Evolution or Revolution for the Sizzling...

The pinacate beetle is black and scabrous. And nasty. If threatened, it hoists up its backside and emits an odor. It gave its name to an equally black, scabrous and nasty landscape--the volcanic field of cinder cones and lava debris called the Pinacate--the dark heart of the Sonoran Desert.

Summer heat nears 200 degrees at ground level. The desert is thick with things that stink, prick, bite, hook or flagellate--things armed and dangerous. Cacti, rattlesnakes, scorpions. Sun. Rock and earth. The air, its ferocious clarity defining all things in razor edges like a comic strip.

The Sonoran spreads evenly between Mexico and the United States. It yokes the Gulf of California at the delta of the Colorado River and spills down the bone-like peninsula of Baja California. It covers parts of California and Arizona, including Yuma, Phoenix and Tucson, as well as the Mexican state of Sonora and its rawboned boom town capital, Hermosillo.

The desert has always been a place to avoid or to overcome. Humans have left their layers like river sediments: ancient canal builders, nomadic Indians, Spanish missionaries, Yankee cattlemen and imperialists, cold warriors, cactus huggers, snowbirds. Many of them, too, were prickly, armed and dangerous.

I spent six weeks traveling across this often bizarre landscape, seeing how the desert absorbed those layers and wondering how it would respond to the next. With population growth pushing land-use and water issues and with the passage of the North American Free Trade Agreement, the desert will change, and soon.

“This region is going to be either formally protected or commercially developed,” said Luther Propst, director of the Sonoran Institute, a conservation and land-protection group in Tucson. “Isolation and aridity are not going to protect it for the future.”

For the most part, the Sonoran still seems vast and untrampled. One of the largest intact arid ecosystems in the world, it shelters endangered animals such as the Sonoran pronghorn and the lesser long-nosed bat. And because it has rainy seasons in both summer and winter, the Sonoran is the world’s most botanically diverse desert, with more than 2,500 species of plants.

Among a menagerie of plants that seems straight from Dr. Seuss is the saguaro cactus, the enduring symbol of Arizona that is unique to the Sonoran and reaches heights of 50 feet, weighs tons and lives as long as 200 years.

Sometimes the fragile balance of life and death in the desert seems irrelevant in Phoenix, where I began my trip. The city grandly ignores the lesson of the plants, that living things cannot clump together on land with little water.

As more people pour into the Sunbelt, 30% of the water in central and southern Arizona is imported through the Central Arizona Project, a diversion of the Colorado River. Phoenix continues to mutate into something like Southern California, an artificial land of green lawns and shade trees.

Arizona’s other urban pillar, Tucson, seems more in tune with the desert and proudly uses local trees and plants to landscape yards and parks. But Tucson also relies on the project’s water, and both cities are rapidly turning desert into suburban tracts and golf courses.

I pulled out of Tucson one spring morning in a four-wheel-drive vehicle, heading for the empty hinterland. About 60 miles west, the Papago Indian Reservation--2.5 million acres flattened against the Mexican border--is home to some 6,000 Papago, or Tohono O’odham, the “desert people.”

The reservation is the country’s second largest, next to the Navajo, but is only the shrunken core of the ancestral homeland. The Tohono O’odham no longer farm, and only some have been successful at cattle ranching.

“Nobody has ever figured out a nice way, a proper way, to take somebody’s land away from him,” said retired University of Arizona anthropologist Bernard Fontana. “This will be on the national conscience forever.”

Sonora today is a rugged livestock culture of cattle ranches, horse races, straw hats and brass belt buckles. When I arrived in Cucurpe, an isolated village on the San Miguel River, I found mestizo farmer-ranchers--people of mixed Spanish-Indian heritage--living almost as they did 200 years ago, in a tough but graceful self-subsistence.

By the 1880s, American cattle had already overgrazed the river valleys of southern Arizona, taken from Mexico 30 years earlier. The border bristled with ruffians and desperadoes, chased by gun-totin’ sheriffs across the saguaro deserts of a thousand Western movies to come.

Today, illegal immigrants and drug smugglers push north across the border, fearing the law; tourists sally south, fearing “banditos” and the drinking water. Thousands of undocumented workers filter across from Mexico each week.

A 2.7 million-acre reserve, the Barry M. Goldwater Air Force Range, provides the military with an immense sandbox for training. Nearly 200 missions a day fly over the area.

The irony is that military stewardship has probably preserved the desert better than others might have, by severely limiting public access. Most defenders of the desert fear businessmen more than colonels.

West of the Mexican border town of Sonoyta is the desolate Pinacate, where NASA astronauts once trained for their mission to the moon. Nominally a Mexican national park, El Pinacate has been protected only by its isolation. No one lives here; no rangers control access or enforce rules.

Environmentalists on both sides of the border hope to eventually combine the Mexican park with Organ Pipe Cactus National Monument and Cabeza Prieta National Wildlife Refuge in the United States. It would then be an international biosphere reserve, part of a system of protected land sponsored by the United Nations.

For the Sonoran to survive the latest layer of development, it will need the wisdom and goodwill of two nations and at least three cultures.