Molecular Traces of the Black Death

Over the last decade a substantial amount of molecular evidence confirming the etiology of the plague over virtually the entire medieval period has been produced. In this rapidly evolving field, evidence for the Black Death of the 14th century has been produced by each new method in turn.

Given the conditions of remains sampled to date, the methods fall into two main categories: genomics and immunology. There are pros and cons to each. Genomics has well-recognized specificity and the ability to compare with living and ancient strains, but non-nucleic acid methods are both specific and far more sensitive. Non-nucleic acid methods (using immunology) will give a better indication of the true incidence within a population, especially important when testing moves beyond mass graves. Immunologic methods have been the primary means of diagnosing clinical infectious disease for at least 30 years. The Rapid Diagnostic Test (RDT) now used to diagnose ancient and modern plague uses technology that has existed for over 25 years with a good track record. The downside of immunology is that it doesn’t give strain specific information. On the other hand, detection of degraded DNA much less getting good enough sequence for strain matching is difficult and inefficient.

This map charts all of the medieval plague molecular data that I have seen (view Plague Map in a larger map). The red balloons mark 6th-9th century, Plague of Justinian, sites. All three early medieval sites are beyond the Alps proving that the plague of Justinian penetrated well beyond the Mediterranean basin.  The yellow balloons represent 14th century data, with the starred balloon specifically dated to the first wave of the Black Death pandemic. The blue balloons represent post-14 century data (14th-17th century). Click the balloons for references.

Even a cursory look at the map makes it apparent that both pandemics reached beyond the Alps into the European plain. Further, the distribution represents the areas of activity of 3-4 research groups rather than as an indication of plague incidence across Europe. Every region so far examined and published has found some evidence of plague. There is both DNA and immunological evidence for the 14th century. Unfortunately, DNA data has been produced by three different groups who have not yet produced a consensus sequence or analyzed their differences. Despite the differences between their sequences, there is plenty of homology between their data and modern reference sequences to ensure that they all identified Yersinia pestis. Their differences are most likely to be primarily related to interpretations of degradative changes in the ancient DNA, though it is possible that more than one strain was active in 14th century Europe.

The map also makes it apparent that we only have molecular evidence from a very small sliver of the territory covered by the medieval pandemics. There are too few sites so far to make any predictions about the routes the plague traveled based on molecular evidence. It never travels from point A to point B as the crow flies! Plague spreads more like a spiderweb than a wave. So, long distance transmission may well exist before lateral spread fills in the countryside. It is absolutely necessary to take in consideration medieval trade and communication routes.

This is an exciting time to be working on the plague. So far, only the tip of the iceberg has been exposed. To date, the molecular evidence has been the most useful for confirming the etiology of the plague of Justinian, the Black Death pandemic, and plague’s endurance in western Europe. We have the technology now to map the geographic extent of Yersinia pestis for the first and second pandemic. It will take at least a generation of work from archaeologists, geneticists, and paleomicrobiologists to gather enough sites and resolve the fine-detail sequencing issues to begin to do strain mapping.


Current debates about sustainability – and the 14th century crisis

The German Leibniz-Gemeinschaft and theFederal Ministry of Education and Research initiated a program of public discussion on sustainability at various research museums (humans culture sustainability). The 4th and last of the Museumsgespräche 2012 “Mensch Kultur Nachhaltigkeit” at the RGZM in Mainz is dedicated to the handling of soil and water in past and present.

Discutants are Prof. Dr. Hans-Rudolf Bork (Kiel unisversity), Prof. Dr. Hans-Georg Frede (Gießen university) and myself; moderation by Axel Weiß (SWR). On November, 2012 at 19PM there will be a livestream at Discussion however will be in German.

The 14th century will probably one topic among others as it seems to be a very interestig case study for sustainability assessment.


Rainer Schreg

archaeologist professor in medieval and postmedieval archaeology at Bamberg university

More Posts - Website

Follow Me:

Medieval pig management

I have a new paper published that explores the impact of Black Death on pig management…I hope it is of interest.
Hamilton, J. and Thomas, R. 2012. Pannage, pulses and pigs: isotopic and zooarchaeological evidence for changing pig management practices in 14th century England. Journal of Medieval Archaeology 56: 235-260.
Zooarchaeological analysis of a substantial assemblage of animal bones excavated from Dudley Castle, West Midlands, suggests that a significant change in pig management occurred during the 14th century. A dramatic decrease in the relative abundance of pigs, combined with an increase in the size of post-cranial bones and teeth, and a higher proportion of neonatal individuals, raises the possibility that greater control over breeding and feeding was being exerted in this period through the emergence of enclosed husbandry practices. Carbon and nitrogen stable-isotope analysis of a sample of 41 pig mandibles from two tightly dated phases of occupation supports this interpretation. Between the late 13th century and later 14th century there was a statistically significant decrease in δ 15N, but not in δ 13C, and pig dietary diversity probably also decreased. This paper discusses several explanations for these patterns, all consistent with a major change in pig management at this time.

Chicken husbandry: pre- and post-BD comparison

Just added in zotero an interesting article from Ph. Slavin about changes on chicken farming after 1350:

Ptolemaios Paxinos

Doctoral candidate of the Graduate Program of the ArchaeoBioCenter at the Ludwigs-Maximilian-Universität. Dissertation Topic: „Die Archäozoologie der Pest. Die Auswirkungen des Schwarzen Todes (1347-1350) auf Viehhaltung, Wirtschaft und Handel in Deutschland“

More Posts