Yersinia Pestis source of early medieval Justinian plague

How Devastating was the Justinian Plague in the 6th Century?

Recently the first complete reconstruction of the early medieval pathogen genome, Yersinia Pestis was carried out on the remains of a 6th century individual from Altenerding. New overview of mass-graves and double burials offers tantalising glimpse of how to measure the impact of the epidemic on the “Fall of Rome”.

There is no doubt social and cultural upheavals in the 5th and 6th centuries resulted in the new European “world order”, we generally label the Middle Ages. Nevertheless, centuries of research have – as is well known – fielded a vast variety of explanations of these events; often these have reflected the political or cultural worldview of the historian more than the facts. One reason, often encountered, is that so little written source material is at hand that it literally remains enigmatic. Continuity versus rupture, migration versus acculturation, military skirmishes versus pitched battles? The questions are many and the hard facts often elude us.

In recent years, however, environmental factors have come to the fore. Focus has been on the deteriorating climate following the Roman Optimum plus the climatic events in AD 536 -40. Some have even claimed that this constituted a perfect “storm” of a combination of horrendous climatic events pared with the Justinian plague, which changed the order of the day. In recent years climatologists have carefully charted the dramatic shifts, which took place in late Antiquity, not least the double volcanic events in 536 – 40. Now, it seems, the time has come to re-evaluate the evidence for the impact of epidemic deceases. More precisely, the time has come to move from literary descriptions of the Justinian Plague to a better understanding of the facts on the grounds, the dead.

From Sens to Altenerding

Double Grave from Altenerding © State Collection of Anthropology and Palaeoanatomy, Munich
Double Grave from Altenerding © State Collection of Anthropology and Palaeoanatomy, Munich

From 1979 -1989 four burial pits radiocarbon-dated to 4th – 6th centuries were excavated at Sens and Les Clos des Cordeliers yielding the remains of 45 adults and 28 immature individuals. Tightly packed, some of these were layered in their graves. In 2004 aDNA was extracted from ten teeth from three individuals demonstrating the presence of Yersinia Pestis. Never replicated in an independent research lab the findings are generally considered liable.

Nevertheless, it took another six years before another search for the microbe was carried out in a small village in Aschheim (published in 2013). Here a chance find in 1997 led to the discovery and excavation of 456 burials. A number of these graves held multiple burials, one with five individuals, one with four individuals, three with three individuals and 22 with 2 individuals. Nearby were found an additional 25 burials of which one held four individuals and two were double burials.

Studies of aDNA at Aschheim have without doubt identified the presence of Y. pestis in the remains of the interred in three double burials, two triple burials, one quadruple burial and the sole burial of five persons. The burials have been dated to the mid 6th century.

Finally, the scientists – regrouped in a new and larger team – recently did a second study of the remains of twenty individuals buried in double graves at Altenerding, 20 km from Aschheim. This revealed aDNA identified as Y. pestis. The gravegoods suggest these individuals were buried c. 550 -75.

It is the extraction of aDNA at Altenerding, which yielded the first complete reconstruction of the early medieval pathogen genome, Yersinia Pestis and which has recently been published.

Both discoveries are significant for a number of reasons. Both were located between five to ten km from a tributary to the Danube, the Isar, which is the fourth largest river in Bavaria and a major transport route. Studies of the spread and recurrence of plague in the 14th century and later have shown that 95.5% of all outbreaks happened within 10 km of navigable rivers

Secondly, the deaths at Aschheim happened in a settlement with an estimated population of c. 250 – 300 individuals. Calculations imply that the impact of the epidemic nearly caused a social collapse c. AD 555.

Thirdly, none of the places have been mentioned in any written sources; thus, the finds from Bavaria seem to indicate that the epidemic in the 6th century might have had equivalent impact as that in the 14th century (even though the evidence is so far patchy)

Tracking Mass Death

Yersinia Pestis - three waves of epidemics
Yersinia Pestis – three waves of pandemics: Red: Junstinian Plague, Green: Black Death, Blue: Modern Plague

One of the more prominent historians working in this sub-field is Michael McCormick, who already touched slightly upon the field in his magisterial account of the Origins of the European Economy. Since then he has expanded his explorations of the complicated interplay between climatic and economic trajectories in the Early Middle Ages. Among other publications, he wrote the concluding chapter on “Towards a Molecular History of the Justinianic Pandemic”, published in the collective volume from 2006: Plague and the End of Antiquity. In this article McCormick promised to make an inventory of mass burials from Late Antiquity in order to open up for further investigations into these questions.

