Kissing did not appear with humans in love, but with the ancestors of great primates, about 20 million years ago, according to a recently published study.
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Researchers from the University of Oxford and the Florida Institute of Technology wanted to find out when kissing began, given that, from an evolutionary point of view, it does not provide a clear survival benefit and may even facilitate the spread of disease, according to Reuters.
However, humans, chimpanzees, bonobos, orangutans and gorillas kiss, strongly suggesting that this habit was inherited from a common ancestor. Scientists have combined observations of primate behavior with data on evolutionary relationships to turn back time and try to determine when the first kiss occurred.
“Using these two key pieces of information, we used a model that allowed us to simulate different evolutionary scenarios”said lead author Dr Matilda Brindle, from Oxford University’s Department of Biology.
The model, run millions of times, indicated that the first kiss took place between 21.5 and 16.9 million years ago.
The findings were published in the journal Evolution and Human Behavior.
How is a kiss defined?
The less romantic definition given to the kiss by the researchers was “mouth-to-mouth contact, non-aggressive, not involving transfer of food”.
This included both sexual and platonic kisses, such as kisses between members of the same family or greetings. How the kiss came about remains a matter of debate, as do the reasons why it was kept.
“Some suggest that sexual kissing is a useful way to assess the quality or compatibility of a partner”Brindle said. “Alternatively, kissing could be a type of foreplay that increases sexual arousal and the chances of fertilization.”
Platonic kisses, researchers say, could be used to navigate complex social relationships or strengthen bonds between individuals.
The study also argues that Neanderthals were kissing too, given evidence that they mated with modern humans and shared an oral microbe – a sign that they exchanged saliva – long after the two species split 450,000-750,000 years ago.
