In the words of Dua Lipa, one kiss is all it took about 21 million years ago. That's roughly when scientists estimate that kissing first emerged in the common ancestor of humans and other great apes.

Kissing occurred around 21.5 to 16.9 million years ago, the researchers said. Stories have long been swapped on awkward first kisses and princesses smooching frogs, but a new study suggests the ...