Scientists are still exploring the mysteries
of one of the deadliest pandemics
the world has ever known:
the Black Death, the medieval disease outbreak
that killed millions in Europe
between 1347 and 1351. At the time, it was
attributed to bad air—some kind of generalized
pestilential miasma. Today, blame is
believed to reside with Yersinia pestis, the
bacteria that causes plague, though the
historical pandemic was clearly more virulent—
and faster-spreading—than any
modern version of the disease.
Several recent DNA studies have confirmed
the presence of Y. pestis in medieval
graves across Europe. The most recent work
in the field is examining its genome to sort
out what exactly made the older version of
the plague different. The study, published in
Proceedings of the National Academy of Sciences,
examined the remains of 100 plague victims
buried near London. It reveals that the Black
Death was caused by a previously unknown
variant of Y. pestis that no longer exists. But
the multinational team has not yet found
the specific genetic reason for the difference
in plague virulence between then and now.
"The search goes on," says study coauthor
Jim Wood of Pennsylvania State University.
