Collapse: How Societies Choose to Fail or Succeed

by Jared Diamond

the modest productivity of Maya agriculture, and their lack of draft animals, severely limited the duration and distance possible for their military campaigns.

Mesoamerican societies lacked metal tools, pulleys and other machines, wheels (except locally as toys), boats with sails, and domestic animals large enough to carry loads or pull a plow. All of those great Maya temples were constructed by stone and wooden tools and by human muscle power alone.

no more signs of anyone in the Copán Valley by around A.D. 1250. The reappearance of pollen from forest trees thereafter provides independent evidence that the valley became virtually empty of people, and that the forests could at last begin to recover.

we have to wonder why the kings and nobles failed to recognize and solve these seemingly obvious problems undermining their society. Their attention was evidently focused on their short-term concerns of enriching themselves, waging wars, erecting monuments, competing with each other, and extracting enough food from the peasants to support all those activities.

collapses of human societies are not inevitable: it depends on how people respond.

The losers in those internecine struggles were the ones who had the most to gain by trying their luck overseas. For instance, in the A.D. 980s, when an Icelander named Erik the Red was defeated and exiled, he explored Greenland and led a band of followers to settle the best farm sites there.

What most horrified European societies targeted by Viking raiders was that Vikings were not Christians and did not observe the taboos of a Christian society. Quite the opposite: they seemed to take sadistic pleasure in targeting churches and monasteries for attack.

Vikings had no sadistic special fondness for plundering churches, nor any prejudice against secular sources of booty.

wealth of churches and monasteries was an obvious source of easy rich pickings, the Vikings were also pleased to attack rich trading centers whenever the opportunity presented itself.

chiefs and kings in Scandinavia began to recognize the political advantages that Christianity could bring them.

When Norway began to convert, the overseas Viking colonies of Orkney, Shetland, Faeroe, Iceland, and Greenland followed suit. That was partly because the colonies had few ships of their own, depended on Norwegian shipping for trade, and had to recognize the impossibility of remaining pagan after Norway became Christian.

source of information about past Greenland climates consists of pollen samples from sediment cores drilled into Greenland lakes and bogs by palynologists, the scientists who study pollen

Radiocarbon dating of organic materials in a mud sample establishes when that particular layer of mud settled out. Pollen grains from different plant species look different under the microscope, so that the pollen grains in your (you the palynologist’s) mud sample tell you what plants were growing near your lake or bog and were releasing pollen that fell into it in that year.

The oxygen in the water that constitutes snow or ice consists of three different isotopes,

(99.8% of the total) is the isotope oxygen-16 (meaning oxygen of atomic weight 16), but there is also a small proportion (0.2%) of oxygen-18, and an even smaller amount of oxygen-17.

The warmer the temperature at which snow forms, the higher is the proportion of oxygen-18 in the snow’s oxygen.

measure the oxygen-18 proportion as a function of depth, you see the oxygen-18 proportion wiggling up and down as you bore through one year’s summer ice into the preceding winter’s ice and then into the preceding summer’s ice, because of the predictable seasonal changes in temperature. You also find oxygen-18 values to differ among different summers or different winters, because of unpredictable year-to-year fluctuations in temperature.

tells us each year’s summer temperature and each year’s winter temperature, and as a bonus the thickness of the ice layer between consecutive summers (or between consecutive winters) tells us the amount of precipitation that fell during that year.

When one finds high concentrations of sodium and calcium in an ice layer of the ice cap, it may mean that that was a stormy year.

Sodium/sea water, calcium/continental dust

According to sagas and medieval histories, around the year 980 a hot-blooded Norwegian known as Erik the Red was charged with murder and forced to leave

spent the next three years exploring much of the Greenland coast, and discovered good pastureland inside the deep fjords. On his return to Iceland he lost yet another fight, impelling him to lead a fleet of 25 ships to settle the newly explored land that he shrewdly named Greenland.

by A.D. 1000 virtually all the land suitable for farms in both Western and Eastern Settlements had been occupied, yielding an eventual total Norse population estimated at around 5,000: about 1,000 people at Western Settlement, 4,000 at Eastern Settlement.

Greenland cows were the smallest known in the modern world, not more than four feet high at the shoulder.

