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Tuesday, August 25, 2015

Teaching the New Paradigm in Black Death Studies

Figure 1: Cover image, The Medieval Globe, vol. 1:
Pandemic Disease in the Medieval World:
Rethinking the Black Death.

In November 2014, I and seventeen colleagues published a collection of essays in the inaugural issue of The Medieval Globe [fig. 1]. We sought to address a simple question: how could we—how should we—reconceive the Black Death in light of the new understanding of plague’s history that has emerged out of research in genetics over the past decade and a half? Since 1998, research in microbiology, and particularly molecular genetics, had seen three great achievements: in 2001, the sequencing of the genome of Yersinia pestis, the causative organism of plague; in 2010, a genetic mapping of modern plague isolates (samples of the organism) from all over the world that showed the unity of plague, that is, that Y. pestis everywhere in the world belonged to a single unified evolutionary family; and most recently, over the course of several years, the successful recovery of Y. pestis DNA from the remains of people who had succumbed to plague in centuries past, culminating, in 2011, with the complete sequencing of Y. pestis from victims of the Black Death in London.

Rather than continuing to live in paralyzing doubt about what disease caused the worst epidemic catastrophe in human history, our group of historians, anthropologists, and microbiologists decided to take the leap with our geneticist colleagues and accept that plague is, and was, plague. Not anthrax, not Ebola, not typhus. And not even any unknown organism, a “black box” category about which speculation was necessarily impossible. By accepting that the Black Death was caused by Y. pestis, we could take modern plague science as a guide into the past. The plotting of the geographical distribution of different strains of Y. pestis on the global map could, potentially, be used to begin a line of questioning about events that caused the physical transfer of this single-celled organism across vast physical distances. Similarly, any modern studies about Y. pestis’s clinical presentations or animal hosts could be used analogically to draw parallels or pose hypotheses about the disease’s apparent ecology or modes of transmission described in historical sources.

Modern science didn’t trump our traditional agenda of making meaning out of the past as medieval people experienced it, of course. Far from it. We argued that traditional humanist skills of interpreting language and social context have never been more necessary. In alliance with the sciences, we could perceive, through humanist lenses, a larger—and thus more terrible—history of plague. In other words, the new science didn’t end historical investigation of the Black Death. It opened new questions that forced us to expand our geographical, chronological, and methodological conceptions to explore this greatest of all human pandemics.

But how to teach this new paradigm of Black Death thinking to undergraduates? The Black Death is a staple in virtually every world history, western civilization, and medieval history course that is taught, whether in K-12 or at the college level. And particularly with Rosemary Horrox’s still superb collection of primary sources on the Black Death in Europe, there are already significant resources for students and instructors to work with. But the “traditional” approach that focuses only on western Europe is no longer adequate. Teaching the Black Death—or rather, the Second Plague Pandemic in a new, lengthened chronology, from the 13th to the 19th centuries, and a broadened geography that encompasses much of the eastern hemisphere—requires something more. Could I, and my students, make the leap into this “brave new world” that incorporated genetics science into History?

Well, we tried! Here’s a quick account of what we did this past semester, in my upper-level course, “The Black Death: Pandemic Disease in the Medieval World,” which I taught at Arizona State University. You can find the full syllabus here. Below are some of the highlights of the approach we took.

First day: we watched the movie Contagion (dir. Steven Soderbergh, 2011). It’s not about plague (not even a bacterial disease) and it’s not medieval. But it’s great at showing panic, the erosion of societal infrastructure because of mass mortality, the strains on government and care providers in the face of an unknown killer. An added bonus is that genetic analysis and epidemiology together are presented as “heroes” in tracking down the disease. The students also did quick Google News searches for keyword combinations like “Oregon – plague – cat,” “Colorado – plague – Girl Scout,” or “Peru – plague – La Libertad.” None of my students, it turned out, had known prior to taking the course that we have plague right here in Arizona, and it was important for them to realize from the outset that plague was not just a medieval disease.

Figure 2: Phylogenetic Tree; Cui, Y., C. Yu, Y. Yan, D. Li, et al. 2013.
“Historical Variations in Mutation Rate in an Epidemic Pathogen,
Yersinia pestis,” Proceedings of the National Academy of Science 110,
no. 2: 577–82, with annotations by M. H. Green.
Second week: We started our headlong introduction into the genetics. Here, we took a basic History of Science approach (the field in which I was trained). There’s been a paradigm shift in science-historical understanding of the plague, I explained to them, because of the shifts in genetics I outlined above. Hence, when you’re reading pre-2010 work vs. post-2010 work, you need to keep in mind the different conceptions of our understandings of plague history. One crucial element of genetics was that, when you have a complete genome sequence, you can study the organism down to its smallest detail. When we have multiple samples of whole genomes, we can use the very subtle differences between them to infer familial (and hence, historical) relations. I introduced them to what I call the Rosetta Stone of the new plague science: the phylogenetic tree [fig. 2] showing all the main subfamilies of the plague bacillus. Making an analogy with text-editing (we medievalists use phylogenetic trees, too, but we call them “stemmas”) was an easy way to demystify these key concepts in evolutionary science. But it was also important to discuss limitations. The new genetics is very good at telling us where the plague organism, Yersinia pestis, evolved, but not quite as good at telling us when.

Third week: I realized I needed more time to explain the basics of Y. pestis evolution and its very peculiar mechanisms, both how it infected mammalian hosts and how the bacterium-flea-rodent cycle worked. We addressed all this in the context of the Justinianic Plague (ca. 541-750), with a brief look back at the evidence from Rufus of Ephesus, who described plague-like symptoms in the first century CE. In retrospect, this was too much to cover in one week, especially given how much we had to learn about plague in Antiquity and the severe devastation it caused. But they learned that the Black Death wasn’t unprecedented, a point particularly crucial in understanding attitudes toward plague in Islam, which arose as a religion during the Justinianic Plague period.

