Collapse

by Diamond, Jared

  A further big factor that now needs to be added to our understanding of Angkor’s decline is a change in climate. Studies of the water network have yielded seemingly contradictory evidence of both floods and droughts in the 14th and 15th centuries. On the one hand, the big canals to the south of Angkor became filled with coarse-grained sand, implying heavy rains and strong flooding. On the other hand, the exit channels of the big baray were blocked, while the East Baray exit was reconstructed to make it narrower and was then converted from an outlet to an inlet—sure signs of water shortages and attempts to keep the reservoir water levels high. The resolution to this paradoxical combination of floods and droughts has just emerged from publication of a 979-year-long record of tree-ring widths, similar to the tree-ring records that have illuminated climate change in the Anasazi area as I discussed in Chapter 4. These records show that monsoon rainfall in Southeast Asia became much more variable after A.D. 1350, with severe droughts from about 1336 to 1374 and from 1400 to 1425, and exceptionally heavy rainfall in some years between and just before and after those two droughts. The period 1322 to 1453 contains a disproportionate number of both the driest years and the wettest years of the last millennium.

  We can now place Angkor’s decline within the framework of the five sets of factors that I proposed in this book’s prologue for understanding a society’s success or failure. First, the Khmer did inflict unintentional damage on their environment: they deforested the Angkor plain and the slopes of the Kulen Hills. Without trees to slow rain runoff, heavy monsoons eroded soil and dislodged sediment that was swept into canals, and floods incised the Siem Riep River’s channel. That river is now about 20 feet below the Angkorian land surface. Second, climate change exposed the Angkor area to conditions both drier and wetter than Angkor’s system was designed to accommodate. Third, the Khmer, like the Roman Empire and the Greenland Norse, faced growing problems from hostile neighbors. Fourth, friendly trade partners played a role, by offering the Khmer maritime economic opportunities more attractive than the inland opportunities available at Angkor, but then those opportunities became restricted. Finally, the Khmer Empire responded to the attractions and the problems of the Angkor environment by becoming committed to an increasingly huge, complex, and hard-to-maintain water management system from which there was no going back. All five of those factors interacted: climate change and erosion weakened the Khmer to the point where they could no longer resist their enemies, no longer maintain and improve their water management system, and turned away from an agricultural economy to maritime trade until shifting trade routes and political power made that, too, less profitable.

  We can also place the Khmer decline within the spectrum of collapses, from quick and lethal to slow and non-lethal. At the former extreme lies the end of Greenland’s Western Settlement, where everybody may have died in a single winter. Angkor’s decline seems to lie toward the opposite extreme: it extended over centuries, people gradually moved away, and there is no evidence of massive die-offs of people. But the result, nevertheless, was unequivocally a collapse: scattered villages in the former metropolitan heartland, on the site of what once had been a world-class city and the capital of the region’s most powerful empire.

  For all of us fascinated by the glory and the mystery of Angkor, these are exciting times. We have gained much detailed knowledge about the city in the last decade, building on the previous century of archaeological investigation. But big questions remain unsolved, and the next decade promises to be even more exciting. Here is my short list of five sets of questions to which I would love to know the answers by the year 2020:

  Where did Angkor’s population get its wood for construction and fuel? The city’s 750,000 people must have needed huge quantities of wood for building houses and other structures, and to make charcoal for cooking. Yet the original forest of the Angkor plains and much of the Kulen Hills was cut down, and it boggles the mind to imagine that the trees then planted by people around their houses could have met the needs of such a large population.

  How did the Khmer manage water? They surely had methods for recording the monsoons and predicting the resulting water flows. What roles did the shrines in the middle of the baray play in managing the canal network? How did the Khmer move water around the landscape without pumps? The West Baray was not dug into the ground but was built on the ground, and cleverly positioned so that the intake canals provided a water surface several feet above ground level at the exit. How did Khmer water engineers shift water flows from one channel to another as needed? Did the canals have movable gates?

  How did the whole water management system function? It includes many big structures that have been located but whose purpose remains unknown.

  Why has it taken so long for Angkor to regain its formerly dense human population, after the city became largely abandoned in the 1600s? The same puzzle arises for the Southern Maya Lowlands, which were still sparsely populated upon Cortés’s arrival in 1524, six or seven centuries after the Classic Maya collapse.

  Finally, I mentioned at the beginning of this chapter that there used to be numerous other low-density cities besides Angkor in the seasonally wet tropics elsewhere in the world, but that all of those cities had declined before the European expansion of the last five centuries. What was the Achilles’ heel that made Angkor and all those other cities unsustainable in the long run?

  ACKNOWLEDGMENTS

  I acknowledge with gratitude the big debts that I owe to many people for their contributions to this book. With these friends and colleagues, I shared the pleasure and excitement of exploring the ideas presented here.

