Professor Kyle Harper
Appearances
The Ancients
Did Plague Destroy the Roman Empire?
And we really are trying to understand what causes these really, really big pandemic events. It does often seem to be an alignment between a lot of things going wrong at the same time.
The Ancients
Did Plague Destroy the Roman Empire?
Exactly. I mean, that's a hypothesis. And I think it's one that's pretty persuasive and has some strong evidence behind it. Start with the Roman warm period, or sometimes it's increasingly called the Roman climate optimum, which is a name for a climate period that maybe goes from like the late Republic to the apex, the Pax Romana, the first and second century.
The Ancients
Did Plague Destroy the Roman Empire?
It's a name for this climate period that was created by the climate people, not by the Roman history people who were sitting there looking at tree rings and ice cores and And observe that in a number of different paleoclimate records, that there's a pretty long phase of three, four centuries where it's relatively stable, where there's relatively few major forcing events.
The Ancients
Did Plague Destroy the Roman Empire?
And we can maybe come back to what causes climate variability. climate forcing mechanisms do. And these include, among other things, volcanic eruptions, which are a very powerful short-term mechanism of climate change. And they're really interesting in lots of different ways. They're interesting historically, they're interesting for understanding the earth system and how the climate system works.
The Ancients
Did Plague Destroy the Roman Empire?
But volcanoes are like this really powerful thing. And I don't mean like the Iceland volcano that dribbles out smoke and disrupts some air travel. As significant as that is, every century or two, even Vesuvius that erupts in the first century and buries Pompeii and Herculaneum is not a big eruption.
The Ancients
Did Plague Destroy the Roman Empire?
It's really big if you're in Pompeii and you're broiled to death, but it doesn't cause the global climate system to wobble. Whereas the big eruptions of 536 and 540 In this Roman climate optimum period, you have three or four centuries where there's only one really, really big eruption. It's aligned with the death of Julius Caesar. One doesn't cause the other unless you're like a
The Ancients
Did Plague Destroy the Roman Empire?
polytheist and think that Vulcan was mad about the assassination or something. It's just pure coincidence. But you have this really long phase where you don't have big volcanic eruptions, where it looks really relatively stable. It is warmer in core parts of the Mediterranean.
The Ancients
Did Plague Destroy the Roman Empire?
And so you do have this kind of background of stability, which arguably creates a kind of condition of favorable climate, of prosperity, of agricultural productivity. This is a farming society. Even in the Roman world, 80% of people at least are working in agriculture. They're very dependent on the immediate climate context.
The Ancients
Did Plague Destroy the Roman Empire?
It has to be warm enough for the growing season to enable crop growth, and it has to be wet enough, but not too warm and not too wet. The Roman climate optimum seems to be this phase where you have a relatively stable climate, which probably means a relatively stable food supply, which probably means a population that's relatively able to contend
The Ancients
Did Plague Destroy the Roman Empire?
by pre-modern standards with the pool of infectious diseases that are out there. And then there may be elements of luck. I mean, this is one of the things that's most fascinating about this is that history involves, you know, you've got to be lucky and good if you want to build a stable empire. And there is just this pure element of contingency of luck that comes into history.
The Ancients
Did Plague Destroy the Roman Empire?
Well, again, to go back to our very first line of conversation, It's always both the human and the natural. So there are really important human factors.
The Ancients
Did Plague Destroy the Roman Empire?
There's important things going on inside Roman society, inside the way the empire works, inside the relation between the center and the periphery, between elites and workers, geopolitically, between the Romans and the peoples across their frontier, especially across the northern frontier.
The Ancients
Did Plague Destroy the Roman Empire?
So the only question is whether those are sufficient to explain what happens, because it's not like the Romans had never faced civil conflict. In the first century, they absolutely do. I mean, in 68, 69, the empire breaks down. The system for controlling power totally melts down. And yet... The empire doesn't fall apart. It doesn't split into permanent pieces. It pretty quickly heals.
The Ancients
Did Plague Destroy the Roman Empire?
The year of the four emperors after the forced suicide of Nero, where there's no script for how you change dynasties and it's settled by force. And these kinds of conflicts are sort of at some level, always there. But you could definitely argue in the second century that there are new kinds of pressures, particularly geopolitically.
The Ancients
Did Plague Destroy the Roman Empire?
But now I think we know enough to say that there are strong clues that we ought to consider the contribution of other factors as well. So two things that I would submit we ought to think about. One is that over the second century, it's now really beyond question that the climate becomes more unstable. It doesn't mean it's necessarily going from good to bad.
