According to the WHO, about 3.7 billion people under the age of 50 are infected with the oral herpes virus. Its worldwide spread could be related to the phenomenon of kissing.
When a kiss makes you ill: According to scientists, the emergence of kissing as a new custom could have promoted the spread of oral herpes. The virus is transmitted through the mouth.
5000 years ago transmission of oral herpesviruses increased
“Something happened about five thousand years ago that allowed one strain of herpes to overtake all the others. The increase in transmissions could potentially be linked to kissing,” said Christiana Scheib of the UK University of Cambridge. She is co-author of the study, which was published in the journal Science Advances.1
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3000 DNA samples from archaeological finds
For the study, the international research team analyzed around 3,000 DNA samples from archaeological finds. The scientists only found the herpes virus in four cases. The oldest sample comes from a man who lived in Russia’s Ural region and was from the late Iron Age, around 1,500 years ago. According to the authors, the oldest genetic data for herpes so far came from a sample from 1925.
By sequencing the genomes and comparing them to samples from the 20th century, a mutation rate and the evolution of the virus could be estimated.
“Facial herpes hides in its host for life and is only transmitted by oral contact, so mutations appear slowly over centuries and millennia,” said co-author Charlotte Houldcroft (also of the University of Cambridge). Every primate species has some form of herpes, Scheib said. It is therefore assumed that people have also carried the virus since they left Africa. Kissing could later have contributed to the spread of oral herpes.
The earliest known record of kissing is a Bronze Age manuscript in South Asia, according to the research team. The custom is far from universal in human culture.
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Link to cultural practice of sexual and romantic kissing
The scientists suspect that the kiss could have come to Europe with a migration movement from Eurasia. The rise of oral herpes may have coincided with the emergence of the cultural practice of kissing sexually and romantically.
Even today, the romantic kiss is not widespread in all parts of the world. A 2015 study by the Kinsey Institute at Indiana University concluded that it occurs in only 46 percent of the 168 cultures examined. A lot of kisses are distributed, especially in the Middle East, North America and Europe. In sub-Saharan African cultures, in New Guinea or in Central America, kissing, which is associated with love and sexuality, tends not to play a role.2
According to the World Health Organization, herpes infections are mainly caused by two types of viruses: cold sore virus (HSV-1) and genital herpes virus (HSV-2). The HSV-1 type, which is also the subject of the study, is transmitted via mouth-to-mouth contact. The virus stays in the body for life, and symptoms can occur again and again. According to the WHO, about 3.7 billion people under the age of 50 are infected with this herpes virus.3