A new study looks at how the mouth-on-mouth smooch came into being, and concludes that Neanderthals also kissed.

Evolutionary biologists don’t know why we kiss — but new research suggests kissing evolved long before humans existed.

New research suggests that kissing probably predates humanity and evolved between 16.9 million and 21.5 million years ago, after the ancestor of the great apes split from the lesser apes, or gibbons.

Kissing is more than just “mouth-to-mouth” touching, and the study doesn’t really shed much light on why humans kiss the way they do, said Adriano Reis e Lameira, an evolutionary psychologist and ...