The Ancients
Did Plague Destroy the Roman Empire?
It's not quite that simple, but it's going from relatively good and relatively stable to more unstable and probably more challenging if you're a farmer. in poor regions of the Roman Empire like Italy.
The Ancients
Did Plague Destroy the Roman Empire?
And so the hydroclimate, the sort of rainfall patterns which are really important for farming, they're also really complicated and they're always kind of variable and on the edge in the Mediterranean where it's arid, where water scarcity is a sort of constant concern for farmers. But in the mid to late second century, the indications are that the climate just starts to wobble more.
The Ancients
Did Plague Destroy the Roman Empire?
And I think that there's probably food shortage, even if it's not quite outright famine in the way we might see later. And that's now attested in tree rings, in marine cores, to some extent in ice cores where we do see volcanic eruptions becoming a factor again.
The Ancients
Did Plague Destroy the Roman Empire?
So this particularly is building, you know, over the decades leading into the reign of Marcus Aurelius, but then from like the 160s and 170s, it seems to become more acute. Simultaneously, so leave aside any causal links, but just observing that at the same time in the 160s, there's a pandemic.
The Ancients
Did Plague Destroy the Roman Empire?
Just unambiguously, for the first time in centuries, there are dozens of indications from all corners of the empire that simultaneously there's an outbreak of infectious disease that people perceive as something different. So it's not just sort of the ordinary disease. background stew of diseases. It's not even sort of the ordinary, just a bad year, right? The Romans, again, they have bad years.
The Ancients
Did Plague Destroy the Roman Empire?
There are epidemics every 10 years, every 5, 10, 20 years. There's dying. That's the nature of the world in a society where infectious diseases are dominant. This stands out. This is absolutely different. In the written record, you have people from all different languages, different ideologies, different genres, who talk about what we call the Antonine Plague.
The Ancients
Did Plague Destroy the Roman Empire?
The Antonine dynasty is in power, and we call it the plague. Plague is a really bad term for it, actually. Plague is kind of an annoying word in English because it's ambiguous. Plague can either just mean pandemic or outbreak of disease or pestilence.
The Ancients
Did Plague Destroy the Roman Empire?
The plague also sometimes implies the specific disease of bubonic plague, the plague, the disease that caused the Black Death, the disease that caused the Justinianic plague. It's caused by a specific bacterium called Yersinia pestis. It's a totally fascinating bacterium. But the Antonine Plague is not the plague itself. It's just, we should call it the Antonine Pestilence.
The Ancients
Did Plague Destroy the Roman Empire?
But we don't think it was caused by the plague, the bubonic plague. It's not totally impossible and like, We should always have a little skepticism in our mind about how much we know about these ancient pandemics. But we don't think it was the plague. So we should call it the Antonine Pestilence.
The Ancients
Did Plague Destroy the Roman Empire?
And whatever caused it, it was highly alarming to people all over the empire who describe significant mortality. And this is a society where they're used to a lot of people dying. And this stands out somehow to their experience, to their background. So simultaneously... You've got the human things going on.
The Ancients
Did Plague Destroy the Roman Empire?
So you have tribes across the Rhine and Danube that seem to be sort of coalescing into bigger confederations that are more capable of confronting the Roman frontier defenses in an organized and dangerous way if you're a Roman. That is, of course, going to put pressure throughout the system because the Roman frontier system isn't designed as a wall. It's designed as a kind of...
The Ancients
Did Plague Destroy the Roman Empire?
hegemonic zone where the Romans can optimize the threat of what's really not a huge, huge army relative to the territory size. Soldiers are expensive. Somebody's got to pay for them. Somebody is provincial farmers. So if you've got more geopolitical pressure, you need more troops. And if you need more troops, you're going to have to recruit them from farms. You're going to have to pay them more.
The Ancients
Did Plague Destroy the Roman Empire?
And that certainly is what happens in the second half of the second century is they have to pay the army more. They have to raise taxes to do it. So these human factors start to reverberate throughout the system. But now we see that's not all that's going on. So while they're struggling and
The Ancients
Did Plague Destroy the Roman Empire?
as a system to maintain the dominance that they have, as the price of that goes up, as that's felt on the ground by taxpayers and farmers, at the same time, you have a disease that's killing more people and you have a climate that's making it harder to grow wheat. And it's the concatenation of those factors that makes the second century different.
The Ancients
Did Plague Destroy the Roman Empire?
There'd been dynastic upheaval, civil war before, but now you have it in a context where you have all of these pressures at the same time.
The Ancients
Did Plague Destroy the Roman Empire?
