Professor Kyle Harper (2:56)

Hello everyone.

Podcast Host (2:57)

A quick note from me before we start the episode. Just a thank you, thank you to everyone who came to our Ancients live show last Friday where we explored the story of Carthage with Dr. Eve MacDonald. We absolutely loved it. It was wonderful to meet so many of you in person. And I'm here to say that we will be releasing the audio of that live show for you, our subscribers next week. So if you want to listen to that live show, if you couldn't make it but really want to listen to it, well, you can. You just need to subscribe to to the Ancients. We'll put a link in the show notes where you can do just that and it's going to be released next Friday.

Professor Kyle Harper (3:44)

The dozen different sources from the period say something very strange. They say basically that the sun disappeared.

Podcast Host (3:52)

Witness a world where nature reigned supreme and catastrophe rewrote the story of civilization.

Professor Kyle Harper (3:59)

Huge volcanic bombs are coming out of the sky.

Podcast Host (4:01)

These great rocks about 3ft across crashing through the material. In the ancient world, disaster was always lurking. Earthquakes and volcanoes flattened and buried mighty cities in an instant. Drought and plague wiped out civilizations without mercy. So if you've got an empire that too becomes immensely vulnerable and prone to collapse, life in the ancient world often hung by a thread. Over the next four episodes, we'll discover that survival was never guaranteed.

Professor Kyle Harper (4:34)

It's like playing Russian roulette with five bullets in the six holes.

Podcast Host (4:38)

It's time to step into the chaos and witness the catastrophe. To uncover how disaster reshaped civilizations and the world itself. This is great disasters. What was the worst year in human history? Well, 541 AD has a lot going for it. This was a time of bubonic plague, of volcanic eruptions, abrupt climate change, crop failures, famine, you name it. This wasn't a great time to be living in the ancient world, especially if you were in Emperor Justinian's Roman Empire. In this episode, we're going to delve into all these tumultuous events that hit the Roman world in the mid 6th century AD and whether this was actually the time that ancient Rome fell. Did this mark the moment where antiquity ended and the Middle Ages began? This is the story of 541 AD, the worst year in history. Episode three of our great Disasters miniseries with Professor Kyle Harper. Kyle, it is a pleasure to have you back on the podcast. It's a pleasure to be back 541ad seems to have a bit of everything. Part of the coldest decade on record, a volcanic winter famine. And to top it all off, at the beginning of this devastating bubonic plague event. Could 541 AD lay claim to the worst year in history?

Professor Kyle Harper (6:14)

I tell you, it would be on my short list of any list of years in which I am grateful I was not alive. There's some stiff competition, to be sure, but I think there's a really strong case that just in terms of the suffering and the unpredictable sudden shifts of fortune, that this moment in the 6th century must rank among the most horrible times to be a human being ever on the face of the planet.

Podcast Host (6:46)

Well, let's set the context. First of all, what does the Roman Empire look like? How is it faring in the early 6th century?

Professor Kyle Harper (6:53)

Well, it's definitely still the Roman Empire, but it's a pretty different empire than you might think of. If your mind conjures the world of Julius Caesar and Augustus or Trajan, Hadrian, the kind of Pax Romana, it's still a very Roman world. But by this time, the Roman Empire has been through a lot. It's been beaten and battered and invaded. It's been fragmented and broken apart a few times. It's a really amazing story of the resilience of the deep idea of a being Roman and the institutional framework of Roman law and empire. But by the sixth century, well, first of all, the fifth century has happened, which means that the west has been really significantly altered by the conquest of largely Germanic cultural groups. So, like, where you are sitting today is no longer the Roman empire. By the 6th century, the Anglo Saxon kingdoms of the early medieval world, the post Roman Britain, has really taken shape. The picture is similar in parts of Western Europe. You know, what's now France, what was Gaul is controlled by Frankish kingdoms. Italy is controlled by Ostrogothic kingdoms. Spain is controlled by Visigothic kingdoms. North Africa is controlled by Vandal kingdoms. And so the Roman Empire is really sort of the Balkans, the Eastern Mediterranean, Egypt and parts of North Africa. But what happens in the middle of the sixth century is you have one of the most remarkable figures in Roman history, Justinian, who sets around from his capital in New Rome or Constantinople, sets out on one of the most remarkable, ambitious projects of imperial restoration. That is legal, we think of the Justinianic legal reforms and codifications. It's religious, it's cultural. Think of the architectural legacy of Justinian and the Hagia Sophia, and above all, it's military and Imperialistic. He takes back North Africa and he's right on the cusp of successfully taking back Italy when disaster strikes.

Podcast Host (9:00)

So it's very much this idea that. I know this is oversimplifying it, this idea that the east is still strong, but the west has collapsed, I guess, in that idea of the Western Roman Empire versus the Eastern Roman Empire. But as you're highlighting there, it's not just a line in the sand. And the Romans never, ever go west again. They do try to recapture territory, like under the time, like at the time of Justinian. And this is his general, Belisarius. Is it not?

Professor Kyle Harper (9:25)

Right? Belisarius is kind of his. His most effective commander in chief and, and leads the. The reconquest of. Of Africa, defeats the Vandals and takes back this really important territory and is then carrying this campaign of restoration to. To Italy to the end of really attaching the old heartland of the Roman Empire, including the city of Rome itself, to the Eastern Roman Empire. We sometimes call it the Byzantine Empire, but all of these are kind of misleading. It's really just still the Roman Empire, and it's really going quite well. But, yes, you're right to say that the east is really remarkably prosperous. And everything we've learned in the last generation or two has really underscored the dynamism, the vitality, even within the context of premodern societies, the prosperity of Egypt and Palestine and Syria and what's Anatolia and Greece in the 5th and the 6th century, right down to the catastrophe that strikes.

