Kissing as a sign of romantic or sexual attachment is a practice among humans that is at least 4,500 years old, a millennium earlier than was commonly believed. The practice could go back much further in antiquity to prehistory, Troels Pank Arbøll of the University of Copenhagen and Sophie Lund Rasmussen of Oxford University say.
The study was published this week in the journal Science, shows evidence that "kissing on the mouth is attested in ancient Mesopotamia and Egypt"