Pathogenesis: A History of the World in Eight Plagues

by Jonathan Kennedy

that the more humans learn about the world, the more insignificant we realize we are—is

if we compressed 4.6 billion years into one calendar year then bacteria evolved in early spring. Humans don’t appear until about half an hour before midnight on 31 December.

The main alternative to the Great Men theory of history is what Lucien Febvre, the French historian, referred to in the early 1930s as “histoire vue d’en bas et non d’en haut,” or “history from below and not from above.”[35] This approach focuses on the masses of ordinary men and women, often fighting against exploitation and oppression.

Prehistory was punctuated by massive waves of migration that resulted in a new population moving into a region and almost completely wiping out the previous inhabitants.

The first people to try to grow plants and breed docile animals probably weren’t motivated by the desire to produce more food: it was already available in abundance in the Fertile Crescent—hence the name—and the change in climate would have been a boon for foragers as well as farmers. Rather, farming likely began as a series of playful experiments or as a way to spend longer each year in a semi-permanent settlement rather than on the move.[11]

“To say that cereal-farming was responsible for the rise of such states is a little like saying that the development of calculus in medieval Persia is responsible for the invention of the atom bomb.” Thankfully, the impact of settled agriculture on infectious diseases is more straightforward to analyze.

This skepticism wasn’t unique to Thucydides but was part of an intellectual movement in fifth-century Athens that is sometimes referred to as the Greek Enlightenment. For example, his contemporary Hippocrates broke with the view that angry gods were responsible for disease outbreaks and instead argued that physicians should observe a patient’s symptoms, diagnose what is wrong with them and take an appropriate course of action.

Rome plunged into a long, debilitating and transformational crisis. But the plague’s most lasting impact was not political. It was religious. The pandemic turned a tiny and obscure Jewish sect on the periphery of the empire into a major world religion, one that today has 2.3 billion adherents and accounts for almost a third of the world’s population.[41]

At a time when plague, as well as war and climate change, appear to have convinced many people that the end of the world was imminent, Islam’s key message—“worship the one God, for the Hour is at hand”—would have been appealing.[67]

The American historian Barbara Tuchman not only describes the 1300s as a “violent, tormented, bewildered, suffering and disintegrating age” in which there was “no sense of an assured future,” she also argues that it was a “distant mirror” to our own troubled times.[1]

The Jewish community in Esslingen in the southwest decided to lock themselves in the synagogue and set it on fire rather than await their fate. As Philip Ziegler wryly notes, “it is a curious and somewhat humiliating reflection on human nature that the European, overwhelmed by what was probably the greatest natural calamity ever to strike his [sic] continent, reacted by seeking to rival the cruelty of nature in the hideousness of his own man-made atrocities.”[24]

The Italian city-states were the first communities to take action to protect themselves from the plague. Starting in the 1370s, all ships wanting to enter Venice had to wait on the nearby island of San Lazzaro until the health magistrates granted the crew permission to disembark. Over time, the waiting period became standardized at forty days—the word quarantine is derived from quaranta, the Italian for forty.

The introduction of regulations such as quarantine and cordons sanitaires in late-medieval societies had significance well beyond public health, because they extended state power into areas of human life that had not previously been subject to political authority.

It isn’t a coincidence that two decades after the Genovese trading colony of Kaffa fell to the Ottomans, Christopher Columbus—himself a Genovese sailor—reached North America. What is more, according to Mikhail the colonization of the Americas was a response to the realization that the Holy Land was irretrievably lost.

Christianity had once replaced paganism because it provided a more appealing and assuring guide to life and death during the Antonine and Cyprianic Plagues. Now, as disease ravaged the population yet again, many people began to reject the teachings of the Catholic Church.

The Church had grown into an extremely wealthy, powerful organization and expected Christians to pay the tithe—10 percent of their income. So many people had left property to the Church when they died that by the Middle Ages it owned about a third of all cultivated land in western Europe.[50]

During the Black Death and subsequent plague outbreaks, people looked to the Church for comfort. All too often, they didn’t find it. Many clergy simply fled; for example, about 20 percent of parish priests in the English dioceses of York and Lincoln abandoned their posts rather than stay and tend to their flocks.[51]

Faced with the failure of the Catholic Church to respond effectively to the trauma of the plague, people began to wonder about alternative means of salvation. There had been challenges to the authority and teachings of the Catholic Church before, but these ideas had failed to gain widespread support until the Black Death.

The expansion of Protestantism was an important factor in some of the most momentous conflicts of the sixteenth and seventeenth centuries, although many wars fought in the name of Protestantism were motivated by the prospect of wresting political and economic power from Rome as much as by doctrinal issues—at times more so.

