What Did Not Work

A course that only tells success stories is selling something, and the failure record is the more useful teacher. Systems that looked sustainable did not hold, and the reasons repeat: salt that would not drain, soil that was plowed when it should have stayed in grass, one crop in one variety across a whole island. This lesson walks the failures, and it refuses the tidy versions of the famous stories, because a myth repeated to make a point is still a myth.

Salt and irrigation

The irrigated grain fields of the Tigris and Euphrates lowlands grew the surplus that supported the first cities and states. The soil was fertile river silt, and the water was the whole system. It was also poorly drained, which meant salt accumulated as irrigation water evaporated. Over centuries, salt-tolerant barley replaced wheat in the record. Cumulative salinity and the fragility of the canals contributed to the decline of the southern cities and a shift of power northward.

That is the honest version, and it is also the disputed one. The general narrative, irrigation surplus producing cities and salinity contributing to decline, is well established. Reading salinization as the primary cause of collapse is not. Political, military and economic factors carry real weight, and the salinity account is plausible rather than proven.

Erosion, and the myth of the single cause

Roman Mediterranean farming ran on thin, erosion-prone soils, and Rome combined intensive smallholdings with large estates and grain imported from the provinces. Over-farming, soil erosion and the disruption of the grain trade are all part of the late empire's troubles. The role of environmental degradation in Rome's fall is contested, and the "erosion killed Rome" line is usually overstated.

The Dust Bowl

The Dust Bowl was a period of severe dust storms that damaged the agriculture and ecology of the American and Canadian prairies in the 1930s. Two things met: a severe drought, and farming practice that had destroyed the natural topsoil without dryland methods to hold it against wind.

The Homestead Act of 1862 offered 160-acre plots, later enlarged, and an unusually wet period convinced settlers and the government that "rain follows the plow," that the semi-arid plains had become farmable. Mechanised plowing then let a single operator work far more ground. Most of the freshly broken sod went into wheat, and wheat production jumped about 300 percent through the 1920s. The drought arrived in three waves, 1934, 1936 and 1939 to 1940, with some High Plains counties dry for as long as eight years. About 33 million acres of the Dust Bowl region were left denuded and vulnerable.

The Irish potato

Ireland's population was about 8.5 million on the eve of the famine. The crop failed when late blight, the oomycete Phytophthora infestans, swept the potato fields of Europe. It destroyed about one third of the 1845 harvest and nearly all of the 1846 harvest. Roughly one million people died in Ireland between 1845 and 1852, over a million more emigrated, and the island's population fell by 20 to 25 percent between 1841 and 1871.

Two mechanisms made the impact catastrophic. The first is genetic uniformity: one variety, the Lumper, was grown across a huge share of the country, so the pathogen had one host with no resistance to work through. The second is political economy. Blight was the spark, and the scale of the disaster came from single-crop dependence, absentee landlordism, and a government that let food continue to be exported while people starved. Call it a monoculture failure and you have told half of it. The other half is who was allowed to eat.

The Maya, and the trouble with the word collapse

The Classic Maya cities of the southern lowlands, among them Palenque, Copán, Tikal and Calakmul, went into decline in the 8th and 9th centuries and were abandoned soon after. But the northern Yucatán prospered afterwards, Chichén Itzá built a state that briefly united much of the Maya region, and Mayapán, Uxmal and the highland kingdoms flourished. Independent Maya civilization continued until 1697. Millions of Maya people live in Guatemala and Yucatán today.

Paleoclimate records support century-scale droughts in the Terminal Classic, and deforestation has long been proposed as a cause. Many scholars now call the period a rupture or a transformation rather than a collapse. The word hides a shift in where the power sat.

Easter Island

The palm forest of Rapa Nui was almost entirely gone by the time Europeans arrived in 1722, and that much is not seriously disputed. What happened to the people is disputed. One scenario, ecocide, has the islanders overharvesting the palms until their society collapsed. A second, genocide, lays the collapse at the door of the diseases and slave raids that arrived with Europeans after 1722. Work on the island's rat bones and its archaeology points to the Polynesian rat as a major agent of the deforestation.

There is no reliable evidence of the precise population dynamics or the timing of any collapse, and the version where the islanders cut down the last tree and ate themselves is not supported as stated.