Podcast Host (10:33)

And before we get to this catastrophe, I mean, what types of sources do we have available to learn more about this period in history and the number of disasters that seem to occur at this time?

Professor Kyle Harper (10:45)

Well, I'll probably want to underscore the differences between this. I don't care if we call it early medieval world and the late medieval world, because there's a sort of roughly similar catastrophe in the 1300s with a series of climate downturns, health catastrophes, famine, and then ultimately, of course, the Black Death. And as a late Roman historian, I am just constantly, you know, overwhelmed with envy at the richness of the late medieval record. So we have, like, a relative paucity and lack of sources. That's really challenging. And yet, okay, we can whine and complain. We've got to just move forward with what we've got. We've got to try and be clever and find new sources if we can, but we're really dependent on a small number of sources, which is one of the things that makes it challenging. But we have multiple documentary or narrative accounts of it by contemporary historians, like the Greek historian Procopius, like the Syriac bishop John of Ephesus, as well as a handful of other sources. And then we have to just piece together as best we can from archaeology, from the inscriptional record, from every kind of stone that we can turn over to try and track down clues about what happened, which now includes a really remarkable kind of new evidence in the form of paleoclimate proxies and ancient DNA.

Podcast Host (12:18)

And how do those things also aid with the literary sources? What can paleoclimate studies and DNA tell us about this period?

Professor Kyle Harper (12:26)

Well, let's start with, let's start with paleoclimate. We'll talk about that, and then we can come back to ancient DNA later. But this is one of the really fun, exciting things about being a historian in this time is that, well, because of the urgency of the human caused climate crisis, there's a really like, urgent need to understand the Earth system, how the climate works. The climate is incredibly complex and, and so we need to understand how it works and its history, its past state and dynamics. And so this has led to a ton of funding as well as really amazing science, human capital and brilliance invested in trying to reconstruct the history of the Earth. And we do this with, you know, among other things, paleoclimate proxies. So finding ways to understand what was happening in the climate before there were instrumental records. You know, I mean, we can, you know, look on our phones and see, you know, hourly what the, what the temperature and precipitation are. But, you know, thermometers have only been around since the 1600s, and even those are pretty crude. So how do you, how do you know what the Earth system was like, what the climate was doing 2000 years ago? And it's not easy and there's always a lot of uncertainty. But we use tree rings. So we find trees whose growth rings in series can provide insights into different climate variables like temperature and precipitation. We find things like ice cores that can, in the little air bubbles that are trapped in the ice, tell us about the chemistry of the atmosphere. We find marine cores at the bottom of the ocean, we find cores at the bottom of lakes where there's sediments, anything, where there's a kind of sedimentary archive that can be understood as a time series, has the potential to tell us about what was happening in the past. And that's really what's happened with climate and the results. One of the most fascinating aspects of this is that it can enrich, complement, challenge the historical record that we have. And so I'll give you an example which is the year 536 that we want to talk about. The. There are, you know, almost a dozen different written sources from the period that say something very strange. They say basically that the sun disappeared. And they tell this in different ways, but they all report some kind of solar veiling. And historians who work on these sources, like John of Ephesus and Procopius, honestly didn't take those reports very seriously. And it's sort of, you can understand why. These are pre scientific cultures, they have all kinds of non scientific superstitious beliefs. They see the world and we want to try and sympathetically understand, but that doesn't mean we take their reports about the world literally. I mean there's a world filled with demons and magic and all kinds of things. And so these reports are sitting there in plain sight saying the sun disappeared. Oh yeah, right. Except that in the 1980s two NASA scientists, in fact looking at some of the early ice core records, noticed that there was evidence for volcanic eruption in the ice record that was chronologically aligned with these written reports. And they, they were the ones that really first grasped that something had happened in the Earth system. We have can piece together now quite a bit about these volcanic eruptions and these written reports. And it's a cool example. Sometimes people call this, I like this word consilience, the way knowledge from different domains leaps together and sort of fits like a puzzle. And here you have these totally independent records, the chemistry of an ice core and the Greek and Latin and Syriac texts that tell us this thing that we had for, you know, for sympathetic reasons, sort of not taken literally. And all of a sudden now we can try and read these sources sort of together to deepen our understanding of what happened.

Podcast Host (16:38)

No, exactly. And this is why I'm finding this topic so interesting. It's one where it's the combination of science and ancient texts to understand like what they were actually talking about. So let's explore that. Now you mentioned that year 536 and that idea of the sun disappearing. I mean Kyle, is this the first sign of this great impending disaster that's about to unfold?

