Why Rome actually fell: plagues, slavery, & ice age — Kyle Harper

To me, a very plausible counterfactual is that a more or less Mediterranean core of the Roman Empire could have survived east and west, really all of Italy, Africa, and probably Spain, if you hadn't had this double shock of climate change and plague. The Romans don't have technology improvements that are really self-sustaining, and the reason they don't have that is because they don't have science. Their science sucks. They have, like, the most advanced financial markets in the world before, like, the 17th or 18th century.

20% of the population is enslaved.

Yeah.

Why aren't there more slave rebellions?

Evolution is just creative and weird and contingent and unpredictable. Billions and billions and billions of microbes constantly seeing if you manage to lock that door, and they're just looking for a way to break in.

Today, I have the pleasure of chatting with Kyle Harper, who is a professor and provost emeritus at the University of Oklahoma, and the author of some really interesting books, The Fate of Rome, Plagues Upon the Earth, Slavery in the Late Roman World, w- an upcoming one called The Last Animal. The reason I wanted to have you on is because I don't think I've encountered that many other authors who can connect, um, biology, economics, history, climate into explaining some of the big things that have happened through human history in the way you can. The most recent reason I r- I wanted to have you on is I interviewed David Reich, uh, the geneticist of ancient DNA, and some of the questions we were discussing, he kept emphasizing this overwhelming role and surprising role that diseases have had in human history, not just in the recent past, but g- I mean, in his work going back, like, thousands of years, tens of thousands of years. And he's like, "You gotta have Kyle on." I emailed him afterwards, like, "Wh- who, who should I interview next?" And he's like, "You gotta have Kyle on." Um, you have this graph in, uh, The Fate of Rome. Yeah, you show human population over the last few thousand years. I assume that these two down spikes are both the bubonic plague, Yersinia pestis, right?

Yeah, yeah.

And so, this is not, like, some small little nudge you can see. Like, the overwhelming, I mean, other than the hyper-exponential growth in human population, the (laughs) overwhelming, not just one, but the overwhelming two major features in human population, going back the last (laughs) 10,000 years is this one bacteria.

Yeah.

Right? One of the things you discuss in the book is that the collapse of the Roman Empire was a result of this one particular event.

Well, I mean, my... The period that I normally work on is sort of from the High Roman Empire, so like the, the glory days of the Pax Romana in the first or second century, which is usually where I start, through what we call the, the late antique or early medieval period, so the sixth or seventh century. And at the beginning of this period, Rome dominates this Mediterranean empire. It's what you think of when you think of, uh, ancient Rome. Um, it's the largest city in the world. It's, it's the center of this huge network. Um, and then by the end of this period, the city of Rome has, you know, we don't know, 50 to 100,000 people. Um, it's a tenth or twentieth of its former size, and I think we now can say pretty clearly that environmental factors like climate, but also especially diseases play a part in that, in that really big transformation. And well, there's a problem because we don't have the same kind of modern government mortality statistics-