Correlation between Crisis Periods and Epidemics

Peter Turchin


After I published my last post on Coronavirus and Our Age of Discord, I’ve been looking through various lists of major epidemics in world history, both on resources such as Wikipedia and in academic articles. I know that there is a strong (although not perfect) association between crisis periods and disease outbreaks (see my 2008 article). The question is, how strong is this correlation?

Below is a table that I put together, based on the data I found. It is not a definitive test of the hypothesis that major epidemics tend to strike during Ages of Discord. The comparison is not systematic enough, it’s too qualitative, and there is a definite Eurocentric bias (or, at least, a bias towards western Eurasia). Still, this is my blog, not an academic article that requires much higher rigor (and we will do a proper job when we complete building the Seshat Crisis Database).

In any case, here’s what I came up with so far. Comments are welcome!

Crisis Period Where Epidemics and pandemics
Late Bronze Age Collapse (XII–XI c. BCE) Eastern Mediterranean and Near East The plagues of Egypt

The plague among Achaeans at Troy

Crete depopulated by the plague

The Philistine Plague

Pestilence in Israel and Judah

Peloponnessian War
(V c. BCE)
Eastern and Central Mediterranean The Plague of Athens

Recurrent pestilence in Rome

The Crisis of the Roman Principate
(II–III c)
Roman Empire Antonine Plagues

The Plague of Cyprian

The Late Antiquity Crisis (VI c) Eastern Roman Empire Justinianic Plague (the First Plague Pandemic)
The Fall of the Umayyad Caliphate (VIII c)

The turbulent Nara Period (VIII c)

The Middle East and the Mediterranean


Second wave of Justinianic plagues (peak in 746-747)


The Japanese smallpox epidemic of 735–737

The Crisis of the XIV c. Afro-Eurasia The Black Death (the Second Plague Pandemic)
The General Crisis of the XVII c. World Second wave of the Black Death (including the Great Plagues of London and Vienna)

The Columbian Exchange: depopulation of the Americas; syphilis epidemic in Europe

The Age of Revolutions (1789–1919: the “long” XIX c.) World Cholera pandemics

The Third Plague Pandemic

The Spanish Flu

The plague of the Philistines at Ashdod. Oil painting by Pie Wellcome

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Chris Morris

Trouble is that waves of disease are like waves on the sea – they keep on coming in all manner of sizes. And the only ones that get mentioned are the really big ones (though even a small wave could drown someone).
Unfortunately, unlike sea waves, disease waves are non-linear. Famine and war lead to a weakened population that is vulnerable to disease, and disease can lead to economic disruption that opens the way to famine and war. (in the UK, there are already warnings of crops rotting in the field if the migrant workers needed to pick them don’t come because of Covid-19)

A C Harper

It would be really useful if the data included ‘Ages of Peace’ – perhaps you have already done so? Otherwise looking for epidemics in Ages of Discord is limiting the search area.

Loren Petrich

I suggest doing what our host has done, at least for (say) Rome and Imperial China. For the purpose of such work, one will need to work out in advance what division into periods one will use, so one doesn’t end up adjusting periods to fit the plagues.

Here’s a timeline that I’ve constructed from our host’s work and Wikipedia’s history of the Byzantine Empire – mostly political/military history.

350 BCE – I – Rome’s rise from a city-state to a major Mediterranean power
130 BCE – D – civil wars, though conquests continued
30 BCE – I – the Principate: the early Empire, ending with the Five Good Emperors
165 CE – D – some bad and short-lived emperors, the Crisis of the Third Century
285 CE – I – the Dominate: Diocletian and Constantine reorganize the Empire
395 CE – D – terminal decline of the western empire, ending in 476 CE. Status of eastern empire unclear
527 CE – I – Justinian I’s conquests
602 CE – D – decline, 20 years anarchy, iconoclasm fights
867 CE – I – Macedonian Renaissance
1025 CE – D – crisis and fragmentation
1081 CE – I – Komnenian period, another renaissance
1185 CE – D – terminal decline, ending in 1453 CE

Ross Hartshorn

So, it would be interesting to figure out a way to distinguish between two alternative models for this correlation (assuming for the moment that it exists even after the Seshat Crisis Database is competed):
alternative 1: major disease epidemics reduce trust and cooperation, leading to a breakdown in society more generally
alternative 2: the same things that lead to a higher incidence of major disease epidemics (e.g. increased traffic between different regions, higher population densities) also are characteristic of a late-stage, ready-to-collapse society

Given that, as you point out, this is a blog not a scholarly article, do you care to hazard a guess as to which of these alternatives is more responsible? Or is there a third that I’m missing?

