"The Fate of Rome: climate, disease, and the end of an empire" - updated

This is the best book I've read in several years.

If someone had asked me a month ago why the Roman empire fell, I might have concocted a reply implicating lead in the drinking vessels, debauchery and dissolution, and the rise of Goths and Huns.  This book very cogently, and reasonably concisely (300 pages) explains how climate change and a series of pandemics absolutely destroyed what had been a pan-Mediterranean empire.

I found this set of parallel timelines to be quite useful:

The first point of note is that the previous rise of the Roman empire had also been fueled by climate change -  in this case the favorable "Roman Climate Optimum."  Starting in about 200 BC the Mediterranean region experienced increased precipitation, resulting in bountiful production of wheat in north Africa, which was in effect the breadbasket for the emerging empire.  With abundant food and population growth, growth was easy, and by the time of emperor Antoninus Pius (who ruled from 138-161) the empire stretched from the north of Britain to the south of Egypt and from the Atlantic to the edges of Asia -

Linking these areas together for the delivery of food, goods, and armies was the key to the establishment and power of the empire, but that network of ships and roads would later become pathways for the dispersion of novel pathogens.  

Prior to the rise of the Roman empire...

"Life was slow, organic, fragile, and constrained.  Time marched to the dull rhythms of foot and hoof.  Waterways were the real circulatory system of the empire, but in the cold and stormy season the seas closed, and every town became an island. Energy was forbiddingly scarce.  Human and animal muscle for force, timber and scrub for fuel.  Life was lived close to the land.  Eight in ten people lived outside of cities... Survival depended on the delivery of rain in a precarious environment.  For the vast majority, cereals dominated the diet.  "Give us this day our daily bread" was a sincere petition.  Death always loomed.  Life expectancy at birth was in the 20s, probably the mid-20s, in a world where infectious disease raged promiscuously..."

Then the rains of the Climate Optimum came, extensively and predictably in a region that even today is noted for extensive dryness.  Human populations grew, cities bloomed, civilization organized.

The collapse of the empire began in the second century, when the Antonine plague became pandemic in extent.  By the middle of the third century the climate had reverted back to seasonal drought, and a second pandemic swept the area.  By the fifth century the climate advanced from drought to the "late antique little ice age," which unleashed the overwhelming Justinianic Plagues from the mid-500s to the mid-700s.  When the cities were depopulated, they were easy prey for the Goths and Huns. 

That's the TL;DR.  Here are some additional notes that I jotted down for myself for future reference.

"Population growth was the unintended outcome of countless, razor-thin changes in the narrow margins between life and death... Mortality was blindingly high... Even by the low standards of all underdeveloped societies, the actuarial tables of the roman world were grim.  Average life expectancy at birth fell somewhere between twenty and thirty years.  The blunt force of infectious disease was, by far, the overwhelming determinant... the obligatory response is high fertility.  The burden of fertility fell heavily on the bodies of women... Roman law allowed girls to be married starting at age twelve.  Most women married in their mid-teens... Women who bore sufficient numbers of children were granted robust legal privileges.  Contraception was primitive, at best... The woman surviving to menopause bore something like six children, on average..."

"... possibility that the Romans had a modest role in accelerating climate change.  Orbital, solar, and volcanic forcing are unmoved by human affairs, and the Romans did not pollute the atmosphere sufficiently to trigger climate change.  But the Romans did fell forests in massive swaths.  Woodland was cleared for agriculture.. and consumed huge forests for fire and fuel... Hadrian was concerned enough about the dwindling supply of long timber to claim certain Syrian forests as imperial property and exert control over their exploitation."

"By its nature, Roman civilization seemed to unlock the pestilential potential of the landscape.  The expansion of agriculture brought civilization deeper into habitats friendly to the mosquito.  Deforestation facilitated the pooling of water... Roman roads... cut directly through the malarial Pontine marshes.. Urban gardens and waterworks brought mosquitoes and humans into unbearably close quarters... The roman Empire was an  unintended experiment in mosquito breeding."

"The effects of malaria include severe malnutrition, leaving its victims vulnerable to other infections...Malaria clears the path for vitamin-deficiency disorders like rickets, and can increase susceptibility to respiratory infections such as tuberculosis... But it could always kill quickly, too, and it is probable that immigrants were particularly vulnerable... If the Roman Climate Optimum was indeed an especially wet period, it was a boon for the mosquitoes and the parasites they ferried... Malaria was endemic in Rome and other core regions..."

