As readers of this blog know well, I don’t claim to be a prophet and I think that prophecy is, in any case, overrated. But I make predictions. A scientific prediction, unlike a prophecy, is not about a future, but about a theory — it’s a way to find out how good is our understanding of the way the world works. I explain more in my 2013 post Scientific Prediction ≠ Prophecy.

As an example of this general philosophy, here’s what I wrote in the final paragraph of an article published in 2008:

Are there any lessons from this history for the current globalization through which we now live? I think there may be, but with two very important caveats. First, as I emphasized repeatedly throughout this chapter, we still have very sketchy understanding of the causes underlying previous world-system pulsations. Much more modeling and empirical research is needed before we could determine just what the history’s lessons are. Second, the world has changed dramatically over the last two centuries. Thus, our understanding of pre-industrial globalizations cannot be mechanically transferred to make predictions about the current one. Our models will have to be greatly modified in order to apply to the modern world. Still, several of the empirical trends associated with the globalization of the twentieth century bear an uncanny resemblance to what has come before. Most obviously, the second half of the twentieth century was a period of massive population growth that has slowed down in the last decade, suggesting that we may be approaching the peak of global population. On the epidemiological front, human emerging infectious diseases have dramatically increased in incidence during the twentieth century, reaching the peak during the 1980s (Jones et al. 2006). The cholera incidence has been on the rise (Figure 11). The AIDS pandemic (Figure 11), as terrifying as it has been, may be the harbinger of even worse diseases to come. These and other trends (for example, the growth of the global inequality of wealth distribution during the last two decades) raise the possibility that studying previous globalizations may not be a purely academic exercise.

For better or worse, these predictions I’ve made have a tendency to eventually become realized (the biggest one is, of course, A Quantitative Prediction for Political Violence in the 2020s). When I wrote of “even worse diseases to come” twelve years ago I, of course, had no idea of Covid-19, or that it would coincidentally hit in 2020, just as other pressures for a structural-demographic crisis are building up to a peak. Rather, this prediction was based on a strong macrohistorical pattern: major pandemics tend to happen during Ages of Discord. For details, see the 2008 article; here I will summarize the main ideas in a nontechnical way.

There are several general trends during the pre-crisis phase that make the rise and spread of pandemics more likely. At the most basic level, sustained population growth results in greater population density, which increases the basic reproduction number of nearly all diseases. Even more importantly, labor oversupply, resulting from overpopulation, depresses wages and incomes for most. Immiseration, especially its biological aspects, makes people less capable of fighting off pathogens. People in search of jobs move more and increasingly concentrate in the cities, which become breeding grounds for disease. Because of greater movement between regions, it is easy for disease to jump between cities.

Elites, who enjoy growing incomes resulting from low worker wages, spend them on luxuries, including exotic ones. This drives long-distance trade, which more tightly connects distant world regions. My 2008 article is primarily about this process, which we call “pre-modern globalizations.” As a result, a particularly aggressive pathogen arising in, for example, China, can rapidly jump to Europe.

Finally, when the crisis breaks out, it brings about a wave on internal warfare. Marauding armies of soldiers, rebels, and brigands, themselves become incubators of disease that they spread widely as they travel through the landscape.

This description is tailored to pre-modern (and early modern) Ages of Discord. Today, in 2020, details are different. But the main drivers — globalization and popular immiseration — are the same.

In my 2008 article I discuss previous waves of globalization (although the early ones are better called “continentalizations” as they primarily affected Afro-Eurasia, rather than the whole world). There is a very strong (although not perfect) statistical association between these globalizations, general crises, and pandemics, from the Bronze Age to the Late Medieval Crisis. The famous previous pandemics such as the Antonine Plagues, the Plagues of Justinian, and the Black Death all coincided (and, typically, helped trigger) prolonged secular crises.

The last two complete crisis periods, the Crisis of the Seventeenth Century and the Age of Revolutions, were truly global in nature. As our data become better for the Early Modern period, we can trace the two pandemics more quantitatively:

The first cycle is traced by resurgent plague, but it should be supplemented by the devastation of the Americas due to such diseases as measles. The second cycle reflects the recurring pandemics of cholera. According to the Encyclopedia of Plague and Pestilence, the great cholera epidemic of 1849 carried away up to 10 percent of the American population. And we shouldn’t forget the Spanish Flu Pandemic, which hit in 1919.

And now it looks like our Age of Discord got its own pandemic.

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