Category Archives: medieval life

Roundtable on Campbell’s Climate, Disease, and Society in the Late Medieval World

by Michelle Ziegler

Bruce Campbell. The Great Transition: Climate, Disease, and Society in the Late Medieval World. Cambridge University Press, 2016.


When I first learned that Bruce Campbell was working on this book, I wondered if it would be the first grand synthesis of the new paradigm. Although there have been some very good regional books in the last couple of years, Campbell has indeed brought forward the first analysis of the Black Death and 14th-century crisis using global evidence. Although not entirely clear from the publisher’s description, this is an economic history that draws on interdisciplinary evidence.

I proposed this session and recruited participants without ever seeing the book (though I had seen his Ellen McArthur Lectures). I got very lucky that the panel matched up so well with the book. The five panelists who were able to attend were (from left to right below) Mongolian historian Christopher Atwood, Historian of Medicine Wendy Turner, Evolutionary Biologist Boris Schmid, Archaeologist Carenza Lewis, and Economic/Environmental Historian Philip Slavin.

roundtable 2017
Great Transition Roundtable: Christopher Atwood, Wendy Turner, Boris Schmid, Carenza Lewis, and Phillip Slavin. (Photo by Nükhet Varlik, used with permission)

Everyone agreed that Campbell’s book will become the foundation upon which the new synthesis of plague history will be built. Campbell synthesized a vast amount of data with a particular appreciation for the integration of climate and disease data. Most agreed that this was a very high-level view of the crisis, an aerial view if you will, that leaves many details to be filled in. Some missed an analysis of the relationship with cascading levels of analysis down to the level of individuals. On the other hand, Atwood remarked that this is far more detailed than would be possible in Asian studies today. Perhaps not surprisingly, this interdisciplinary panel would have liked to see more evidence from other fields such as archaeology and social history used.  As Lewis noted, archaeology, in particular, could have given more support to the economic and environmental arguments without pulling away from the flow of the book.

The global evidence is primarily limited to climate data. Several panelists remarked that it is still very Eurocentric view, and Anglo-centric on top of that. There is more data that could have been gathered particularly from the Mediterranean. War as a syndemic factor and as a result of climate or disease weakened societies was not given much space in Campbell’s analysis. One effect of such a high-level regional treatment is that causes of local mortality from war (including the environmental destruction of war) can be overlooked because it doesn’t effect a large enough piece of territory. Slavin has also pointed out that Campbell’s interpretation tends to come across as somewhat deterministic, here and there. Thus, in discussing the Great European Famine of the early 14th century, Campbell provided an engaging analysis of the environmental context of the famine as its causation, without considering various intermediate links, demographic and institutional. As a result, Slavin noted that Campbell’s interpretation of the Great Famine as an exogenous disaster stands out as unilateral; famines, across space and time, are incredibly complex phenomena.

Developing a historical paradigm based heavily on scientific data is like building a house on shifting sand. Eventually, the sand will swallow the house. The best you can hope for is to be precariously perched on the ridge of a dune.  Most biological data is out of date by the time it is printed in a book. While there were a few misunderstandings, most of the discrepancies between Campbell’s portrait of the plague and other diseases is simply out of date even though he incorporates information up to about 2015. For example, ancient DNA studies have found evidence for at least one, and probably several, (still unlocated) local reservoirs of plague in or near Europe, so the idea that plague was frequently imported from the East no longer holds (but Boris disagrees on this view).

Some other hypotheses on plague transmission, though proposed several years ago, have failed to gain much traction. While evidence continues to mount that the soil plays a role in Yersinia pestis’ survival and that human ectoparasites could be the primary vector at the pandemic level, these hypotheses are not proven yet. This doesn’t mean that they won’t eventually be accepted, just that we are not yet there.

Figure 4.05 REV 6
Stages in the plague cycle (Figure 3.27, Campbell 2016)

I am reproducing figure 3.27 here because I think this will prove to be popular with teachers. With that being said there are a few comments that need to be made about it. The role of the soil in the enzootic environment of the rodent’s burrow is poorly understood at the moment. However, teachers could just explain that level 1 simply represents the environment of the rodent burrow.  Level 5 is where the real debates are going on now among those who study transmission. Campbell does leave open which ectoparasites are involved, human fleas or lice, but there is not yet general acceptance of human ectoparasites as major vectors. It may yet come, but we aren’t there yet. While local cases of pneumonic plague will occur any time there is bubonic plague, it is unlikely to be a major driver in a pandemic. The red box that I have added to the figure is where the really critical events are happening for human epidemics and pandemics. While I do believe that humans should be considered hosts in pandemic level transition, a variety of other hosts, always including rodents, will continue to be instrumental in the amplification and must be involved for the endurance of an outbreak in a locality.