This is a really interesting and still a little bit open question. We're always interested in where do pandemics come from? We've seen in our own worlds how political and tricky those kinds of questions can be. And it's really not so different. The Romans are curious, where does this
The Ancients
Did Plague Destroy the Roman Empire?
come from they they tend to perceive disease through different lenses often at the same time religiously so pestilence is sent by the gods usually by the god Apollo and he's mad because the Romans aren't
The Ancients
Did Plague Destroy the Roman Empire?
showing sufficient respect they aren't keeping the peace with the gods maybe it's Christians that are upsetting the gods we can throw a few of them to the lions and see if that will stop the plague they also think of it in terms of I mentioned miasma, this idea that the air can be corrupted and the pollution can sort of spread through the air.
The Ancients
Did Plague Destroy the Roman Empire?
They don't have our sense of germ theory, but we do have contemporary and later sources that reflect that. different beliefs about where this plague comes from. And clearly, one of the hypotheses that gets thrown around in the Roman world is that it comes back from Parthia with the armies of Ovidius Cassius and Lucius Verus were coming back from the east. In my view, look at COVID.
The Ancients
Did Plague Destroy the Roman Empire?
We have millions of brilliant scientists, and there's still honest disagreement about the origins of the virus. In the ancient world, we have only a handful of sources. Many of them are indirect or come from later versions of the story in a world where they don't understand infectious disease. So it's very hard to actually piece together.
The Ancients
Did Plague Destroy the Roman Empire?
And it's made more difficult by the fact that we don't know what the pathogen was. It's super frustrating for me, for a lot of us who work on this period. We want to know what caused this pestilence. And trust me, we're looking like
The Ancients
Did Plague Destroy the Roman Empire?
the we collectively including myself like we're trying to find bones if you have a mass grave if you're listening to this and you have a bunch of skeletons from the second century call me people have looked we've looked and we may find out we may get a hit in the lab but there's not a huge number of really obvious second century mass graves that's part of the problem so there's not a ton to work with and it may be a path that it takes a lot of luck to get
The Ancients
Did Plague Destroy the Roman Empire?
the DNA of pathogens. It has to be present in the blood in high concentration when the person dies. Their body has to be preserved in a burial environment where the DNA doesn't degrade too much. And it has to be a pathogen whose DNA you can get. So if it's a single-stranded RNA virus, there's a very good chance we'll never get it. So without knowing what disease it was, you can't say
The Ancients
Did Plague Destroy the Roman Empire?
very much about the evolutionary history of it. You can't say this probably came from this evolutionary family tree. So it's a little bit hard to root. But I do think that it's quite possible that the perception that the army is spreading the disease reflects some kind of genuine observation that At the very least, armies concentrate lots of people. They move around.
The Ancients
Did Plague Destroy the Roman Empire?
And so even if there's probably a little bit of invective, like this is probably a way of criticizing the memory of Ovidius Cassius, who later revolts against Marcus Aurelius and goes down in the annals of history as a bad guy. So I'm a little bit skeptical about some elements of it, but probably the Roman army catches this contagion
The Ancients
Did Plague Destroy the Roman Empire?
and when it demobilizes after the campaign's in Parthia, is a vector for the transmission of the disease to other provinces of the Roman Empire.
The Ancients
Did Plague Destroy the Roman Empire?
Well, in the middle of the 3rd century, first for the bigger context, The Roman Empire does melt down. And my colleague, the Roman historian, Walter Scheidel, has called this the first fall of the Roman Empire. I love that framing because I think it jars us into thinking about this the right way. The Roman Empire falls. middle of the third century.
The Ancients
Did Plague Destroy the Roman Empire?
It's actually weirder that it's put back together. And when it is put back together, it's a really different empire. I would say 268 is the year of the new empire that lasts down to the early seventh century. It's a second Roman empire. It has a totally different kind of emperor. Most of the emperors from Julius Caesar and Augustus to Decius, are sociologically of the same type.
The Ancients
Did Plague Destroy the Roman Empire?
They come from wealthy Mediterranean senatorial families who work through the imperial system where the senatorial elites serve as military commanders as part of their careers. They're socially pretty similar. They geographically come from different places, but they're all kind of Mediterranean. Even the Spanish emperors are kind of really Italian Mediterranean emperors and so on.
The Ancients
Did Plague Destroy the Roman Empire?
And they represent kind of an urban elite social stratum. From 268, most of the emperors come from a tiny little region, mostly in what's now Serbia, the bend in the Danube. These are not wealthy Mediterranean senators. These are career soldiers.
