The Black Death was the second pandemic of bubonic plague and the most devastating pandemic
in world history. It was a descendant of the ancient plague that had afflicted Rome, from
541 to 549 CE, during the time of emperor Justinian. The bubonic plague, caused by the
bacterium Yersinia pestis, persisted for centuries in wild rodent colonies in Central
Asia and, somewhere in the early 1300s, mutated into a form much more virulent to humans.
At about the same time, it began to spread globally. It moved from Central Asia to China
in the early 1200s and reached the Black Sea in the late 1340s. Hitting the Middle East
and Europe between 1347 and 1351, the Black Death had aftershocks still felt into the
early 1700s. When it was over, the European population was cut by a third to a half, and
China and India suffered death on a similar scale.
Traditionally, historians have argued that the transmission of the plague involved movement
of plague-infected fleas from wild rodents to the household black rat. However, evidence
now suggests that it must have been transmitted first by direct human contact with rodents
and then via human fleas and head lice. This new explanation better explains the bacteria’s
very rapid movement along trade routes throughout Eurasia and into sub-Saharan Africa.
At the time, people thought that the plague came into Mediterranean ports by ship. But,
it is also becoming clear that small pools of plague had been established in Europe for
centuries, apparently in wild rodent communities in the high passes of the Alps.
We know a lot about the impact of the Black Death from both the documentary record and
from archaeological excavations. Within the last few decades, the genetic signature of
the plague has been positively identified in burials across Europe.
The bacillus was deadly and took both rich and poor, rural and urban: the daughter of
King Edward III of England died of the plague in the summer of 1348. But quickly—at least
in Europe—the rich learned to barricade their households against its reach, and the
poor suffered disproportionately. Strikingly, if a mother survived the plague,
her children tended to survive; if she died, they died with her. In the late 1340s, news
of the plague spread and people knew it was coming: plague pits recently discovered in
London were dug before the arrival of the epidemic.
The Black Death pandemic was a profound rupture that reshaped the economy, society and culture
in Europe. Most immediately, the Black Death drove an intensification of Christian religious
belief and practice, manifested in portents of the apocalypse, in extremist cults that
challenged the authority of the clergy, and in Christian pogroms against Europe’s Jews.
This intensified religiosity had long-range institutional impacts. Combined with the death
of many clergy, fears of sending students on long, dangerous journeys, and the fortuitous
appearance of rich bequests, the heightened religiosity inspired the founding of new universities
and new colleges at older ones. The proliferation of new centers of learning
and debate subtly undermined the unity of Medieval Christianity. It also set the stage
for the rise of stronger national identities and ultimately for the Reformation that split
Christianity in the 16th century. The disruption caused by the plague also shaped
new directions in medical knowledge. Doctors tending to the sick during the plague learned
from their direct experience and began to rebel against ancient medical doctrine. The
Black Death made clear that disease was not caused by an alignment of the stars but from
a contagion. Doctors became committed to a new empirical approach to medicine and the
treatment of disease. Here, then, lie the distant roots of the Scientific Revolution.
Quarantines were directly connected to this new empiricism, and the almost instinctive
social distancing of Europe’s middling and elite households. The first quarantine was
established in 1377 at the Adriatic port of Ragussa. By the 1460s quarantines were routine
in the European Mediterranean. Major outbreaks of plague in 1665 and 1721
in London and Marseille were the result of breakdowns in this quarantine barrier. From
the late 17th century to 1871 the Habsburg Empire maintained an armed “cordon sanitaire”
against plague eruptions from the Ottoman Empire.
As with the rise of national universities, the building of quarantine structures against
the plague was a dimension in the emergence of state power in Europe.
Through all of this turmoil and trauma, the common people who survived the Black Death
emerged to new opportunities in emptied lands. We have reasonably good wage data for England,
and wage rates rose dramatically and rapidly, as masters and landlords were willing to pay
more for increasingly scarce labor. The famous French historian Marc Bloch argued
that medieval society began to break down at this time because the guaranteed flow of
income from the labor of the poor into noble households ended with this depopulation of
the plague. The rising autonomy of the poor contributed both to peasant uprisings and
to late medieval Europe’s thinly disguised resource wars, as nobles and their men at
arms attempted to replace rent with plunder. At the same time, the ravages of the Black
Death decimated the ancient trade routes bringing spices and fine textiles from the East, ending
what is known as the Medieval World System, running between China, India, and the Mediterranean.
By the 1460s, the Portuguese, who had been elbowed out of the European resource wars,
began a search for new ways to the East, making their way south along the African coast, launching
an economic globalization that, after 1492, included the Americas.
We should remember that this first globalization would lead directly to another great series
of pandemics, not the plague but chickenpox, measles, and smallpox, which in the centuries
following Columbus’s landing would kill the great majority of the native peoples of
the Americas. In these ways we still live in a world shaped
by the Black Death.