Romantic kissing may go a long way back in our evolutionary past
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Recent research suggests that romantic kissing may have a much longer evolutionary history than previously thought. Evidence points to early humans like Neanderthals engaging in kissing, and even our ape ancestors potentially practicing this behavior as far back as 21 million years ago.
While there is debate over the origins of romantic kissing, with some arguing it is a cultural phenomenon that emerged relatively recently, there are indications that Neanderthals exchanged oral bacteria with Homo sapiens, and various primate species have been observed engaging in kissing behaviors.
To delve deeper into the evolutionary history of kissing, Matilda Brindle and her team at the University of Oxford set out to trace the origins of this behavior. By defining kissing as non-antagonistic mouth-to-mouth contact involving lip movement but not food transfer, they conducted a comprehensive study across primate species.
Through mapping out this information on a primate family tree and utilizing Bayesian modeling, the researchers estimated that kissing likely evolved in ancestral apes around 21.5 to 16.9 million years ago. Additionally, there is an 84% chance that Neanderthals also engaged in kissing.
While the exact reasons for the evolution of kissing remain unclear, two main hypotheses have been proposed. One suggests that sexual kissing could aid in mate assessment and post-copulation success, while the other theory posits that non-sexual kissing may have originated from grooming behaviors, serving to strengthen social bonds.
Zanna Clay, a researcher at Durham University, highlights the affiliative function of kissing in social relationships, particularly in repairing conflicts among chimpanzees. Although the evolution of kissing is evident from the research findings, the cultural element cannot be disregarded, as cultural preferences may influence the prevalence of kissing in different societies.
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