We used this definition to trawl published scientific papers, searching for observations of kissing in the group of monkeys ...

Our results paint early apes in an amorous light, showing that the ancestors of large apes were kissing each other as far back as 21.5 – 16.9 million years ago. Clearly, they were onto a good thing ...

A nd now researchers have reconstructed the evolutionary origins of kissing. Their study suggests that the mouth-on-mouth ...