Collapse begins with Diamond describing the ecological pressure in his summer home in Bitterroot, Montana. Then he discusses a number of historical civilizations that have collapsed: Easter Island, Henderson Island, the Aztecs in the Yucatan, the Anasazi, and, in some detail, the Norse settlement in Greenland. That is followed by the success stories of Tokugawa Japan, the New Guinea highlands, and the very small island of Tikoa which has few resources, but which has survived into modern times. The rest of the book describes how the world is near the edge of ecological collapse.
Diamond begins with Bitterroot, Montana because it is a story of ecological pressure in an area that he understands the dynamics of the problem. Bitteroot used to be a beautiful paradise in the river valley, surrounded by mountains. Rich people were attracted to the beauty and built houses in the valley. At the same time, Montana’s mines were no longer a large scale industry (in part due to push-back from mining’s previous destruction. Farming was slowly becoming uneconomical, so the farmers were gradually selling out to the summer-home subdivision builders. The increase of population brought increased pressure on the natural beauty that everyone had come for, and was in danger of destroying it.
Diamond eventually came to the conclusion that a society’s collapse is caused by the interplay of five factors:
- Environment damage
- Climate change
- Hostile neighbors
- Friendly trade partners
- The society’s responses to it’s environmental problems.
The first collapsed society Diamond examines is Easter Island. DNA evidence indicates that Easter Island was colonized by Polynesians (not South Americans, as Thor Heyerdahl famously theorized) in about AD 900. They originally found the island forested with giant palm trees, blessed with good fishing stocks offshore, and inhabited by huge bird colonies, which were rapidly eaten. Politically the island ended up being divided into twelve sections, each ruled by a chief. The sections had different resources, so an integrated trade developed out of sheer necessity. As society became more structured, and the honor of a chief became related to the size of his ahu statues, food production moved beyond the easily farmed areas into plantations in the middle of the island. This land was so poor that it could only be farmed by putting rocks in the field to keep moisture in the soil and protect the plants from the wind. The original forest was cleared for the plantations in order to provide the extra 30% food required to build massive show-off ahu. Wood was also used for canoes, charcoal, heating during the winter, and to cremate bodies. After the wood was exhausted, no more canoes could be made, which meant that fishing was very limited. Ultimately, the collapse of Easter Island’s society was due to human factors: by clearing the forest in order to make bigger and bigger ahu to satisfy the pride of the chiefs, and by hunting the native bird and animal populations to extinction. Since Easter Island has poor rainfall and receives no windborne soil from Asia to improve the soil, plants grow slowly. Once lost, the island’s isolation ensure that these could not be regained.
The second society is the Pitcairn and Henderson Islands. These are small, remote islands to the west of Easter Island. Pitcairn Island was originally settled by people from the larger island of Mangareva, and probably held a population of about 100 people. Unlike Mangareva, which is an atoll with no stone, Pitcairn island has plenty of stone that is excellent for making tools. Mangareva, unlike Pitcairn, has a large food supply, so the two made natural trading partners. A ways to the east is Henderson Island, a coral reef that was elevated above sea level, and which has great fishing and used to have large numbers of birds. Since it is not volcanic, Henderson has no rock, and it has no large trees. Apparently a few dozen people eked out an existence living in caves and recesses. Trade among the islands sprung up: Pitcairn provided rock for Mangareva, Henderson provided feasting for Pitcairn, and Mangareva provided wives and tools like fishhooks carved from the plentiful black oysters. By about 1500 trade had stopped, because Mangareva had cut down all their trees, which caused soil erosion, which decreased food production. Additionally, since there were no trees, they could not to go to sea to fish or trade, and the island disintegrated into constant civil war and cannibalism. Pitcairn and Henderson, cut off from their trading partners, were forced to overuse their land. Henderson was so marginal for living that the entire population died off by 1606 at the latest, and Pitcairn was uninhabited in 1790 when the Bounty mutineers landed there. In the case of these three islands, collapse was caused by environmental damage (on Mangareva) and by loss of their trading partner (Pitcairn and Henderson).
