview
- The paper, published Nov. 19 in Evolution and Human Behaviour, estimates the trait emerged in the common ancestor of humans and great apes between 16.9 and 21.5 million years ago.
- Authors define a kiss as non-aggressive mouth-to-mouth contact without food transfer to distinguish it from feeding or conflict behaviors.
- Comparative data across primates and the primate phylogenetic tree underpin the inference that the behavior has been maintained in most great ape species.
- The study concludes Neanderthals probably kissed, citing prior findings of shared oral microbes via saliva and documented genetic admixture with Homo sapiens.
- The original function remains unresolved, with hypotheses proposing reproductive roles for sexual kissing and affiliative bonding for lighter contact.