AAAS: "Ancient sheep virus found hiding in medieval parchment," by Andrew Curry.
"In ancient Rome, shepherds feared the appearance of bumpy pustules on their sheep—a telltale sign of deadly sheeppox." In a study in Science Advances, researchers pin the virus’ emergence to about 5000 years ago, roughly the same time people started to intensively shear sheep for wool. "The peek into the pathogen’s past came from an unusual source: dozens of medieval books + legal documents written on parchment, which is made from specially treated animal skins."
"Turns out parchment is an extremely good preserver of this type of biological data," says University of Leicester historian Joanna Story. "As part of a larger look at the origins of medieval manuscripts, researchers rubbed pages of the books with erasers, then extracted DNA from the rubbings."
Historically, cow, goat, + sheep skins were soaked for days in pits filled with lime, a caustic chemical, + then painstakingly scraped + stretched by hand. "It’s a pretty disgusting process," says University College Dublin geneticist Kevin Daly.
"Manuscripts were often written on + handled, giving DNA trapped in the parchment ample time to degrade or become contaminated." Yet even after centuries on the shelves of monasteries + archives, the manuscripts contained enough intact DNA to identify the species skinned...as well as viruses + other pathogens that afflicted the animals, including dozens of extinct sheeppox strains.
The average medieval manuscript was a huge investment, requiring anywhere from a few dozen animals to hundreds of skins for the largest Bibles. “When you pick up a book, you’re picking up a flock of sheep or herd of cattle.”
Though not as well-known as its distant cousin, smallpox, farmers in Europe + Africa still consider sheeppox a major threat. 'An outbreak can kill between 50% + 80% of a flock’s young.' Comparing various strains taken from medieval manuscripts from between 700 C.E. + 1450 C.E., the team estimated the samples all had a common ancestor that evolved into a sheep-specific disease ~ 5000 yrs ago.
So, allow me 2 deductions. DNA is a very tough molecule. And sheep are not just detectives.