The Anasazi people in the American southwest built a flourishing civilization in the desert desert of the American Southwest. While not as large as the Maya cities, Anasazi cities nonetheless had thousands of people and contained the tallest structures in North America until skyscrapers were invented in Chicago in the 1880s. The largest Anasazi settlement was at Chaco Canyon, from about 600 to 1200. The canyon captured water from a large area, resulting in higher groundwater levels, and the low elevation meant it was warm enough to have a long growing season. We have more information about the Anasazi’s environment than the previous two societies because the rings in the well-preserved timber beams in the houses show rainfall levels, and the packrat middens provide information on the local vegetation. So we know that initially there were pinyon pines that provided wood for building beams and for fires. Farming could be done by relying on the flooding on the large canyon floor, but as the population rose and more food needed to be produced, they turned to irrigation. In the desert, water can quickly cut a shallow channel into a deep one, which meant that the water-level would be substantially below the level of the field, ruining the agricultural possibilities. So they created dams and other irrigation channels. Eventually population increased to the point that all the wood around Chaco Canyon was used up, and the city was too big to feed itself, so it developed satellite communities which provided food and other resources to the Chaco Canyon city, connected by a large network of roads. Around 1130 there was a drought, but unlike during previous droughts, Chaco Canyon’s society was now interdependent; each settlement could not support itself independently. Obviously the farmers in the outlying settlements did not want to send what little food they had to the city, and society devolved into civil war and cannibalism. Collapse in this case was caused by climate change, environmental damage, and reliance on trade. The inability to harvest trees and grow enough food in the city combined with the drought meant that Chaco Canyon could not survive on it’s own, and since the society was interdependent, it took the entire society down with it.
The Maya civilization lived in an area of the Yucatan that receives a highly variable amount of water, but the karst landscape means that water drains quickly and does not collect in pools. In the northern part the elevation is low enough that groundwater is accessible, but the higher elevations in the south make that impossible. However, the region is productive enough for a system of city-states to arise. The region never united into an empire because the Maya had no pack animals, which meant that the distance an army could travel was severely limited by the amount of food a person could carry. Also, the wetness of the region meant that corn could not be stored over a year, limiting the ability to withstand a drought. The city-states rose and fell largely as the population increased, which caused less productive land higher up to be clear-cut for farms, leading to soil erosion and an inability to feed the population during a drought. A severe drought around 900 AD caused the collapse of the society, in part because the king and his nobles had a lavish lifestyle because they could perform the ceremonies to bring the rain; if the rain did not come, the king and broken his promise and the peasants got upset. So the Maya collapse was due to environmental damage, climate change, and structural problems within the society.
Three chapters are devoted to the collapse of Viking Greenland; since the Greenland colony existed from about 980 to the mid-1400s and was European, we have easily understood records of much of what happened. When Erik the Red led settlers to Greenland, it looked like a lush green place, perfect for the Norwegian pastoral ideal of cows, supplemented by sheep. The reality was that growing conditions for hay to feed the livestock through the winter were marginal, and the climate during the settlement period was slightly warmer than later on, meaning that it was only temporarily warm enough to support a Norwegian-style society. Even so, cows did not thrive except on the best farms, and cutting down the trees caused massive soil erosion. Unlike their native Norway, the soil erodes quickly and is not deep, so once the soil is gone, that area is permanently barren. Much arable land was destroyed until the settlers realized the difference in conditions. The colony relied on growing hay in the summer to feed their animals over the winter, on the caribou hunt to provide meat for late winter, and on seals to provide (distasteful) meat when the caribou meat ran out. Greenland also relied on Norway to for the yearly ship that carried iron tools in trade for walrus tusk ivory. As the weather started turning cooler in the 1300s, the conditions became even more marginal, the ice clogged up the shipping lanes so much that the last ship came in 1410. Despite the marginal conditions, however, the Inuit, who arrived on northern Greenland shortly after the Vikings arrived on the southern part, were able to survive. The difference is that the Norwegians clung to a Norwegian way of living. They prized the meat of cows, which took too many resources in Greenland, and they refused to adopt Inuit ways. In fact, relations with the Inuit were hostile, which did not help the colony’s survival chances. The Greenland Norse’ lifestyle was vulnerable to the failure of any one piece: lower hay production, poor caribou hunts, seals not migrating to Greenland. The proximate cause of the collapse was climate change, but ultimately the collapse happened because the society chose to live in way that the environment could not really support.
