The New Yorker reviews Jared Diamond's new book, which in many ways sounds like a follow-up to his previous, excellent Guns, Germs, and Steel: The Fate of Human Societies (previously mentioned here and here). The central thesis of that book was that the shape of the continents was the predominant factor in the success of Eurasian civilizations against the indigenous populations of Africa, Australia, and the Americas; the ability to spread across a wide, horizonal swath of territory without developing new agricultural techniques or technology allowed Europe and China to expand rapidly, while in the more vertical continents expansion was limited each time to about a 100- or 200-mile band of similarly climated land.

In Collapse: How Societies Choose to Fail or Succeed, Diamond extends this theme to the disappearance of societies, tying the failure of populations to mismanagement of available environmental resources. Consider, for example, the Norse colonies in Greenland:

There was nothing wrong with the social organization of the Greenland settlements. The Norse built a functioning reproduction of the predominant northern-European civic model of the time -- devout, structured, and reasonably orderly. In 1408, right before the end, records from the Eastern Settlement dutifully report that Thorstein Olafsson married Sigrid Bjornsdotter in Hvalsey Church on September 14th of that year, with Brand Halldorstson, Thord Jorundarson, Thorbjorn Bardarson, and Jon Jonsson as witnesses, following the proclamation of the wedding banns on three consecutive Sundays.

The problem with the settlements, Diamond argues, was that the Norse thought that Greenland really was green; they treated it as if it were the verdant farmland of southern Norway. They cleared the land to create meadows for their cows, and to grow hay to feed their livestock through the long winter. They chopped down the forests for fuel, and for the construction of wooden objects. To make houses warm enough for the winter, they built their homes out of six-foot-thick slabs of turf, which meant that a typical home consumed about ten acres of grassland.

But Greenland's ecosystem was too fragile to withstand that kind of pressure. The short, cool growing season meant that plants developed slowly, which in turn meant that topsoil layers were shallow and lacking in soil constituents, like organic humus and clay, that hold moisture and keep soil resilient in the face of strong winds. "The sequence of soil erosion in Greenland begins with cutting or burning the cover of trees and shrubs, which are more effective at holding soil than is grass," he writes. "With the trees and shrubs gone, livestock, especially sheep and goats, graze down the grass, which regenerates only slowly in Greenland's climate. Once the grass cover is broken and the soil is exposed, soil is carried away especially by the strong winds, and also by pounding from occasionally heavy rains, to the point where the topsoil can be removed for a distance of miles from an entire valley." Without adequate pastureland, the summer hay yields shrank; without adequate supplies of hay, keeping livestock through the long winter got harder. And, without adequate supplies of wood, getting fuel for the winter became increasingly difficult.

The Norse needed to reduce their reliance on livestock -- particularly cows, which consumed an enormous amount of agricultural resources. But cows were a sign of high status; to northern Europeans, beef was a prized food. They needed to copy the Inuit practice of burning seal blubber for heat and light in the winter, and to learn from the Inuit the difficult art of hunting ringed seals, which were the most reliably plentiful source of food available in the winter. But the Norse had contempt for the Inuit -- they called them skraelings, "wretches" -- and preferred to practice their own brand of European agriculture. In the summer, when the Norse should have been sending ships on lumber-gathering missions to Labrador, in order to relieve the pressure on their own forestlands, they instead sent boats and men to the coast to hunt for walrus. Walrus tusks, after all, had great trade value. In return for those tusks, the Norse were able to acquire, among other things, church bells, stained-glass windows, bronze candlesticks, Communion wine, linen, silk, silver, churchmen's robes, and jewelry to adorn their massive cathedral at Gardar, with its three-ton sandstone building blocks and eighty-foot bell tower. In the end, the Norse starved to death.

Sounds fascinating.