Kissing did not begin with humans, but with primates, the ancestors of great apes, about 20 million years ago, according to a study published today. Researchers from the University of Oxford and the Florida Institute of Technology wanted to examine when kissing began, given that from an evolutionary perspective it has no benefit and may even transmit disease.
However, humans, chimpanzees, orangutans, bonobos and gorillas kiss, suggesting that it is a habit inherited from a common ancestor. The scientists in the study combined observations of primate behavior with data on evolutionary relationships to go back in time and try to date the first kiss.
The scientists defined kissing as “non-aggressive mouth-to-mouth contact that does not involve the transfer of food.” This definition includes sexual kisses as well as platonic kisses, such as those between family members or in friendly greetings. “We used this definition to examine published scientific papers, looking for observations of kissing in the group of monkeys and apes that evolved in Africa, Asia and Europe. We concluded that some monkeys and most apes have been observed to kiss,” explained the study’s lead author, Dr. Matilda Bridle of Oxford’s Department of Biology.
"We combined this data with information about the evolutionary relationships between different species, in what is known as phylogenetic comparative analysis. This technique allowed us to model the evolutionary history of kissing and explore whether it was possible that the ancestors of different species groups had the habit," Bridle added.
Based on this data, "we applied a modeling approach that allowed us to simulate different evolutionary scenarios" and, after running the model millions of times, the scientists calculated that the first kiss dates back to 21,5 to 16,9 million years ago.
The findings were published in the scientific journal Evolution and Human Behavior.
How kissing originated remains a matter of debate, as does why the practice continues. “Some argue that sexual kissing is a useful way to assess the quality or suitability of a partner,” Bridle noted. “Alternatively, kissing could be a type of foreplay, increasing sexual arousal and enhancing the likelihood of fertilization,” she added.
Platonic kisses, according to her, are used to strengthen social bonds.
The research also sheds light on Neanderthal behavior. Previous research has suggested that modern humans (homo sapiens) and Neanderthals shared a common oral microbe long after the two species diverged. For this to happen, the microbe would have to have been transferred between the two species. In other words, Neanderthals and modern humans exchanged saliva.
Source: protothema.gr