While working with scientific detail is challenging for historians, after Campbell’s book I think it will be necessary to address scientific information at least to the level where there is a consensus. As long as historians stay with information that has been confirmed by a second study or that has obviously gained scientific consensus, the risks of using scientific information really are manageable. Finding a scientist who has your trust to comment on drafts is a good practice (and the reverse for scientists writing history!).

There were some concerns. There was a feeling that correlation does not necessarily equal causation. Schmid and Slavin would have liked to see more evidence of statistical analysis to support the conclusions drawn. They had a sense that the patterns that Campbell noted in a number of his overlapping time series might prove to be coincidental, rather than significant when tested with robust statistics.

Wendy Turner addressed pedological uses of the book. She found that, at least for a history of medicine course, it could not be used alone as a textbook. It does not have enough social history to address the complete impact of the Black Death. I don’t think that was its purpose, as much as some of us hoped it would be.  “The” Black Death book has yet to be written. When it is it will have to address all the social, medical, scientific, economic, and political impacts — a tall order. It is likely that aDNA studies will have more to contribute to shore up the transmission routes of such a project. Campbell’s book could be a major text (if not the only one) for an economic or environmental history course if it is supplemented by other texts. Archaeology as done by Carenza Lewis or Per Lagerås would support Campbell’s overall argument.  Turner and others agreed that it is not written for introductory students and they wondered how even upper-level students would respond to the density of the material. It should be required reading for graduate students who focus on the 14th century or any of the infectious/famine crises.

Atwood observed that historians tend to recognize a “crisis” about every couple of centuries and wondered if these mostly European events/crises over millennia were not tied to changes that had swept across all of Eurasia. In effect, Campbell’s book lays the supportive groundwork for arguing that the Eurasian land mass should be considered as a whole rather than European only or Asian only.  I think we could make an argument that the Afro-Eurasian landmass is one historic unit. The Indian Ocean is still an underappreciated communication avenue.

The most lively discussion with the audience concerned the terminology for the 14th-century events — transformation, crisis, collapse, etc. Positions seemed to be based at least partially on training, with some rejecting the term collapse under any circumstances, while others were more open to its use in areas like “population collapse”.  For me, this is an internal matter for historians to resolve. Terminology can be a fickle thing, but data is always preeminent. And that is a good place to leave this post. Campbell has done us all a service by compiling a huge amount of data that will be the foundation of a new era of analysis of the 14th century and the Black Death. For this above all else, we must be grateful.


Looking back on the autumn


This fall was quite the chaotic jumble — not all bad. One project successfully completed. A door closed but I think another better one may be opening. Somehow in the midst of all this I managed to do a little reading, so here is what that stood out for the fall (and early winter).

My publications

Ziegler, M. (2016) Landscapes of DiseaseLandscapes, 17.2. 99-107. An introduction to the concept of ‘landscapes of disease’ and the articles in the issue. (Open access)

Ziegler, M. (2016) Malarial Landscapes in Late Antique Rome and the Tiber Valley  Landscapes, 17.2: 139-155.


  • Yong, Ed. (2016) I Contain Multitudes: The Microbes Within Us and a Grander View of Life. Ecco.  microscope23 (1)microscope23 (1)microscope23 (1)microscope23 (1)microscope23 (1)
  • Holland, John. (2014) Complexity: A Short Introduction. OUP microscope23 (1)microscope23 (1)microscope23 (1)
  • Bronton, Jerry (2004) The Renaissance: A Short Introduction. OUP. microscope23 (1)microscope23 (1)microscope23 (1)
  • Tim Clarkson (2016) Scotland’s Merlin: A Medieval Legend and It’s Dark Age Origins. John Donald/Birlinn.      microscope23 (1)microscope23 (1)microscope23 (1)microscope23 (1)microscope23 (1)
  • Hamerow, Helena. (2012) Rural Settlements and Society in Anglo-Saxon England. OUP. microscope23 (1)microscope23 (1)microscope23 (1)microscope23 (1)


