Basic Conditions for Bubonic Plague in Medieval Europe
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PART THREE BASIC CONDITIONS FOR BUBONIC PLAGUE IN MEDIEVAL EUROPE O. Benedictow - 9789004193918 Downloaded from Brill.com09/27/2021 05:40:03AM via free access CHAPTER THREE RATS Introduction: How to Study Rats in History Advocates of alternative theories on the microbiological nature of historical plague epidemics insist triumphantly that there was no murine basis in the form of black rats in Europe at the time (see below). Th ey concede that there could have been a signifi cant presence in Southern Europe and along the Mediterranean coasts, especially in the urban centres, but elsewhere in Europe, they maintain, there could only have been an incidental and transitional presence caused by ship transportation and they deny that the black rat could have had a per- manent presence in Northern Europe. All of these scholars agree that black rats play a crucial role in epidemics of bubonic plague. Th us, the opposite is obviously true: if there were no or only a tiny presence of black rats in medieval Europe restricted to the southern and Mediterranean parts of the Continent, there could not have been epi- demics of bubonic plague, or there could not have been more than the occasional small outbreak in the southern parts of it. It is also generally agreed that the brown (or grey) rat did not arrive in Europe until the early eighteenth century.1 Consequently, if there were rats in medieval Europe, they would have to have been black rats. Th is does not mean, as the zoologist D.E. Davis asserts, that black rats are the cause of bubonic plague.2 Th ese rats have lived peacefully with human beings for thousands of years. Rats are principally victims of bubonic plague. As soon as their dead bodies start to loose temperature, their fl eas begin to desert them, fl eas which have satiated themselves on septicae- mic rat blood and can transmit the real cause of bubonic plague to human beings, namely infective and lethal doses of the bacterium 1 See, Zinsser 1934/1985: 200; Hirst 1953: 123, 142; Twigg 1984: 75; Davis 1986: 456; Audoin-Rouzeau 1999: 423, asterisked footnote. In a personal communication by e-mail of 10 January 2006, Anne Kristin Huft hammer of the Zoological Museum of the University of Bergen, Norway, has confi rmed to me that this arrival date for the brown rat is still generally accepted. 2 Davis 1986: 455. O. Benedictow - 9789004193918 Downloaded from Brill.com09/27/2021 05:40:03AM via free access 74 chapter three Yersinia pestis. Methodologically, necessary conditions and causes are very diff erent matters and should also be sharply diff erentiated from suffi cient conditions and causes. Methodology is not Davis’s strong suit, as will unavoidably be shown below. Th en there is the question whether or not the brown rat played a part which may aff ect our understanding of medieval and early-modern plague epidemics. In his “review” of my monograph on the Black Death, Cohn rejects my view that, according to the IPRC’s reports, the black rat was of paramount importance in the aetiology and epidemiol- ogy of plague in India: However, he [Benedictow] has read these reports selectively. For instance, he maintains that the black rat (Rattus rattus) was responsible for plague in the years 1346 through 1353 as well as during the 20th century, but the Indian plague researchers found as many dead brown rats as black ones in dwellings where infection was active.3 Cohn’s accusation warrants a closer look at the IPRC’s conclusion as to the relative importance of the brown rat (today called Rattus norvegi- cus, until 1910 Mus decumanus) and the black rat (today called Rattus rattus, until 1910 Mus rattus): In Bombay city Mus rattus and Mus decumanus both occur in prodigious numbers, in the country villages, however, Mus decumanus is very rarely found. Mus rattus in Bombay is essentially a house rat […] it may almost be said to be a domesticated animal. Mus decumanus, as is well known, is a rat which lives for the most part outside houses in sewers, storm-water drains, stables, etc. Mus rattus is apparently much more common in Bombay than Mus decumanus […]. It is necessary at the outset to insist upon the fact that in Bombay City there is a Mus decumanus epizootic and a Mus rattus epizootic. […] there cannot be the slightest doubt that the place-infection of man is intimately related to that of M. rattus […] that M. rattus is essentially a house-rat and that it lives in close association with man. It necessarily follows from this association that the place-infection of M. rattus must correspond closely to that of man in the sense that both must be referred to inhabited buildings. We think it justifi able to conclude that the epidemic is directly attrib- utable to the rattus epizootic.4 3 Cohn 2005: 1354. 