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The Germs That Destroyed An Empire

Why did Rome fall? Historian Kyle Harper says plague had a lot to do with it
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The COVID-19 pandemic has brought the global economy to a halt. The geopolitical upheavals yet to come will dramatically change world history, in unpredictable ways. The United States is only three months into its struggle with coronavirus, and is experiencing an Icarus-like plummet from the economic heights. The tiny coronavirus will ravage the nations, and may even cause empires to fall.

We have been here before. In his 2017 book The Fate Of Rome: Climate, Disease, and the End of an Empire, Oklahoma University historian Kyle Harper examined the roles that climate instability and plague played in weakening the Roman Empire. The fate of Rome reveals an eternal truth: that not even the greatest concentration of wealth and power in the world can infallibly protect a nation from Nature. I spoke to Prof. Harper by phone yesterday from his home in Oklahoma:

RD: You open your book with ceremonies in Rome, in the year 400. The emperor and his consul have arrived in the imperial city, to much public fanfare and ritual celebrating the greatness of the Roman Empire. Ten years later, the city of Rome was sacked by barbarians; by the end of the century, the Western Empire was gone. “The Fate of Rome” explores the role the natural world played in Rome’s decline and fall. Would you summarize your argument?

KH: It’s in the simplest terms, that the natural environment, including the physical climate and biological environment, played an important role in what we normally refer to as the fall of the roman empire. To me, it’s both a political and economic transformation that occurs over the course of several centuries.

You start in the middle of the 2nd century, Rome is the biggest empire in the world, one in every four people in the world lived in the Roman empire. It was poor by modern standards, of course, but by preindustrial standards, it was prosperous, and powerful. Flash forward five centuries, there is still a Roman state, but it controls maybe a quarter or a fifth of what it had controlled. There’s significant population decline, far less trade and economic specialization, and de-urbanization. The combination of state failure in most of the empire, and the economic decline, or collapse, and population decline, that’s what I mean by the fall of the Roman Empire.

When we look at that with fresh eyes, we can see that the natural environment played a big role. Every generation of historians looks at the past differently, because we see with the eyes of our own world, and because we have new evidence. It was true of Herodotus, and it was true of Edward Gibbon, who wrote the greatest treatment of the fall of Rome, and saw it through Enlightenment eyes. This gave him certain insights, but also gave him certain prejudices. In our time, we know so much more about the germs the Romans had, and periods of climate instability. We can see things that we couldn’t see as recently as ten years ago.

The climate changes for natural reasons, as well as for now human-caused ones – nobody who studies climate change denies that climate changes for natural reasons too. We historians have learned a lot about climate in the past. Ice cores, tree rings, and all sorts of paleoclimate data from periods when you don’t have pressure and temperature and humidity records, are used to piece together a puzzle. During the period when the Roman Empire was growing, the climate was very stable and very favorable for agriculture in the Mediterranean, which was the economic basis of the Roman economy.

And then, what’s come into much greater focus on the past few years is what is now called the Late Antique Little Ice Age. From the 530s, it gets much cooler across the entire northern hemisphere. It was caused by volcanic eruptions. It plunged the climate system into a new period. That was bad in the immediate term, but also in slower, longer term ways, for the agricultural economy.

Health in the Roman Empire was bad, and then it got worse, and still worse. You can divide human history into two periods if you want: before 100 years ago, when the leading cause of death was infectious disease, and the time since then, when infectious disease has been exceeded as a cause of death by cancer, heart disease and other causes. Certainly in the Roman Empire infectious diseases would have been the leading cause of death. Life at the best of times was short and precarious. Life expectancy at birth was in the twenties. People died from a range of diseases – malaria, tuberculosis, dysentery, and so forth. There is evidence that the Romans were particularly unhealthy, even by premodern standards. The Romans were short, which could be caused by a lack of nutrition, but I think it can be argued that in a dense urban environment without antibiotics, the population is highly conducive to parasites.

Then boom, Rome suffered a series of really shocking pandemic events. The first of these is in 160 AD, the Antonine Plague. We don’t know with certainty what caused it, but the leading suspect is smallpox. It was tremendously disruptive to the Roman population. Then in the middle of the 3rd century there was a shadowy plague, the Plague of Cyprian, named after the Christian bishop of Carthage, whose writings are the main source of our knowledge of the disease. We don’t know a lot about it, but we do know that it coincided with a period of really great crisis for the Roman Empire. The Roman Empire should have fallen apart in the middle of the 3rd century.

