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

The city of Rome likely had a population of over a million by the time the Emperor Augustus died (August 19th, AD 14).

· 17 min read
The Fate of Rome: Climate, Disease, and the End of an Empire—A Review

A review of The Fate of Rome: Climate, Disease and the End of an Empire by Kyle Harper, Princeton University Press, 417 pages (October 2017)

Why did the Roman Empire fall? The classic answer is given by Edward Gibbon (1737 — 1794), in chapter 38 of the third volume of The History of the Fall and Decline of the Roman Empire (1776 — 1789):

The decline of Rome was the natural and inevitable effect of immoderate greatness. Prosperity ripened the principle of decay; the causes of destruction multiplied with the extent of conquest; and as soon as time or accident had removed the artificial supports, the stupendous fabric yielded to the pressure of its own weight.

Kyle Harper, Senior Vice President and Provost of the University of Oklahoma, seeks to complement Gibbon’s account by emphasising the role of nature, and specifically climate change and infectious disease, in the fall of Rome in his provocative, exceptionally well-written book The Fate of Rome: Climate, Disease and the End of an Empire. Is Harper correct? Were plagues and climate events fatal for Rome?

Harper accepts the conventional view that Rome’s civilizational collapse began in the later second century AD, accelerated amidst chaos and bloodshed during the third century, and culminated in the humiliations of the fifth century, when Rome was famously sacked by barbarians, and the last, weak, insignificant Roman Emperor was pushed off the throne in AD 476.

The Fate of Rome does not neglect literary and archival sources, or archaeological evidence related to the fall of Rome; but Harper thinks historians have neglected “natural archives,” which is how he describes genome evidence from DNA, biological data (as found in bones and teeth of excavated ancient skeletons), tree rings, glaciers, marine sediments, and all other materials studied by environmental historians, geochemists, and other scientific researchers:

Most histories of Rome’s fall have been built on the giant, tacit assumption that the environment was a stable, inert backdrop to the story.

Harper goes to great lengths to correct this perceived misconception.

The Fate of Rome begins with the premise that the Roman state’s growth and relentless gains in strength and influence coincided with a period of optimal climate conditions between 200 BC and AD 150. The fall of Rome was hastened and exacerbated by a period Harper refers to as the “Late Antique Little Ice Age,” which lasted from AD 450 to 700. He also insists:

…the Romans built an interconnected, urbanized empire on the fringes of the tropics, with tendrils creeping across the known world. In an unintended conspiracy with nature, the Romans created a disease ecology that unleashed the latent power of pathogen evolution. The Romans were soon engulphed by the overwhelming force of what we would today call emerging infectious diseases. The end of Rome’s empire, then, is a story in which humanity and the environment cannot be separated.

According to this view, plagues helped fatally weaken, not just imperial institutions, but Roman society itself.

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The city of Rome likely had a population of over a million by the time the Emperor Augustus died (August 19th, AD 14). Perhaps it was at its most splendid a few decades after the Great Fire of Rome (July AD 64) that destroyed two-thirds of the city. Building projects under the Emperors Trajan (who ruled AD 98 — 117) and Hadrian (who reigned until AD 138) culminated in the Pantheon, which was dedicated circa AD 126, and remains the most important single ancient monument in Rome. By the time Hadrian died, the city was far more beautiful than it had been during the Augustan era; the empire was prosperous, stable and secure. Harper estimates its population at this point in history at 75 million.

Rome’s imperial government was seriously threatened during the reign of Commodus (AD 180 — 193), the first in a century-long sequence of paranoid, thuggish emperors who tended to die violently. Under Commodus, the Praetorian Guard, the most elite unit of the imperial army, transformed from a combined security detail and intelligence service for the Emperor to a politicized menace to the state. It was all but impossible to control. The Praetorian Guard was finally defanged by the Emperor Diocletian in AD 296; but by then it had done irreversible damage to the empire.