The Ancients
Did Plague Destroy the Roman Empire?
They're mostly career cavalry officers, people like Claudius Aurelian, and then ultimately Diocletian and Constantine, who very much come from this social stratum. The Roman Empire has taken over by Serbian cavalry officers who run the show for the whole rest of the way. And there's only real weird exceptions, like the Theodosian dynasty, which is sort of the exception that proves the rule.
The Ancients
Did Plague Destroy the Roman Empire?
But they change the geography of empire, the social dynamics of empire. Rome ceases to be central at all. People like Diocletian It's not totally obvious he goes there before the 20th year of his reign. It's still a culturally symbolic capital, but they say, just screw it. We're going to rule the empire from Trier and Sirmium and eventually Constantinople.
The Ancients
Did Plague Destroy the Roman Empire?
And they changed the money system from silver to gold. And eventually they say, we really need some new gods too. Maybe Sol. Nah, let's go. There's this even cooler god and we're going to try him out. So they change everything about the empire. It's a totally different empire. So what happens? Between 251 and 268, These are some of the most transformative years in Roman history.
The Ancients
Did Plague Destroy the Roman Empire?
The Roman Empire melts down. It's this comprehensive crisis. There's a financial dimension where the silver coinage, which had a large fiduciary element, the Roman emperors had gotten away with debasing it without the price scale getting totally out of whack. And eventually they go too far. And for whatever reason, the money system really collapses. So there's a financial, economic element to it.
The Ancients
Did Plague Destroy the Roman Empire?
There's a geopolitical element. You not only have Goths crossing inside the Roman Empire, and they're clearly organized, they're clearly dangerous, they're capable of, they confront Decius. a Roman emperor leading the legions into battle and kill him. And that's something new and different.
The Ancients
Did Plague Destroy the Roman Empire?
And at the same time, to make matters worse, you have a revanchist Persian regime that's pretty aggressive, that takes power on your eastern frontier. So you now have a totally new level of geopolitical threat. So you have financial breakdown, you have geopolitical change, you have a complete collapse of dynastic legitimacy. This is why we have over 20 emperors in a 20-year period.
The Ancients
Did Plague Destroy the Roman Empire?
And all of the trouble that that entails, including ultimately fragmentation of the empire into three empires, the empire of the Gauls, the empire out of the East, and the sort of core empire in the Mediterranean and Italy. The Roman Empire should have totally come apart. And in that mix, there's a pandemic. And it's a pandemic that's been far too neglected.
The Ancients
Did Plague Destroy the Roman Empire?
It's not by any means the sole cause of this total meltdown. And in fact, the causal arrows go both ways. I think that the pandemic doesn't cause the crisis, but the crisis also aggravates the pandemic. Society's that are unable to respond to problems seem to suffer the biggest consequences of pandemics. When you can't feed your population, then you're more vulnerable to an explosive pandemic.
The Ancients
Did Plague Destroy the Roman Empire?
But there is a pandemic. It's called the Plague of Cyprian, which is named after the Bishop of Carthage. I don't know that he would want his name associated with the plague because he didn't cause it. He just happened to write a sermon that happened to get preserved, that happens to be one of our lengthier descriptions of it, and so we call it the Plague of Cyprian.
The Ancients
Did Plague Destroy the Roman Empire?
But in fact, there's dozens of testimonies to this disease outbreak from what is actually maybe the darkest period of Roman history in terms of its obscurity to us. There are times during these decades where there are people we're not totally sure if they were emperor or if they're made up. That's how bad it is.
The Ancients
Did Plague Destroy the Roman Empire?
There's a lot we don't know about this period where we lack basic facts about emperors and battles and the elites. And yet we have dozens of witnesses to this pandemic event. It was clearly, again, something that really stood out. It caused a very nasty, severe disease that they describe. It's disappointing. We don't know what it was. This is another one.
The Ancients
Did Plague Destroy the Roman Empire?
These two have not yet been unlocked by laboratory identification. We're trying. We're trying right now. So we may figure this out. But whatever it was, it was perceived to be a major factor in the troubles that afflicted the Roman Empire. So the plague, and again, we should call it the plague of Cyprian, but it's not really the plague.
The Ancients
Did Plague Destroy the Roman Empire?
It's just a pestilence of the 250s that seems to show up about 251. That's been something I've changed my opinion a little bit about because of some work of others, that the plague probably shows up around 251. It's a little obscure when it shows up. The only contemporary source we have that comments on its geographic origin says it comes from Ethiopia, which is tricky because
The Ancients
Did Plague Destroy the Roman Empire?
