Scientists now propose that Neanderthals engaged in kissing, and may even have exchanged lip-to-lip contact with early humans. The study, published in Evolution and Human Behavior, redefines kissing beyond human behavior, identifying it as a friendly, mouth-to-mouth interaction between members of the same species, excluding food transfer. This broad definition, supported by observed kissing behavior in primates such as bonobos, chimpanzees, and orangutans, suggests the practice evolved between 21.5 and 16.9 million years ago in the ancestors of large apes.
Researchers, led by Dr. Matilda Brindle of the University of Oxford, point to shared mouth microbes between humans and Neanderthals as evidence of saliva exchange, implying intimate contact. Further supporting this is the presence of Neanderthal DNA in the genomes of non-African humans, confirming interbreeding occurred. The study challenges the notion that kissing is uniquely human, arguing that the behavior likely existed in Neanderthals given their position on the primate evolutionary tree.
The function of kissing remains debated, but researchers suggest it could have served reproductive or bonding purposes. Sexual contexts may have used kissing to increase reproductive success or help select mates, while platonic kissing could have reinforced emotional bonds.
Dr. Jake Brooker of Durham University, not involved in the study, notes that kissing behavior is widespread among apes, suggesting even deeper evolutionary roots. He believes that analyzing kissing in a wider variety of species could push its origins back even further.
Professor Penny Spikins of York University adds that while kissing is not universal across all human societies, it underscores the importance of emotional bonds in human evolution. She suggests that Neanderthals, and even interactions between Neanderthals and early humans, likely included kissing, challenging perceptions of a purely aggressive past.
The research expands the understanding of behaviors previously considered uniquely human, demonstrating that kissing, like other behaviors, may be a shared trait across primate species