Endless power struggles resulted in the period that historians refer to as the Crisis of the Third Century (AD 235 — 284), which combined multiple constitutional and economic crises. There was a financial collapse: Rome’s monetary system disintegrated. Meanwhile, the Roman Senate battled for control of the government with various provincial army officers. Eighteen emperors died violently. In the midst of this chaos, the empire’s borders all but dissolved on two fronts, resulting in invasion as well as loss of territory. Finally, there was a cultural crisis, as Rome’s traditional civic religion eroded, losing followers to unofficial religions. Manichees and Christians were seen as a serious threat to order because they did not obey the same gods as everybody else.

Stability returned under Diocletian, who came to power in AD 284, and was the first emperor to resign the office voluntarily, on May 1st, AD 305. He split the administration between four emperors; two senior and two junior. This worked only as long as he was in control. After another unstable period, Constantine the Great became sole emperor in AD 324, and moved the empire’s administrative capital to Byzantium, which he renamed Constantinople and dedicated on May 11th, AD 330. Constantine died in AD 337; the dynasty he established became extinct when Julian the Apostate died in June AD 363.

The last Roman Emperor to rule the entire empire was Theodosius I, who reigned from May 15th, AD 392 to January 17th, AD 395. His dynasty lasted almost until the fall of the western half of the empire. But by the time of his installation the empire had lost prestige and confidence in the wake of the army’s catastrophic defeat at the hands of the Goths in the Battle of Adrianople (August 9th, AD 378). The Romans lost 20,000 men—two-thirds of their forces. According to some accounts, the Emperor Valens died in battle alongside his men; another version suggests that he was burned to death while trying to escape. After Adrianople, there was no hope of recovery.

Harper begins The Fate of Rome with a description of Rome as it advertised itself in AD 400. Contemporary inventories record: 28 libraries, 19 aqueducts, two circuses, 37 gates, 423 neighborhoods, 46,602 blocks of flats, 1,790 grand houses, 290 granaries, 856 public baths, 1,352 cisterns, 254 bakeries, 46 brothels, and 144 public latrines. The population is estimated at 700,000 or so. This figure diminished rapidly after August 24th, AD 410, when Rome was sacked by an army of Goths.

The traditional date of Rome’s fall is September 4th, AD 476, when the 16-year-old Emperor Romulus Augustus, the son of a former secretary to Attila the Hun, was forced to abdicate the throne by a barbarian warlord, and dismissed to spend the rest of his days at a seaside villa near Naples. His date of death is not recorded; he was too unimportant to fear assassination. At this point, the city of Rome’s population was still as high as 400,000.

Rome was invaded and sacked a few times over the centuries; more and more of it was abandoned; by the 10th century it was a suburb to nowhere surrounded by malarial swamps, and may have had only 9,000 inhabitants. Most of the economy was related to religious pilgrimages; the city was controlled by gangsters and petty warlords. What was left amidst the ruins was sacked again in AD 1084 by an army that outnumbered residents by as much as three to one.

In The Fate of Rome, Harper focusses on four major events that contributed to the empire’s destruction: three were plagues; the fourth was a sudden change in climate that completely destabilized what was left of the eastern empire after the western half disintegrated. Harper notes that pestilence of one sort or another was relatively commonplace; he counts nine epidemics in the city of Rome between 43 BC and AD 148. Most were likely outbreaks of malaria. The best-known ancient victim of this disease is Saint Monica of Hippo (AD 322 — 387), whose son Saint Augustine describes her final illness in book nine of the Confessions (AD 397/398).

Roman aqueducts were feats of engineering: The multiple arches of the Pont du Gard in Roman Gaul (modern-day southern France).

The Romans were formidable engineers: The Aqua Virgo aqueduct in Rome, constructed in 19 BC, continues to function today. Rome’s sewer system was highly sophisticated, as was the plumbing required for public baths and public toilets; but waste disposal was not necessarily hygienic. Perhaps the biggest killers in Roman cities were diarrhoea and dysentery. Also, the Romans’ efficient networks of transportation, commerce, and communication could sometimes facilitate the spread of disease: Harper suggests that the ease and speed of travel throughout the empire may have contributed to the spread of leprosy and tuberculosis.

The first pandemic that Harper discusses is the Antonine Plague (AD 165 — 180), named after the Nerva-Antonine dynasty that began with the accession of Nerva to the imperial throne (AD 96) and ended with the murder of Commodus by his personal trainer Narcissus (New Year’s Eve AD 192). This plague is also known as the Plague of Galen, because it was described at some length by Galen of Pergamum (AD 129 — 216), who served for a time as personal physician to Commodus, and is the most important medical scientist of antiquity.