The classical Greek historian Thucydides describes the plague of Athens going back to the 5th century BC as coming from Ethiopia. And since everybody wants to be Thucydides, if you're a historian, he's like the Michael Jordan of historians. He's like the best of all time. And so everybody imitates him.
The Ancients
Did Plague Destroy the Roman Empire?
So we never totally know when somebody says something that Thucydides said, if it's reliable or if it's just imitation, but it's our only claim for the geographic origins. But when it gets to the Roman Empire, it spreads everywhere. Latin sources, Greek sources, Christian sources, pagan sources, all describe it as something extraordinary.
The Ancients
Did Plague Destroy the Roman Empire?
And it certainly contributes to this phase of crisis that I think we should rightly consider the first fall of the Roman Empire.
The Ancients
Did Plague Destroy the Roman Empire?
Right. I mean, I think more of the latter. We don't have evidence for major pandemics. There's certainly epidemics. There's certainly this sort of not only the normal stew, but the sort of like normal variation in the death rate where there are going to be bad years.
The Ancients
Did Plague Destroy the Roman Empire?
We have literary sources that describe years when there's higher levels of mortality from disease, but there's nothing like the plague of Cyprian where all of a sudden in the record, you have dozens of testimonies and nothing like the plague of Justinian in the sixth century, which is the granddaddy of them all. And yet the fourth century is the most richly documented period of antiquity.
The Ancients
Did Plague Destroy the Roman Empire?
This is something that's sometimes underappreciated. But the fourth century is the most well-documented period of the entire ancient world. And there's various reasons for that. The most...
The Ancients
Did Plague Destroy the Roman Empire?
powerful one is that with the conversion of Constantine to Christianity, you have the rapid spread of the faith and you have the sudden entry into what had been theretofore a minority religion of a highly educated elite. And so this is the social background of
The Ancients
Did Plague Destroy the Roman Empire?
the fourth century church, where you have people like Gregory of Nyssa, Basil of Caesarea, Gregory of Nazianzus, you have Ambrose of Milan, who's been a governor, and you have Augustine. And so for about a century, you have the entry into the church during a really formative phase when orthodoxy is sort of being finalized and there's still a lot to fill in.
The Ancients
Did Plague Destroy the Roman Empire?
You have these incredible people who are there in this century, and they become the fathers of the church. Their writings that fill out Trinitarian Orthodoxy have a huge impact in both the Greek, the Eastern tradition, and in the Latin West. Their writings are abundant, and they're preserved. We just have masses of material.
The Ancients
Did Plague Destroy the Roman Empire?
I wrote my dissertation long ago on slavery in this period, and there are hundreds of thousands of references to the slaves in the fourth century. You can write about the realities of life in the fourth century in a way you can't for any other period. The sermons of John Chrysostom, a priest of Antioch and one-time bishop of Constantinople, fill shelves. They're incredibly rich and vivid. So
The Ancients
Did Plague Destroy the Roman Empire?
All that's a little bit of a long way of saying, yes, there's recovery in certain ways. And if there had been a plague of Justinian-like pandemic that had wiped out some huge portion of the population, we would be more likely to know about it in the century after Constantine than any other period of the past. We know it in a level of detail that we don't know any other century of antiquity.
The Ancients
Did Plague Destroy the Roman Empire?
And there's nothing. There's nothing like the plagues of the second, third, or sixth century. There's some big outbreaks. There's clearly an outbreak in the 311, 312, and parts of the Eastern Mediterranean. There's some spikes in the death rate that are probably pretty serious. If you're a victim of them, they're nothing to minimize.
The Ancients
Did Plague Destroy the Roman Empire?
but nothing really of the scale and certainly nothing of the consequence that sort of has these cascading consequences where it sort of knocks out a pillar of the system and then things start to crash. We just don't have that in the fourth century.
The Ancients
Did Plague Destroy the Roman Empire?
Right. And this is a very, very active area of research. It's one that I think is interesting and I'm still open-minded and I'm kind of excited to see what we learn in the next 10 years or so. A lot of this is very difficult. I would even separate the Goths and the Huns. The Goths
The Ancients
Did Plague Destroy the Roman Empire?
are a difficult people group to study because we're so reliant on archaeology, but there's lots of it and it's very good archaeology and we know a lot. So I wouldn't understate the challenges, but I would also emphasize that we've learned an incredible amount. Whereas the Huns are just next level difficult to understand. We don't We struggle to know who they are.
The Ancients
Did Plague Destroy the Roman Empire?
