The Ancient Art of Kissing: 21 Million Years in the Making

Scientists have uncovered evidence that the mouth-to-mouth kiss evolved over 21 million years ago, long before humans appeared on Earth. A recent study published in Evolution and Human Behaviour suggests that kissing behavior was likely present in the common ancestor of humans and other great apes. Researchers defined kissing as non-aggressive, directed oral-oral contact with lip or mouthpart movement and no food transfer. They found evidence of this behavior in multiple species, including wolves, prairie dogs, polar bears, and even albatrosses. The study’s lead author, Dr. Matilda Brindle, explained that the common ancestor of humans and great apes probably engaged in kissing. The research also suggests that Neanderthals may have kissed, as evidence of shared oral bacteria between humans and Neanderthals indicates they swapped saliva for hundreds of thousands of years after the two species diverged. While the study determined when kissing evolved, it did not explain why. Theories include that kissing might have evolved from grooming behavior or serves as a way to assess a potential partner’s health and compatibility. Dr. Brindle emphasized the importance of studying this behavior scientifically, rather than dismissing it as merely romantic. ‘It’s important for us to understand that this is something we share with our non-human relatives,’ she said.