Harper concludes that the Antonine Plague was an outbreak of smallpox. There is evidence that this pestilence may have spread throughout the Roman Empire; estimates of the death toll range from 1.5 million to a scarcely credible 25 million. Harper guesses around six million. The precise figure would be easier to pin down if the 72nd volume of Dio Cassius’s Roman History survived. Dio Cassius (AD 155 — 325) describes another plague in volume 73 of his work (LXXIII.xiii.3 — 4) that took place in AD 191, and killed two thousand Romans a day at its height. He describes this as the single worst plague he had seen in his lifetime.

For whatever reason, Harper refers to this passage of Dio Cassius only in a footnote. He also neglects to spell out the Antonine Plague’s most disastrous political consequence: on January 23rd, AD 169, it killed the Roman junior co-emperor Lucius Verus, whom the Emperor Marcus Aurelius had been grooming as a successor. Instead, Marcus Aurelius’s only surviving son Commodus ended up succeeding him. Commodus, a cruel, cowardly, simple-minded megalomaniac, can be said to have single-handedly precipitated the empire’s decline.

The second pandemic that Harper highlights in The Fate of Rome is the relatively little-known Cyprianic Plague. Students of early Christianity will be familiar with this from a treatise by Saint Cyprian of Carthage (AD 200 — 258), a bishop and martyr who is also one of the most important Latin writers of the third century. The plague that Saint Cyprian describes broke out in Carthage not long after the city of Rome celebrated the 1,000th anniversary of its foundation on April 21st, AD 248.

The Roman Empire had been in crisis since March 19th, AD 235, when the Emperor Severus Alexander was assassinated along with his mother. Over 70 years would pass before another Roman emperor died peacefully in his bed. The two third-century emperors who allegedly died of natural causes were said to have been felled by pestilence while on campaigns, though one of them may in fact have been poisoned. There was an increasing crisis of legitimacy from the 230s and 240s onwards, as the army and Senate began to put forward competing emperors, while refusing to recognize the authority of other claimants to the throne.

Roman money was devaluating rapidly. Emperors debased the currency so that they could buy the loyalty of their soldiers; this led to hyperinflation throughout the empire. Infrastructure and administration began to crumble; in many provinces it became virtually impossible to collect taxes. Meanwhile, the Romans were losing control of their frontiers; in AD 260 an invading force from the upper Danube region almost reached the suburbs of Rome itself. The empire was effectively splitting into three parts.

Harper claims that the Crisis of the Third Century was made even worse by a widespread outbreak of infectious disease. We know that the Emperor Claudius Gothicus died from pestilence at Sirmium in AD 270; Harper thinks it possible that he too was a victim of the Cyprianic Plague.

Harper brought this plague to widespread attention in his article “Pandemics and Passages to Late Antiquity: Rethinking the Plague of c. 249 — 270 Described by Cyprian” (Journal of Roman Archaeology 28, 2015, pp. 223 — 260). This remains the most comprehensive collection of literary and archaeological material related to this plague; though Harper’s account in The Fate of Rome lays out most of the evidence clearly enough.

Harper suggests that the Cyprianic Plague was a viral hemorrhagic fever that originated in Ethiopia, concluding that it must have been a filovirus with a very high fatality rate (over 50 percent). The best-known filovirus is Ebola, which spreads through contact with bodily fluids; the corpses of victims remain highly infectious. Harper calculates that the population of Alexandria alone fell from half a million to slightly over 300,000 as a result of this plague—190,000 people either died or fled the city. It seems peculiar that an Ebola-like pandemic on this scale should have gone largely unnoticed until now, particularly if, as Harper claims, it spread all over the Roman Empire.

The Fate of Rome focusses more on disease than climate change; though Harper devotes considerable attention to food shortages during the fourth and fifth centuries, and what they might indicate about changing conditions throughout the empire. He dwells at some length on the Cappadocian famine of AD 368/369 (described by Saint Basil the Great of Caesarea) and the “general famine” of AD 383 that led to a once-famous dispute between the pagan senator Symmachus and Saint Ambrose of Milan. These food shortages are known only because they left some mark in literary history. But for Harper they further support his case that the Romans were increasingly unable to cope with sudden changes in their environment.

