Could it be Apocalypto for the Southwest?

  Thanks to Hollywood movies showing the first North Americans as wandering hunters grunting to each other, Westerners may perhaps be forgiven for failing to appreciate the urban civilizations that arose in the New World long before Europeans arrived.

Now, moviegoers have a chance to correct this oversight by seeing "Apocalypto," Mel Gibson's gruesome depiction of the Maya, who dominated Mexico's Yucatan peninsula for nearly 1,000 years. Although the movie suffers from the excesses audiences have come to expect from Gibson's work, it represents a welcome excursion into an unexplored corner of history.

Unfortunately, the film does a poor job of revealing the most likely reasons for the collapse of Mayan civilization, which developed advanced capabilities in art, science and technology before vanishing. These reasons, most likely overpopulation, environmental degradation and climate change, merit our understanding for they have direct relevance today. And perhaps nowhere are they more relevant than in the semi-arid American West, where some of the nation's most rapid population growth -- Arizona, for example, leads the nation -- is occurring in places vulnerable to drought and resource depletion.

If we have at least heard of the Incan, Aztec and Mayan civilizations, it is because they scattered spectacular stone structures across Central and South America. But few are familiar with the older New World civilizations, such as the Moche, Chimu, Wari, Nazca, Olmec and Toltec. Closer to home, relatively few Americans are aware that this continent had its own counterparts to the monument-building civilizations of Mesoamerica and the Andes.

In Missouri, for example, the Gateway Arch on the St. Louis waterfront is within view of Cahokia Mounds State Historic Site, location of the largest pre-Columbian settlement in North America. At its height, between 1100 and 1200 A.D., this great city covered nearly six square miles and had as many as 20,000 residents. Cahokia's people erected steep-sided platforms to support ceremonial buildings and residences. The largest rises in four terraces to a height of 100 feet and contains 22 million cubic feet of earth.

The silent stone ruins and cliff dwellings scattered about the mesas and canyons of the desert Southwest give further evidence that there's more to Native American prehistory than bows, arrows and buffalo robes. But for sheer romantic mystery, it's hard to top the lost cities of the Maya. Archaeological evidence indicates the Maya had begun building huge structures as early as 500 B.C., with the most elaborate monuments showing up 750 years later. From A.D. 250 on, the population grew rapidly, as numerous city-states rose to power, accumulated wealth and waged war against each other. The entire area suffered decay and depopulation after A.D. 800, and by the time the Spanish arrived in the early 16th century, which roughly coincides with the period depicted in "Apocalypto," the population had fallen to about 10 percent of its peak.

There have been many attempts to explain the Mayan collapse, and the movie is not clear on this point, focusing so much on the cruelty and greed of the Mayan ruling class that it seems this is what the filmmakers had in mind when they chose to open with a quote from historian Will Durant: "A great civilization is not conquered from without until it has destroyed itself from within."

But moral and spiritual decay are less effective than starvation as an engine of social collapse. The likely explanation for the Mayan mystery is more disturbing than an obsession with conquest, displays of wealth and human sacrifice: The Maya outgrew the capacity of their soil, water supply and agricultural technology to provide food. They made things worse by stripping the fragile hillsides of trees for building materials and fuel, accelerating erosion and compromising cropland. Then they were dealt a knockout blow by a drying climate, which spawned a succession of severe droughts that caused repeated crop failure.

I think this is the lesson of the Mayan collapse: Vast disparities of wealth and power are disruptive to a society, as is a liking for unnecessary war. And even a technologically sophisticated civilization can find itself vulnerable to climate change and depleted resources, particularly if it fails to admit what is happening.

John Krist is a contributor to Writers on the Range, a service of High Country News (hcn.org). He is a senior reporter for the Ventura County Star in California.