Professor Kyle Harper (17:02)

Well, yes, we should start by underscoring that the, the climate, global climate system is really complex and it changes all the time. And it changes for natural reasons. And our world is changing very rapidly because of anthropogenic greenhouse gas emissions. But it changes naturally too. And it changes for different reasons. It changes because the orbital dynamics of the Earth affect The amount and seasonality and distribution of solar radiation that reaches the atmosphere, it changes because the sun itself sort of flickers. You know, it's more or less the solar dynamo is going through internal cycles that mean that there's more radiation arriving from the sun. The internal dynamics of the system itself are complex. So like the, say the El Nino Southern Oscillation is sort of a natural mechanism of variability. But one of the really, really powerful drivers, forcing mechanisms of short term climate change is, is volcanic eruption. And we sort of come to appreciate this, that large volcanic eruptions can eject huge amounts, lots of stuff, but sulfur that gets into the stratosphere where it aerosolizes and forms like a kind of blanket, a gaseous blanket that scatters solar radiation. And so it has the effect largely of cooling the planet. And there are lots of variables. It depends where the volcano is, when it erupts, what the climate is already doing. But the sort of quick and dirty mechanism is volcanic eruptions. Less sunlight, more ice and big eruptions can have big short term effects. And what's now clear is that this period of Justinian's reign sees not just one but actually a series of significant volcanic eruptions in 536 somewhere in the Northern hemisphere, maybe Iceland, as a scientific team has proposed. And then again in 541 there's an even bigger tropical eruption. And so you have this double blow that seems to have really significant effects. You alluded to the fact that, that a team of scientists working on tree rings both in the Alps and in the Altai Mountains of Central Asia that have built a very robust record of climate change in the Holocene, identify the decade that follows as the coldest decade on record. And this is the tree rings speaking, but it seems to be the coldest decade on record. In the, in the late Holocene, in the last few thousand years, one of the two or three coldest, depending on which record you're looking at. But it's really cold, really fast. You have rapid climate change that is triggered by these volcanic eruptions.

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Professor Kyle Harper (23:03)

So.

Podcast Host (23:03)

We know then, now, thanks to the science, that it was the first volcanic eruption in 536 that led to the authors like Procopius explaining that the sun seemed to disappear, and we're quite certain on that now. And also the fact that it's not this idea that the volcano covers the sun for a little bit of time and then the climate heals relatively quickly. It endures, as you said there, for a decade. So this is an incredibly significant moment. Well, for the Roman Empire and for people who lived in an agricultural world.

Professor Kyle Harper (23:34)

Yeah, exactly. And look, there's still. This is what makes science exciting. There's still things about this we don't understand. We don't really understand why. What is it about the volcanic eruption that seems in 536 to make it so prolonged? Why do they think that the sun is dimmed for a year and a half? We don't totally understand that. What is it about the double impact of 536 and 541 that sort of makes the cooling seem so severe and last decadally and even in some ways. And this is also still being very much debated. But the Tree Ring team proposed that we call this the onset of the late antique Little Ice Age. And that in fact, it's the onset of like a century and a half of prolonged cooling. That doesn't mean it like, goes to a really cold level. It just stays flat for a century and a half, but that it's generally the onset of a sort of cooler phase that really is kind of enduring. And this is certainly supported by their record, as well as some other Marine Corps records that we've worked with. And we don't understand that, and it's kind of scary. Let me give you one possibility. The climate system is really complex, which means that there are all kinds of feedbacks in the system that can absorb change, that can amplify change. And one of the main feedback mechanisms is called the ice albedo feedback. And so we all know this from walking on pavement and asphalt. Black colors absorb heat, light colors reflect heat. And this is true of the Earth's surface. If you have white, it, like ice bounces heat back off, whereas, like, deep blue absorbs the heat. And so what may happen is when you get in the Holocene, when you get more cold, if the ice sheets can expand, then it's going to reflect heat and it's going to get colder. So it's an amplification, it's a feedback that, that churns up and causes more of whatever direction it's going. And the same work, it works in the other direction, too, unfortunately, which is scary for us because as the ice sheets melt, the more heat gets absorbed, and particularly by the oceans, which is really kind of scary. And so it can, can accelerate warming, too. So it's just sort of an open question where people are trying to figure out with the models, you know, what, does it really get that much colder? Does it stay colder? Are there some of these feedbacks that are possibly active? This is one of the reasons why paleoclimatology is really important, is because it gives climate scientists ways to sort of study what happens when you force the climate system, when you play around with it. But it definitely seems like this episode of volcanic triggering really sets on, represents the onset of a. Of a colder period.

Podcast Host (26:36)

I mean, Karl, do we know how far and wide this volcanic veil almost, you know, kind of covering the sun and then leading to this great decline in climate? Do we know how large a geographic area we should roughly be talking about, is it, is it beyond the borders of the Roman Empire too?

Professor Kyle Harper (26:52)

Yeah, and this is why it matters. What I said briefly earlier, that the timing and the location, especially the latitude of the, the volcano can really matter. And so it's, to take a familiar example, the Vesuvius eruption in the Roman Empire, the first century, that buries Pompeii in the reign of Titus. It's a huge deal if you're in Pompeii and you get buried under, you get melted by the volcano. But the Vesuvius eruption doesn't seem to have a big effect on the global climate system. It takes really big eruptions to have these kinds of effects and it depends on where the volcano is. So if it's a very high latitude volcano, then the sulfur blanket that I described can circulate in the atmosphere and sort of stay in the hemisphere, whereas the tropical low latitude eruptions have a much greater potential to affect global atmosphere. And so the, the 536 volcano probably just affects the northern hemisphere, but way beyond the Roman Empire. So for the volcano to affect the climate system, it's never just like a local cloud, it's in the stratosphere and it's affecting a much broader part of the planet than just the regional area where the volcano is located. And the 541 eruption seems to have global impacts. Wow.