During the winter the cows were fed on harvested hay, but if its quantities weren’t sufficient, it had to be supplemented with seaweed brought inland. The cows evidently didn’t like the seaweed, so that farm laborers had to live in the barn with the cows and their rising sea of dung during the winter, and perhaps to force-feed the cows, which gradually became smaller and weaker. Around May, when the snow started to melt and new grass came up, the cows could at last be brought out of doors to start grazing themselves, but by then they were so weak that they could no longer walk and had to be carried outside.

the main occupation of most Greenland Norse during the late summer had to be cutting, drying, and storing hay.

each September the Norse had to make the agonizing decision how many of their precious livestock to cull, basing that decision on the amount of fodder available and on their guess as to the length of the coming winter. If they killed too many animals in September, they would end up in May with uneaten hay and just a small herd, and they might kick themselves for not having gambled on being able to feed more animals. But if they killed too few animals in September, they might find themselves running out of hay before May and risk the whole herd starving.

Dairy products alone were not enough to feed the 5,000 Norse inhabitants of Greenland.

Contemporary Norwegian documents mentioned that most Greenland Norse never saw wheat, a piece of bread, or beer (brewed from barley) during their entire lives.

the main other component of the Greenland Norse diet was meat of wild animals, especially caribou and seals,

The May arrival of harp and hooded seals was critical to Norse survival,

made the Norse vulnerable to starvation from a failure of the seal migration, or from any obstacle

especially likely in cold years when the Norse were already vulnerable because of cold summers and hence low hay production.

Every archaeologist who comes to excavate in Greenland refuses initially to believe the incredible claim that the Greenland Norse didn’t eat fish,

Greenland Norse had to develop a complex, integrated economy in order to make ends meet.

Greenland’s Norse population of about 5,000 lived on 250 farms, with an average of 20 people per farm, organized in turn into communities centered on 14 main churches, with an average of about 20 farms per church. Norse Greenland was a strongly communal society,

tightly controlled society, in which the few chiefs of the richest farms could prevent anyone else from doing something that seemed to threaten their interests—including

Fishing was abandoned in the earliest years of the colony, and Greenlanders did not reconsider that decision during the four-and-a-half centuries of their society’s existence. They did not learn from the Inuit how to hunt ringed seals or whales, even though that meant not eating locally common foods, and starving as a result.

While they succeeded in developing an economy that let them survive there for many generations, they found that variations on that economy were much more likely to prove disastrous than advantageous. That was good reason to be conservative.

Much of what the Greenlanders obtained materially by trade with Europe in return for those walrus tusks and bearskins was just luxury goods for churches and chiefs.

maintained for the whole society the psychologically vital contact with Europe.

more European than Europeans themselves, and thereby culturally hampered in making the drastic lifestyle changes that could have helped them survive.

a more immediately fatal consequence was that, by losing iron, the Norse lost their military advantage over the Inuit.

the impact of the Norse on the natural vegetation left them short of lumber, fuel, and iron. Their other two main types of impact, on soil and on turf, left them short of useful land.

Almost all Greenland buildings were constructed mostly of turf,

Greenland turf walls tended to be thick (up to six feet thick!) in order to provide insulation against the cold.

A large Greenland residential house is estimated to have consumed about 10 acres of turf.

Estimates suggest that the loss of only one-quarter of the total pasture area at Eastern Settlement or Western Settlement would have sufficed to drop the herd size below that minimum critical threshold. That’s what actually appears to have happened at Western Settlement, and possibly at Eastern Settlement as well.

the Greenland Vikings would have had a better chance of surviving if they had learned from or traded with the Inuit, but they didn’t.

As church-oriented Christians, the Norse shared the scorn of pagans widespread among medieval Europeans.

Other peoples besides the Greenland Norse have similarly discovered their economies (or even their survival) to be at risk when their major trading partners encountered problems; they include us oil-importing Americans at the time of the 1973 Gulf oil embargo, Pitcairn and Henderson Islanders at the time of Mangareva’s deforestation, and many others. Modern globalization will surely multiply the examples. Finally, the arrival of the Inuit, and the inability or unwillingness of the Norse to make drastic changes, completed the quintet of ultimate factors behind the Greenland colony’s demise.