Neanderthals and early humans likely to have kissed', say scientists

"Now researchers suggest Neanderthals did it too and might even have locked lips with modern humans. It is not the first time scientists have suggested Neanderthals and early modern humans were intimately acquainted. Among previous studies, researchers have found humans and their thick-browed cousins shared the same mouth microbe for hundreds of thousands of years after the two species split, suggesting they swapped saliva."

"Writing in the journal Evolution and Human Behavior, Brindle and colleagues report how, to investigate the evolutionary origins of kissing, they first had to come up with a definition that was not limited to how humans smooch. There have been some previous attempts to define a kiss, but it's very much been human-centric, which means that basically other animals don't kiss. Now we know that they probably do, it might just not look exactly what human kissing looks like, said Brindle."

Certain nonhuman species such as Galapagos albatrosses, polar bears, chimpanzees, and orangutans display mouth-to-mouth contact resembling kissing. Neanderthals likely engaged in similar mouth-to-mouth behaviour and may have locked lips with modern humans, consistent with evidence of shared oral microbes and Neanderthal DNA in non-African human genomes. A functional definition of kissing was developed as friendly, directed mouth-to-mouth contact within a species, involving some mouth movement but no transfer of food. Behaviours that transfer food or involve aggressive ‘kiss-fighting’ were excluded from this definition.

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