Kissing’s Ancient Roots: Oxford Study Traces the Practice Back 16.9 Million Years
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A new study published November 19 in the journal Evolution and Human Behaviour reveals that kissing isn’t a uniquely human behavior – its origins stretch back at least 16.9 million years, predating even the emergence of our direct ancestors. Biologists at the University of Oxford, United Kingdom, have amassed substantial data suggesting that our extinct great ape ancestors engaged in what they define as kissing, effectively resolving a long-standing “riddle of evolution.”
Defining a Kiss: Beyond Romance
For years, scientists struggled to pinpoint the evolutionary origins of kissing due to a lack of a clear definition. Researchers ultimately agreed that kissing is a “non-aggressive interaction” characterized by mouth-to-mouth contact, some lip movement, and crucially, no food exchange. This precise definition allowed them to broaden their observational scope beyond humans.
A Widespread Behavior in the Animal Kingdom
With a working definition in place, the team observed that kissing-like behaviors are surprisingly common across the animal kingdom. From wolves and prairie dogs to albatrosses and even polar bears – some of whom are described as “rather fans of French kiss, with the tongue” – mouth-to-mouth interactions are frequently observed. This widespread prevalence prompted researchers to investigate the behavior in our primate ancestors.
Phylogenetic Analysis Reveals Deep Roots
The Oxford team conducted a phylogenetic analysis, essentially creating a “genealogical mapping” of kissing behaviors across different primate species. This analysis confirmed that the ancestors of modern chimpanzees, bonobos, and orangutans were already engaging in smooching. Furthermore, the research corroborates a previous study that identified the sharing of oral microbes between Homo sapiens and Neanderthals, indicating an exchange of saliva between these hominids.
The Evolutionary Purpose Remains Elusive
Despite establishing the ancient origins of kissing, the Oxford researchers remain perplexed by its evolutionary purpose. “What is the point of kissing?” one researcher stated, noting that the behavior doesn’t appear to directly contribute to survival or reproduction. The potential risks associated with disease transmission further complicate the evolutionary puzzle.
The study highlights the enduring mysteries surrounding even the most seemingly natural of human behaviors. While the origins of kissing are now clearer, its ultimate function remains a fascinating question for future research.
