Dangerous misuse of historical data

UPDATE (01/12/2017): the article can now been accessed in a ‘ahead of print’ online version on the following URL
https://wwwnc.cdc.gov/eid/article/24/1/17-0477_article

In a recent blogpost on the current outbreak of plague in Madagascar, historian Monica Green wrote the following quote:

‘I see dead people. That’s my job. I’m a historian.’

This is also true for me, in fact the majority of my time researching is spent counting dead people. This would be quiet a depressing job, were it not for the fact that these people died over five hundred years ago during the Black Death and recurring plague outbreaks (my research focuses on the period 1349-1500).

Historians are far from the only scientists interested in the Black Death, the biggest killer-disease ever to have hit humankind. In recent years aDNA testing and genome sequencing has allowed micro-biologists and bio-archaeologists to study plague on a geographical (and temporal) scale that often dwarfs localized historical studies from the past. Remarkable breakthroughs have been achieved in the laboratory, attaining results far beyond the possibilities of historical analysis. However, history and especially historical ‘big data‘ are not out for the count (yet).

Emboldened by the advances in the more exact sciences, scholars in the social sciences (often non-historians) have sought to expand their research-horizons as well. In doing so, they rely not on evidence gathered in the field or the laboratory. Instead, they rely on pre-existing historical datasets to make grandiose claims about plague activity in pre-modern Europe.

However, unlike laboratory results, historical data are much more difficult to quantify and cannot be taken at face-value. Adding to this problem, some scholars have even failed to apply source critique when using these datasets. This has significantly undermined the reliability of their results. To make matters worse, some of these results have been turned into recommendations for governments trying to deal with modern-day plague outbreaks.

A 2016 study published in NATURE Scientific Reports on the link between navigable rivers and the spread of plague mentions:

‘We sought to shed light on inland transmission of plague in pre-industrial Europe and hence, contributing to plague prevention in [the] underdeveloped world nowadays.‘

It is at this point that historians need to sound the alarm. In an article that will appear in the January 2018 edition of the journal Emerging Infectious Diseases, Daniel Curtis and myself explore the dangers of uncritical use of historical plague databases.

Historians and students of history should not be too quick to doubt the fact that historical contextualization and historical data can be relevant for various fields, even those as technologically advanced as medicine. Too often history is seen as a science that is of little relevance for current problems. However, it is only through analyzing long time series offered by the historical record that disaster planning can evolve from symptomatic treatment into a structural understanding of vulnerability and resilience in the face of disease and other calamities. For this type of analysis to be conducted in a meaningful way, the opportunities and limitations of the historical data need to be fully understood. This is why historians have an important role to play in ongoing research in fields outside of the discipline of history.