Then there’s a little bit of a lull, until the biggest bang of them all, the Justinianic Plague, which started in the 540s, under the rule of the late Roman Emperor Justinian. It is the worst biological event, not only in the Roman Empire, but probably all of human civilization to that point. We now know for sure what it was, the same bacterium [Yersinia pestis] that brought about the Black Death. It spread amazingly quickly over Roman trade and road networks. It killed, I think, as much as half the population, like the Black Death, in parts of the empire. It recurs every ten years or so, in various parts of the empire. It provides a kind of bookend to this entire period.

It’s impossible to read your work and not think about how the American Empire in this time of pandemic. The very thing that made us so rich and powerful – a global trading system that we have dominated – also has made us more vulnerable to plague. And, the relative mastery of nature by science and technology has given us moderns a false sense of security. What are the similarities between America today and Rome then that stand out most to you?

History gives us perspective on these kinds of events. Sometimes it means similarities, sometimes differences. Sometimes you can only see the pattern when you zoom out. I do think there are patterns that can help us have perspective on the Covid-19 pandemic. I really see it as emerging at this point of tremendous pressure between two countervailing tendencies over very long sweep of history. We encourage the emergence of new diseases as we expand in numbers, and are more interconnected and interdependent. All of that, when you look at it from perspective of a pathogen, is quite appealing.

I think that there are definitely similarities here with what happened in the Roman world, because we’re part of a continuous history of population growth and globalization. The ancient plagues were new pathogens introduced by the Roman Empire over global trading networks. The Romans really had an early form of globalization. For example, it’s during the High Roman Empire that the Romans and the Chinese become aware of each other. The Romans were part of a massive trading network over the Silk Road and over the Indian Ocean. Their consumer culture and their early capitalism creates this enormous market. Where goods and people go, germs go too. Covid-19 is only the latest example.

But the big difference [between Rome and us] is our science, and the whole medical apparatus, has freed us from the burden of infectious disease, up to a point. I’m talking about the developed world, though in much of the undeveloped world, there is still a big problem of infectious disease. But to grow up in a place like the United States is to be largely free from fear of infectious disease. Our daily routine is marked by an almost constant taking-away of the harm from pathogens. Even without thinking about it, we’re surrounded by all this technology and culture that insulates us from disease. That works, until it doesn’t. We certainly still have vulnerabilities. Covid hits all of them. We couldn’t predict when, precisely, this was going to happen, but it was predictable that at some point, a new, highly contagious respiratory virus was going to happen.

But is it helpful to compare these two periods – America under the Covid plague, and the plagues that struck the Late Roman Empire?

These worlds are so different. As a humanistic pursuit you want to understand how other humans have grappled with this. If anything, we learn more about the past from the present, as opposed to the present from the past. You can read these [ancient] sources talking about their fear and trauma, with a deeper sense of what that was like.

But it’s harder to do the opposite. It’s very hard to import lessons from history. You can see from history that these events are often moments of great cultural change, but that’s very complex and hard to understand. In the middle of the 3rd century crisis, of which the plague of Cyprian was one part, it was a moment that galvanizes really deep change, in ways we don’t have the sources to follow entirely. It’s down to the deepest elements of the human psyche that are hard to fathom. Paganism doesn’t die, or decline, but it does sputter. Even without the presence of Christianity, there was bound to be big changes in the spiritual life of the Roman world. The emperor Aurelian brought in the worship of the sun god, Sol Invictus. That’s a very weird thing to do. Also, we saw the rise of the Christian church in the later third century. I’ve been increasingly convinced that by the time Constantine converts [in 312], most people aren’t Christians, but a significant number are.

As the empire crumbles, and civil life begins to change, people’s relationship with the gods, and ideas about the gods, begin to change.

You write about Pope Gregory the Great, who served as pope from 590 to 604, as a key figure in post-imperial Roman West. He came to power amid the Justinianic Plague. Why was he so important?