David Fallon

One of the most enduring cliches and biggest essay no-nos of Early Modern History #101, is “Did the Black Death Lead To The Renaissance.” It is a lot more complex than that. That Plague did expose many social and economic fractures, as well as having a disastrous social and cultural effect, as the extreme death toll concentrated among the then dominant monastic clergy, as well as the death toll among peasants, leading to immerse labour shortages, certainly altered the dynamics of culture and economic activity for a generation. The point I would make, is what are the consequential and unexpected outcomes of any mass disaster? Your question to do with the tandem features of criss and pandemic, also leads to the possible outcomes, that as cold-blooded as it sounds, can be considered positive. An almost complete obliteration of an intellectual monastic cohort, certainly helped the debates around church authority, and to the reformation. Fewer labourers led to more social mobility and higher wages plus more specialised trades, with the rise of guilds and proto-unions among surviving skilled workers. Already, in this current crisis, especially in the United States, but in every global economy, questions arise as to the structures and efficiency of the health system, the preparedness and relationships of local, state and federal responses, and the supply chain reliance on dislocated offshore manufacturing – our old friends neoliberalism, austerity, and globalisation. The other familiar cliche of international relations studies is the “Role Of The Nation State and Democracy In A Globalised Offshore Financed World.” Will this crisis lead to significant rethinking of relationships that have dominated political discourse since the 1980s? For your consideration, is it possible to track, not only the crisis relationships, but the “benefits,” if that’s not too harsh and insensitive a word, that may come from disaster, as societies reassess old assumptions?

Peter van den Engel

That’s very interesting. Yes there can be positive effects from disruptions. But the plague neither resulted in the renaissance nor the reformation.
The reformation hsd two main drivers. The first one is alchemists had prescribed a natural test for people for the. church to find out if they were good or bad, by applying a fire probe (the stake) or a water test (if the witch would float or not).
Since this was false (but spread like an artificial virus) people in north western Europe called the catholic faith an imposter, because they were actually surpressing them with taxes and were only called bad because they refused to pay.
Underlying it was the growing trade power of the north, whitch undervalued the south as a weaker force. While it believed is was the stronger, also based on the north being barabarians with no or the wrong faith in the past.

It was a case of swapped proportions, while the other side still believed and acted upon the old one which was surpassed. This represented the conflict in timespace.

The second driver (as a fabric potential) was the invention of book printing around the same period in the north, which led to the unification of the right in their own language instead of latin (the old elite which was surpassed by it: cannot be everywhere at the same time), because they were right.

So, although it tumbles around different curves, making a mistake (causing crisis) can lead to as positive outcome.
I presume this one will as well.

J. Daniel

Any correlation between pandemics and periods of social crisis would presumably be indirect. More direct correlations might be (a) more easily established, and (b) imply a pandemic-crisis correlation.
So one could conjecture a correlation (and direct cause-and-effect) between poverty/crowding and pandemics, on the one hand, and on the other, a correlation (and direct cause-and-effect) between structural-demographic crisis and poverty/crowding. Having established these correlations, what would be the point of then showing that there exists a correlation between structural-demographic crisis and pandemics? It would be obvious. However, showing the *amount* by which structural-demographic crisis causes pandemic deaths (for example) would certainly be an interesting question.


Do you have an idea how a plague could make a crisis worse? It can’t affect parameters like elite overproduction or demographics much. If anything I’d expect a plague to make a crisis less severe. Death among the elites reduces elite overproduction, death among commoners makes work more valuable.

j. Daniel

> Do you have an idea how a plague could make a crisis worse? … death among commoners makes work more valuable.

And with work more valuable, wealth should shift downward, putting increased financial pressure on the already overproduced elite and making them compete with each other even more.
At least, that’s the only argument I can think of to address your question.


A plague can also disrupt the military allowing regions and parties, for example cities or more distant provinces, to break away from central authority.

A plague could slow trade, reducing import earnings. This would have a particular impact on port cities and their backwaters weakening the trade elite and their clients while strengthening others.

I’m sure there are other examples. Elites are rarely essential, however they rely on “essential” workers. If those workers are fall ill or die, elites may not die, but competition would get fiercer.

Peter van den Engel

Sure there is a correlation. Since crisis, meaning war, would disrupt the fabric of sociey in comparison to it behaving normaly. So food stock anf crops would start rotting when labor is no longer available, when people flee or are demotivated.
Inviting pests containing virusses and the rest is history.

This would have happened in Egypt after the cultural collapse, when first Greec and later the Romans took over power, but it still was the largest grain supplier. Leaving it to rot in silos. Causing the plague elsewhere.
The Greec society consisted of 80% foreign slave servants, so when the war between Athens and Sparta happened, large fractions of these workers would lose their entitlement or flee and leave crops to rot for pests. Causing the plague.

Apart from that there is also a general spacetime parallel between the behavior of virusses based on RNA, which is circular progressive in stead of a fabric field and that of human behavior as described above (leaving a simular impression in the consciousness of it: being aware of what it is aa a disruption in believe systems and the hierarchy of a society).
Therefore you can also compare it (the virus) to the behavior of fanatics causing a wildfire, like an anarchist or a fanatic ecologist wirh no trust in people, killing a president or a pope, or setting fire to a city or contaminating a source on purpose. Either to disrupt/ or to orchestrate unanimity.

