Kissing began in the Middle East 4,500 years ago - 1,000 years earlier than previously believed, new research by Oxford University suggests.
Humanity’s earliest recorded kiss was in Mesopotamia - the historical region made up of present-day Iraq as well as parts of Iran, Kuwait, Syria and Turkey.
Previous research had suggested that the earliest evidence of human lip kissing originated in a very specific geographical location in South Asia 3,500 years ago.
But written sources document that kissing was practiced by the peoples of the ancient Middle East at least 1,000 years earlier, according to the new study by Oxford University in collaboration with the University of Copenhagen.
Dr Troels Pank Arbøll and Dr Sophie Lund Rasmussen, who drew on several written sources from the earliest Mesopotamian societies, found kissing was already a well-established practice 4,500 years ago in the Middle East.
They say their findings, published in the journal Science, move the earliest documentation for kissing back 1,000 years compared to what was previously acknowledged in the scientific community.
Dr Arbøll said: “In ancient Mesopotamia, which is the name for the early human cultures that existed between the Euphrates and Tigris rivers in present-day Iraq and Syria, people wrote in cuneiform script on clay tablets.
"Many thousands of these clay tablets have survived to this day, and they contain clear examples that kissing was considered a part of romantic intimacy in ancient times, just as kissing could be part of friendships and family members’ relations.
“Therefore, kissing should not be regarded as a custom that originated exclusively in any single region and spread from there but rather appears to have been practiced in multiple ancient cultures over several millennia.”
Dr Rasmussen said: “In fact, research into bonobos and chimpanzees, the closest living relatives to humans, has shown that both species engage in kissing, which may suggest that the practice of kissing is a fundamental behaviour in humans, explaining why it can be found across cultures.”
The research team said that, in addition to its importance for social and sexual behaviour, the practice of kissing may have played an unintentional role in the transmission of microorganisms, potentially causing viruses to spread among humans.
However, the suggestion that the kiss may be regarded as a sudden biological trigger behind the spread of particular pathogens is more doubtful.
They said that the spread of the herpes simplex virus could have been accelerated by the introduction of kissing.
Dr Arboll said: “There is a substantial corpus of medical texts from Mesopotamia, some of which mention a disease with symptoms reminiscent of the herpes simplex virus."
He says that the ancient medical texts were influenced by several cultural and religious concepts, so it must be emphasised that they can't be read at face value.
Dr Arboll added: “It is nevertheless interesting to note some similarities between the disease known as buʾshanu in ancient medical texts from Mesopotamia and the symptoms caused by herpes simplex infections.
"The bu’shanu disease was located primarily in or around the mouth and throat, and symptoms included vesicles in or around the mouth, which is one of the dominant signs of herpes infection.”
Dr Rasmussen added: “If the practice of kissing was widespread and well-established in a range of ancient societies, the effects of kissing in terms of pathogen transmission must likely have been more or less constant."