The first "great pestilence" (the Antonine Plague) was probably smallpox.  Contemporary accounts suggest it arrived via the Red Sea axis after having devastated Arabian kingdoms in ancient Yemen.  For diagnosis we have detailed descriptions by the renowned physician Galen, who treated "countless" victims: "its attendant symptoms were fever, a black pustular rash, conjunctival irritation, ulceration deep in the windpipe, and black or bloody stools."  If the scabs dried and fell off like scales, the victim might recover.

Smallpox would be directly transmitted by the inhalation of infectious droplets expelled by an infectious person.  The incubation period averaged about 12 days, so the virus could travel a long distance before overwhelming the host.  The rash started as vesicles, then became pustular, then scabbed.  The patient would be infectious until after the scabs fell off, leaving disfiguring scars.  There are references to smallpox-like epidemics in China in the fourth century and in Indian texts of the sixth century.  A Persian physician devoted an extraordinary treatise to the differential diagnosis of smallpox vs. measles.

"A fuller picture is likely to emerge as more genomic data is recovered from archaeological samples.  At present, one hypothesis is that Variola evolved from a rodent orthopoxvirus to become an obligate human pathogen, in Africa, sometime before the Antonine Plague.  The biologcal agent of the second-century pestilence could represent an especially virulent lineage of Variola that went extinct, or an ancestral form of the virus that evolved into a milder medieval form of smallpox.  And it still could have been caused by some other biological agent altogether, although there are no serious candidates at present."

In April of AD 248, the city of Rome celebrated its 1000th birthday by slaughtering a "veritable zoo, of the most extravagant creatures from around the world... thirty-two elephants, ten elk, ten tigers, sixty lions, thirty leopards, six hippopotami ten giraffes, one rhinoceros... and countless other wild beasts, not to mention a thousand pairs of gladiators."

"... just when the Romans most needed a buffer against bad fortune, the Nile abandoned them spectacularly.  In AD 244, the waters failed to rise.  IN AD 245 or 246, the floods were weak again."  [grain prices soared spectacularly]

The second pandemic (the Plague of Cyprian) struck in recurring waves from AD 249-262.  The etiology is a bit uncertain, but it is known to have emerged from Africa (Ethiopia), then extended north and west.  Archaeologists have found mass graves in Upper Egypt with lime poured over bodies that were then incinerated.

"The geographic scope of the pestilence was vast.  'There was almost no province of Rome, no city, no house, which was not attacked and emptied by this general pestilence.'  It hit the largest cities like Alexandria Antioch, Rome, and Carthage, but also remote urban areas.  It was an "empire-wide event."  

The pandemic disease was characterized by fever, diarrhea, ischemia of the extremities, conjunctival hemorrhages, with deafness and blindness in the aftermath - symptoms suggestive of a viral hemorrhagic fever.  The winter seasonality suggests an organism that transmits by interpersonal contact.  "Only one family of hemorrhagic viruses seems to provide a best match for both the pathology and epidemiology of the Plague of Cyprian: filoviruses, whose most notorious representative is the Ebola Virus."

After the second pandemic there was widespread anarchy, loss of resilience, and increasing problems contending with barbarians.

"By design, the Roman frontier system was defensible, not impenetrable.  But almost simultaneously, in the early AD 250s, the defensive network imploded along all of the main fronts.  'The Alemanni, having devastated the Gauls, penetrated into Italy... Greece, Macedonia, Pontus, and Asia were destroyed by Goths.  Pannonia was plundered by Sarmatians and Quadi.  Germans advanced all the way to the Spains.'"

Slavery was ubiquitous across the empire in this era.

"To own a slave was a standard of minimum respectability.  In the fourth century, priests doctors, painters, prostitutes, petty military officers, actors, inn-keepers, and fig-sellers are found owning slaves.  Many slaves owned slaves.    Even assistant professors in Antioch had a few slaves."

And economic stratification was enormous.

"The top senatorial families of late antiquity owned stupendous wealth... each of the great senatorial houses in Rome was like a city in its own right... incomes the equivalent of something like the production of 80,000 family farms, per year."

The fourth century also marked the rise of the Huns.  Their migration toward the west can be considered an environmental event.  It was a time of megadrought in the steppe.  

"The last two decades from ca AD 350 to 370 were the worst multidecadal drought event of the last two millennia.  The nomads who called central Asia home suddenly faced a crisis as dramatic as the Dust Bowl.  The Huns were armed climate refugees on horseback.  Their mode of life enabled them to search out new pastures with amazing speed.... By AD 370, Huns had started to cross the Volga River.  The advent of these people on the western steppe was momentous."