As is the case with the work of McCormick, he always aims to get a full and comprehensive overview of the evidence as yielded by sources before he “rides”. In time, this has nevertheless led to three articles published in 2015 and 2016 in which he tracks events of mass death during the fall of Rome’s empire.

In these articles, he outlines not only what insights we might gain from re-examining the written evidence (otherwise outlined in the book on Plague and the End of Antiquity.

His point is that “whatever their origin, the sharpest mortality challenges had the capacity suddenly to shock the “system”. Whether the result of invasions, battles, famines, epidemics, and natural disasters, such as the Mediterranean tsunamis of Late Antiquity, they all led to mass death. “But how many people and structures were lost”, he asks?

This is a complicated question to ask, especially since contemporary descriptions of the horrors waged by wars and pestilences seems difficult to corroborate archaeologically. Also, scant epigraphic records have traditionally given pause.

Tracking Mass Burials

Map of Altenerding
Map of Altenerding © State Collection of Anthropology and Palaeoanatomy, Munich

One way of getting to the bottom of all this, seems to be to re-examine the archaeological evidence of mass burials. His papers, thus, build on the examination of 85 graves witnessing to mortality crises on 55 sites from Late Antiquity. In the first article (from 2015) the evidence is presented and discussed in a wider context. Recently published articles are an archaeological inventory of these graves and an appendix listing sites, “whose identifications as late-antique mass graves seem uncertain, problematic and erroneous”.

In his overview he notes that double (or triple, quadruple or more) burials are not an uncommon feature in other cemeteries of the 6th century in the Early Medieval rural countryside; although they are often explained as the result of violent deaths even though marks on the skeletons have not been detected. McCormick suggests it might be interesting to do further investigations akin those carried out in Aschheim and Altenerding to see if epidemics might be a more reasonable explanation.

McCormick writes in a conclusion to his catalogue that this first inventory will hopefully inspire archaeologists to “critique, improve and expand” upon the role played by mortality crises in the understanding of the “powerful and sinister drama of the fall of the Roman Empire”. It is clear that he has his eyes set up a reinvestigation of such places at Pfalheim in Ellwangen, with 27 graves, including seven double graves, one triple burial, and one grave with eight individuals. Although the excavation took place in the 19th century, a re-examination of the evidence might pay off.

Number of burials in graveyards

Distribution of burials in cemeteries in the Merovingian Rhineland
Distribution of burials in cemeteries in the Merovingian Rhineland

Another indicator – number of burials per cemetery per period – is not explored in these studies, but may perhaps be fruitfully combined with them

The background for this hypothesis are some very interesting studies on the use of burial grounds over time carried out in 6th and 7th century Rhineland. The reason behind these studies by Bernd Päffgen and Karl Peter Wendt, was to calculate the population density in Merovingian Rheinfranken. As part of this project they studied in detail the composition of eight cemeteries, which had been fully excavated and which in total yielded 1965 graves from 400 – 740. The main reason was to calculate the period during which a larger number of cemeteries (42) might have been claimed to be in fully working order; it is generally believed that the “Reihengräber” phenomena was introduced around 500 and superseded by new Christian cemeteries around 670 (located around the new village churches). The point here was to define the period of time, during which it might be claimed the cemeteries were not up and fully working; which might mean that a number of graves might be overlooked, thus making the final calculation of population density too “low”. For this reason, they pinpointed AD 530 – 670 as the relevant period to cover. The interesting fact, now, is that this is during this same period, the Justinian Plague hit. Which means that the number of deaths may have swollen in this period. This is what might perhaps be gleaned from a detailed study of the table presented by Päffgen and Karl Peter Wendt (here rendered as a diagram).[1]

