Collapse: How Societies Choose to Fail or Succeed (29 page)

a.d.
800 to 1350, based on numbers of house sites containing pottery that changed in style with time, thereby permitting dating of the house sites.
They also calculated the valley's annual corn harvests as a function of time,
from annual tree rings that provide a measure of rainfall, and from soil
studies that provide information about the rise and fall of groundwater lev
els. It turned out that the rises and falls of the actual population after
a.d.
800 closely mirrored the rises and falls of calculated annual corn har
vests, except that the Anasazi completely abandoned the valley by
a.d.
1300,
at a time when some reduced corn harvests sufficient to support one-third
of the valley's peak population (400 out of the peak of 1,070 people) could
still have been extracted.

Why did those last 400 Kayenta Anasazi of Long House Valley not re
main when most of their relatives were leaving? Perhaps the valley in
a.d.
1300 had deteriorated for human occupation in other ways besides its
reduced agricultural potential calculated in the authors' model. For in
stance, perhaps soil fertility had been exhausted, or else the former forests
may have been felled, leaving no nearby timber for buildings and firewood, as we know to have been the case in Chaco Canyon. Alternatively, perhaps
the explanation was that complex human societies require a certain mini
mum population size to maintain institutions that its citizens consider to be
essential. How many New Yorkers would choose to remain in New York City
if two-thirds of their family and friends had just starved to death there or fled, if the subway trains and taxis were no longer running, and if offices
and stores had closed?

Along with those Chaco Canyon Anasazi and Long House Valley Anasazi
whose fates we have followed, I mentioned at the start of this chapter that
many other southwestern societies
—the Mimbres, Mesa Verdeans, Ho-
hokam, Mogollon, and others—also underwent collapses, reorganizations,
or abandonments at various times within the period
a.d.
1100-1500. It
turns out that quite a few different environmental problems and cultural re
sponses contributed to these collapses and transitions, and that different
factors operated in different areas. For example, deforestation was a prob
lem for the Anasazi, who required trees to supply the roof beams of their
houses, but it wasn't as much of a problem for the Hohokam, who did not
use beams in their houses. Salinization resulting from irrigation agriculture
iiurt the Hohokam, who had to irrigate their fields, but not the Mesa Verdeans, who did not have to irrigate. Cold affected the Mogollon and

Mesa Verdeans, living at high altitudes and at temperatures somewhat mar
ginal for agriculture. Other southwestern peoples were done in by dropping water tables (e.g., the Anasazi) or by soil nutrient exhaustion (possibly the
Mogollon). Arroyo cutting was a problem for the Chaco Anasazi, but not
for the Mesa Verdeans.

Despite these varying proximate causes of abandonments, all were ultimately due to the same fundamental challenge: people living in fragile and
difficult environments, adopting solutions that were brilliantly successful and understandable "in the short run," but that failed or else created fatal
problems in the long run, when people became confronted with external
environmental changes or human-caused environmental changes that soci
eties without written histories and without archaeologists could not have
anticipated. I put "in the short run" in quotation marks, because the
Anasazi did survive in Chaco Canyon for about 600 years, considerably
longer than the duration of European occupation anywhere in the New
World since Columbus's arrival in
a.d.
1492. During their existence, those various southwestern Native Americans experimented with half-a-dozen
alternative types of economies (pp. 140-143). It took many centuries to
discover that, among those economies, only the Pueblo economy was
sustainable "in the long run," i.e., for at least a thousand years. That should
make us modern Americans hesitate to be too confident yet about the sustainability of our First World economy, especially when we reflect how
quickly Chaco society collapsed after its peak in the decade
a.d.
1110-1120,
and how implausible the risk of collapse would have seemed to Chacoans of
that decade.

Within our five-factor framework for understanding societal collapses,
four of those factors played a role in the Anasazi collapse. There were indeed
human environmental impacts of several types, especially deforestation and
arroyo cutting. There was also climate change in rainfall and temperature,
and its effects interacted with the effects of human environmental impacts.
Internal trade with friendly trade partners did play a crucial role in the col
lapse: different Anasazi groups supplied food, timber, pottery, stone, and
luxury goods to each other, supporting each other in an interdependent
complex society, but putting the whole society at risk of collapsing. Reli
gious and political factors apparently played an essential role in sustaining
the complex society, by coordinating the exchanges of materials, and by motivating people in outlying areas to supply food, timber, and pottery to
the political and religious centers. The only factor in our five-factor list for
whose operation there is not convincing evidence in the case of the Anasazi

collapse is external enemies. While the Anasazi did indeed attack each other
as their population grew and as the climate deteriorated, the civilizations of
the U.S. Southwest were too distant from other populous societies to have
been seriously threatened by any external enemies.