Fourth and Fifth Weeks: Now we turned to the great geographical challenge of the “new plague paradigm.” Ever since 2004, the Qinghai-Tibet Plateau (in what is now western China) has been suspected as the likely origin point for Y. pestis’s evolution. This was likely also the region that saw an abrupt divergence of Y. pestis into several distinct strains, probably in the 13th century. Modern descendants of those strains are very similar to what was retrieved in 2011 from the Black Death cemetery in London. We’ve known for a long time the routes by which plague got from Kaffa on the Black Sea into the Mediterranean and then North Africa and western Europe. But how did it get from the Qinghai-Tibet Plateau to Kaffa? We still can’t answer that question, but we learned a lot about the Mongol Empire, its postal system, and the astounding levels of human migration (forced or otherwise) in this period. We also watched a neat video on hunting marmots, and learned how their use as a source of food and furs could spark a plague outbreak among humans.

Sixth through Tenth Weeks: Now we turned to the Black Death’s effects in the Islamicate world and western Europe, the usual foci of Black Death narratives. (Week Nine was Spring Break, so this was just four weeks of class time.) Here, my objective was to reconceive the traditional European narrative (what I call the Boccaccian narrative) in ways that allowed us to use our “scientific” approach as a new lens in reading accounts on inexplicable death and disaster. For example, when we studied plague’s onslaught in the Islamicate world, we looked at Ibn Khaldun and Ibn Khatima (a historian and diplomat in North Africa, on the one hand, and a physician in southern Spain, on the other), both of whom had direct experience of the plague’s first onslaught. But we also looked at modern case reports of plague being transmitted by eating camel meat or by rodents scampering in nomads’ tents, as well as transmission patterns in pneumonic plague, all of which helped us think through, from the 14th-century perspectives of our sources, the inexplicable nature of the devastation.

Figure 3: Amulets that may have made up a child’s necklace,
found in the Jewish cemetery of Tàrrega; see Anna Colet,
Jordi Ruíz, Oriol Saula, M. Eulàlia Subirà, et al. 2010.
“Els amulets de la necrópolis medieval hebrea de les Roquetes,
Tàrrega (L’Urgell),” in Actes del IV Congrés d’Arqueologia
Medieval i Moderna a Catalunya 2: 1021-24,

Still, reading through the historical and archeological materials on the slaughter of Jewish communities in 1348 was made no easier by knowing how palpable the fear must have been. The excavations of the Jewish cemetery at Tàrrega, in eastern Spain [Fig. 3], published in the Medieval Globe volume, only seemed more awful in linking them to evidence of pogroms elsewhere in France, Switzerland, and Germany. We saw then, as we would see in the remaining weeks of the semester (which brought plague’s history up to the present day), how intimately plague was tied to so many other currents in political and economic history.

Near the end of the semester, students were still indicating that key points I had covered earlier were only then sinking in. “Oh, now I get it!” For example, because of our broadened understanding of how many different species of animals plague can move through, I had de-emphasized stories about rats alone as transmitters of plague. When we got to the Third Plague Pandemic (mid-19th to early 20th century), it was only then that they understood how the “rat paradigm” had become dominant, obscuring so much of what we needed to know about plague’s many other reservoirs.

Towards the end, I asked the students to reflect on the structure of the course overall. “What do you know now that you wish you had learned earlier in the semester?” Several were satisfied with the order in which we had proceeded. One indicated he wished it had been made clear earlier why it was so significant that plague had originated in China. (This was a reminder to me that teaching in a global mode brings its own demands.) Some wanted more science: one asked for more information about animal vectors, another for more on environmental factors. One wished we had addressed earlier the documentary lacunae and the fundamental problem that, for a pandemic of such wide geographic dimensions, no single scholar was ever going to be able to have command over all the languages, let alone types of skills, necessary to investigate this phenomenon.

What were my desiderata? What would I do differently next time? Fleshing out the central Asian narrative is still the biggest need in terms of finding primary sources, whether documentary or bioarcheological. We still have to wait before much can be said about sub-Saharan Africa and the genesis of the still-extant plague strains there. And much more needs to be done on plague in other areas of Eurasia in the early modern period. But overall, I was pleased that the course was able to present a cohesive and coherent narrative for plague’s global history. The course drew students from history, anthropology, and the sciences, and all were able to develop research projects that connected with their interests.

My one oversight? Not anticipating the depressing effect of dealing week after week with death at this appalling scale. The still on-going Ebola outbreak (which we talked about periodically and addressed explicitly at the end of the course) only added to the effect. We were facing Dementors without the benefit of any patronus charm to defend us.

Chocolate helped. As did, ultimately, the conviction that although plague has not been (and likely never will be) eradicated, knowledge of the history of this dreadful disease is the best defense we have.

Monica H. Green

Arizona State University

Figures and Credits
1: Cover image for Pandemic Disease in the Medieval World: Rethinking the Black Death.
2: Phylogenetic tree: Cui, Y., C. Yu, Y. Yan, D. Li, et al. 2013. “Historical Variations in Mutation Rate in an Epidemic Pathogen, Yersinia pestis,” Proceedings of the National Academy of Science 110, no. 2: 577–82, with annotations by M. H. Green.
3: Amulets that may have made up a child’s necklace, found in the Jewish cemetery of Tàrrega; see Anna Colet, Jordi Ruíz, Oriol Saula, M. Eulàlia Subirà, et al. 2010. “Els amulets de la necrópolis medieval hebrea de les Roquetes, Tàrrega (L’Urgell),” in Actes del IV Congrés d’Arqueologia Medieval i Moderna a Catalunya 2: 1021-24,