By Durrie Bouscaren Ancient ruins of Jerash, Jordan — scene of a devastating pandemic in the 7th century. Gatsi/Getty Images hide caption In the middle of the 7th century, a plague swept through the walled city of Jerash, in what is now modern-day Jordan. Ceramicists abandoned their workshops under the Hippodrome, leaving unfired pottery in their haste. Young and old alike succumbed to a bacteria called Yersinia Pestis, the same microbe responsible for the Black Death seven centuries later. The city, unable to manage the dead and dying, converted those workshops into a mass grave. "It was filled within days — hundreds of bodies," says Rays Jiang, a University of South Florida geneticist and lead author of a new study in the Journal of Archeological Science, highlighting the plague victims of Jerash. "There's no ceremony, there's no grave goods.…