Sequencing the Plague Genome without Archaeology?

In a previous post I discussed the role of the Black Death and DNA studies in tracing the origins of the plague. In a new study published this week by Bos et al. (2011) the genome for Yersinia pestis has been sequenced and reconstructed from the remains of 100 plague victims from the 1348 outbreak in London. There has been scholarly debate over whether the modern plague is the same as the one that was called the Black Death. Some of the symptoms are recorded as being different from those that appear today, although the most poignent difference is the lack of virulence of the modern plague. There had been prior thought that based on text and images that the plague we know today was a different strain from that which ravaged England in the Middle Ages (Wood and Dewitte-Avina 2003). However, by sequencing the genome from the remains of Black Death victims they found that only 97 units within the gene have been altered in the intervening 660 years. While they don’t know the exact effect of these changes, which will be analyzed in future reports, they do know that the alterations were not enough to cause drastic changes in virulence and symptoms.

Museo del Prado, Madrid- Ely Janis

Since the gene itself is fairly similar, the research team argues that the virulence and symptoms are a reflection of the environment and living conditions during the time period rather than change in the virus itself. It is interesting that they note the importance of the historical context, but do not provide the reader with any. This led me to question whether an archaeologist or bioarchaeologist was included on the team that is attempting to reconstruct and understand a historic pathology- skeletal expertise yes, archaeological no. Given the news last week about the Governor of Florida denouncing Anthropology and the outrage of all anthropologists including archaeologists and biological anthropologists, this is the perfect time to discuss the role of archaeologists in modern day pathology studies, and what they can offer to the geneticists.

The outbreaks of the plague in Europe during the 14th century is one of the most deadly epidemics in recorded  history. The Black Death, as it was known during this period, took the lives of approximately 100 million people, reducing Europe’s population by 30-60%. These estimates are taken from a combination of texts from the period including the Domesday Book, personal and medical accounts, and the recovery of mass graves throughout the region. The remains that were used for this study are from East Smithfield, a well known research collection from the Museum of London. It was excavated in the mid-1980’s, and was identified from texts as being the first established Black Death cemetery in London. In total there were 750 individuals excavated; 300 came from the western mass grave, 102 from the eastern mass grave, and 348 were single inhumations. The demographic curve of the population is very different from others found in London, with most individuals being under 35 years. They argue that this is because it is a reflection of the living population hit by catastrophe, rather than the normal dying population. However, see my previous post on demography and plagues for an argument why this may not be true.

Museum of London- East Smithfield

As an archaeologist reading the report on the draft of the genome, I noticed that there was some key information missing. First, we do not know which 100 individuals were studied. This is important because the cemetery was spatially divided into four discrete sections; western inhumation, western mass grave, eastern inhumation and eastern mass grave. Since we do not know if these divisions were arbitrary, due to increases in death tolls, reflection of class, or even a reflection of manner of death, it is an important factor that needs to be considered in sampling. Second, we do not know the selection criteria for the skeletons. The geneticists took the plague DNA from the teeth of the remains, which means that they were required to only use individuals with intact dentition. Likely this means that all individuals with dental pathologies and deciduous teeth were left out of the analysis.

Finally, and most important, the team argues that living conditions were the reason for the differences in manifestation of the Black Death and modern plague rather than differences in the virus itself. In efforts to avoid further outbreaks of the plague (which can still kill an individual in 8 days), it seems that studies should be done comparing historic living conditions to modern ones in outbreak areas. Given that the plague was spread throughout Europe and the living conditions varied widely between countries and cities, archaeological evidence could aid them greatly in discerning these conditions and which are relevant in the prevention of modern outbreaks. Given that the next step for the geneticists is to reconstruct the gene and create a living strain of the Black Death, you would think they would be extremely interested in knowing all the conditions of the past that caused the 100 million deaths. My advice: its time to call up some archaeologists.

Works Cited
ResearchBlogging.orgBos KI, Schuenemann VJ, Golding GB, Burbano HA, Waglechner N, Coombes BK, McPhee JB, Dewitte SN, Meyer M, Schmedes S, Wood J, Earn DJ, Herring DA, Bauer P, Poinar HN, & Krause J (2011). A draft genome of Yersinia pestis from victims of the Black Death. Nature PMID: 21993626

WOOD, J., & DEWITTEAVINA, S. (2003). Was the Black Death yersinial plague? The Lancet Infectious Diseases, 3 (6), 327-328 DOI: 10.1016/S1473-3099(03)00651-0

One response to “Sequencing the Plague Genome without Archaeology?

  1. Pingback: Contagions Round-up 16: Pestilence and Burials « Contagions·

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