In November 2014, I had the great privilege of publishing, as guest editor, the inaugural issue of a new journal, The Medieval Globe. Carol Symes, who is the founding and managing editor of the journal, and her Editorial Board, had taken a great leap of faith that our new synthesis on the Black Death would offer both compelling questions and bold new methodologies for thinking about global connections in the medieval world. Having now passed the 5000 mark in open-access downloads of the volume (just seven months after its debut), we feel our goal of sharing this new synthesis with scholars around the world has already been achieved.

London, British Library, MS Royal 6.E.VI, f. 301rb. An image of leprous clerics that was falsely circulated as if it were a depiction of plague

The driving question of the volume was simple: what difference did the “new genetic synthesis” on the evolutionary history of Yersinia pestis, the causative organism of plague, make for the history of the largest known pandemic in human history? Microbiological genetics has achieved two breakthroughs with respect to Y. pestis in the past 15 years. First, it has shown that all the strains of the organism currently known in the world (and it is still present on all continents save Australia, where it has not been found since the 1930s) can be shown to belong to the same family tree. The entire history of the organism may be only a few thousand years old. Second, a type of research called aDNA (“ancient DNA”) has been able to reconstruct the entire genome of Y. pestis from victims of the Black Death (as well as the earlier Justinianic Plague, c. 541-c. 750). This is tour de force science, among the most exciting work being done in genetics today. Still, the historian must ask, “So what?” How does that change how we, as humanists (working with human cultural sources), view this pandemic?

We proposed to take the evolutionary leap with these scientists and let their understandings of Y. pestis be our guide. The geographic origin of Y. pestis, including strains immediately ancestral to the strains that caused the Black Death in Europe, was not western Europe or even anywhere nearby. It was the highlands of the Qinghai-Tibetan Plateau in what is today China. Immediately this pushed the Black Death’s story into the realm of the global—or at the very least, the hemispheric. And how did this single-celled organism that has no mechanism of self-propulsion get from China to the lands where we normally situated the Black Death (Kaffa, Messina, Marseille, Cairo, Barcelona, London)? How did a disease that does not normally inhabit human bodies (unlike, say, tuberculosis or leprosy) travel nearly the entire length of Eurasia? And did it perhaps even go beyond Eurasia? Again, the genetics gave us data we could not explain as historians: the extant strains of Y. pestis that are most closely related to the strain found in 14th-century London are not found anywhere in Europe, or central Asia. They are found in sub-Saharan Africa. A global Middle Ages indeed!

The volume brought together 17 researchers: not simply historians of various stripes, but also anthropologists and archeologists, and two microbiologists. Topics ranged from the case study of an excavation of a Jewish community in Spain attacked during the first wave of the Black Death in 1348 to an essay on the continuing threats of plague in the present-day world, where antibiotic resistance may be even more of a threat to our ability to control plague than bioterrorism. Our geographic coverage ranged from the Gansu corridor in China to Egypt to London to Uganda and Kenya. Our sources ranged from medieval and early modern texts (including a widely disseminated but misdiagnosed “plague” image) to maps to gravesites to the most complicated modern genetics. In short, by tracking this single-celled organism halfway across the globe, we were able to begin to reconstruct extraordinarily complex systems of human (and animal) interactions from the time of the earliest Mongol conquests up to the present day. 

What’s next for this “new synthesis” on the history of plague? Various scientific labs continue their own research not simply on Y. pestis aDNA, but also climate patterns and animal host dynamics that may have contributed to plague’s evolution or movement across species and landscapes. Certain of our contributors have already moved into new topics such as the pre-existing conditions that made populations vulnerable to plague’s effects, or comparative work with the most recent epidemic threat, Ebola. Although our project had no Digital Humanities component, it is  obvious that that will be the next horizon, as we need to gather and assess massive amounts of data to bring our new, enlarged geography and chronology of the Second Plague Pandemic into focus. Quite simply, we have the potential now to reconstruct the history of the Black Death as the ultimate model of pandemic disease. As the world has learned through the hard lessons of the West African Ebola outbreak, and as my own students learn when I tell them why we have plague today in Arizona, there is still much we can learn from studying the Global Middle Ages.

Monica Green, Arizona State University, monica.green@asu.edu