The activity of kissing would be much older than you might think – 21 million years ago – and that it can even date back tocommon ancestor of man and great apes. This is what emerged from a recent study, conducted by Matilda Brindle And Stuart Westof theUniversity of Oxfordtogether with Catherine Talbot of the School of Psychology of Florida Institute of Technology.
Although we tend to think that kissing is a purely human activity, this is absolutely not the case. It is in fact one very common activity between different species of hominids (chimpanzees, bonobos, orangutans, gorillas, mostly primates related with our species), but also macaques and baboons and many other species, even very distant from us evolutionarily. Taking this into consideration, it is very likely that kissing is a phylogenetic trait of our species, present almost certainly also in the other extinct species of the genus Homoincluding the one closest to us, Homo neanderthalensis. It is therefore an activity that can trace its own origins untilcommon ancestor between Homo and other hominidslived about 10-20 million years ago. Notably, the team that conducted the study says that the findings suggest that kissing evolved between 21.5 and 16.9 million years ago in the ancestors of great apes.
From this point of view, the relationship between our species, Homo sapiensAnd Homo neanderthalensiswe do even more tightand it goes right through the mouth. In fact in oral cavity a detail of both species is found microbiota bacterium, Methanobrevibacter oralis. Sapiens and Neanderthals, in the evolutionary history of man, are separated from their common ancestor (probably Homo heidelbergensis) between 750,000 and 450,000 years agobut the genetic heritage of the microbiota Methanobrevibacter oralis yes it is differentiated between the two species “just” between 143,000 and 112,000 years ago. This data could tell us how Sapiens and Neanderthals have “exchanged saliva” for about half a million years, probably in the Middle East, where the two species coexisted in that very long period of time.
The kiss, by its very nature (contact between sensitive parts of the body) is an activity risky: it can in fact favor the infection and the transmission of illnesses. From an evolutionary point of view, therefore, it must be a behavior that has been preserved because allows greater benefits than potential risks. Kissing most likely evolved from pre-chewingor that activity common to many animal species that occurs in adult individuals chew food and then pass it with your mouth to their little ones. It cannot be excluded that this activity was also practiced by ancient Sapiens and Neanderthals.
Considering the kiss as a ancient sublimation of pre-chewing (therefore an activity that triggers positive feelings), the theories proposed by researchers to explain the conservation of this trait are different. There is a theory of sexual selectionwho sees in the kiss a possibility of “test” a potential partner or of increase sexual arousal to improve the chances of reproducing, but also a social theorywho sees this activity as a possibility of create bonds between individuals and favor the relaxation and the resolution of social conflicts.