From that perspective, we can propose a simple answer to the long
standing either/or debate: was Chaco Canyon abandoned because of human impact on the environment, or because of drought? The answer is: it was abandoned for both reasons. Over the course of six centuries the human population of Chaco Canyon grew, its demands on the environment
grew, its environmental resources declined, and people came to be living in
creasingly close to the margin of what the environment could support. That
was the
ultimate
cause of abandonment. The
proximate
cause, the prover
bial last straw that broke the camel's back, was the drought that finally
pushed Chacoans over the edge, a drought that a society living at a lower
population density could have survived. When Chaco society did collapse,
its inhabitants could no longer reconstruct their society in the way that the
first farmers of the Chaco area had built up their society. The reason is that
the initial conditions of abundant nearby trees, high groundwater levels,
and a smooth floodplain without arroyos had disappeared.

That type of conclusion is likely to apply to many other collapses of past
societies (including the Maya to be considered in the next chapter), and to o
ur own destiny today. All of us moderns
—house-owners, investors, politi
cians, university administrators, and others—can get away with a lot of waste when the economy is good. We forget that conditions fluctuate, a
nd we may not be able to anticipate when conditions will change. By that t
ime, we may already have become attached to an expensive lifestyle, leaving a
n enforced diminished lifestyle or bankruptcy as the sole outs.

CHAPTER
5

The Maya Collapses

Mysteries of lost cities
■ The Maya environment ■ Maya agriculture ■

Maya history
■ Copan * Complexities of collapses ■ Wars and
droughts ■ Collapse in the southern lowlands ■ The Maya message
■

B

y now, millions of modern tourists have visited ruins of the ancient
Maya civilization that collapsed over a thousand years ago in Mexico's
Yucatan Peninsula and adjacent parts of Central America. All of us love a romantic mystery, and the Maya offer us one at our doorstep, almost
as close for Americans as the Anasazi ruins. To visit a former Maya city, we
need only board a direct flight from the U.S. to the modern Mexican state capital city of Merida, jump into a rental car or minibus, and drive an hour
on a paved highway (map, p. 161).

Today, many Maya ruins, with their great temples and monuments, still lie surrounded by jungle, far from current human settlement (Plate 12). Yet they were once the sites of the New World's most advanced Native Ameri
can civilization before European arrival, and the only one with extensive de
ciphered written texts. How could ancient peoples have supported urban
societies in areas where few farmers eke out a living today? The Maya cities
impress us not only with that mystery and with their beauty, but also be
cause they are "pure" archaeological sites. That is, their locations became
depopulated, so they were not covered up by later buildings as were so
many other ancient cities, like the Aztec capital of Tenochtitlan (now buried
under modern Mexico City) and Rome.

Maya cities remained deserted, hidden by trees, and virtually unknown
to the outside world until rediscovered in 1839 by a rich American law
yer named John Stephens, together with the English draftsman Frederick
Catherwood. Having heard rumors of ruins in the jungle, Stephens got
President Martin Van Buren to appoint him ambassador to the Confedera
tion of Central American Republics, an amorphous political entity then
extending from modern Guatemala to Nicaragua, as a front for his archaeo
logical explorations. Stephens and Catherwood ended up exploring 44 sites
and cities. From the extraordinary quality of the buildings and the art, they

realized that these were not the work of savages (in their words) but of a
vanished high civilization. They recognized that some of the carvings on the
stone monuments constituted writing, and they correctly guessed that it re
lated historical events and the names of people. On his return, Stephens
wrote two travel books, illustrated by Catherwood and describing the ruins,
that became best sellers.

A few quotes from Stephens's writings will give a sense of the romantic
appeal of the Maya: "The city was desolate. No remnant of this race hangs
round the ruins, with traditions handed down from father to son and from
generation to generation. It lay before us like a shattered bark in the midst
of the ocean, her mast gone, her name effaced, her crew perished, and none
to tell whence she came, to whom she belonged, how long on her journey, or what caused her destruction.... Architecture, sculpture, and painting, all the arts which embellish life, had flourished in this overgrown forest; ora
tors, warriors, and statesmen, beauty, ambition, and glory had lived and
passed away, and none knew that such things had been, or could tell of their
past existence.... Here were the remains of a cultivated, polished, and peculiar people, who had passed through all the stages incident to the rise and
fall of nations; reached their golden age, and perished.
...
We went up to
their desolate temples and fallen altars; and wherever we moved we saw the
evidence of their taste, their skill in arts.
...
We called back into life the
strange people who gazed in sadness from the wall; pictured them, in fanci
ful costumes and adorned with plumes of feather, ascending the terraces of
the palace and the steps leading to the temples.
...
In the romance of the
world's history nothing ever impressed me more forcibly than the spectacle
of this once great and lovely city, overturned, desolate, and lost,... over
grown with trees for miles around, and without even a name to distinguish it." Those sensations are what tourists drawn to Maya ruins still feel today,
and why we find the Maya collapse so fascinating.

The Maya story has several advantages for all of us interested in prehistoric collapses. First, the Maya written records that have survived, although
frustratingly incomplete, are still useful for reconstructing Maya history in much greater detail than we can reconstruct Easter Island, or even Anasazi
history with its tree rings and packrat middens. The great art and architecture of Maya cities have resulted in far more archaeologists studying the
Maya than would have been the case if they had just been illiterate hunter-
gatherers living in archaeologically invisible hovels. Climatologists and pa-
leoecologists have recently been able to recognize several signals of ancient
climate and environmental changes that contributed to the Maya collapse.