Podcast Host (28:27)

And let's say after the 535, 536 event, do we know how long it is before Justinian seemingly revived, seemingly stable and successful Roman Empire really starts to get put under strain? Because I presume one of the biggest things that will affect it with this great decline in climate so rapidly is the availability of food, of crops.

Professor Kyle Harper (28:53)

Right. And we have to remember that we're very lucky to live at a time where our agricultural system is very advanced. It's scientific, it's high yield, it's robust. We have integrated global markets. So if there's a bad wheat harvest in Oklahoma, we can import food from somewhere else. It's not like that in the ancient world. It's an Agricultural Society. 80% of people or more live very close to the land, are farmers. Their agricultural system is far less advanced. They have low yield crops, they're smart, they are resourceful, they know how to withstand some tension, some, some stress from the climate. That's normal. They, you know, they, they've evolved, they've adapted to be really smart within the, the technologies that they have because the climate system is always unpredictable and they're going to be good years and bad years and so they know how to store food. They know how to hedge their bets with different crops planted at different times. They know how to trade. But there are real limits. You know, your food storage runs out. You don't, you can't store years and years of food. You have to have seed for the next, for the next planting. You have to have, you know, you're competing against rot and rodents. There are limits. When the bad harvest is more than just regional, when it affects different parts of the Roman world at the same time, they can't trade because all of a sudden everybody's hungry. And so what happens is you get episodes of stress that sort of break the system, that go beyond what they're capable of withstanding. And that seems to happen in the 530s and 540s. And probably some places weather it or endure it more successfully than others. Some places are more impacted than others. But what seems to happen is real famine. It's important to underscore because this is so unfamiliar to people who have been lucky never to experience it. But a famine is when there's a food shortage that leads to not just hunger, but mass mortality. And the biological condition of a population is really deeply affected by the scarcity of food. And this is, you know, sadly, it still happens in modern times. It's mostly due to war and to misgovernance, but that's a historical change. In the past, societies were extremely vulnerable to climate induced episodes of famine. And that's what we think happens in the 530s and 540s, is that you just have a society that ultimately is confronted with the fact that all of its resourcefulness, all of its means of resilience are sort of overwhelmed by the fact that ultimately, if the sun doesn't shine and the crops don't grow, you run out of food. And when you run out of food, really bad and dangerous things happen.

Podcast Host (32:17)

Yes. Nice tee up there. Absolutely. But does this also affect. Because we did mention earlier that General Belisarius and Justinian's plans to kind of take back control of Italy and Sicily. I can imagine a large group of soldiers all together. All of a sudden, the food sources aren't there for campaigning in Italy. Can you see a real clear effect of this downturn in climate, of this advent of famine on this army?

Professor Kyle Harper (32:46)

Yeah. And just remember too, that usually the armies feed themselves first. And so we, we have to imagine that the impact is greater on the population that's getting their food taken away from them. But yes, you know, we should ask if it affects the army and then that is inseparable too, from what happens next, because armies are large groups of people that are living in usually extremely close proximity under conditions, particularly in this world, of dubious hygiene. And they can, they can take food from peasants, but in the end they're going to be just as vulnerable as the population around them when the disease shows up. And probably the bigger effect on military mobilization is the demographic impact of the. The health crisis that follows the food crisis.

Podcast Host (33:50)

Kyle, take it away. So what is this disease that breaks out once the famine is very much alive and kicking?

Professor Kyle Harper (33:58)

Our, our historical sources, which are not numerous, but include two very vivid lengthy accounts written in different languages by completely different kinds of people. If they knew each other, and it's not totally impossible that they would have been in the same room at the same times, they would have totally. They would have hated each other and had nothing to talk about. Procopius and John of Ephesus. One's a fanatic religious leader, the other's a kind of Greek cultured traditionalist writing in the style of historiography that goes back to Thucydides. So they see the world through very different perspectives, but they agree on this, that in 541 catastrophe arrived, and it came through Egypt. It probably arrived across the trading networks of the Red Sea that connected Rome to the kingdoms in what's now Ethiopia and Yemen and possibly beyond. And it works its way into the Roman Empire. And in 541, a disease starts to grip the cities of first Roman Egypt and then moving across the eastern Mediterranean, and in the following spring of 542, reaching the capital of Constantinople. And their descriptions of this disease are so vivid that there was relatively little doubt about what disease it was. Sometimes, sometimes when we read historical sources about diseases and epidemics in the past, it can be hard to identify what the disease was. In this case, we had very strong reasons to believe that it was bubonic plague, because their descriptions of it so vividly describe the characteristic symptom of this disease, which is the swelling of your lymphatic glands, what they call these bubonic swellings that affect especially the groin, but also you have lymphatic glands in your armpits, your neck, your knee, everywhere. And it's such a weird disease in terms of its symptoms that we sort of knew that this is what it was. And in the last 15 years or so, the revolutionary arrival of ancient DNA methods lets us sometimes, when you're very, very lucky, know with total certainty not from the description of the Disease, but from the. The genome of the pathogen itself recovered from the. The bodies, the skeletons, usually the dental remains of victims of the disease, using genetic sequencing to identify what the pathogen was. And we have these two different kinds of evidence. The written sources of people like Procopius and John, the DNA sources of the pathogen itself, recovered from the teeth of victims that again, cohere and tell us this was the bacterium Yersinia pestis, which is the agent of bubonic plague and is probably the weirdest disease in human history.