There are many overlaps and parallels. . Like current corona appears to hit obese above average because it’s an open weak field compared to the agressive circular penetration of RNA disrupting it. Although you would not call that a political crisis perse.

What is remarkable is medics are talking about contagion vulnerability/ while it is the virus itself replicating so fast, which is curious. As if it is our fault it can do so. But why?

[…] Corrélation entre périodes de crise et épidémies […]


Once the lockdown is over, I think we should submit a petition to the authorities, demanding that Peter remains under house arrest. He’s never updated his blog so frequently before!

In addition to listing the epidemics between crises, it would be informative to list the crises that didn’t have major epidemics. Other than some outbreaks of tularemia in the trenches, I can’t remember anything epidemiological happening during WWII, am I missing something?

Chris Morris

As regards the Rome timeline, 1204CE is a key date.Up to then, the Byzantines were a single polity. Thereafter, they were fragmented and spent a good bit of their time fighting each other, rather than resisting the Turks. Arguably, the first fall of Constantinople in 1204 spelt the end of the Roman Empire. The following 250 years were little more than burying the pieces


Oui mais sont-ce les “pestes” qui on créés les crises économiques ou l’Inverse ? Je pense que le lien n’est pas si facile à établir. Toutefois, je pense que si les révoltes (comme la prise de la Bastille) sont toujours le résultat de la faim, les révolutions ne sont jamais que le résultat d’un changement de rapport de force. Ce changement de rapport de force survient toujours quand la mains d’œuvre fait défaut et n’est plus exploitables sans limite par les dominants. Les épidémies peuvent être déterminantes (fin de l’empire romain d’occident, fin de l’empire Byzantin…) ou les guerres (émergence de l’Europe sociale après les 2 guerres mondiales). Je ne suis pas persuadé, à ce stade, que l’épidémie du Covid-19 soit suffisamment meurtrière pour générer un véritable effondrement systémique susceptible de modifier les rapports de force. Combinée à l’effondrement du marché pétrolier (en réalité juste aggravé par le covid-19), elle pourra peut-être provoquer l’effondrement des USA et par propagation faire basculer les rapports géostratégiques.

Mais c’est le mieux qu’on peut attendre (car j’en rêve). Non je crois que à pars quelques petits ajustements à la marge (comme la recréation d’industrie produisant localement des produits considérés stratégiques et le développement de stocks stratégiques -qui ne seront maintenus que le temps du souvenir vivace de l’épidémie, ce qui sera relativement bref-). Le système se remettra en marche fondamentalement comme avant et parce que si c’est la volonté des dominant ce sera avant tout la volonté de la plus grande majorité des citoyens y compris ceux qui prétendent vouloir aujourd’hui un changement. Tous souhaitent retrouver leur confort d’avant si pas mieux.

Mais j’ai l’espoir que cette crise sanitaire ait fait prendre au corps social de la nécessité d’un changement systémique. Néanmoins, le corps social devra encore passer par d’autre crises pour que la prise de conscience en vienne à l’intégration de cette nécessité. Alors et seulement alors pourront émerger, du corps social, de véritable utopies, porteuses de projet qui se concrétiseront dans un renversement systémique. C’est en fait le long processus de toute véritable révolution (à ne jamais confondre avec une révolte comme dit supra toujours motivée par la faim même si souvent instrumentalisées).



Yes, but are they the “plagues” that created the economic crises or the reverse? I think the connection is not so easy to make. However, I think that if revolts (like the storming of the Bastille) are always the result of hunger, revolutions are never the result of a change in the balance of power. This change in the balance of power always occurs when there is a lack of manpower and is no longer exploitable without limit by the dominant forces. Epidemics can be decisive (end of the Western Roman Empire, end of the Byzantine Empire…) or wars (emergence of social Europe after the 2 World Wars). I am not persuaded, at this stage, that the Covid-19 epidemic is sufficiently deadly to generate a real systemic collapse likely to change the balance of power. Combined with the collapse of the oil market (in reality just aggravated by Covid-19), it could perhaps cause the collapse of the USA and by propagation tip the geostrategic balance of power.

But this is the best we can expect (because I dream of it). No, I believe that with some small adjustments at the margin (such as the recreation of industries producing locally products considered strategic and the development of strategic stocks – which will only be maintained for the time of the vivid memory of the epidemic, which will be relatively brief). The system will fundamentally be back on track as before, and because if it is the will of the dominant players, it will above all be the will of the vast majority of citizens, including those who claim to want change today. All of them wish to regain their former comfort if not better.

But I have hope that this health crisis has made the social body aware of the need for systemic change. Nevertheless, the social body will still have to go through other crises for awareness to come to the integration of this necessity. Then and only then will it be possible to emerge, from the social body, true utopias, the bearers of a project that will take shape in a systemic reversal. This is in fact the long process of any true revolution (never to be confused with a revolt as said above, always motivated by hunger, even if it is often instrumentalized).

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