An international team of researchers has uncovered new information about the Black Death in Europe and its descendants, suggesting it persisted on the continent over four centuries, re-emerging to kill hundreds of thousands in Europe in separate, devastating waves. The findings address the longstanding debate among scientists about whether or not the bacterium Yersinia pestis – responsible for the Black Death – remained within Europe for hundreds of years and was the principal cause of some of the worst re-emergences and subsequent plague epidemics in human history. Until now, some researchers believed repeated outbreaks were the result of the bacterium being reintroduced through major trade with China, a widely-known reservoir of the plague. Instead, it turns out the plague may never have left. ​