  A special badge of heroism was earned by six friends who read and critiqued the entire manuscript: Julio Betancourt, Stewart Brand, my wife Marie Cohen, Paul Ehrlich, Alan Grinnell, and Charles Redman. That same badge of heroism, and more, are due to my editors Wendy Wolf at Penguin Group (New York) and Stefan McGrath and Jon Turney at Viking Penguin (London), and to my agents John Brockman and Katinka Matson, who besides reading the whole manuscript helped in myriad ways to shape this book from its initial conception through all stages of production. Gretchen Daily, Larry Linden, Ivan Barkhorn, and Bob Waterman similarly read and critiqued the concluding chapters on the modern world.

  Michelle Fisher-Casey typed the whole manuscript, many times. Boratha Yeang tracked down books and articles, Ruth Mandel tracked down photographs, and Jeffrey Ward prepared the maps.

  I presented much of the material of this book to two successive classes of undergraduates at the University of California at Los Angeles, where I teach in the Geography Department. I also offered a mini-course as a visitor to a graduate seminar in the Department of Anthropological Sciences at Stanford University. As willing guinea pigs, those students and colleagues contributed fresh and stimulating outlooks.

  Earlier versions of some material of seven chapters appeared as articles in Discover magazine, the New York Review of Books, Harper’s magazine, and Nature. In particular, Chapter 12 (on China) is an expanded version of a joint article that Jianguo (Jack) Liu and I wrote, that Jack drafted, and for which he gathered the information.

  I also thank other friends and other colleagues in connection with each chapter. They variously arranged my visits to countries where they lived or conducted research, guided me in the field, patiently shared their experience with me, sent me articles and references, critiqued my chapter draft, or did several or all of these things. They generously gave me many days or weeks of their time. My debt to them is enormous. They include the following people, listed by chapter:

  Chapter 1. Allen Bjergo, Marshall and Tonia and Seth Bloom, Diane Boyd, John and Pat Cook, John Day, Gary Decker, John and Jill Eliel, Emil Erhardt, Stan Falkow, Bruce Farling, Roxa French, Hank Goetz, Pam Gouse, Roy Grant, Josette Hackett, Dick and Jack Hirschy, Tim and Trudy Huls, Bob Jirsa, Rick and Frankie Laible, Jack Losensky, Land Lindbergh, Joyce McDowell, Chris Miller, Chip Pigman, Harry Poett, Steve Powell, Jack Ward Thomas, Lucy Tompkins, Pat V
aughn, Marilyn Wildee, and Vern and Maria Woolsey.

  Chapter 2. Jo Anne Van Tilburg, Barry Rolett, Claudio Cristino, Sonia Haoa, Chris Stevenson, Edmundo Edwards, Catherine Orliac, and Patricia Vargas.

  Chapter 3. Marshall Weisler.

  Chapter 4. Julio Betancourt, Jeff Dean, Eric Force, Gwinn Vivian, and Steven LeBlanc.

  Chapter 5. David Webster, Michael Coe, Bill Turner, Mark Brenner, Richardson Gill, and Richard Hansen.

  Chapter 6. Gunnar Karlsson, Orri Vésteinsson, Jesse Byock, Christian Keller, Thomas McGovern, Paul Buckland, Anthony Newton, and Ian Simpson.

  Chapters 7 and 8. Christian Keller, Thomas McGovern, Jette Arneborg, Georg Nygaard, and Richard Alley.

  Chapter 9. Simon Haberle, Patrick Kirch, and Conrad Totman.

  Chapter 10. René Lemarchand, David Newbury, Jean-Philippe Platteau, James Robinson, Vincent Smith.

  Chapter 11. Andres Ferrer Benzo, Walter Cordero, Richard Turits, Neici Zeller, Luis Arambilet, Mario Bonetti, Luis Carvajal, Roberto and Angel Cassá, Carlos Garcia, Raimondo Gonzalez, Roberto Rodríguez Mansfield, Eleuterio Martinez, Nestor Sanchez Sr., Nestor Sanchez Jr., Ciprian Soler, Rafael Emilio Yunén, Steve Latta, James Robinson, and John Terborgh.

  Chapter 12. Jianguo (Jack) Liu.

  Chapter 13. Tim Flannery, Alex Baynes, Patricia Feilman, Bill McIntosh, Pamela Parker, Harry Recher, Mike Young, Michael Archer, K. David Bishop, Graham Broughton, Senator Bob Brown, Judy Clark, Peter Copley, George Ganf, Peter Gell, Stefan Hajkowicz, Bob Hill, Nalini Klopf, David Paton, Marilyn Renfrew, Prue Tucker, and Keith Walker.