Podcast Host (37:30)

Why is it so weird?

Professor Kyle Harper (37:32)

Well, so down until like, roughly 100, 150 years ago, most people, even in developed societies, die of infectious diseases. So, I mean, some little microbe gets in and wins and you die. And infectious diseases are caused by microbes of different taxa, different biological categories. So bacteria and viruses are the big ones. And humans have a really nasty list of pathogens that can infect us. So think about all of the big killers of history. Malaria, tuberculosis, shigellosis, influenza, smallpox, typhus, typhoid, leprosy. All of these diseases are measles are adapted to humans. So they come from somewhere. They probably are. Most of them are animal diseases that evolve, and so they. They experience mutations in their genome that adapt them, ultimately, most of them to specialize in humans. So measles is related to a number of rodent and bat diseases. It's got close relatives that are out there circulating. It evolves. It actually first becomes a disease that can infect livestock, and then it becomes a human specialist. So it keeps evolving. Measles is a human disease. In fact, measles can't really infect animals. It adapts to the human host. Most of our diseases are like that. Most of the infectious diseases of human history are like that. They evolve and they become human diseases. Plague is weird. So for lots of reasons, actually, first of all, because it never becomes a human disease. So this bacterium that causes some of the worst outbreaks in human history, like the Justinianic plague, like the Black Death, actually is an animal disease that is adapted to wild rodents, particularly rodents like marmots and gerbils and ground squirrels. It likes social rodents that live in the dirt, and it causes these explosive pandemics among humans, but it never really becomes a human disease. It can transmit between humans, it can transmit between humans, but not for very long. It always goes back to the animals. And so that's like the number one way in which this is a weird disease is it causes some of the greatest pandemics of humans, and yet it's not a human disease. It's also weird in lots of other ways. It's a vector borne disease. So an infectious disease has to get from me to you. It's just like a basic evolutionary problem. The tuberculosis bacteria, the flu virus, has to get from one host to the next. It can do this via the respiratory route, it can do it usually through the fecal oral route, meaning it goes through the digestive tract and gets from the one end to the other and sexual transmission. So there's only a handful of ways that a pathogen can do this, but vector transmission is one of them. It's actually really hard to be a vector borne disease. We're lucky that actually only a small subset of our diseases are vector borne, meaning that they, they hitch a ride on some kind of intermediate host like a mosquito, a flea, a louse. And there aren't as many of these kinds of diseases, but they tend to be really nasty. Malaria, typhus, these are, these are diseases that figure out the trick of how to hitch a ride. And when they do that, they are often really nasty in the diseases that they cause. And plague is one of those. It's exquisitely adapted to use fleas, little blood sucking parasites as intermediate hosts. And flea borne transmission seems to be one of the keys that makes this disease the disaster that it is.

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Podcast Host (44:00)

So how does the, the cold climate and these previous disasters, how do you think they contribute then to this rapid spread of this plague from Roman Egypt and as you mentioned, beyond, so Ethiopia and the like to elsewhere in the Roman Empire and beyond so quickly within a matter of years?

Professor Kyle Harper (44:18)

Well, it's not just a good question, it's a great question and one that a lot of us are trying to sort out because this is still really new. And so I can't tell you that that's something that, that we all have figured out and agree on. And I'll tell you, it starts with the fact that we now realize that the climate catastrophe was real, that something major happened in the climate system, and then almost immediately you have an outbreak of this huge pandemic disease. And so the fact that we've now kind of deepened our knowledge of sort of the basics of that makes us realize, okay, so you have like a flash and a bang simultaneously. Maybe the flash and the bang aren't related, but they probably are. It's very unlikely that you just happen to get somebody flashing a strobe light at the same time that somebody, you know, sets off a firecracker. Right? These have to be related. You have what looks like from the tree ring records, the most severe climate anomaly of the first millennium. And what I would certainly maintain from the written records is the most severe mortality event of the first millennium. And they happen at the same time. Okay, so coincidences happen. We have to be open minded and always scientifically a little bit skeptical. But that's too big of a coincidence. There's some link and we don't know really fundamentally with certainty what it was, but we can make some, some reasonable hypotheses. And that's sort of where the, the field is. So did the climate perturbation, the climate shock, did it play some role in the, the animal part of the story? Because again, this is, remember, plague is a weird disease because it's an animal disease. It lives in wild rodents and then it spreads through what we call commensal rodents or rodents that live with humans. Like black rats. So did the plague shock affect rodents, particularly like the wild rodents? Maybe. Did the plague shock cause human groups to move? Are people starving and desperate for basic subsistence? Do they move and does that move the disease from one place to another? Quite possibly. Does the climate shock cause famine, that causes human populations to be susceptible to bad outcomes when you get infected or to greater rates of transmission? That seems very possible and it's much investigated at the moment because we need to clarify that you're getting infected all the time. Sorry to say, all of us are much less than in the past. We've gotten rid of the nasty ones. But, but the human body, particularly in pre modern times, is just constantly being assaulted. And your immune system is amazing. It's like it's. The evolution of the immune system is one of the most ingenious creations ever. And, and yet it's very expensive. Your immune system takes a lot of energy and when you don't have food, you don't have fuel, you don't have energy and your immune system becomes weaker and weaker. And this is a really fundamental ingredient of human health and some diseases, it really affects the course of events. So like I mentioned measles, the measles virus is a really good example. Measles are really nasty little virus, get vaccinated. But if you are healthy, if you're a kid, if you're a 35 year old kid and you live in the UK or America and you get lots of food and you get measles, you're probably going to live okay, again, it's a nasty disease, get vaccinated. But you're not going to die of measles. The vast majority of the time. It has unacceptably high mortality rates for us not to get vaccinated. But if your body is hungry, if you're fighting off lots of other infections, measles is deadly. And so your biological status affects the clinical outcome of that disease really, really strongly. And there's a whole spectrum. Measles is sort of at one end, your nutritional status, your biological status really affects the outcome of a measles infection. There are other diseases where your pre existing biological status is just less important. And plague is one of those. Like plague kills healthy people before antibiotics. By the way, this is a bacterial disease. Plague is still out there. You know, if you're in New Mexico, where I am, don't mess with the prairie dogs. But if you do get plague, somebody died of plague in Arizona a few weeks ago. Sadly, if you do get plague, go get treated and get antibiotics. Thank goodness we live in the 21st century. This disease that caused this huge pandemic is bacterial and it can be treated. But in the pre antibiotic era, plague is not an absolute death sentence. But it's like playing Russian roulette with five bullets in the six holes. Most people get it and die. But what we don't understand well is exactly how much the, the pre existing biological status contributes to the, to the risk of severe disease and death. Because even in plague, I mean, I don't care. It's just basic biology. If your body is strong and well fed, you've got a chance against any infectious disease, even plague. So plague is sort of at the other end of the spectrum for measles in that it's pretty indiscriminate. It kills rich people, it kills young people, it kills healthy people. But I don't care. If you're a population that's starving and you're confronted with an infection, then it's going to go worse than if you're well fed. So there's no doubt that at some level, to some extent, the climate induced famine makes these populations hungry and that makes them vulnerable. It probably helps the disease spread because if people get sick, the bacteria multiplies in them and they become more likely to transmit the disease and it makes it more likely that they'll die. So there's some link between the famine and the severity of this disease, but we're still teasing out to what extent we think that that's a factor.

