The HSV-1 virus strain behind facial herpes, commonly known as cold sores, emerged approximately 5000 years ago, according to University of Cambridge-led research published in Science Advances. The virus arose in the wake of vast Bronze Age migrations into Europe from the Steppe grasslands of Eurasia, and associated population booms that boosted transmission.
Two-thirds of the world’s population below the age of 50 now carry HSV-1, manifesting as occasional lip sores. In combination with other ailments – sepsis or even COVID, for example – the virus can be fatal. In 2018, two women died of HSV-1 infection in the UK following Caesarean births.
Herpes has an ancestry dating back millions of years, infecting species from bats to coral. Despite being prevalent among humans today, however, scientists say that ancient examples of HSV-1 were surprisingly hard to find.
According to the study authors of the study, , the Neolithic flourishing of facial herpes detected in the ancient DNA may have coincided with the advent of a new cultural practice imported from the east: romantic and sexual kissing.
“Facial herpes hides in its host for life and only transmits through oral contact, so mutations occur slowly over centuries and millennia,” said Dr Charlotte Houldcroft, co-senior author.
“We need to do deep time investigations to understand how DNA viruses like this evolve. Previously, genetic data for herpes only went back to 1925.”
The team managed to hunt down herpes in the remains of four individuals stretching over a thousand-year period, and extract viral DNA from the roots of teeth. Herpes often flares up with mouth infections: at least two of the ancient cadavers had gum disease and a third smoked tobacco.
The oldest sample came from an adult male excavated in Russia’s Ural Mountain region, dating from the late Iron Age around 1500 years ago.
Two further samples were local to Cambridge, UK. One a female from an early Anglo-Saxon cemetery a few miles south of the city, dating from 6-7th centuries CE. The other was a young adult male from the late 14th century who had suffered appalling dental abscesses.
The final sample came from a young adult male excavated in Holland: a fervent clay pipe smoker, most likely massacred by a French attack on his village by the banks of the Rhine in 1672.
“We screened ancient DNA samples from around 3000 archaeological finds and got just four herpes hits,” said co-lead author Dr Meriam Guellil, from Tartu University’s Institute of Genomics.
“By comparing ancient DNA with herpes samples from the 20th century, we were able to analyse the differences and estimate a mutation rate, and consequently a timeline for virus evolution,” said co-lead author Dr Lucy van Dorp, from the UCL Genetics Institute.
Co-senior author Dr Christiana Scheib said: “Every primate species has a form of herpes, so we assume it has been with us since our own species left Africa.”
“However, something happened around five thousand years ago that allowed one strain of herpes to overtake all others, possibly an increase in transmissions, which could have been linked to kissing.”
The first known report of kissing is a Bronze Age manuscript from South Asia, and suggest the custom, not found in most human cultures, may have travelled westward with migrations into Europe from Eurasia.
In fact, centuries later, the Roman Emperor Tiberius tried to ban kissing at official functions to prevent disease spread, a decree that may have been herpes-related.
However, for most of human prehistory, HSV-1 transmission would have been ‘vertical’: passing from infected mother to newborn child.
Source: University of Cambridge