Infectious disease and famine became increasingly common throughout both the eastern and western halves of the Roman Empire. Isaac of Antioch, a classical Syriac author, appears to have thought that Constantinople was saved from an invasion by Attila the Hun in AD 447 because the barbarian forces were worn down by fever and diarrhea before they could come anywhere near the city. Harper suggests that Attila’s invasion of Italy in AD 452 was cut short by the threat of malaria as well as famine.

The imperial administration became chronically unable to meet its obligations. Poor Romans received free rations of bread, olive oil, and pork, in addition to heavily-subsidized wine. The empire could not survive without its large, expensive army; though there was less and less revenue to pay for it. Soldiers were also increasingly difficult to recruit. Large numbers of men joined the clergy, not because they had vocations to the priesthood, but because they did not want to work. At least the Church could still afford to feed people. For lazier members of wealthier families, the increasingly bloated civil service seemed a better option than the military or the Church.

Infrastructure was disintegrating; so was internal security. The empire was menaced, not only by Huns, but by Goth refugees from the Huns as well. Numerous Goths settled in Roman territory, then began to attack imperial forces after they were mistreated by corrupt local officials. After the Gothic War (AD 376 — 382), the western half of the Roman Empire limped along for almost a century, steadily losing territory to enemies and authority to the popes. The eastern half based at Constantinople seemed more resilient; then it was struck by a plague—the most devastating single event described by Harper in The Fate of Rome.

The Emperor Justinian the Great ruled over the Eastern Roman Empire (or Byzantine Empire) between AD 527 and 565. According to chroniclers, the year AD 536 was bitterly cold; the sun was partly obscured by haze for a year and a half; temperatures cooled throughout the empire for almost a decade, leading to crop failures and famines in some parts of the empire. The Monophysite bishop John of Ephesus (AD 507 — 588) complained that weather conditions allowed no fruit to ripen properly; wine was particularly sour. This was known as the “Year Without Summer.” Harper describes this as the beginning of the Late Antique Little Ice Age.

This period of low temperatures and weak sun all over Europe was likely the result of a volcanic eruption that spewed ash into the atmosphere. The winter of AD 540 — 541 was particularly frigid; though it wasn’t nearly as disruptive as the plague that broke out in Constantinople at the end of February. During its initial phase, the Plague of Justinian was said by John of Ephesus to have killed over a quarter of a million people in Constantinople in four months—half of the city. The Emperor Justinian caught the disease, but survived.

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Literary sources likely exaggerate the number of deaths, and are unreliable in many respects; though unquestionably the Plague of Justinian had far-reaching effects. This was not the bubonic plague, but it appears to have been related, and was probably carried by rats aboard ships to ports all around the Mediterranean. Around this time the Byzantine Empire entered a period that some historians refer to as the Byzantine Dark Age. Within a few decades, the population of Constantinople had shrunk from 500,000 to scarcely 100,000.

The Fate of Rome is undeniably impressive. Harper has familiarized himself with a wide range of scientific and economic data as well as the more traditional literary and archaeological materials necessary for this study. Nobody can read this book without learning a great deal. As a popular historian, Harper puts other classicists to shame: He understands better than any of his professional colleagues how to communicate with a general audience. Yet The Fate of Rome is ultimately not convincing. Harper comes nowhere near to proving his case that environmental factors had more than a modest effect on the decline and fall of the Roman Empire.

Harper overstates the effect of climate change and disease on institutions and society. He writes old-fashioned narrative history well; but his analysis is often surprisingly crude, and some reviewers have accused him of “environmental determinism.” This, alas, seems fair. He presents a wealth of interesting and valuable information, without successfully incorporating it into his overall argument. Some of the best-written, most memorable passages in the book are ultimately irrelevant to the story he is trying to tell.

