Kissing Isn’t Just Human: Ancient Roots of Affection Trace Back 21.5 Million Years, Study Suggests
New research indicates kissing, defined as non-aggressive mouth-too-mouth contact, isn’t a uniquely human behavior, but an inherited trait possibly stretching back to a common ancestor of great apes living between 21.5 and 16.9 million years ago. The groundbreaking study, utilizing phylogenetic analysis, statistical modeling, and behavioral observations, even suggests our Neanderthal cousins engaged in the practise, not solely for reproduction, but for social bonding.
Researchers supporting this hypothesis point to observed kissing behaviors in modern great apes like bonobos and orangutans, documented through platforms like YouTube, occurring during play, reconciliation, and to strengthen social ties. The study deliberately adopted a “strict definition” of kissing - excluding food transfer and aggressive interactions – to identify a core evolutionary behavior.
“The most parsimonious conclusion remains: they were probably kissing,” states Dr. Matilda Brindle, regarding the Neanderthal evidence. This evidence comes from the analysis of fossilized dental tartar revealing shared oral microorganisms between Homo sapiens and neanderthals, bacteria primarily transmitted through saliva contact.
The team’s work involved carefully redefining the act of kissing beyond human cultural interpretations. Behaviors like “kiss-fights” observed in fish and food-sharing gestures were excluded, focusing rather on the emotional context – appeasement, social connection, and reconciliation.
This broadened definition allows for exploration of kissing behaviors in other social mammals and provides “a more worldwide reading grid” for studying behaviors frequently enough overlooked due to their perceived ”humanness.” Ultimately, the research positions kissing not as a cultural invention, but as ”an indicator of social connection” deeply embedded in our evolutionary history, observable and analyzable across species.