They play a major role in history, although even that has been contested, whether or not we exaggerate it, whether Ammianus Marcellinus, the contemporary historians going to the 4th and 5th century are exaggerating the role of the Huns. So the difficulties are hard to overstate. There's archaeology, but it's more difficult. They're a nomadic group.
The Ancients
Did Plague Destroy the Roman Empire?
They're harder to pin down in every way archaeologically. They're culturally adaptive, so they clearly at times are allied with and integrating their society with Germanic groups beyond the Rhine and Danube. And so it's very difficult to piece together who are the Huns? What's their real role in history? Much less than to go a level even deeper, which is to
The Ancients
Did Plague Destroy the Roman Empire?
to try and understand causally what causes them to show up. Why are they a formidable challenge in the 4th and 5th century? But I think you can certainly start to build a really plausible case that nomadic groups are dependent on the grassland, on the steppe, for their herds. They can move great distances very quickly. This is what they do.
The Ancients
Did Plague Destroy the Roman Empire?
And they benefit from climate conditions that allow the basis of their wealth, their economic system to multiply and flourish. And so, you know, I think that we need to try and tease out like what's going on on the step. Are there phases when probably there's population growth because there's economic strength?
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Did Plague Destroy the Roman Empire?
Are there phases where there's economic challenge because there's, say, extreme aridity? And then do these change over time? And there's increasingly pretty good evidence.
The Ancients
Did Plague Destroy the Roman Empire?
Some of it, too, like we lean on comparison with the study of Central Asian step groups in the Middle Ages, the late Middle Ages, even early modern times, where we have sometimes better data, where there's a pretty strong case to be made that there's a climate link to things like population growth and migration patterns.
The Ancients
Did Plague Destroy the Roman Empire?
So when we go back to the fourth century, we can at least have that model in the back of our mind to develop ideas and hypotheses. But I think it's certainly possible that one of the drivers of migration in the later fourth century is climate variability. And I do think there's a very strong case to be made that
The Ancients
Did Plague Destroy the Roman Empire?
that a big part of the story of the Roman Empire is what's going on across the frontier in the trans-Denubian world. And that in my view, the sort of new Roman Empire created by Ecclesian, Constantine, and others, you can certainly make a case that it's sort of doomed to fail. It clearly has its structural weaknesses, but so did the earlier Roman Empire. I think that's kind of
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Did Plague Destroy the Roman Empire?
a lack of imagination and taking seriously the possibilities or the counterfactuals. The empire also had a lot of strengths and it got really, really unlucky.
The Ancients
Did Plague Destroy the Roman Empire?
And somewhere in the interplay of those structural weaknesses and the problems that grew and grew in the form of geopolitical pressure, the Roman empire cracks in ways that ultimately do divide it and then lead to this thing we call the fall of the Roman empire.
The Ancients
Did Plague Destroy the Roman Empire?
Yeah, I mean, certainly that's happening at some level. It's just inevitable. When people move, they encounter different environments, they encounter different microbial pools. I will say one of the really surprising things has been the sort of big global history comparison. The Black Death, which is the giant plague at the end of the Middle Ages,
The Ancients
Did Plague Destroy the Roman Empire?
is definitely facilitated by things that are going on on the steppe by Mongol takeover, the disruptions that follow that, then the networks of trade and conflict that connect Central Asia to Eastern Europe, the Black Sea. The Black Death comes across the nomadic world The plagues of late antiquity, so far as we can tell, seem not to, which is interesting.
The Ancients
Did Plague Destroy the Roman Empire?
The plague of Justinian in the 6th century, which is the plague, it's bubonic plague, Yersinia pestis, it does come from Central Asia. We know the evolutionary origins of the plague lie in a pretty specific region. It's right at the intersection of Kazakhstan, Kyrgyzstan, and Western China, Xinjiang. Somehow, this bacterium doesn't have legs. It can't walk.
The Ancients
Did Plague Destroy the Roman Empire?
Something carries it, animals and people. We're piecing together, but I believe that this plague actually doesn't come across Central Asia. It actually goes down through South Asia and comes across the oceans And for whatever reason, it actually seems like the Indian Ocean world is a bigger network for the movement of all kinds of things in the Roman Empire.
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Did Plague Destroy the Roman Empire?
Ivory, spice, silk, wine, gold, coral, all kinds of interesting things moving around the Indian Ocean, but this includes pathogens. I think we didn't know this until recently, really, that in fact, the kind of step as far as we can tell, seems not to be the main conduit. And that in itself is kind of this interesting comparative point that contrasts with the late Middle Ages.
