The Fate of Rome: Climate, Disease, and the End of an Empire

Published by EH.Net (April 2018)

Kyle Harper, The Fate of Rome: Climate, Disease, and the End of an Empire. Princeton: Princeton University Press, 2017. xiii + 417 pp. $35 (hardcover), ISBN: 978-0-691-16683-4.

Reviewed for EH.Net by Peter Temin, Department of Economics, MIT.

 
This is an exciting book that provides a fresh look at a perennial topic, the fall of the Roman Empire, in sparkling prose accessible to all economic historians. Harper, Professor of Classics and Letters and Provost of the University of Oklahoma, has written extensively about the later Roman Empire. In this book, he argues that climate change and pandemics caused the empire to collapse. The book alternates between ancient history and biological analyses, but it is clear and understandable to readers from all disciplines.

In Harper’s words, “The fate of Rome was played out by emperors and barbarians, senators and generals, soldiers and slaves. But it was equally decided by bacteria and viruses, volcanoes and solar cycles” (pp. 4-5). Harper gives space to both of these sets of characters, and he indicates along the way how far we have gotten in understanding the causes of ancient diseases and climate changes. For example, we are quite sure of the bugs involved in some Roman plagues and still in the process of figuring out which bugs were causing other plagues. While convincing to this reader, the book is a progress report in the use of modern biological tools to understand ancient history.

Harper starts his exposition with the early Roman Empire, arguing that both population and real incomes were rising. The cause of this violation of Malthusian rules has been debated in the ancient history literature, and the current thought is that it was due to increased trade as the Romans extended and pacified the shipping lanes around the Mediterranean Sea. Harper reproduces a graph from his article “People, Plagues and Prices from the Roman World: The Evidence from Egypt” (Journal of Economic History, 76 (3), 803-39) containing regression analyses of the trends in Egyptian prices and showing that wages were rising faster than wheat prices in Egypt. Readers of the book should consult the article for details of the regressions, which support the existence of trade throughout the Roman Mediterranean.

This economic integration, Harper argues, gave rise to germ mobility and then plagues as well. The first Roman plague, known as the Antonine Plague, took place in the late second century, after 160. It was caused by an outbreak of what probably was smallpox, and it began the deterioration of the Roman Empire. Inflation began after the plague, and the turnover of emperors became more frequent. I argued in The Roman Market Economy (Princeton, 2013) that these changes were due to the Antonine Plague, and Harper extends this argument.

The second Roman plague, known as the Cyprian Plague, took place about a century later. This plague may have been caused by what is now known as the Ebola Virus from recent outbreaks in Africa. Note that while smallpox is bacterial, plagues also can be caused by viruses. And the Cyprian Plague intensified the inflation and political instability of the Roman Empire.

The third shock to the Roman Empire was caused by climate change rather than a plague. The early Roman Empire was blessed with a stable and warm climate which lasted for several centuries. It began to break down in the late fourth century, and droughts and colder temperatures drove Rome’s neighbors to the northeast to move southward into what had become the Western Roman Empire. In Harper’s words, “These invasions were not mere raids; they were migrations, movements of people, with women and children in train” (p. 194). The Huns overwhelmed the Roman soldiers, but Alaric led his Goths into Italy and conquered Rome in 410. This dramatic event symbolized the decline of Rome and stimulated Augustine to write The City of God.

The third Roman plague, known as the Justinian Plague, and the fourth of Harper’s natural shocks, began in the sixth century and lasted for two centuries in and around the surviving Eastern Empire based in Constantinople. It was caused by a bacterium known as Yersinia pestis, or Y. pestis, and took the form of bubonic plague in most places and times. Given the spread-out population in the East and the paucity of human remains in any one place, historians have struggled to describe the Justinian Plague for a long time. Only recently have our powers of recovery and analysis become accurate enough for Harper and others to describe the causes and the extent of the plague.

Justinian’s reign had an epic cold snap that was global in scale; there were years in the mid-sixth century that had no summer at all. Harper speculates that the cold snap created conditions that tied the bacterium to black rats and their fleas and finally to us — with a few more steps in between. He says that interaction of diseases and plagues is very complex and decidedly non-linear, but he is sure it will be found. The cold snap also was a harbinger of what has been called the Little Ice Age that followed the Justinian Plague and intensified the chaos that followed.

The Justinian Plague devastated the remaining Roman parts of the Empire just as Islam was making its push into Europe. The disorganized and ailing Romans were no match for the invading Muslims. The Justinian Plague, in other words, not only caused the Eastern Roman Empire to collapse; it also increased the scope of Islam in and around Europe that lasted for many centuries.

I have emphasized the innovative parts of Harper’s work in this review, but ancient historians will find lots of descriptions of ancient events mixed in with the biological analyses. Others interested in plagues will find time lines and stories to ground the biology in its Roman context. And anyone who is attempting to use the fall of the Roman Empire as an example in contemporary life should read this book before expounding one or another outmoded theory of the fall of the Roman Empire.
Peter Temin is Professor Emeritus of Economics at MIT and author of, most recently, The Vanishing Middle Class: Prejudice and Power in a Dual Economy (MIT Press, 2017).

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