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Home > Features > Causes and Consequences of the Black Death -- A Reappraisal
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Causes and Consequences of the Black Death -- A Reappraisal
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by Samuel K. Cohn, Jr.
University of Glasgow
Glasgow, Scotland
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| | The End of a Paradigm
HIV/AIDS and the threat of biological warfare have refuelled interest in the Black Death among professional historians, biologists, and the public, not only for assessing the toxic effects of the bacillus, but for understanding the psychological and longer-term cultural consequences of mass death. My essay, "The Black Death -- End of a Paradigm," in the American Historical Review, 107 (2002): 703-38, makes two arguments. First, against the assumptions of historians and scientists for over a century and what continues to be inscribed in medical and history texts alike, I argue that the Black Death and its subsequent waves of pestilence were not the rodent-based bubonic plague whose agent (Yersinia pestis) was first cultured at Hong Kong in 1894. Second, I maintain that the epidemiology of the Black Death helps to explain new mentalities in Europe circa 1400 that we usually subsume under the rubric of the Renaissance.
A comparison between the detailed epidemiological reports on the bubonic plague in India and elsewhere in the twentieth century and the sources from late-medieval Europe -- over 400 chronicles and literary works, 200 medical plague tracts, and 40,000 death records, including last wills and testaments, monastic necrologies, and burial records -- fails to show the two diseases matching up on any front. First, the Black Death spread so fast and was so contagious that contemporaries thought it could be transmitted by sight. On the other hand, Yersinia pestis, dependent on the homely rat and its flea for transmission, spreads so slowly that it takes almost as long to travel over land per year as the medieval plague did per day. Nor does modern bubonic plague spread ferociously from person to person, even in its rare pneumonic form. Thus, in India, British doctors, well aware of the medieval plague's contagion, were dismayed to discover that the safest place to be in their plague time was the plague ward. This plague almost never spread to doctors, nurses, or relatives who stood close by the bedsides of the plague infected.
Second, the medical core in India hypothesized that fleas were their plague's vector before they had dissected a flea or spotted the deadly bacillus in its guts. Their suspicions were aroused by the consistent seasonal patterns of the bubonic plague; cases peaked at the time of the flea's annual apex in population and declined sharply or disappeared entirely when conditions became unbearable for the flea, that is, when relative humidity fell below 50 percent and temperatures either fell below 50 degrees Fahrenheit or rose above 78 degrees. The Black Death and its subsequent strikes through the early modern period show no such pattern. Indeed, in Mediterranean cities such as Rome, Florence, Pisa, Valencia, and Millau (in southern France), the medieval plague consistently peaked in June or July, the hottest and driest months, when rat flea populations are at their lowest in the Mediterranean, and thus are the least likely months for modern plague to have peaked.
So why have doctors and historians assumed that the two diseases were the same? Using the famous descriptions of Giovanni Boccaccio and a handful of others, they have asserted that the signs of the two -- the buboes in the armpits and groin -- were identical. But their selection of texts, even of Boccaccio, has been highly selective and problematic. Boccaccio, Michele da Piazza, Geoffrey le Baker, the Irish friar, John Clyn, Giovanni Morelli, and many other contemporaries described the buboes and even more deadly pustules as spreading all over the body. In thousands of clinical reports from hospitals in the Bombay Presidency in 1896-7, as well as from other places such as Glasgow in 1900, not a single case showed such a cutaneous development. Moreover, with modern bubonic plague, 55 to 72 percent of the buboes form in the groin. By contrast, the medieval bubo's pride of place was in the cervical region, on the neck or behind the ears.
Cultural Consequences of the Plague
I also argue that the plague's cultural consequences hinged on an epidemiological characteristic of the disease. While humans have no natural immunity to modern bubonic plague, populations of Western Europe adapted with extraordinary rapidity to Black Death's pathogen, whatever it may have been, for at least the disease's first hundred years. In India from 1896 to the 1920s, plague mortalities first climbed with successive strikes, then jumped randomly from year to year, then declined, once the rats -- not humans -- began to acquire immunity. Further, the age structure of modern-plague victims -- between 20 and 40 years old -- has remained the same since the bacillus's discovery. By contrast, the Black Death's plague mortalities declined sharply with each successive strike of plague; by the fourth hit in the early 1380s (in localities where good records exist), they sank to less than a twentieth of the causalities scored by the "magna mortalitas" of 1348. Commensurate with this trend and evidence of the human immune system functioning, the Black Death became increasingly a childhood disease with each strike of pestilence. By the fourth plague in Pisa and Siena, where reports and burial records survive, a staggering 80 percent or more of the victims were children under the age of 10, that is, those who had not been born at the time of the previous bout of plague and thus were unexposed to the plague's venom. In 1348 children comprised less than a third of the victims.
The human immune system's increasing success in resisting plague during the later fourteenth century conditioned a cultural response that departs from the common wisdom about "plagues and peoples." As far back as Thucydides, historians have seen the aftershocks of pestilence as raising the levels of violence, tearing asunder secular, "this worldly" cultures, and spawning pessimism and transcendental religiosities. A fresh reading of the late-medieval sources across intellectual strata from merchant chronicles to the plague tracts of university-trained doctors shows another trajectory, an about-face in the reactions to the plague after its initial onslaught. Unlike during the immediate aftermath of 1348, later plagues of the fourteenth and fifteenth centuries did not provoke attacks against the Jews or lead to widespread flagellant movements outside the Church's control. In addition, chroniclers of later strikes of plague from the late 1350s on turned from supernatural and religious causes to ground their explanations of plague in social, political, and even medical realities; doctors went from utter despair in 1348 to offer specific cures and preventive measures, which they maintained had been proven successful in treating themselves and their patients during later plagues. As Doctor Stephanus from Padua proclaimed in his plague tract at the end of the fourteenth century, by his remedies he had "triumphed over plague." Far from slavishly following the ancients, doctors by the 1360s and 1370s boldly accused their venerable forerunners of "leaving everything [about plague] in confusion." Because of their experience of plague, these latter-day doctors claimed to have surpassed the ancients, Hippocrates and Galen included.
These doctors' emboldened attitude toward plague casts new light on the Renaissance. It helps to explain why a new spirit of hope and hubris should have arisen in the wake of the West's most monumental mortality, and why those most intimately associated with death should have been the first to boast of superseding the ancients in any field of secular learning.
Samuel K. Cohn is professor of medieval history at the University of Glasgow. He has published a number of books and articles on social and medical history in the late Middle Ages. His most recent book, The Black Death Transformed, was co-published in 2002 by Arnold and Oxford University Press, and was recently published in paperback. |
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