How a medieval grain market can help us understand the Covid recovery

Charles Mendelson
ILLUMINATION
Published in
5 min readMay 22, 2021
A field of grain
Photo by Tobias Hort-Giess on Unsplash

Part 1, a single pestilential shock

TLDR;

  1. A single outbreak of plague didn’t impact the grain market in the long term
  2. We can use data to get a weekly view of a plague outbreak from 500 years ago
  3. Combining history and data is really cool

Introduction:

Yersinia Pestis, commonly referred to as the plague, or the black death, raged through Europe in the middle of the 14th century. Estimated to have killed a third of the population of Europe, it left a long legacy on world history. Less well known is that the plague became a generational feature of life in the old world for the next 5 centuries. While later outbreaks were not quite as catastrophic as the initial one, they were still a devastating experience for everyone who experienced them.

During the same period, there was a weekly grain market held in the German city of Köln (also called Cologne) on the Rhine. This grain market served as a major grain trading hub in the Hanseatic League, a loose affiliation of Northern European merchant republics. We have remarkably detailed records of the grain market, including mostly intact weekly ledgers recording the quantity and price of grain sold. This gives us a remarkably detailed look at the economic activity, which we can cross-reference against plague outbreaks to see the impact of the plague on economic life. Using this, we can get a glimpse of what the future of our own recovery might look like.

Understanding the grain market:

The Cologne grain market was a seasonal business with the bulk of activity in the fall and winter, when sellers would have plenty of stock from their own harvest, and buyers would need to buy food to supplement their own stores

Fall: 38.87%, Winter: 33.95, Spring: 14.30%, 12.88%
Image by author
A chart showing the weekly averages, with seasonal highlights for the Cologne grain market from 1532–1550
Image by author

Consequently, it was much easier to shut down the market in the spring and summer, than in the fall and winter.

Plague Year

A graph showing the weekly grain sales in 1540 and 1541, with the averages for the period from 1532–1539
Image by author

1540 started as a fairly normal year for the grain market. January through April.

The first signs of trouble show up in May when grain volumes were about half the typical year. Is this when the first infections occurred? Did residents whisper rumors about the stricken, hoping they were isolated incidents instead of dreadful portents of an upcoming pestilence?

Then in June, all recorded activity stops and the market doesn’t open again until the middle of September when it opened for three weeks. The silence in the data speaks volumes about what the people of Cologne were experiencing in the summer of 1540.

For the reopening, did the city council knuckle under pressure from the grain merchants? Perhaps the plague was slowing down, and reopening the market was essential to making sure people had food for the winter.

Whatever the reasons behind the reopening, the experiment was short-lived, and the market closed again until the second week of August 1541.

The rest of 1541 saw fitful activity at the market with short bursts, followed by extended closures.

It is possible that activity at the market continued, but no one recorded it. If this is the case, it still speaks to a massive social disruption given the completeness of the records both before and after the outbreak.

The uneven reopening pattern reminds me of our own halting efforts to return to normal.

The long term effects:

The grain market rebounded quickly after the plague subsided.

Image by author

1542 was a slightly below-average year for the period around the plague, but by 1543 most of the next 7 years were high performing years for the grain market.

In fact, only one year in the decade prior to the plague outperformed any of the years between 1543 and 1550.

That suggests the market was resilient and able to absorb a single shock and continue to grow. Quick recoveries from short-term pestilential shocks are possible, as long as the market has time to recover.

Obviously, we shouldn’t over-index a single data point, but we can admire our forebearers’ resilience and remember that during the pandemic recovery we can be just as resilient.

In the next article, we will explore what repeated shocks do to the grain market.

Notes:

To identify Plague outbreaks, I used J.-N. Biraben’s list of plague outbreaks. We need to use caution when using his list because his methodology was not particularly well documented. We do have corroborating evidence in the grain ledger.

A malter is a medieval German unit of measurement, usually for volume, but varied place to place in Germany.

The grain prices are from the MEMDB maintained by Rutgers University.

I cannot get over how cool it is seeing evidence of a 500 + year old plague outbreak in this kind of fidelity

Data was analyzed and visualized in Tableau Desktop

References

Basic information about the black death can be found here: https://en.wikipedia.org/wiki/Black_Death

Plague outbreak data can be found here: https://zenodo.org/record/14973

Grain Market Data can be found here: https://memdb.libraries.rutgers.edu/metz-prices

Information on the Hanseatic League: https://en.wikipedia.org/wiki/Hanseatic_League

About

Charles Mendelson is a Data Analyst/Engineer based out of Seattle. If you are looking for a guest for your data-focused podcast or YouTube channel you can reach him via LinkedIn.

Originally published at https://charlesmendelson.com on May 22, 2021.

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Charles Mendelson
ILLUMINATION

Seattle based data engineer with a bias towards process and UX.