Plague hunters

They looked for surviving fragments of DNA in bones and teeth that archaeologists had excavated from the East Smithfield site in the 1980s. The DNA matched that of the modern-day microbe, confirming, as have several other studies, that Yersinia pestis was indeed the agent of the Black Death. Sharon DeWitte, a member of Dr. Poinar’s team, was one of several skeptics who had doubted the microbe’s role. “I’m very happy to find out I was wrong,” said Dr. DeWitte, a paleodemographer at the University of South Carolina. “In science, if you’re open to alternative possibilities, you can change your mind.”

Dr. Poinar’s team also looked for the microbe’s DNA in another medieval London cemetery, that of St. Nicholas Shambles, which was closed before the Black Death struck. They found no sign of it there, indicating that Yersinia pestis was not already present in the English population before the Black Death, so it must have arrived from elsewhere.

If Yersinia pestis was indeed the cause of the Black Death, why were the microbe’s effects so different in medieval times? Its DNA sequence may hold the answer.

Posted by David on September 1, 2011 5:04 PM