The Ancients
Did Plague Destroy the Roman Empire?
Yeah, I think so. We're still debating, for instance, how do we think about the aftermath of 476. It's a huge date. It's not just symbolic. I mean, it is. It's symbolic. I mean, because we've all taught a history survey course, and you've got to give your students a date when the empire ends to put on the final exam, and 476 is a convenient one.
The Ancients
Did Plague Destroy the Roman Empire?
So it's a handy symbol, but it's clearly more than that. There's real underlying political change. But one of the things we still debate is, let's think about the 50 years that followed that. Is that a period of recovery? Is that a period of decline? This more or less Ostrogothic phase between the
The Ancients
Did Plague Destroy the Roman Empire?
the deposition of the last Roman emperor and the recovery of the Roman empire by the Eastern Rome under Justinian that takes back the Italian peninsula. And count me among the people who think that there may even be some kind of modest stabilization after 476 that the empire wasn't doomed to fall apart, and that even Justinian's reconquest wasn't a totally doomed effort from the beginning.
The Ancients
Did Plague Destroy the Roman Empire?
I think 476 is a handy date, it's a real enough moment And yet the real falls of the Roman Empire, I would date to the 3rd century crisis and then to the 6th century crisis.
The Ancients
Did Plague Destroy the Roman Empire?
Yeah. I mean, I think the third century is a period of crisis and transformation. And what you get in the aftermath of that is something really structurally different. And this structurally different empire then lasts for a really long time. I mean, it in some ways is really as long lasting, if not even slightly longer than the time period between Augustus and Decius.
The Ancients
Did Plague Destroy the Roman Empire?
And so we need to think about it on its terms. It's clearly something that is structurally stable enough to prove really, really enduring. And so we have to ask why, you know, I think we shouldn't see that its sort of fate was sealed from the beginning. And we need to be able to imagine alternatives in which
The Ancients
Did Plague Destroy the Roman Empire?
If the Huns hadn't invaded, or if the Goths hadn't been such a formidable force, or if there hadn't been a devastating change in the climate and pandemic disease, history could have been very different. And the second Roman Empire lasts a very long time, but it could have even lasted longer than it did.
The Ancients
Did Plague Destroy the Roman Empire?
Well, I hope we do debate it for ages and it keeps historians employed. But the exciting thing to me is that we don't have to just debate it with the same evidence, with the same data sets, with the same texts. We can now... read Ammianus Marcellinus, but we can also look at what does tree rings in Central Asia or the Alps tell us about the world in which these people lived.
The Ancients
Did Plague Destroy the Roman Empire?
So we can keep debating it, but we should also try and get new clues to piece together the past.
The Ancients
Did Plague Destroy the Roman Empire?
The Fate of Rome, Climate, Disease, and the End of an Empire. 2017, which is already a long time ago in this world, but it certainly touches on many of these themes.
The Ancients
Did Plague Destroy the Roman Empire?
We're familiar with the human factors. It's easy for us to relate to. And I'll be the first to insist that the human factors are enormously important, from the character of individual leaders to the sort of random fate of individual battles that can really turn the course of history one way or the other. So to me, it's not an either or. Those factors are really important. They still matter.
The Ancients
Did Plague Destroy the Roman Empire?
But I think we now have new insights, new data, new ways of thinking about the past that previous generations of historians didn't have. And One of the really important and exciting things that these new kinds of archives have told us is that the environment in which human societies operate is a really important factor.
The Ancients
Did Plague Destroy the Roman Empire?
And climate change, sudden changes in health, in the arrival of infectious disease, of pandemics, have had also a really significant effect on the course of human history.
The Ancients
Did Plague Destroy the Roman Empire?
There's no single technology or innovation that's really responsible. In fact, you could trace the way that archaeology for the last several generations has been really empowered by laboratory science, by radiocarbon, by chemistry. But over the last 20 years or so, there have been, I would say, two really important changes. One is the proliferation of paleoclimate data.
The Ancients
Did Plague Destroy the Roman Empire?
This is driven by the urgency of understanding the Earth system, understanding its history, so that we can understand the dynamics of anthropogenic life. warming. And for historians, it's really exciting because it tells us things that we absolutely didn't know before about the climate context in which these societies operated.
The Ancients
Did Plague Destroy the Roman Empire?