This has of course no repercussions for the calculation of population density, as this builds on a simple equation: estimated size of catchment area for settlement divided by estimated size of population, calculated on the basis of graves pr. year (or rather period) and the estimated average length of life of the individuals living in these settlements. (As a side note it may be mentioned that the population density calculated for the whole area and the period AD 530 – 670 were rather lower than most historians operate with: between 0,78 – 1,04 pr. km2 with a concentration of 4,42 – 6,54 pr. km2 in the region between Aachen and Cologne, centre of the Austrasian kingdom from AD 567; which even if some of this calculation is mixed with a periodic surplus of deaths caused by plague, would still be very low).

This study builds on impressive amount of material and not least examination of localities, burial grounds and presumed settlements.  Now, it stands to reason that some of these burial grounds must have included double and triple burials. Perhaps a careful evaluation of this material may lead to further studies of the population dynamics inside this rather long period? Some of which might even have been caused by calamities fostered by the Justinian plague?

There is – as McCormick tells us – obviously room for further explorations into this until now somewhat murky corner of the history of the Early Middle Ages.


This argument was already voiced by Tapio Seger in 1982, concerning Finland. See: The Plague of the Justinian and other scourges: an analysis of the anomalies in the development of the iron Age Population in Finland. By Tapio Seger: Fornvännen (1982), Vol 77. pp. 184 – 197.


A high-coverage Yersinia pestis Genome from a 6th-century Justinianic Plague Victim
Michal Feldman, Michaela Harbeck, Marcel Keller, Maria A. Spyrou, Andreas Rott, Bernd Trautmann, Holger C. Scholz, Bernd Päffgen, Joris Peters Michael McCormick, Kirsten Bos, Alexander Herbig, and Johannes Krause,
In: Molecular Biology and Evolution (2016), Open Access

Yersinia pestis and the Plague of Justinian 541–543 AD: a genomic analysis
David M Wagner, PhD, Jennifer Klunk, BS, Michaela Harbeck, PhD, Alison Devault, MA, Nicholas Waglechner, MSc, Jason W Sahl, PhD, Jacob Enk, MSc, Dawn N Birdsell, PhD, Melanie Kuch, MSc, Candice Lumibao, MSc, Debi Poinar, MA, Talima Pearson, PhD, Mathieu Fourment, PhD, Prof Brian Golding, PhD, Julia M Riehm, PhD, Prof David J D Earn, PhD, Sharon DeWitte, PhD, Jean-Marie Rouillard, PhD, Prof Gisela Grupe, PhD, Ingrid Wiechmann, PhD, Prof James B Bliska, PhD, Prof Paul S Keim, PhD, Holger C Scholz, PhD, Prof Edward C Holmes, PhD, Dr Hendrik Poinar, PhD
In: The Lancet, Infectious Diseases (2014) Volume 14, No. 4, pp. 319–326

Tracking mass death during the fall of Rome’s empire (I)
By Michael McCormick
In: Journal of Roman Archaeology (2015), Volume 28, pp. 325-357

Tracking mass death during the fall of Rome’s empire (II): a first inventory of mass graves
By Michael McCormick
Journal: Journal of Roman Archaeology (2016) Volume 29, pp. 1004-1007

Tracking mass death during the fall of Rome’s empire (II): a first inventory
By Michael McCormick
In: Journal of Roman Archaeology (2016), Volume 29, pp. 1008 -1046

Navigable rivers facilitated the spread and recurrence of plague in pre-industrial Europe
Ricci P. H. Yue, Harry F. Lee and Connor Y. H. Wu
In: Scientific Reports 6, Article number: 34867 (2016)

Die Bevölkerungsdichte der Merowingerzeit.
By Bernd Päffgen and Karl Peter Wendt
In: Landschaftsarchäologie III. Untersuchungen zur Bevölkerungsdichte der vorrömischen Eisenzeit, der Merowingerzeit und der späten vorindustriellen Neuzeit an Mittel- und Niederrhein. Bericht der Römische-Germanischen Kommission Band 91, 2010, Philipp von Zabern 2012, pp. 217 – 338.