4 IPRC 1907g: 743, 746–7, 752, 766–7. O. Benedictow - 9789004193918 Downloaded from Brill.com09/27/2021 05:40:03AM via free access rats 75 Th is proves that IPRC researchers were of the opinion that the plague epidemics were mainly or wholly a refl ection of epizootics among black rats; in the countryside where the brown rat was very rare, the epidem- ics in the villages would be about entirely based on the black-rat epiz- ootic. Th is demonstrates also that bubonic plague epidemics can develop and spread on the basis of the black rat alone, a fact that under- lies the conclusion that historical plague was bubonic plague. Also in Mumbai where the brown rat had a substantial presence the epidemic was predominantly based on the epizootic among black rats. As can also be seen, the black rat was apparently much more common in Mumbai than the brown rat, and since the brown rat was also largely an out-of-door rat, its signifi cance for the epidemic process would una- voidably be relatively small. Cohn’s assertion that the IPRC found as many dead brown rats as black rats in the dwellings of people in India is spurious. Th is is confi rmed by G. Lamb in his summary of the Commission’s work to May 1907 which is an excellent source for reli- able information on the Commission’s fi ndings and views in the early years.5 Clearly, Cohn misrepresents my view.6 Th us the relationship between the rat plague epizootic and human plague epidemic in India must have been very much the same as in historical plague epidemics, if they were indeed epidemics of bubonic plague. Having clarifi ed this point, we can now focus on the presence and distribution of the black rat in medieval and early modern Europe. Leading plague researchers such as Hirst, Pollitzer, Wu Lien-Teh, and J.J. van Loghem who studied the bubonic plague epidemics of the fi rst half of the twentieth century argue for a broad presence of the black rat in medieval Europe. Th is view is based mainly on contempo- rary medieval and early modern written sources which also contain some drawings. Th eir view is also supported by peculiar epidemiologi- cal features of the spread and seasonality of the epidemics that were taken as refl ections of a basis in rats and their fl eas. In support of this conclusion, they emphasized the interval between the fi rst case(s) and the subsequent endemic and epidemic developments, the latency 5 Lamb 1908: 22–3. 6 It is, however, not clear to me what point he is trying to make, since it is quite generally believed, as mentioned above, that the brown rat did not arrive in Europe until around 1700. O. Benedictow - 9789004193918 Downloaded from Brill.com09/27/2021 05:40:03AM via free access 76 chapter three period which is a defi ning feature of bubonic plague,7 and the strong tendency of epidemics to break out in the warmer seasons and disap- pear or be substantially diminished by cold weather, which they explained, on the basis of the fi ndings of the IPRC and other scholars, through the role of rats and their fl eas.8 When Davis refers to Hirst’s monograph and write “that a search for evidence to support these state- ments [as to the presence and role of rats] produces nothing,”9 this is not correct and also his reference to page 119 is wrong, since this mat- ter is not discussed on this page. Further, his reference to a single page, when in fact Hirst addresses the matter broadly over quite a number of pages elsewhere in the monograph, can also produce an incorrect impression, because Hirst has not taken this question lightly as Davis’s remarks suggest (see below). Since all medieval European references to house rats, both textual and graphical, as a present type of animal clearly refer to black rats, the discussion must address the question of whether or not black rats were present in suffi cient numbers and with a suffi ciently widespread geo- graphical distribution to constitute the basis for bubonic plague epidemics. Advocates of theories that historical plague epidemics were not bubonic plague but were caused by some alternative microbiological agent assert, as mentioned above, that there either were no rats at all (so Scott and Duncan, with an incorrect reference to Twigg10 and Gunnar Karlsson11) or that the presence of black rats was restricted to a tiny and transient incidence in urban centres, “if it existed at all” (so Davis and also Twigg, who fi rst advocated this view, and who is sup- ported by Scott and Duncan12).