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In a new paper for the Belfer Center, “The Collapse of Civilizations”, acclaimed Aegean prehistorian Malcolm Wiener explores five paramount causes of collapse of civilizations.
Dr. Wiener’s paper finds that major episodes of climate change have had profound impacts upon cultural continuity, and that the interactions between climate change, famines, migrations, pandemics, and major innovations in the means of transport and warfare are critical in understanding the collapse of past civilizations.
“The prime movers of collapse throughout history,” Wiener writes, “all present risks for today.”
The Role of Climate and Plague in the Collapse of the Roman Empire
While the Western Roman Empire collapsed by the beginning of the 5th century AD, the Byzantine Eastern Roman Empire revived until the dramatic events of the Late Antique Little Ice Age of AD 536 to 680. The frigid climate of the period was due in part to a series of volcanic eruptions in early AD 536, AD 539–540, and AD 547, a cluster of eruptions unmatched in the last 3000 years. Aerosols from these eruptions partly obscured the sun. AD 536, the year of the first eruption, was known as the year without sun, and 539–540 may have been even worse. The 530s and 540s were the coldest decade since the Ice Age. The significantly stunted tree rings at AD 550 signal a year of particular frigidity. At the time of the volcanic eruptions, the sun itself may have entered a periodic cycle during which it radiated less heat toward the earth.The decline of solar output is now measurable for the first time via analyses of beryllium isotopes. It is worth noting that the years AD 550–600 mark a period of reduced rainfall and societal collapse at the great center of Teotihuacan in Mexico as well.
Famine induced by the highly unsettled weather of the 6th century AD contributed to the deadly impact of the Justinianic Plague of AD 541 to 543, which worked its way across the Roman Empire in three years, causing an estimated 30 million deaths, or about one-half the entire population. The Byzantine Greek historian Procopius reports that the plague originated in Pelusium in northeastern Egypt and then spread throughout the Empire via maritime and land transport routes, with the result that “the whole human race came near to being annihilated.” With regard to Rome itself, Procopius states that by AD 547 the population had declined from one million people to five hundred. While he may have exaggerated the extent of the decline, it was surely drastic in any event. The enormous seaborne commerce of the 1st century AD all but disappeared by the mid-6th to early 7th centuries, and all of Italy reverted to a prehistoric condition not seen since before the Etruscans, with signs of recovery only emerging in a new medieval guise in the 11th century.
The Eastern Roman Empire under Justinian and Theodora displayed great resilience in the face of the increasing cold and other challenges during the years AD 527 to 541. It made peace with Persia, recaptured large areas of the Roman Empire in the west, built grand structures including the imposing Hagia Sophia in Constantinople, and enacted the famous codification of Roman law whose effects are still felt today. In the end, however, the Eastern Empire, weakened by the frigid weather, succumbed to the Plague of Justinian. Adverse climate, mass migrations, and disease, interacting with human agency in the form of mad rulers and internal strife (plus the occasional role of chance in the outcome of battles) combined to destroy the Roman Empire, with plague the final fatal stroke.
Two-hundred forty-one years after the publication of Edward Gibbon’s The History of the Decline and Fall of the Roman Empire, the best-seller of its day, the subject retains its fascination while undergoing reconsideration via a torrent of new and ongoing scientific research.
The Curse of Benign Weather
In the 10th century, a period of general warming known as the Medieval Warm Period began. This period includes the special and counter-intuitive case of benign weather playing a major role in the destruction of cultures. Examination of tree rings of Siberian pines in central Mongolia provides evidence for a period of sustained rainfall and unusually mild weather between AD 1211 and 1225, which coincides precisely with the conquests of the Mongols under Genghis Khan, accompanied by widespread destruction and slaughter. Pastures suddenly rich after a preceding drought provided fodder for the herds of war horses which enabled the Mongol armies to conquer lands from China to Hungary. In short, the unusually mild climate produced the grasspower that provided the critical horsepower, plus the necessary fodder for the camels, yaks, cattle, and sheep accompanying the invaders. Warrior peoples move and seek to conquer not only when they must, but also when they can.
