Until recently, scrutiny of tree-ring records seemed to establish that a
prolonged dry spell called the Great Drought drove the Anasazi Indians to
abandon their magnificent stone villages on the Colorado Plateau.
Line Groundbreaking climatological studies have convinced many archaeologists,
(5) however, that the Great Drought was not sufficiently austere to coerce the
sudden evacuation of the Anasazi. Reviewing tree ring records, including
moisture levels, Van West disputed the Great Drought theory by presenting
evidence that enough corn could have been grown during the drought to support
the population, that the Anasazi had weathered many severe droughts in the
(10) past, and that the evacuation actually began before the dry spell set in.
Belying the popular image of the Anasazi as a peaceable kingdom of farmers
and potters, some new research puts the blame for the evacuation on a bloody
internecine war. Noting that the Anasazi had been suffering from malnutrition,
shorter life spans and increased infant mortality, Adler suggests that the
(15) Anasazi were not able to move around freely to farm because their once open
range was becoming balkanized into hostile fiefdoms. Perhaps as a reaction to
drier weather, people in the Mesa Verde area began building clams and canals to
trap and divert water, and the result may have been conflict and warfare.
Unfortunately, other archeologists, having trouble envisioning how even
(20) drought, balkanization and warfare could make an entire civilization evacuate,
are trying to combine archeological evidence with anthropological studies of the
modern pueblo Indians to make the case that the Anasazi were roiled by a
religious crisis as divisive as European medieval heresies. Analyzing the spread
of religious symbols found on rocks or pottery and the distribution of ceremonial
(25) structures, some argue that the Anasazi may have been pulled from their
homeland by a new religion emerging to the south, whose egalitarian spirit
would have had great appeal to a civilization, like the Anasazi’s, that was
entering a dark age. Ware comes closest to a plausible synthesis of his
predecessors’ theories in suggesting that the Anasazi world was rocked by a
(30) spiritual crisis catastrophic enough to cause a collapse of a civilization, and that
the uprooted Anasazi apparently embraced a variety of new beliefs on migration
to their new homes.
Ware further argues that the precipitating factor in the evacuation may
have been a change in climate after all. Recent climatological studies suggest
(35) that indeed, rainfall patterns were disrupted in a way that might have made the
Anasazi disillusioned with their old religion: the customary pattern of heavy
snows in the winter followed by summer monsoons had become unpredictable.
Even if there was not a great drought, moisture may have been coming at the
wrong times, and the summer rains, essential for nourishing the spring crops,
(40) were no longer reliable-the rain dances were not working anymore. Thus,
Ware’s theory accommodates the greatest variety of factors that may explain
the Anasazi’s evacuation.

The author considers the explanations put forward by Van West and Adler for the causes of the Anasazi evacuation to be（）