Podcast Host (51:19)

Speaking of someone who's absolutely not an expert on this at all, but could it be this idea that. Yes, okay, rats may be attracted to grain pits or stores of grain, whether it's on a merchant ship leaving Alexandria to go elsewhere in the Roman Empire, or maybe the faltering grain supplies of a local village somewhere in the Roman Empire. And then all of a sudden you have that plague infected rat in the storage pit where you're getting your last bits of grain. And then all of a sudden those places where you're getting your food from, for your community is actually the place where that animal is, that is actually infecting the whole. Well, could ultimately infect the whole community.

Professor Kyle Harper (52:00)

Right. And I really want to underscore that we think that this one particular rodent, the black rat, plays a significant role in the, the nature, the transmission of the, the plague. And black rats are really weird animals. They're, you know, there's thousands of rodents in the world and there's a handful of them that have really adapted to live with humans. The house mouse, the black rat, now the gray rat. So the gray rat has sort of taken over the, the niche that used to be dominated by the black rat. But the, these things used to be absolutely everywhere around humans in a way that's kind of hard for us to wrap our minds around. And they particularly love grain. And so one argument is that the Roman Empire by its nature creates an ecology that's very conducive to the spread of this disease. So the Romans like cities. They live in a relatively, for pre modern society, urbanized world, big cities. And cities depend on connectivity to feed themselves. This is how the Roman economy works. You have large urban centers like Alexandria, Jerusalem, Constantinople, Ephesus, where you have big populations that of course specialize in all kinds of production of industry and services. And they import their food from the countryside. And in the case of Constantinople, because the population is so big, they have to import grain from Egypt. And so you have an urbanized society, you have a very connected society where there's lots of food transport, grain transport, in particular storage and movement of wheat. And what loves grain, rats. And particularly the black rat. And the black rat is also known as the ship rat. One of its names, people, you know, didn't, didn't have the same taxonomy we had. It's perfectly willing to travel in wagons, in ships. Anywhere there's grain, there's going to be rats. And so the, the Roman Empire kind of, as I said, creates this ecology. The network of grain production, storage and distribution is sort of almost designed to help the plague spread. And so there's, there's certainly an element of this tragedy where the, the nature of their society and the way that it creates this network of rodents and rodent fleas sets the stage for the pandemic.

Podcast Host (54:42)

And how devastating a pandemic does it ultimately prove to be? Whether in a city, great city like Constantinople, or maybe let's say Belisarius army in Italy. Just how devastating is it for this revived Justinian Roman Empire?

Professor Kyle Harper (54:57)

Yeah, so imagine there's like a huge room, like the size of a basketball gym, and you can sort of hear lots of noise, but you have to like look through a little keyhole. And all you can see is through this tiny little keyhole. The, the giant room is the Roman world. And the little keyhole are the two textual sources we have. We've got such a tiny little insight into what's really going on back there. And so these written texts, and in particular the two that we've talked about, Procopius And John are the keyhole. We're extremely dependent on what they tell us. And. And they tell this story through different cultural perspectives, through different media. They're writing very different kinds of texts. In fact, we don't even really know what John's text is. Very mysterious. It's hard to even know sort of what it is, but it's very vivid, very detailed. And they both happen to be in Constantinople in 542. John, interestingly, is in Alexandria when the plague arrives in 541, and he leaves and he gets to Constantinople in time for the plague to arrive.