The Little Ice Age
The succeeding Little Ice Age of c. AD 1300 to 1750 produced prolonged freezing winters and colder, damper summers in much of Europe, the Near East, and China as well, with famines common. Cold weather accompanied by famine reappears in Scandinavia around AD 1300, with land abandoned and marked population decline. We still seek evidence as to whether lack of nourishment diminished resilience to the massive epidemic which followed. By mid-century, the expansion of sea travel in the Mediterranean, which marked the beginning of the early Renaissance in Italy, brought with it the great plague known as the Black Death of 1347–51, which spread through Europe. Estimates of the death toll range from about one-quarter to one-half of the total population of Europe, depending on the area. A widely though not universally accepted reconstruction of events holds that the epidemic, caused by bubonic plague as we now know from DNA analysis, originated in China and decimated the Mongol army besieging a Genoese trading port in the Crimea. The Mongols catapulted plague-infested corpses into the town. From here Genoese ships carried the plague to Mediterranean ports, including of course those of Greece and Italy. The medieval Book of Hours, the first text read across Europe by people at every level of literacy, illustrates (in every sense) the great fears of humankind via prayers to forestall death, plague, warfare, and crop-destroying weather. The subsequent onset in Ottoman territories of a period of cold and drought, beginning around AD 1400 and continuing through the 16th century and into the 17th, was accompanied by regional abandonment and conflict in parts of the Ottoman Empire as well. Waves of bubonic plague during this period affected both the Ottomans and their enemies. The early 16th century also saw the conquest and collapse of the Aztec and Inca Empires of Mexico and Peru, brought about by Europeans utilizing new methods of warfare (horses and firearms) and transport (horses and sailing vessels) but above all bringing pathogens to which Native Americans had no resistance, resulting eventually in the death of an estimated 90% of the indigenous population.
At the culmination of the Little Ice Age, Dutch paintings of the 17th century AD show the canals and ponds of the Netherlands frozen over, with locals engaged in various activities on ice. Marked population decline is documented in France, where about 15% of the population died of starvation between 1692 and 1694, and in Germany, England, the Netherlands, Denmark, Finland, Poland, Estonia, Castile, and Catalonia. Smallpox, plague, typhus, and measles attacked many already weakened by starvation. During the Little Ice Age, Europeans were also frequently at war, with the Thirty Years’ War of 1618 to 1648 taking an enormous toll in lives. Overall, population may have been reduced by a third or more. The decline in temperatures and populations coincides in time with the virtual absence of sunspot activity known as the Maunder Minimum between AD 1645 and 1715. Recent research suggests that variations in solar activity may have a profound influence on climate.
Conversely, warming climate beginning in the latter half of the 18th century was accompanied by population increase. The increase in population was halted one more time, however, not by adverse climate but by war and epidemic, in this case World War I and the influenza pandemic of 1918, which took the lives of somewhere between 50 million and 100 million people around the globe. The broad history of epidemics was stated 40 years ago by William McNeill in his classic work, Plagues and Peoples, as follows: agriculture brought us into close contact with domesticated animals; the growth of cities provided the dense population in which germs could circulate; and improvements in transport led to a convergence of disease pools.
ABOUT THE AUTHOR
Malcolm H. Wiener is an Aegean prehistorian who has written extensively on the Eastern Mediterranean world in the Bronze Age. His many published papers span the emergence, florescence, and collapse of the first complex societies of the western world in Minoan Crete and Mycenaean Greece, their relationship to the civilizations of the Near East and Egypt, the absolute chronology of the ancient world (science, texts, and interconnections via objects), warfare in the ancient world, the acquisition of copper and tin for bronze tools and weapons, and the interaction of climate change, mass migrations, pandemics, warfare, and human agency in the collapse of civilizations. His awards include the honorary doctorates of the Universities of Sheffield, Tübingen, Athens, Cincinnati, University College London, Dickinson College, and the University of Arizona, the Gold Cross of the Order of Honor (Greece), and the Ring of Honour of the German Academy in Mainz. Mr. Wiener is a Fellow of the American Academy of Arts and Sciences and the Society of Antiquaries in London, a Corresponding Member of the Royal Swedish Academy, the Austrian Archaeological Institute, the Austrian Academy of Science, the Deutsches Archaologisches Institut, and the Academy of Athens, holds the rank of Chevalier in the Ordre des Arts et des Lettres of France, and is an Honorary Director of the Greek Archaeological Society. He is the founder of the Institute for Aegean Prehistory and the Malcolm Wiener Laboratory for Archaeological Science at the American School of Classical Studies at Athens, and a recipient of the Archaeological Institute of America Bandelier Award for Public Service to Archaeology and the Athens Prize of the American School of Classical Studies at Athens.
Mr. Wiener is a Trustee Emeritus of the Metropolitan Museum of Art, Chairman Emeritus of the Board of Trustees of the American School of Classical Studies in Athens, and Chair of the Board of Directors of the Malcolm Hewitt Wiener Foundation. The Center for Social Policy at Harvard Kennedy School is named in his honor. He chaired the independent task force of the Council on Foreign Relations on “Non-lethal Technologies: Military Implications and Options” and wrote its report.
Mr. Wiener was born in Tsingtao, China, is a graduate of Harvard College (1957) and the Harvard Law School (1963), served at sea as an officer in the U.S. Navy, practiced law in New York City, and was the founder and CEO of related New York City investment management firms employing algorithmic methodologies in futures markets between 1971 and 1987.