• First evidence of kissing traced back to the primate ancestors of great apes 20 million years ago.
• Researchers used evolutionary data and primate behavior observations to date the origin of kissing.
• The study suggests Neanderthals and humans also engaged in kissing, supporting interbreeding theories.

Research led by scientists from Oxford University and the Florida Institute of Technology has traced the origins of kissing back to the ancestors of great apes around 20 million years ago. This study, published in the journal Evolution and Human Behaviour, sought to investigate the evolutionary background of kissing, an act with no clear survival advantage, according to researchers. The findings show that humans and other primates such as chimpanzees, bonobos, orangutans, and gorillas share this behavior, indicating it was inherited from a common ancestor, as stated by lead author Dr. Matilda Brindle from Oxford University.

The researchers employed a modeling approach that simulated various evolutionary scenarios to pinpoint the initial occurrence of kissing between 21.5 and 16.9 million years ago. The study rigorously defined kissing as "non-aggressive, mouth-to-mouth contact that did not involve food transfer", encompassing both sexual and platonic interactions among individuals, suggesting its role in social bonding, according to evidence presented in Channel News Asia, South China Morning Post, and The Jakarta Post.

Interestingly, the study also suggests that humans and Neanderthals likely engaged in kissing, supported by evidence of interbreeding and shared oral microbes, a sign of saliva exchange observed long after the two species diverged approximately 450,000 to 750,000 years ago. This aligns with earlier speculations that our ancestors had complex relational dynamics, pointing to an ancient origin of this behavior, as discussed by ABC News and Channel News Asia.

Brindle remarked on the significance of understanding kissing from an evolutionary perspective, noting that it is a behavior not only observed in humans but across various species, including polar bears. This broad occurrence urges a reevaluation of how human interactions fit into the greater context of animal behavior, emphasizing that "a kiss is more than a lovely trick designed by nature to stop speech when words become superfluous," as referenced in studies highlighted by South China Morning Post, ABC News, and The Jakarta Post.