  • Arnold, E. F. (2017). Rivers of Risk and Redemption in Gregory of Tours’ Writings. Speculum, 92(1), 117–143.
  • Arnold, E. F. (2014). Fluid Identities: Poetry and the Navigation of Mixed Ethnicities in Late Antique Gaul. Ecozon@, 1–19.
  • Bahl, J., Pham, T. T., Hill, N. J., Hussein, I. T. M., Ma, E. J., Easterday, B. C., et al. (2016). Ecosystem Interactions Underlie the Spread of Avian Influenza A Viruses with Pandemic Potential. PLoS Pathogens, 12(5), e1005620–20.
  • Carmichael, A. G., & Silverstein, A. M. (1987). Smallpox in Europe before the seventeenth century: virulent killer or benign disease? Journal of the History of Medicine and Allied Sciences, 42(2), 147–168.

  • Duggan, A. T., Perdomo, M. F., Piombino-Mascali, D., Marciniak, S., Poinar, D., Emery, M. V., et al. (2016). 17th Century Variola Virus Reveals the Recent History of Smallpox. Current Biology, 1–7.
  • Fauci, A. S., & Morens, D. M. (2016). Zika virus in the Americas—yet another arbovirus threat. New England Journal of Medicine, 374(7), 601–604.

  • Jones, L. (2016). The Diseased Landscape: Medieval and Early Modern Plaguescapes. Landscapes, 17(2), 108–123.
  • Marciniak, S., Prowse, T. L., Herring, D. A., Klunk, J., Kuch, M., Duggan, A. T., et al. (2016). Plasmodium falciparum malaria in 1st–2nd century CE southern Italy. Current Biology, 26(23), R1220–R1222.
  • Slavin, P. (2016). Epizootic Landscapes: Sheep Scab and Regional Environment in England in 1279–1280. Landscapes, 17(2), 156–170.
  • Valtuena, A. A., Mittnik, A., Massy, K., Allmae, R., Daubaras, M., Jankauskas, R., et al. (2016). The Stone Age Plague: 1000 years of Persistence in Eurasia. BioRxiv Preprint, 28.
  • Walsh, M. G., Amstislavski, P., Greene, A., & Haseeb, M. A. (2016). The Landscape Epidemiology of Seasonal Clustering of Highly Pathogenic Avian Influenza (H5N1) in Domestic Poultry in Africa, Europe and Asia. Transboundary and Emerging Diseases, 1–14.
  • Whittemore, K., Tate, A., Illescas, A., & Saffa, A. (2017). Zika Virus Knowledge among Pregnant Women Who Were in Areas with Active Transmission. Emerging Infectious ….

  • Yue, R. P. H., Lee, H. F., & Wu, C. Y. H. (2016). Navigable rivers facilitated the spread and recurrence of plague in pre-industrial Europe. Scientific Reports, 1–8.

Rivers in European Plague Outbreak Patterns, 1347-1760

by Michelle Ziegler

The era of big data is coming to historic epidemiology. A new study published this month in Scientific Reports took a database of 5559 European outbreak reports (81.9% from UK, France, and Germany) between 1347 and 1760 to analyze the role of rivers in the incidence and spread of plague. Their hypothesis was that river trade played a similar role as maritime trade in disseminating the plague but that the correlation would grow weaker over time as movement of goods over land became less expensive. In the 14th century, water transport was approximately ten times cheaper than land transport; the cost ratio diminishes to two to four times as expensive by the 18th century.  While it is not surprising that rivers had a role in disseminating the plague, the high correlation Yue, Lee, and Wu (2016) found between not only the proximity of the river but also its size and elevation is striking. Over 95% of the outbreaks occurred within 10 km of a ‘navigable’ river, defined as 5 m or greater in modern width and to differentiate maritime from riverine trade, excluded outbreak sites within 5 km of the maritime coastline. To ensure that rivers were suitable as trade routes, they only included rivers that linked two cities and excluded rivers that flowed into a lake without an outlet.

“Figure 1. Temporal and spatial distribution of plague outbreak in Europe in AD 1347–1760 (modifed from Büntgen et al 2012).” Yue, Lee, & Wu, 2016.