What made the Huns overwhelming were their horses and speed of movement, and their composite reflex bow (effective to about 150 meters).  The land north of the Danube had been dominated by Goths in a kind of equilibrium."In AD 376, in flight from the Huns, Goths appeared en masse seeking asylum inside Roman borders.  Upwards of 100,000 Goths - men, women, and children - may have sought help."  With the Roman empire "reeling," Attila "scaled up the Hun war machine." "Throughout the 440s, he wasted the Balkans and engorged his royal circle on plundered wealth.

In AD 447 a massive earthquake knocked down the great walls of Constantinople, including 57 defensive towers.  The city was defenseless.  What saved Constantinople were its endemic diseases.  

"'Against the stone of sickness they stumbled and the steeds fell... He who was skillful in shooting with the bow, sickness of the bowels overthrew him...'  What actually repulsed the invaders was seen, from one perspective, as "heaven-sent disasters: famine and some kind of disease."  The retreat was in fact the predictable biological consequence of intruders colliding with the indigenous disease ecology.  The heartland of empire was a gauntlet of germs.  The unsung savior of Italy in this affair was perhaps even malaria."

After the Huns retreated in the fifth century, the Roman empire was in ruins.  The western Roman army "ceased to exist as a state institution."  By AD 476 there was no Roman emperor in the west.  The cities shriveled.  Money was scarce.  The churches found themselves the wealthiest landowners and institutions.

When Rome tried to rebuild in a suboptimal climate, their focus was on securing huge hoards of food.  The principal food was bread, which required huge granaries full of wheat. 

Granaries were everywhere in the later Roman world.  the stockpiling of grain was deeply rooted in the Mediterranean psyche.  In the empire, the vast network of cities, ships, and stores of grain created an ecosystem.  This ecosystem served as an invitation for a species uncannily evolved to be commensal - literally, to "share a table" - with us: Rattus rattus, the black or ship rat...

The fusion of global trade and rodent infestation was the ecological precondition for the greatest disease event human civilization had ever experienced: the first pandemic of plague... In 541 plague appeared on the shores of Egypt..." [presumably having come from the Indian subcontinent via the trade routes along the Red Sea]

It required one last twist of fate for the bacterium to make its grand entrance into the roman world.  The Asia uplands had prepared a monster iin the germ Yersinia pestis.  The ecology of the empire had built an infrastructure awaiting a pandemic.  The silk trade was ready to ferry the deadly package.  But the final conjunction, what finally let the spark jump, was abrupt climate change.  The year AD 536 is known as a "Year without Summer."  It was the terrifying first spasm in what is now known to be a cluster of volcanic explosions unmatched in the last three thousand years.  Again in AD 540-541 there was a gripping volcanic winter... the AD 530s and 540s were not just frosty.  They were the coldest decades in the late Holocene.  The reign of Justinian was beset by an epic, once-in-a-few-millennia cold snap, global in extent."

Because this Antonine [bubonic] plague was rat-borne, it had the ability to infiltrate and devastate rural areas as well as urban ones.  The Medieval Black Death (14th century) is estimated to have killed 40-60% of all the people in Europe, the Middle East, and North Africa.  This sixth century one was probably similar.  The empire crashed again.  There were no people to harvest the decreased crops, no money to pay the armies, inheritance systems were obliterated, building activity ceased.  During this Late Antique "Little Ice Age", Pope Gregory's Rome "may have been home to as few as 10-20,000 souls huddled inside its walls; they would barely have filled a corner of the Colosseum."

"AD 536 was the coldest year of the last two millennia.  Average summer temperatures in Europe fell instantly by up to 2.5 degrees, a truly staggering drop.  In the aftermath of the volcanic eruption in AD 539-40, temperatures plunged worldwide.  In Europe, average summer temperatures fell again by up to 2.7 degrees."

There is modern evidence that the volcanic activity at this time may also have been accompanied by diminished solar output.   When Pope Gregory sent missionaries to convert the pagans of the British Isles, "there were no towns, no villas and no coins."

"Most towns suffered a fate somewhere between hollowing out and utter annihilation.  Rome is only the most famous and dramatic instance of the urban death spiral.  Procopius claimed that by AD 547 there were only 500 people in the city: the number may not be entirely credible, but the point is made. 

I'll end this mega-post here, with the observation that not only is the book interesting because of the factual material, but it is also extremely well-written from a language and stylistic standpoint.  This author knows how to tell a story.  I'll write a separate post to list the new words I learned while reading the book. 

p.s. - I'm not back to blogging regularly yet.  Just had to finish this post so I can return the book to the library.