  Chapter 14. Elinor Ostrom, Marco Janssen, Monique Borgerhoff Mulder, Jim Dewar, and Michael Intrilligator.

  Chapter 15. Jim Kuipers, Bruce Farling, Scott Burns, Bruce Cabarle, Jason Clay, Ned Daly, Katherine Bostick, Ford Denison, Stephen D’Esposito, Francis Grant-Suttie, Toby Kiers, Katie Miller, Michael Ross, and many people in the business world.

  Chapter 16. Rudy Drent, Kathryn Fuller, Terry Garcia, Frans Lanting, Richard Mott, Theunis Piersma, William Reilly, and Russell Train.

  Support for these studies was generously provided by the W. Alton Jones Foundation, Jon Kannegaard, Michael Korney, the Eve and Harvey Masonek and Samuel F. Heyman and Eve Gruber Heyman 1981 Trust Undergraduate Research Scholars Fund, Sandra McPeak, the Alfred P. Sloan Foundation, the Summit Foundation, the Weeden Foundation, and the Winslow Foundation.

  FURTHER READINGS

  These suggestions of some selected references are for those interested in reading further. Rather than devote space to extensive bibliographies, I have favored citing recent publications that do provide comprehensive listings of the earlier literature. In addition, I cite some key books and articles. A journal title (in italics) is followed by the volume number, followed after a colon by the first and last page numbers, and then by the year of publication in parentheses.

  Prologue

  Influential comparative studies of collapses of ancient advanced societies around the world include Joseph Tainter, The Collapse of Complex Societies (Cambridge: Cambridge University Press, 1988), and Norman Yoffee and George Cowgill, eds., The Collapse of Ancient States and Civilizations (Tucson: University of Arizona Press, 1988). Books focusing specifically on environmental impacts of past societies, or on the role of such impacts in collapses, include Clive Ponting, A Green History of the World: The Environment and the Collapse of Great Civilizations (New York: Penguin, 1991); Charles Redman, Human Impact on Ancient Environments (Tucson: University of Arizona Press, 1999); D. M. Kammen, K. R. Smith, K. T. Rambo, and M.A.K. Khalil, eds., Preindustrial Human Environmental Impacts: Are There Lessons for Global Change Science and Policy? (an issue of the journal Chemosphere, volume 29, no. 5, September 1994); and Charles Redman, Steven James, Paul Fish, and J. Daniel Rogers, eds., The Archaeology of Global Change: The Impact of Humans on Their Environment (Washington, D.C.: Smithsonian Books, 2004). Among books discussing the role of climate change in the context of comparative studies of past societies are three by Brian Fagan: Floods, Famines, and Emperors: El Niño and the Fate of Civilizations (New York: Basic Books, 1999); The Little Ice Age (New York: Basic Books, 2001); and The Long Summer: How Climate Changed Civilization (New York: Basic Books, 2004).

  Comparative studies of relations between the rises and the falls of states include Peter Turchin, Historical Dynamics: Why States Rise and Fall (Princeton, N.J.: Princeton University Press, 2003), and Jack Goldstone, Revolution and Rebellion in the Early Modern World (Berkeley: University of California Press, 1991).

  Chapter 1

  Histories of the state of Montana include Joseph Howard, Montana: High, Wide, and Handsome (New Haven: Yale University Press, 1943); K. Ross Toole, Montana: An Uncommon Land (Norman: University of Oklahoma Press, 1959); K. Ross Toole, 20th-Century Montana: A State of Extremes (Norman: University of Oklahoma Press, 1972); and Michael Malone, Richard Roeder, and William Lang, Montana: A History of Two Centuries, revised edition (Seattle: University of Washington Press, 1991). Russ Lawrence offered an illustrated book on the Bitterroot Valley, Montana’s Bitterroot Valley (Stevensville, Mont.: Stoneydale Press, 1991). Bertha Francis, The Land of Big Snows (Butte, Mont.: Caxton Printers, 1955) gives an account of the history of the Big Hole Basin. Thomas Power, Lost Landscapes and Failed Economies: The Search for Value of Place (Washington, D.C.: Island Press, 1996), and Thomas Power and Richard Barrett, Post-Cowboy Economics: Pay and Prosperity in the New American West (Washington, D.C.: Island Press, 2001), discuss the economic problems of Montana and the U.S. Mountain West. Two books on the history and impacts of mining in Montana are David Stiller, Wounding the West: Montana, Mining, and the Environment (Lincoln: University of Nebraska Press, 2000) and Michael Malone, The Battle for Butte: Mining and Politics on the Northern Frontier, 1864-1906 (Helena, Mont.: Montana Historical Society Press, 1981). Stephen Pyne’s books on forest fires include Fire in America: A Cultural History of Wildland and Rural Fire (Princeton, N.J.: Princeton University Press, 1982) and Year of the Fires: The Story of the Great Fires of 1910 (New York: Viking Penguin, 2001). An account of fires focused on the western United States by two authors, one of them a resident of the Bitterroot Valley, is Stephen Arno and Steven Allison-Bunnell, Flames in Our Forest: Disaster or Renewal? (Washington, D.C.: Island Press, 2002). Harsh Bais et al., “Allelopathy and exotic plant invasion: from molecules and genes to species interactions” (Science 301:1377-1380 (2003)) show that the means by which Spotted Knapweed displaces native plants include secreting from its roots a toxin to which the weed itself is impervious. Impacts of ranching on the U.S. West in general, including Montana, are discussed by Lynn Jacobs, Waste of the West: Public Lands Ranching (Tucson: Lynn Jacobs, 1991).

