Category Archives: vectors

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.


Presentations on the Plague from the European Association of Archaeologists, Vilnius, Lithuania, 2016

I just discovered that most of the presentations from the “Plague in Diachronic and Interdisciplinary Perspective” session of the Europan Association of Archaeologists meeting in Vilnius, Lithuania on 2 September 2016 are now on YouTube.  I think I have collected them all here. Enjoy 3 hours of plague talks!

Introduction-Plague in diachronic and Interdisciplinary perspective by Marcel Keller

From Mild to Murderous: How Yersinia pestis Evolved to Cause Pneumonic Plague by Wyndham Lathem (30 min)

Reconstructing ancient pathogens – discovery of Yersinia pestis in Eurasia 5,000 Years Ago by Simon Rasmussen (15 min)

Plague in the eastern Mediterranean region 1200-1000 BC? by Lars Walloe (15 min)

Placing the Plague of Justinian in the Yersinia pestis phylogenetic context by Jennifer Klunk (15 min)

A demographic history of the plague bacillus revealed through ancient Yersinia pestis genomes by Maria Spyrou (15 min)

Analysis of a High-coverage Yersinia pestis Genome from a 6th Century Justinianic Plague Victim by Michal Feldman (15 min)

Early medieval burials of plague victims: examples from Aschheim and Altenerding (Bavaria, Germany) by Doris Gutsmiedl-Schumann (15 min)

Fleas, rats and other stories – The palaeoecology of the Black Death by Eva Panagiotakopulu (15 min)

Plague in Valencia, 546: A Case Study of the Integration of Texts and Archaeology by Henry Gruber (15 min)

Germany and the Black Death: a zooarchaeological approach by M.A. Paxinos

Ötzi’s Lyme Disease in Context

One of the ancient DNA finds that continues to intrigue me is the discovery of Borrelia burgdorferi, the agent of Lyme disease, in Ötzi the 5300-year-old ice mummy from the Italian Alps. As far as I know, this is the only finding of B. burgdorferi in ancient remains of any date.  I discussed the initial report of these findings back in the summer of 2012. 


The more we learn about Ötzi’s environment and lifestyle, the less mysterious it seems. There are no signs of human habitation or land management in these high Alpine regions. Indicators of deforestation, farming, and pasture maintenance are lacking from lake sediment and pollen studies. Festi, Putzer and Oeggl (2013) found the first signs of human land management in the Ötztal Alps to began about 1000 years after Ötzi’s time. During the Copper Age, subsistence occupation of the valley floor was sufficient for the population of Ötzi’s time. They did minimal farming, and breeding of caprines (sheep, goats, and ibex). Festi, Putzer and Oeggl (2013) note that Ötzi’s mummy is the only piece of evidence for humans that high in the Otztal Alps before the Bronze Age.

Before Ötzi’s time, landscape management in the Mesolithic was to support red deer herds that were “in a state of semi-domestication by means of active hunting” (Rollo et al, 2002). (Native Americans managed deer populations in similar ways by promoting a landscape where deer thrive near their hunting grounds.) The importance of deer to Ötzi is underscored by everything about him from the red deer meat in his stomach to the roe deerskin that made up his quiver and antler in some of his tools (Rollo et al, 2012). Two different species of deer have been confirmed by genetic analysis.  Most of his clothing was made of sheep and goat skins (O’Sullivan et al, 2016).

The agent of Lyme disease, B. burgdorferi, is transmitted primarily by the tick Ixodes ricinus, common on deer, sheep, cattle, humans and dogs as adults and feed on rodents and small mammals as nymphs. Ticks often thrive at the forest edge where there are grasses for them to climb up to catch passing deer. It seems likely that they would also thrive in along upland forest edges as well. Ixodes ricinus is found throughout the Alps.  It is feasible that Lyme disease was a greater problem for humans when we relied on deer as a staple food.

Ötzi’s B. burgdorferi has yet to be confirmed by a second group. Interestingly, a recent study of B. burgdorferi’s phylogeny suggests that it originated in Europe and later spread to ‘post-Columbian’ North America (Margos et al, 2008). Although Lyme disease was only recognized in the 20th century, it is apparently an ancient disease caused by multiple Borrelia species. And Ötzi’s sequence has not been added to any phylogeny I’ve found, odd. Overlooked, or a problematic sequence?


Festi, D., Putzer, A., & Oeggl, K. (2013). Mid and late Holocene land-use changes in the Otztal Alps, territory of the Neolithic Iceman “Otzi”. Quaternary International, 353, 1–18.

Margos, G., Gatewood, A. G., Aanensen, D. M., Hanincová, K., Terekhova, D., Vollmer, S. A., et al. (2008). MLST of housekeeping genes captures geographic population structure and suggests a European origin of Borrelia burgdorferi. Proceedings of the National Academy of Sciences, 105(25), 8730–8735.

O’Sullivan, N. J., Teasdale, M. D., Mattiangeli, V., Maixner, F., Pinhasi, R., Bradley, D. G., & Zink, A. (2016). A whole mitochondria analysis of the Tyrolean Iceman’s leather provides insights into the animal sources of Copper Age clothing. Scientific Reports, 6, 1–9.

Rollo, F., Ubaldi, M., Ermini, L., & Marota, I. (2002). Otzi’s last meals: DNA analysis of the intestinal content of the Neolithic glacier mummy from the Alps. Proceedings of the National Academy of Sciences of the United States of America, 99(20), 12594–12599.