By Carol Symes, University of Illinois Urbana-Champaign
In an ongoing research, Professor Robert Hymes is gathering evidence from medical treatises which indicate that the Black Death pandemic was raging in imperial China by the 1230s. Its spread, in multiple directions, was accelerated by the Mongol conquests of the mid-13th to early 14th centuries, which eventually brought it to the Mediterranean world and then to northern Europe.
The Spread of the Plague
This new history has now led to the debunking of a famous medieval story of how the plague reached Europeans. According to the Italian account of Gabriele de’ Mussis, who lived in Piacenza, the Black Death had been deliberately spread by the Mongols during their siege of the Genoese trading post at Caffa, on the Black Sea, as form of chemical warfare. However, the historian Hannah Barker has shown that the Black Death arrived in Italy from the Black Sea via the much more quotidian and regular shipment of grain from that region.
Witnesses like Gabriele de’ Mussis observe things that are very useful and which we can now better contextualize. Although he did not understand how the plague was spreading through the besieged population, he grasped its virulence. He also observed that it manifested in at least two puzzling ways: It could cause painful and noxious swellings, buboes, and it also seemed to spread (as he says) “by breath and sight” and to kill without leaving a visible mark.
Marmot: Main Culprit of the Black Death?
What we now know is that labeling the Black Death as bubonic plague misses the entire point that Yersinia pestis was so terrifying because it had morphed into so many forms that it could present and be contracted in a variety of different ways.
It was not just bubonic—that is, attacking the lymphatic system—but also septicemic, contracted through an open wound or even a scratch; pneumonic—very deadly, caused by breathing in droplets; and gastrointestinal and pharyngeal, caused by eating one of the many host animals that were also domestic livestock.
A main culprit during the Black Death was the marmot, an enormous rodent which flourishes in precisely the cool, high plateaus favored by Yersinia pestis. Indeed, the Mongols’ appreciation of this giant rodent as a source of food and fur is well known. So is the marmot’s prevalence and popularity in the mountainous regions of medieval Europe, where their sociable character put them in close proximity to humans and ensured regular outbreaks in even remote alpine areas.
This article comes directly from content in the video series The Medieval Legacy. Watch it now, on Wondrium.
Preventing Local Outbreaks
Historian Ann Carmichael has shown that urban officials in the major cities of northern Italy, especially Milan, maintained a special information-gathering network that tracked outbreaks and transmission of disease well before they could reach the city limits.
This highlights the most effective measure that medieval municipalities could mobilize to prevent local outbreaks—quarantine, named for the Venetian practice of forcing newly arrived ships to stay offshore for 40 days (or quarantena) before their crews were allowed to disembark. But then, these measures were only as effective as the governments that could enforce them and the sense of mutual obligation that community members felt for one another.
Medieval Climatic Anomaly
Another contributing factor to the virulence of the Black Death, and another which we can see better in hindsight, is the drastic and quite sudden cooling of the Earth’s climate at the end of the Medieval Warm Period. This phenomenon, also known as the Medieval Climatic Anomaly, had begun in the 8th century and had, for hundreds of years, fostered more favorable conditions for agriculture in the northern hemisphere, lengthening the growing season and making the cultivation of crops possible for the first time in many regions.
As a result, it caused a population explosion which, in turn, meant putting more and more land under cultivation and thus destroying animal habitats and increasing the chances of zoonotic transfer of diseases.
By 1300, as a result of over-farming, Afro-Eurasia had reached its own ecological limits. The population had at least tripled within three centuries. A sea of grain fields stretched, almost unbroken, from Ireland to Ukraine to North Africa. Forests had been cleared, marshes drained, and pastureland reduced—and yet there was barely enough food to go around.
When the Medieval Warm Period came to an end, even a reduction of one or two degrees centigrade was enough to cause substantial changes in rainfall patterns, shorten growing seasons, and decrease agricultural productivity—with disastrous consequences.
Then, for a period of at least seven years, between 1315 and 1322, the cooling climate caused nearly continuous adverse weather conditions, especially in northern Europe. In 1316, the Baltic Sea froze over, and ships were trapped in the ice. Torrential rains prevented planting in spring, and when a crop did manage to struggle through in summer it would be dashed by more rain or hail in autumn.
Amid these natural calamities, large-scale warfare—intensified by competition for resources—continued in the sodden wheatfields, as the princes of Scandinavia and the Holy Roman Empire fought for supremacy and succession.
The Great Famine
The result was the Great Famine, which in turn contributed to the rapid spread of the Black Death and its virulence a generation later.
Weakened by years of malnutrition, between 10 and 15 percent of the population of northern Europe had already perished. In southern Europe, around the shores of the Mediterranean, the effects were more muted, and food could be still distributed through different channels. Nonetheless, the overall health of this region suffered from the disruption of trade and the shortage of staple goods, as well as from the highly unstable political situation.
Common Questions about the Rapid Spread and Virulence of the Black Death
Yersinia pestis could be contracted in a variety of different ways. It was not just bubonic—that is, attacking the lymphatic system—but also septicemic, contracted through an open wound or even a scratch; pneumonic—very deadly, caused by breathing in droplets; and gastrointestinal and pharyngeal, caused by eating one of the many host animals that were also domestic livestock.
There was drastic and quite sudden cooling of the Earth’s climate at the end of the Medieval Warm Period. This phenomenon is known as the Medieval Climatic Anomaly.
By 1300, as a result of over-farming, Afro-Eurasia had reached its own ecological limits. The population had at least tripled within three centuries. A sea of grain fields stretched, almost unbroken, from Ireland to Ukraine to North Africa.