Podcast Host (56:15)

So he doesn't bring the first rat across, basically. He's not the inadvertent patient zero or something.

Professor Kyle Harper (56:20)

No, he's probably not the vector, but, you know, and he's. He goes up the coast of Palestine into Mesopotamia for reasons we don't totally understand, and then back across the Mediterranean. So he actually sees the plague at several different junctures. He's a better witness than Procopius, just to put it in those terms. But they're both in Constantinople. That's the center of their world. It's the biggest city, it's the center of power. It's where the emperor is, it's where the culture is centered. And the plague there is a total catastrophe. And they both describe the sequence of events in the spring and into the summer in Constantinople, and they. They focus on the things that strike them. So they're struck by the pathology of the disease, the way that it affects people. They're struck by the fact that it affects rich and poor people alike. They're both very struck, really, really affected by what happens during a mass death. So the breakdown of social order. The markets stop, you can't go outside. And they're both sort of, above all, the thing that really grips their attention is the problem of burial. And there's just no doubt that the outbreak in Constantinople becomes so severe that at first there's a struggle to keep up with the problem of burying the corpses. And they build huge trenches outside the city, outside the walls of Constantinople. And they can sort of, for a time, keep up just by piling in bodies. And then in a later phase. So sometime in the course of the summer of 542, the city, the people that are alive can't keep up and they can't bury people. And so people are throwing bodies that. Just putting them in the street. They're throwing them into the. Into the sea, into the Golden Horn. And, you know, both of them pretty vividly describe this they describe, like, the bodies are just like bobbing back against the, the coast. So at some point they, they can't, like, they, they fall behind and they can't, they can't even get rid of piles of bunnies. And then in a, a third phase, sort of the Emperor who actually gets the disease but survives, orchestrates a kind of emergency operation. And they both actually, fascinatingly mention the name of the official Theodorus, the referendarius. It's kind of the Emperor's secretary of letters. It's interesting. Like, there's something about that detail. Like this is not the way it was. The Roman imperial administration isn't supposed to work this way. The Emperor is so desperate that the Emperor's secretary of letters is given bags of gold and soldiers and allowed to conscript anybody who's standing to do whatever it takes to get rid of the bodies. So you have this incredibly vivid account of what a mass death is like in a city. And they're gripped by some different things, but above all by this same challenge. So for a historian who wants to ask about the severity of this disease, the, you know, we're lucky to have the sources that we have and we shouldn't whine too much. We have this little keyhole, you know, 90% of the textual record, I'm making that up, but it's probably roughly right of the description of the plague of Justinian is focused on one city. We have absolutely no reason to think that their choice to focus on that city is because the plague only struck that city. In fact, they both say the opposite. They both say this plague struck everywhere. And John is clear, he's in Alexandria, he moves through Palestine, Mesopotamia and then parts of what's now Turkey and says it was just as bad everywhere. And the other sources that we have, as brief as they are, and there's, there's one sentence from Italy that's contemporary, that's from somebody who, who knows what's going on in Italy. We have one sentence. What do we do with it? It says there was a mass mortality in Italy. What do you do with that? It's a huge challenge and it's, it's one where we're trying to understand, we're trying to, to develop good hypotheses. And it's one where the ancient DNA is playing a really important role. Because what's so interesting about the ancient DNA record right now, among. Actually, there's many things about it that are interesting, but for the plague of Justinian or the first plague pandemic more broadly, because this disease recurs every 10, 15, 20 years for two centuries, and then it goes away until the Black Death from the Mediterranean. We don't know why, but the ancient DNA from the first pandemic is very often, or so far, what we have in most cases actually comes from little villages. So in the uk, the, the positive plague samples that have been published so far come from a village that's called Edex Hill. It's in Cambridgeshire, it's outside Cambridge. This seems to be from the first wave, so it's probably from the 540s. That's the end of the world at this time. I mean, this is as far really as you can be from Constantinople, geographically, socially. Edexel is a village of. I forget we have an estimate. It's like a hundred people. It's the opposite of the metropolis. It's a tiny little village in the countryside on a kind of back road in Cambridgeshire. If the plague made it there, that doesn't mean that it made it everywhere. We don't know enough to say that yet, but it certainly means that it could make it anywhere. If it made it there, it was capable of getting anywhere. And so we're filling in this, this huge gap in our knowledge where we can't see, but we're now starting to get these little clues from, from ancient DNA that are very powerful, among other reasons, because they come from places that are so different from Constantinople, where we have our, our written sources.

Podcast Host (63:12)

It's amazing how far and wide it spreads. And I guess that example highlights that. Yes, the plague of Justinian stretched much further than the territories that Justinian directly controlled. Right, Carl, this has been absolutely fascinating. You also highlighted there this idea that this was the first wave in the early 540s. Does it seem like you have this brutal first wave at this time, when the climate is lower, goes away for a bit, maybe when the climate recovers, but then comes back again and again and again at intervals again.

