The identity of the bacterium behind the Black Death, a plague that killed as many as 50 million people in medieval Europe, was finally verified in August. It was a strain of Yersinia pestis, long believed to be at large, that researchers now confirm died out nearly seven centuries ago.
The precise identity of the bacterium that played a leading role in the largest pandemic in human history remained unknown until scientists studying the remains of plague victims in a mass grave in East Smithfield, England, discovered fragments of the bacterium’s DNA in the bones and teeth. Careful genetic analysis not only confirmed long-standing suspicion that Y. pestis was the microbe responsible for the plague, but also found slight genetic differences among bacteria from various remains at the site—suggesting that even as it killed millions, the bacterial strain itself was dying off.
Experts believe Y. pestis originated in or near ...