  Current information on some Montana problems discussed in my chapter can be obtained from Web sites and e-mail addresses of organizations concerned with these problems. Some of these organizations, and their addresses, are as follows: Bitterroot Land Trust: www.BitterRootLandTrust.org. Bitterroot Valley Chamber of Commerce: www.bvchamber.com. Bitterroot Water Forum: brwaterforum@bitterroot.mt. Friends of the Bitterroot: www.FriendsoftheBitterroot.org. Montana Weed Control Association: www.mtweed.org. Plum Creek Timber: www.plumcreek.com. Trout Unlimited’s Missoula office: montrout@montana.com. Whirling Disease Foundation: www.whirling-disease.org. Sonoran Institute: www.sonoran.org/programs/si_se. Center for the Rocky Mountain West: www.crmw.org/read. Montana Department of Labor and Industry: http://rad.dli.state.mt.us/pubs/profile.asp. Northwest Income Indicators Project: http://niip.wsu.edu/.

  Chapter 2

  The general reader seeking an overview of Easter Island should begin with three books: John Flenley and Paul Bahn, The Enigmas of Easter Island (New York: Oxford University Press, 2003, updating Paul Bahn and John Flenley, Easter Island, Earth Island (London: Thames and Hudson, 1992); Jo Anne Van Tilburg, Easter Island: Archaeology, Ecology, and Culture (Washington, D.C.: Smithsonian Institution Press, 1994); and Jo Anne Van Tilburg, Among Stone Giants (New York: Scribner, 2003). The last-mentio
ned book is a biography of Katherine Routledge, a remarkable English archaeologist whose 1914-15 visit enabled her to interview islanders with personal memories of the last Orongo ceremonies, and whose life was as colorful as a fantastic novel.

  Two other recent books are Catherine and Michel Orliac, The Silent Gods: Mysteries of Easter Island (London: Thames and Hudson, 1995), a short illustrated overview; and John Loret and John Tancredi, eds., Easter Island: Scientific Exploration into the World’s Environmental Problems in Microcosm (New York: Kluwer/Plenum, 2003), 13 chapters on results of recent expeditions. Anyone who becomes seriously interested in Easter Island will want to read two classic earlier books: Katherine Routledge’s own account, The Mystery of Easter Island (London: Sifton Praed, 1919, reprinted by Adventure Unlimited Press, Kempton, Ill., 1998), and Alfred Métraux, Ethnology of Easter Island (Honolulu: Bishop Museum Bulletin 160, 1940, reprinted 1971). Eric Kjellgren, ed., Splendid Isolation: Art of Easter Island (New York: Metropolitan Museum of Art, 2001) assembles dozens of photos, many in color, of petroglyphs, rongo-rongo boards, moai kavakava, barkcloth figures, and a red feather headdress of a type that may have inspired the red stone pukao.

  Articles by Jo Anne Van Tilburg include “Easter Island (Rapa Nui) archaeology since 1955: some thoughts on progress, problems and potential,” pp. 555-577 in J. M. Davidson et al., eds., Oceanic Culture History: Essays in Honour of Roger Green (New Zealand Journal of Archaeology Special Publication, 1996); Jo Anne Van Tilburg and Cristián Arévalo Pakarati, “The Rapanui carvers’ perspective: notes and observations on the experimental replication of monolithic sculpture (moai),” pp. 280-290 in A. Herle et al., eds., Pacific Art: Persistence, Change and Meaning (Bathurst, Australia: Crawford House, 2002); and Jo Anne Van Tilburg and Ted Ralston, “Megaliths and mariners: experimental archaeology on Easter Island (Rapa Nui),” in press in K. L. Johnson, ed., Onward and Upward! Papers in Honor of Clement W. Meighan (University Press of America). The latter two of those three articles describe experimental studies aimed at understanding how many people were required to carve and transport statues, and how long it would have taken.