The New York Times-20080129-Clues to Black Plague-s Fury In 650-Year-Old Skeletons
Return to: The_New_York_Times-20080129
Clues to Black Plague's Fury In 650-Year-Old Skeletons
Full Text (622 words)Many historians have assumed that Europe's deadliest plague, the Black Death of 1347 to 1351, killed indiscriminately, young and old, hardy and frail, healthy and sick alike. But two anthropologists were not so sure. They decided to take a closer look at the skeletons of people buried more than 650 years ago.
Their findings, published on Monday in The Proceedings of the National Academy of Sciences, suggest that the plague selectively took the already ill, while many of the otherwise healthy survived the infection.
Although it may not be surprising that healthy people would be more likely to survive an illness, it is not always the case. The Spanish flu of 1918 killed thousands of healthy people in their prime while sparing many children and the elderly, whose weaker immune systems did not overreact to the infection. Sexually transmitted infections like H.I.V. disproportionately affect the strongest and healthiest, for the obvious reason that they are the most sexually active.
Plague is caused by a bacterium called Yersinia pestis, and it is usually transmitted to humans by fleas; flea-infested rats caused the 14th-century epidemic. The bacteria invade the bloodstream, causing internal bleeding that leads to shock and death.
In the new study, the researchers examined 490 skeletons exhumed from the East Smithfield cemetery in London. The site, like many other cemeteries, was set up to bury victims of the Black Death and was almost certainly used for no other purpose.
The scientists determined the victims' state of health when they died by counting bone lesions, defects that suggest previous infections and other existing health problems. The researchers also estimated age at death by noting dental development and using other established methods. As a comparison, they analyzed the bones of 291 genetically and culturally similar people buried in a Danish cemetery shortly before the plague began.
The aim was to find out whether the Londoners, who all died of the plague, were frail when the epidemic struck. In the nonplague Danish cemeteries, bone lesions were strongly associated with earlier death. If the Black Death killed without discrimination, such skeletal defects would not be associated with an increased risk of death in East Smithfield. Many of the victims would have had healthy-looking bones when the plague killed them.
But this was not the case. Among the East Smithfield plague victims, bone lesions were also associated with excess mortality. In other words, many of those people were already in poor health when the Black Death struck.
Most of the bone defects that the researchers found can be caused by malnutrition, and the scientists suggest that the findings may show effects of starvation on immune function. It is known from contemporary chronicles that many survived the plague, and they, the authors write, were probably well fed and healthy enough to mount an effective immune response.
Even something as clearly deadly as the Black Death is still selective, said Sharon N. DeWitte, a co-author of the study and an assistant professor of anthropology at the State University at Albany. The Black Death, she continued, is comparable in some ways to various emerging diseases of today like Ebola or SARS, and studying it gives us some insight into who might be at highest risk for these new diseases.
The authors acknowledge that their findings are not conclusive. The samples used were from two geographic areas, and similar lesions could have been caused by diseases of varying severity in the two areas.
Still, the authors write, the fact that a pattern of excess mortality was associated with different kinds of lesions suggests that the plague more often killed the weak than the strong.
[Illustration]PHOTO: EXHUMED: Remains of black plague victims in East Smithfield cemetery. (PHOTOGRAPH BY TREVOR HURST/MUSEUM OF LONDON)