The other that's been, I mean, I would say revolutionary is gene sequencing. And in particular, the kind of what are called high throughput gene sequencing technologies that make it
The Ancients
Did Plague Destroy the Roman Empire?
fast and relatively affordable to sequence huge amounts of DNA, DNA from people's bones that can tell us about their ancestry, but also at times about the identity of the pathogens that infected them and made them sick. So the rise of these new genetic technologies, which really are new, it's 15 years ago now that the first complete ancient human genome was published. So this is new.
The Ancients
Did Plague Destroy the Roman Empire?
For historians, this is really exciting. It's telling us about human population history, it's telling us about animal history, and it's telling us about microbe history.
The Ancients
Did Plague Destroy the Roman Empire?
Yeah, absolutely. A lot of diseases are caused by infectious agents. They're infectious diseases because something invades your body and causes the infection. And those are little organisms. They're usually bacteria or viruses. And those little organisms have genetic codes, so RNA or DNA. And under the right circumstances, it takes a little bit of luck. Bacteria are easier to find than viruses.
The Ancients
Did Plague Destroy the Roman Empire?
There are DNA viruses and RNA viruses. RNA viruses are like measles. It's very hard to recover. But with the right pathogen and the right circumstances of preservation, it's sometimes possible to get the DNA of the microbe that killed a specific individual at a specific point in time. And that has really, really revolutionized what we know about the past of human health, of pandemics.
The Ancients
Did Plague Destroy the Roman Empire?
Exactly. I think it's very easy for us to forget how radically population-level human health has been transformed over the last century and a half. This transition has revolutionized everything about our world. It's prolonged life expectancies by two to three times. In the Roman world,
The Ancients
Did Plague Destroy the Roman Empire?
We don't know, and there's probably not like one stable number, but if I want to pin down a number, life expectancy at birth is probably something like 25 years, plus or minus a few years. A lot of that's infant mortality, a lot of it's childhood mortality, but all the same, the average life expectancy is so much worse in the pre-modern period than the modern period.
The Ancients
Did Plague Destroy the Roman Empire?
There's several variables that account for that. The most fundamental one is that they don't have modern science. So we are lucky to benefit from modern science, which helps us understand the body, helps us understand the infectious cause of infectious diseases, helps us develop things like vaccines, hygiene, water treatment, antibiotics, other pharmaceuticals. None of those are available.
The Ancients
Did Plague Destroy the Roman Empire?
in the Roman world. And consequently, most people, even in a good year, most people die of infectious causes. So they die of, frankly, of diarrhea. Probably the largest category of infectious disease in the pre-modern world is probably diarrhea. I'm not talking about a tummy ache. I'm talking about dysentery, like
The Ancients
Did Plague Destroy the Roman Empire?
We take for granted a world where you can drink a cup of water and not think twice about whether you're putting your life in danger. But that's really recent. We have water treatment. We know to keep human waste matter and contamination apart from the drinking supply. But in pre-modern contexts, they didn't have germ theory.
The Ancients
Did Plague Destroy the Roman Empire?
They thought of disease as a miasma, and they were constantly threatened by infectious pathogens that cause dysentery, infectious diseases that cause respiratory illness, and so on.
The Ancients
Did Plague Destroy the Roman Empire?
It's a good question. And I think we don't have a totally clear answer to that. An epidemic is one of these things. It's a scientific term. It actually is just a rough and ready term. There's no like minimum number of people that have to die to make it an epidemic. It just kind of means an outbreak of disease in a population.
The Ancients
Did Plague Destroy the Roman Empire?
And in ancient Rome, you know, one out of every 10 years must have really stood out, right? We're just conditions aligned. There's a bad harvest and there's a bad strain of something. So epidemics are really bad years, but even epidemics are kind of normal. A pandemic is something else. It's where you have a really big interregional outbreak of disease. So people are dying in Alexandria.
The Ancients
Did Plague Destroy the Roman Empire?
People are dying in Rome. People are dying in Athens. all at the same time. And those seem to have a kind of big bad cause behind them. So most of the pandemics that we can understand historically are a sort of fateful alignment of really bad conditions.
The Ancients
Did Plague Destroy the Roman Empire?
So sometimes it's not just that there's a food shortage, it's that there's nothing to eat, that there's a real harvest failure that causes a real famine. And or And usually there's this conjunction of food shortage and virulence. But one of the things that seems to lie behind these rare events that happen every century or two is there is a big bad microbe.
The Ancients
Did Plague Destroy the Roman Empire?
There's plague, there's smallpox, there's typhus. There's certain diseases that are just nastier than others. And then there's this elite class of nightmare germs that seem capable of causing just a different level of destruction. And so we don't totally understand this. This is like an incredibly interesting and rich area of research that combines biology, that combines history and archaeology.