Mesopotamians were kissing 4500 years ago, earlier than previously believed.

The earliest recorded kiss dates back at least 4,500 years to Mesopotamia, according to a new review paper in the journal Science. The researchers found accounts of kissing from Mesopotamia written in both the Sumerian and Akkadian languages, as well as a calcite sculpture in the British Museum called the “Ain Sakhri Lovers,” which is estimated to be about 11,000 years old. The act of kissing may have played a secondary and unintentional role throughout history by enabling disease-causing microorganisms to spread from one mouth to another.