Pandemics and Economics in History #3

Cities, Health, and Growth

Podcast: Pandemics and Economics in History #3: Cities, Health, and Growth

There is a lot to explore in economist Charles Kenny’s book, The Plague Cycle, mentioned last week One key theme is that, over the course of history, improvements in health and hygiene helped humans live together in denser populations; while, in turn, denser settlement led to greater spread of disease.

The book has plenty of specific details…

…these details are important for understanding the spread of disease, but they are not necessarily conducive to pleasant conversation. So, we’ll slide by them for now…

For our purposes, we’ll simply note that very early in human development one regular source of mortality was what Kenny summarizes as “confronting, hunting, and eating wild animals.” For tens of thousands of years people generally kept distance from one another. Then, gradually, humanity began settling together, with major health consequences.

In fact, Kenny says, “agriculture and civilization set off a global firestorm of disease” (p.18).

It was instructive to this lifelong city-dweller to be reminded that it isn’t only in towns and cities that people gathered in groups large enough to matter:

Even the most inefficient early agriculture was associated with populations per square mile that were ten or twenty times higher than among nomadic groups…. While less movement equals less exposure to new disease pools, the combination of population density and settlement was vital to the growth of infection.
— Charles Kenny, The Plague Cycle, p.18

In turn, Kenny explains, for thousands of years, urban centers experienced death rates greater than their birth rates; immigration, often coerced through war and other forms of violence, brought new populations into cities….until people found more effective ways to fight infection:

With the medical advances of the twentieth century, cities world-wide finally became healthy enough to expand. In many of the world’s poorest cities today, most urban population growth is due not to migration but to city residents having children that survive more often. Looking at recent survey data… among the world’s poorest–those who live on less than a dollar a day– infant mortality rates in urban areas were lower than rural rates in two-thirds of the countries for which they had data. That slum living in many developing countries is healthier than the rural alternative is a complete reverse of the global situation a century ago.

That helps to account for the global growth of cities….
–Kenny, p.155, survey citation below

The book goes on to note that half the world’s population now lives in urban areas and that these urban areas “generate more than 80 percent of global output.” Kenny praises “urban living” as “healthier for the environment as it tends to involve less travel and smaller housing.” He praises urban dwellers as “comparatively liberal, international, trade- and migration-loving…and open-minded in matters of religion,” concluding: “The city is progressive — and it’s where progress happens” (Kenny, p. 157).

Now, I am a lifelong city girl. I love city life and city people. Still, this unqualified praise of city attitudes, output, and growth, strikes me as worrisome.

Hidden behind the low infant mortality rates in two-thirds of urban areas worldwide, for example, is the knowledge that in this city, the very capital of the nation, infant mortality may look relatively low while remaining higher for Hispanic mothers than for non-Hispanic white mothers and far higher for non-Hispanic black mothers, than for either of the other groups, with clear differences by ward of residence. While the treatment of density as part of city growth, over thousands of years, makes sense in the context of The Plague Cycle, it also hides the pushing out of many people here in DC and in many other cities.

I am learning a lot from The Plague Cycle: The Unending War between Hunaity and Infectious Disease. And I hope these moments of historical reflection do give us new perspectives. We can use Kenny’s book and others on plagues and economics to help us ask different questions on where we are today. And we can use our own experiences to ask questions that some books seem to omit.

Pleases visit for more on related topics.


Kenny, Charles. The Plague Cycle: The Unending War Between Humanity and Infectious Disease. NY: Scribner, 2021. Booktalk on C-SPAN in January. Also available on YouTube.

Survey results citation: Abhijit V. Banerjee and Esther Duflo, “The Economic Lives of the Poor,” Journal of Economic Perspectives, 21, no 1 (2007): 141

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