The Justinianic Plague was a major event in the Latin West. What’s amazing is we didn’t know that for sure until a year or two ago. Even in my book, I was trying to build out an argument based on very limited evidence. It used to be called the Dark Ages because it’s hard to see into these centuries. We don’t have the richness of evidentiary documents. Just in the last few years DNA evidence has been increasingly acquired that shows the Justinianic Plague reached all the way to the far west, to Britain.

The plague struck a Western world that was already quite fragmented, particularly north of the Alps. Italy was still very much a part of the Mediterranean Roman world. Someone like Gregory the Great grew up in that world. Gregory was born around the time of the first plague, and grew up in a world where the plague came back frequently. It’s likely that his immediate predecessor died of the plague. Someone like Gregory was nevertheless a late Roman person. He spent a lot of time at Constantinople, and knew the Greek East. But he would also look into the post-Roman world. The famous episode of missionizing Anglo-Saxon Britain is a story of a Roman pope sending out missionaries to a formerly Roman world.

His entire papacy takes place against a background of great environmental stress and change. You can read his letters and see this. In his view, it all presaged the Last Judgment. These Christians thought the plagues were warnings from God telling them that the Last Judgment was imminent, and they should prepare for that. His leadership was extraordinary in the city of Rome. Without intending it, and in terms that he would never put it, he was sketching a first draft of what a medieval papacy would look like. It’s not a coincidence that they would later look back to Gregory as the first kind of medieval pope.

You write about how much it meant to the plague-stricken city of Rome that their bishop, the Pope, led penitential processions around the city to ask God to deliver them from plague. Why was this important?

These were very authentic intercessory prayers meant to mobilize an entire community to a change of heart, to repentance. He thought that was the medicine called for. It would certainly have galvanized the energy of the community. Gregory didn’t invent these kinds of rituals himself, but they were still fairly new. He was inventing a model of how to behave in this kind of crisis. What does a leader do? Gregory was very visible.

The apocalyptic mood of the era was not just confined to religious figures, you write, but was general throughout Roman society. “the sense of impending doom was not a weight around the neck; it was more like a hidden map, a way of orienting motion in confused times.” What do you mean?

What we have are a number of texts, mostly by bishops, that present events in the world around them in apocalyptic terms. But this was widely shared. Sometimes they are in inscriptions by lay people, or show up in cultural practices. It’s easy for us to think about Christians back then being apocalyptic in the sense that they were desperate, or giving up because the world was about to end. I don’t think that’s how it was. For them, it was a positive program. This life was always meant to be transitory, and just part of a larger story. What was important to the Christians was to orient one’s life towards the larger story, the cosmic story, the story of eternity. They did live in this world, experience pain, and loved others. But the Christians of that time were called to see the story of this life as just one of the stories in which they lived. The hidden map was this larger picture.

What spiritual reverberations do you predict will emerge from the coronavirus panic? What are you keeping an eye on now?

Historians are terrible futurists. It’s a hard question. I’m an optimist by nature, but all this has been dispiriting to watch. I have been overwhelmingly impressed by the ways in which a traumatic event like this is shaped and configured by the pathologies we have. This is a very disheartening time for our country. We are very dysfunctional right now. That didn’t cause the pandemic, but the pandemic seems to eat away at what are already our vulnerabilities. The cultural canyon between different parts of American society. The vast inequality that seems hopeless – the two Americas. This crisis has painfully exacerbated all of those. The lack of empathy and graciousness all around is very dispiriting. I’m a bit of a pessimist in the short term. We will eventually get this virus under control. But do I think we will learn from it in the short term, and that it will cause us to heal as a country, turn away from consumerism, degradation of the environment, and all the problems we have? I can’t say that I see that changing in the short term.

Let’s end with a personal question: as a historian of the ancient world, and as a believing Christian, where do you find hope in this pandemic?

We just have to do what we are called to do in good times and in bad. You just try in the little ways that you can to love everyone around you all the time. This just gives Christians a chance to exhibit that in little ways. That’s always a ground for hope. You get different chances in life to be given the gift of trying to love others. I don’t think that’s profound theology, but it’s the truth.

Kyle Harper’s book The Fate of Rome: Climate, Disease, and the End of an Empire, was published by Princeton University Press in 2017.