Yersinia pestis, a cause of the Black Death, wiped out nearly half of Europe’s population in the mid-1300s. Although Y. pestis is still around, infections are not as deadly or frequent as previously. Johannes Krause and his team at the University of Tübingen, Germany, recovered DNA from the skeletons of four 660-year-old plague victims buried in London’s East Smithfield Cemetery. When compared with modern Y. pestis, no genomic differences accounted for the lethal power of the Black Death. Researchers think its high mortality may be partially explained by the 14th century environment – where malnutrition, poor hygiene, and crowded housing were common.
Did you know? Y. pestis was carried by fleas that live primarily on rats and other rodents that were common in medieval cities.