Planting a big wet smooch on someone you love didn’t start with us. Well, technically it did, just not the version of us around today. According to new research, kissing may have begun with our great ape ancestors around 16.9 to 21.5 million years ago.

Researchers from the University of Oxford took the first wide-angle evolutionary look at the biological origins of kissing. Lead author Matilda Brindle and her team had to begin by defining what counts as a kiss across multiple primate species. After ruling out behaviors that looked like kissing but were actually just food delivery systems, they landed on a definition for a romantic gesture that, in typical scientific fashion, has been stripped of all romance: non-aggressive mouth-to-mouth contact without the transfer of food.

Doesn’t that

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