Pestilential Complexities: Understanding Medieval Plague (review)

This collective volume is focused on the endless debate about the disease identity of historical plagues, specifically that of the medieval Black Death and of subsequent epidemics that ravaged western Europe until well into the eighteenth century. Yet its aim is not so much uncovering this identity as clarifying the crucial questions that separate those who defend a common identity between historical pestilences and the bubonic plague (on the basis that their common pathogen is Yersinia pestis) from those who deny it.

Pestilential Complexities includes six essays. Five are revised versions of papers presented at a 2006 conference on the matter held at the Wellcome Trust Centre for the History of Medicine at University College London by two historians with a long and fruitful research dedication to medieval plague (Ann G. Carmichael and Samuel K. Cohn, Jr.), one archaeologist of plague (Daniel Antoine), one biomedical expert on Yersinia and bubonic plague (Elisabeth Carniel), and one physiologist concerned about historical demography (Lars Walløe). The sixth essay is a brief comment by the historian Kay Peter Jankrift. An introduction by the organizer of the conference and the editor of the supplement, Vivian Nutton, provides the reader with a valuable, synthetic state of the art.

The volume's contributors hold different views about the medical identity of the Black Death, and Nutton generically introduces them as "sceptics" or "believers"—as though the theory that this condition was caused by Yersinia pestis and spread primarily by rat fleas (p. 14) were a matter of faith. But the volume represents a useful interdisciplinary exercise, bringing together and discussing the evidence supplied by conceptualizations and methodologies from research areas as disparate as history, archaeology, biomedicine, and epidemiology.

The volume's contents fuel the impression that the question of the medical identity of the Black Death cannot be tackled in unproblematic, reductionist terms. It might be useful to remember that the factors shaping the clinical and epidemiological peculiarities of infectious diseases in human populations are numerous, complex, and dynamic, since infectious conditions are the evolutionary expressions of parasitic interactions among living beings within specific natural and social environments subject to innumerable changes (climate, natural disasters, human action, and so on). For diseases like the bubonic plague—a primary bacterial infection of rodents, both wild and domestic, that is most often accidentally transferred to human beings through fleas that have fed on rodents' infected blood—the multiple combinations among all of these variable factors make it hard not to be openly skeptical about the feasibility of retrospective diagnoses in modern medical terms. Because of the excessive expectations that historians of science and archaeologists have put on biomolecular technologies, Antoine's remarks about the reliability of molecular genetics methods, such as polymerase chain reaction in analyzing the DNA preserved within the bones and teeth of skeletal remains, and his assessment of some alleged results with regard to Yersinia pestis appear to me particularly revealing (pp. 110–13).

The last sentence of Carniel's closing essay might summarize the major conclusion of the volume, namely, "Although we cannot prove anything one way or the other, it should be emphasized that it is not possible to reject the plague etiology of the Black Death simply because certain symptoms and epidemiological features do not match those found today" (p. 122). Right at the end of his introduction, Nutton claims that "the gap between sceptics and believers . . . is smaller than might be assumed at first reading," although he finds it "uncertain" that "a totally satisfactory solution can be reached" (p. 16). Not least, I may add as a skeptic on this thorny matter, because retrospectively diagnosing the historical pestilences in modern medical terms involves not only the above-mentioned biomedical difficulties, but also historiographical and epistemological ones beyond the specific question of whether the Black Death can be identified with bubonic plague. For...