Diamond notes that it is possible for societies to live within their environmental means. He cites the people of the New Guinea highlands, who, through their insatiable curiosity, developed terraced farming and tree agriculture, the latter of which enabled the continuing use of wood. Population was kept in control by infanticide and constant warfare. Another successful society is the people on the remote island of Tikopia. The island supports about 1000 people, and is small enough that everyone will have walked over the entire island and met all the people. Thus the group can decide together how to solve its problems. The Tikopians survived by limiting the children that could be born, by abortion and by the practice of coitus interruptus. Also, at one point they realized that their prized pigs were using too many resources and made the collective decision to kill all the pigs. The final society given is that of Tokugawa Japan. In the early Tokugawa period, Japan’s insatiable appetite for wood was leading to the elimination of the forests. However, the shogun foresaw the problem, claimed all the forests, and made strict rules about who could cut down trees. As a result, Japan is still about 70% forested.
At this point Diamond transitions to discussions of modern societies. The first is the genocide in Rwanda. Although the usual narrative is the history of tribal hatreds, the real issue is that there were simply too many people. Friends of Diamond’s visited Rwanda in 1984 and noticed that steep hills were farmed right up to the top without using protection measures such as contoured farming. This suggested a coming ecological collapse: nearly the maximum possible food was being produced, but the land would quickly erode and reduce food production. A few years later, streams dried up from cutting down the forests, and famines reoccurred. The Rwandans themselves recognized the problem as one of too many people. 1994 provided an opportunity to take revenge on wealthier landowners or people you had a grudge against. The people killed were generally large landowners, or poor, starving people who enlisted in the militias and killed each other.
The next chapter is a discussion of Haiti and the Dominican Republic, which share the same island but which have very different societies. Haiti is mostly former sugar plantation slaves, who who rebelled against the plantation owners when France abandoned the island in 1804 and destroyed the plantations. This destroyed the knowledge that the white farmers had, and created a culture hostile to foreign investment. As a result, Haiti has been unable to develop an economy, and has deforested its side of the island to create charcoal for heating and cooking. The other side of the island, the Dominican Republic, has been much more receptive to foreign investment, but has been under military dictators for much of the twentieth century, so its economy has developed slowly. The dictator Duvalier appears to have been somewhat of a lover of nature, and set aside a large amount of land as national parks, where logging is prohibited. As a result, the Dominican Republic has been seen much less environmental degradation than Haiti. Same island, different approaches to society.
Diamond finishes the book by discussing environmental problems in China and Australia. Australia, while large, is actually only marginally inhabitable at a European standard of living. The original British settlers tried to recreated the British way of life, which destroys the land in Australia within about 30 years. Australia can maintain large populations of wildlife, but cannot replenish them quickly, so while the large amount of fish, trees, appears to indicate rich resources, it simply indicates that the population has had a long time to build up. Finally, Diamond finishes by observing that the world cannot support all of us living at a first-world lifestyle, and it is not even clear that it can support the first-world living that way for much longer. The question is, are we going to take the steps necessary to prevent our own collapse?
I had been looking forward to reading this book for a long time, because I have always wondered what caused the mysterious collapses of ancient societies. Diamond definitely delivers on that. He is very thorough in analyzing the archeological evidence in detail to describe what life was like and how it changed over the years. Diamond has spent many years in New Guinea doing field research and his academic rigor shows through. Sometimes there are arguably too many details—Greenland has three long chapters—but generally they are very helpful in making his case for how the collapse happened. At it’s heart, though, Collapse is not really about the why societies collapsed, but is really an environmental book, which was not really what I had signed up for. Still, the book is very thorough, I learned what I wanted to learn, and the consequences of our way of life are worth thinking about.