Professor Kyle Harper (63:46)

Yeah. And this is another place where it's worth underscoring that we can learn from the Black Death and what's called the second plague pandemic, because the Black Death isn't a one off. And one of the reasons why the Black Death is significant isn't just that it's so bad and it kills like half the population and huge parts of Western Asia, North Africa and Europe, but that it's the beginning of an enduring pandemic in which the disease keeps striking. And so as bad as the Black Death was, even the Black Death, if that had Just been a one off. The populations recover. These are high mortality, high fertility societies. They can come back, they start having babies, and they. They can build back. But Wham, again in 1361. And then again and again and again, you get this just powerful disease that keeps striking. What's interesting about the plague in the second pandemic is we really. This is debated, and it's been heavily debated, but I think we're getting close to really, really saying there's a right answer here, is that the plague doesn't keep coming from Central Asia, at least not every time. The plague is an animal disease, and when it arrives in the Mediterranean and Europe, it kills humans, but it's also moving through animals, and it can move around in animal populations, and it probably finds new rodent reservoirs, new wild rodents where it lurks, and then it moves back into human populations. Personally, I think that's what happens in the first pandemic as well. The plague of Justinian comes. Whoomp. It's this disaster that strikes in 541, 542 and on, and then it goes away for about 10, 15 years, but it doesn't go away completely. It's got to be somewhere. The bacterium is lurking, it's circulating in animals, probably in wild rodents somewhere in the broader Mediterranean world, and then it spills out into human populations, and we don't know why. It looks to me this is. Even some of this is unpublished. There's like a very striking correlation between little episodes of climate change, even within the first pandemic, and the outbreak of disease. But we don't know enough to really say what's going on. We do know that the. It's not just. It's like the Black Death. It's not just the Black Death that matters. It's not just the plague of Justinian that matters. It's the. The fact that this disease gets into this. This world, which is a human and animal world, and keeps moving around for over two centuries, and then it goes away.

Podcast Host (66:39)

Kyle, this period in history is often seen as like, cusp. On the cusp of the end of antiquity and the beginning of the Middle Ages. How big a turning point would you argue that? And I guess we say these disasters, if we also include the volcanic eruptions beforehand. How big a turning point in history is this? Could it actually be at this time that you could have the fall of ancient Rome as it was, and the beginning of the early Medieval Roman period?

Professor Kyle Harper (67:08)

Right. I mean, these are our terms, not theirs. They don't say, you know, now we're The Byzantine Empire and it's the Middle Ages. But we use these ideas to help us sort out the balance between continuity and change. I mean, if you want to say that the Byzantine Empire is the Roman empire down to 1453, because they call themselves Romans, absolutely down to that point, you, you have an argument. I mean, you know, the Kaiser calls himself Caesar, but, but I'm not sure that it's, it's really the Roman Empire. So we need, you know, we need tools that help us think about the balance between continuity and change. And there's something, of course, it's our artificial imposition of this chronology to say this is the ancient world, this is the medieval world. But I think that the period from the later part of Justinian's reign down to the third or fourth decade of the seventh century. So you have this, it's not just like a one off. You have this period from the 540s to the 630s, 640s. I think you can defend the view that that's the twilight of an ancient world, that the Justinianic Empire is really a version of the Roman Empire in a way, that by the late 7th century you're in a very different world, the Romans. And this doesn't all happen in the reign of Justinian, but the reconquest stalls and so it doesn't completely falter. But what happens is towards the end of Justinian's reign, in fact, a new group, the Lombard people, invade Italy and just sort of take much of what Justinian had reconquered. So his project stalls and then is slowly reversed. And you can see the Roman Empire struggling, struggling with the same level of military manpower. You can see that cities in many cases are struggling. There's less population, there's less tax base, there's fewer people to recruit the army from. And again, the Roman Empire doesn't just collapse in one fell swoop. But this is a moment, this is a turning point, as you put it. I would say that's a good way to think of it, that over the next century, and also in part because of the recurrence of both climate stress and health, catastrophe witnesses really profound, lasting and meaningful change. And I think this sort of culminates in the crisis of the seventh century in which the Roman Empire loses the most valuable, prosperous, significant remaining parts of the empire. The world of Mesopotamia, Syria and Palestine, Egypt and North Africa are just taken in the space of a few years, quite remarkably by the nascent Caliphate.

Podcast Host (70:09)

This idea that this returning bubonic plague has weakened the Roman Empire. So it's really, really interesting to end on that point. Carl, it has been fascinating to get you back on the podcast. Last but certainly not least, you have written a book which covers this and so much more.

Professor Kyle Harper (70:24)

It is called the Fate of Climate Disease and the End of an Empire, Prince and University Press, 2017. So it's already, it's already eight years old. A lot has happened since then, but, but it at least tells a version of the story that, that we've been talking about.

Podcast Host (70:37)

Absolutely. We, we still happily promote it here on the Ancients.

Professor Kyle Harper (70:40)

Always.

Podcast Host (70:41)

Carl, it just goes me to say thank you so much for taking the time to come back on the podcast.

Professor Kyle Harper (70:45)

It's a pleasure. Anytime. Thank you.

Podcast Host (70:50)

Well, there you go. There was Professor Kyle Harper talking you through these devastating years in the mid 6th century A.D. the plague of Justinian, the climate change, volcanic eruptions and so much more. And whether this was the worst period ever in human history. I hope you enjoyed the episode. Thank you very much for listening. Please follow the Ancients on Spotify or wherever you get your podcasts. It really helps us. You'll be doing us a big favour. Don't forget you can also leave us a rating as well. And if you do well, we'd really appreciate that. You can also listen to us and all of History Hit's podcasts ad free and watch hundreds of TV documentaries when you subscribe@historyhit.com subscribe that's enough from me. There is still one more episode to go in our Great Disasters miniseries and that is coming very soon.

Professor Kyle Harper (71:49)

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