RUSSIA: Between the 14th and 18th centuries, the Black Death killed as much as 60 percent of Europe’s population. The bacterium that caused the plague has now been traced to the town of Laishevo, near the Volga River. Scientists reconstructed the bacterium’s genome by taking samples from the teeth of 34 victims buried at 10 different sites. They concluded that the sample from Laishevo was ancestral to the others, indicating that the plague must have originally struck there before spreading westward.