Eventually, some people began to read the scriptures and reject them altogether. Instead, they tried to explain the world using reason and observation. In this sense, existential questioning triggered by the Black Death didn’t just lead to the rise of Protestantism but also paved the way for the emergence of secularism.

Fearing Atahualpa was conspiring against the Spanish, Pizarro killed him but kept the treasure that had been accumulated to pay the ransom: six tons of gold and 11 tons of silver. Almost all of the plunder was melted down, and each foot soldier received 20 kilograms of gold—cavalrymen twice that.

In a letter to the king, Charles V, Cortés described with amazement how Tenochtitlan’s buildings, pottery, jewelry, clothes, shoes, food, markets and barber shops were either similar to or of better quality than those in Spain.

Diamond’s emphasis on guns and steel over germs was an argument formulated in the 1990s, before the U.S.-led invasion of Afghanistan reminded us just how ineffective military technology can be in the face of determined local resistance.

Without the help of Old World pathogens, early efforts to colonize the American mainland foundered.

The conquistadors remained healthy. While the world was falling apart for the indigenous people of Central America, the Spanish were able to watch the horrors unfold and then pick up the pieces.

According to two sagas written by Icelandic scholars in the thirteenth century, the first sighting of the New World occurred around the turn of the millennium, when a ship was blown off course on its way from Iceland to Greenland—two recently settled Norse colonies in the northwest Atlantic.

If modern-day Americans want to be historically accurate, then their gratitude at Thanksgiving should be directed to the Old World pathogens that made the settlement of Plymouth Colony possible.

If Cortés, Pizarro or Aguirre had attempted to search for El Dorado in Africa rather than the Americas, they would have almost certainly been killed by infectious diseases too.

In order to comprehend the contemporary world, we must understand how an institution as horrific and iniquitous as American slavery came into being.

On Columbus’ third voyage to the Caribbean in 1498 he advocated importing Africans who were already working on sugar plantations in Atlantic outposts like Madeira and the Canary Islands. Soon afterward the transatlantic slave trade began.

The French defeat at the hands of the Haitian rebels—and the island’s mosquitoes—helped to shape the modern world. Without a base in Saint-Domingue, Napoleon had little choice but to abandon his grand plan of building an empire in the western hemisphere.

Enslaved African labor was a crucial part of the southern plantation economy, whereas the north’s growing manufacturing sector relied on free labor from Europe; this led to very different understandings of liberty.

Malaria didn’t change the outcome of the Civil War: the North won despite the disproportionate toll that Plasmodium falciparum had on the Union Army. But it probably delayed victory by months or even years, which in turn had a momentous effect on the postwar settlement.

Because the marked increases in wealth and health occurred at roughly the same time, it is widely believed that economic growth led automatically to improved human welfare. This is the crux of the theory that as countries get richer they pass through an “epidemiological transition” in which life expectancy improves as fewer people die young from infectious diseases, and more people are killed at an older age from chronic diseases such as cardiovascular disease and cancer.[15]

The new provincial towns and cities really dragged down the national life-expectancy figures. They were not only considerably lower than the figure for England and Wales, they also fell markedly in the second quarter of the nineteenth century.

Britain’s towns and cities had grown rapidly and haphazardly, and lacked basic infrastructure such as sewerage and safe drinking water. Human waste was thrown on to the unpaved streets, stored in cellars and piled up in overflowing cesspits.

As the civic gospel spread, the new breed of municipal politicians didn’t just want their towns and cities to be wealthy. Taking inspiration from their idealized vision of the great city-states of classical Greece and Renaissance Italy, they aimed to use the prosperity to encourage their inhabitants to flourish.[60] From the mid-1870s onward, all the efforts of the sanitary movement over the previous four decades began to coalesce.[61]

In almost every country that industrialized in the nineteenth century, including most of Europe, the U.S. and Japan, the urban working classes experienced a generation-long decline in health and life expectancy.

Klimt’s message is clear: life is painful, death is certain, and modern medicine hasn’t altered this fundamental reality.[*1] The rather depressing stance reflects his personal experience.

Despite the remarkable advances in public health, human existence is still plagued by disease and death.

In Uganda, treatment of TB is free but associated non-medical costs such as travel to and from the health center still account for more than one-fifth of annual household expenditure for most patients.[12]

Sachs and his collaborators argue that infectious diseases create a “poverty trap” that is almost impossible to escape.[16] Poor people are more likely to get ill, making them even poorer and even more prone to infectious disease.

The United States spends more on health care than any other country—almost $11,000 per person every year, compared to $4,300 in the UK, for example.[65] And yet health coverage is patchy.

Pathogens thrive on inequality and injustice.

The Enlightenment has put some lucky people on what seems like a “perpetual path of progress,” but much of the world’s population lives in what must feel more like a dystopia.