Those of us who are not meteorologists, epidemiologists, biochemists, economists, or other such experts will be unable to evaluate Harper’s grasp of these disciplines. Though a great deal of complex information is clearly swept into the footnotes; the main body of the text tends to avoid scholarly controversies, and alternate readings of the evidence. Harper’s division of Roman history into three climate-related phases is elegant—too elegant; and it does not necessarily cohere with the available literary or historical evidence.

Some of Harper’s conclusions seem self-evidently questionable. His account of the Cyprianic plague relies on fragile evidence. Undoubtedly there was a plague in Alexandria around AD 250; though the exact date is disputed. There was also a pestilence at Carthage, as Saint Cyprian vividly describes. But an Ebola-like international pandemic that resulted in the death or flight of almost 200,000 people from the city of Alexandria alone ought to have left more of a mark, both in contemporary accounts and in modern historical studies. Particularly if, as Harper claims, it spread all over the Roman Empire, and contributed to the Crisis of the Third Century. If the story told in The Fate of Rome is true, why has nobody noticed this before?

Harper’s 2015 article “Pandemics and Passages to Late Antiquity” deserves close attention. The archaeological evidence that he describes to support his claim of an Ebola-like international pandemic does not in fact prove his case. The two mass graves that he describes are not obviously associated with one another. One, in Rome, may predate the Cyprianic Plague by at least a decade; the other, in Egyptian Thebes, is not necessarily a mass grave, and cannot securely be dated to the period between AD 248 and 270. There are contradictory archaeological reports for this site—an inconvenient fact that is avoided in the footnotes. Nothing really links the Roman graves to the Theban ones, except insofar as they were used to bury corpses.

Harper’s use of literary evidence is also questionable in many parts of his book. His translations and summaries are not incorrect, but some passages seem to have been rendered tendentiously into English in support of the preferred narrative. This is purely a matter of nuance, of course. More seriously, Harper is often insensitive to questions of context, genre and style that relate to his sources, particularly where Greek-language materials are concerned. Byzantine literature can be exceedingly difficult to interpret, even where the language is superficially straightforward; Harper is not always cautious in handling these sources.

The principal source for the Cyprianic Plague is Saint Cyprian’s De Mortalitate, a consolatory text likely written in the wake of a local epidemic around AD 252. The passage describing the disease that struck Carthage is not long; it is impossible to provide more than a vague, tentative diagnosis on the basis of this evidence, for hemorrhagic fever or any other condition. A similar caution should apply to Harper’s (more plausible) claim that the Antonine Plague was a smallpox pandemic.

Whatever the Cyprianic Plague was, it does not appear to have lingered for more than a season. Saint Cyprian’s career is exceptionally well-documented: He served as bishop of Carthage for less than a decade before he was martyred in AD 258. He spent much of this period in hiding or exile, and was forced to administer his diocese through writing letters or issuing tracts. Except for some lines in De Mortalitate, and an even shorter passage in another apologetic tract, the epidemic of AD 252 does not show up in his work. Pontius, Saint Cyprian’s friend and biographer, does not describe anything that sounds like an empire-wide pandemic; nor does Eusebius of Caesarea (AD 260/265 — 339/340), author of the first full-length history of Christianity.

There definitely was a Plague of Cyprian; it may have even been an outbreak of hemorrhagic fever as Harper claims. But there is little reason to believe that it spread beyond Carthage. Localized pestilences were relatively commonplace at this point in history, as Harper himself makes clear. A pandemic is not in evidence here. The Fate of Rome features more than one attention-grabbing conclusion that does not match the data and material that Harper has collected. The graphs and visual aids throughout this book are sometimes patently misleading.

Harper simply has not made the case that climate change or pandemics of infectious disease had much to do with the fall of the Roman Empire. The sheer ambition of The Fall of Rome is energizing, and the book is a pleasure to read. But Harper ought to have immersed himself more fully in conventional sources (ancient texts, coins, archaeological evidence), and thought harder about historians’ traditional concerns (law, politics, diplomacy, defense, trade, commerce, currencies, infrastructure, institutions, religion, culture) before attempting to master the basic principles of epidemiology and climate science. Gibbon’s fundamental conclusions about the end of Rome, as expounded over the course of The Decline and Fall of the Roman Empire, remain unchallenged.

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