If we drill down into their results more directly, then we find that 84% of the city centers were less than 1 km from a river with 79.5% of those being on a river at least 20 meters wide. By their calculations, the average river width was 84.6 m. This correlates well with increased traffic and goods following to and through cities on substantial rivers. It is worth nothing here that the specific examples they give in England, Fossdyke, River Great Ouse, and the River Derwent are either canals or fit into an extensive canal system.

Looking at relationships between the outbreak sites and geography also favors high traffic river routes. When they included a “spatial lag in the regression models” they showed that there is a “highly significantly correlation with the spatial lag (p <0.01), indicating that plague outbreaks were spatially dependent upon previous outbreaks in adjacent cities” (Yu, Lee & Wu, p. 2). There was also a negative correlation between elevation and plague incidence, which they attribute to a lack of navigable rivers at higher elevations noting that only 20 incidents were recorded above 1000 m over sea level.  They also tested their results with controls for population density and economic status which did not impact their results for the likelihood of plague incidence or the association between outbreaks and river width. This will have to be evaluated by those with more modeling experience than I have.

There are a few caveats. First, such studies are only as good as their database. Yue, Lee and Wu used the digitized database constructed by Büntgen et al (2012) that was itself based on a 35-year-old archive published in French. I’ll leave its scrutiny to historians. They also do not address potential biases in all such databases, such as the likelihood that urban sites are recorded at a higher frequency than rural sites or that the political climate can impact the survival of records. Indeed, economic records are likely to note pestilence as a factor affecting commerce. While the environmental destruction of an enduring war could increase plague incidence, the high level of records from the ’30 years war’ needs a historian’s eye to evaluate. They also note that they are using measurements of modern rivers and canals that may have been significantly different in the past, modified by both natural processes such as silting or flooding and man-made changes such as straightening, dredging, or canal development.

They also assume there were no European reservoirs, which we now know is not true. Ancient DNA studies have indicated that there were at least two strains descended from the Black Death circulating within late medieval Europe (Bos et al, 2016;  Spyrou et al, 2016). The European reservoir(s) have not yet been located. However, relatively few of the incidents reported in the database are likely to be actual zoonotic events linked directly to a local sylvatic (wild) reservoir, plus many known reservoirs outside of Europe are found at high elevation (for example in Tibet or Madagascar) and so are unlikely to be in this particular database given the absence of sites at higher elevations. Once a new outbreak emerges from a high elevation reservoir and comes off the mountain so to speak, then its transmission by rivers is as likely as a strain entering from outside of Europe. On the other hand, if cities or even river networks are the actual reservoirs, it would significantly affect their results.

River and canal networks or large river ports could function as reservoirs. River ports are similar to coastal maritime ports in that they have wharfs, warehouses and nearby markets that would support large rodent populations. Barge traffic would specialize in transport of grain and other foodstuffs attractive to rodents.  Yue, Lee, and Wu  (2016) state that they did not query their database for the effect of flooding because they could not accurately predict where floods would occur, that flooding is not predictable based solely on river width. Flooding along these river and canal systems is something that needs to be investigated because it would force rodents out of their normal shelter and could be related to human outbreaks (as the plague of 589 in Rome probably was). Floods could also carry infected rodents or fleas downstream on floating debris.

This study is an interesting jumping off point for future work. The database needs to be evaluated by historians and perhaps subdivided into smaller time periods. Division of the database into regional studies would also allow local archaeology and ecology to be more informative on precise outbreaks. I’m looking forward to all of the questions big data studies like this one open up!


Yue, R. P. H., Lee, H. F., & Wu, C. Y. H. (2016). Navigable rivers facilitated the spread and recurrence of plague in pre-industrial Europe. Scientific Reports, 1–8.

Büntgen, U., Ginzler, C., Esperf, J., Tegel, W., & McMichael, A. J. (2012). Digitizing historical plague. Clinical Infectious Diseases, 55(11), 1586–1588.

Bos, K. I., Herbig, A., Sahl, J., Waglechner, N., Fourment, M., Forrest, S. A., et al. (2016). Eighteenth century Yersinia pestis genomes reveal the long-term persistence of an historical plague focus. eLife, 5, 17837.

Spyrou, M. A., Tukhbatova, R. I., Feldman, M., Drath, J., Kacki, S., de Heredia, J. B., et al. (2016). Historical Y. pestis Genomes Reveal the European Black Death as the Source of Ancient and Modern Plague Pandemics. Cell Host and Microbe, 19(6), 874–881.