Recent studies maintain that the first known record of human romantic-sexual kissing originates in a Bronze Age manuscript deriving from South Asia (India), tentatively dated to 1500 BCE (1). Yet, a substantial corpus of overlooked evidence challenges this premise because lip kissing was documented in ancient Mesopotamia and Egypt from at least 2500 BCE onward. Because this behavior did not emerge abruptly or in a specific society but appears to have been practiced in multiple ancient cultures over several millennia, the kiss cannot be regarded as a sudden biological trigger causing a spread of specific pathogens, as recently proposed (2). Further understanding of the history of kissing in human societies—and its secondary effect on disease transmission—can be gained from a case study of sources from ancient Mesopotamia (modern-day Iraq and Syria).