Chaco Canyon

The Anasazi, one of several Native American cultural traditions, moved into Chaco Canyon in northwest New Mexico around 600 AD.* They were ancestors of the first humans to reach the Americas from Asia around 11,000 BC. The Anasazi were probably drawn to the Canyon floor because it presented an oasis in an otherwise arid and desolate countryside:

• Numerous side channels funneled rainwater and nutrient-rich soil onto the Canyon floor. The ensuing high groundwater level meant farming was less dependent on local rainfall. And the lower elevation of the Canyon floor provided a longer growing season.
• A high diversity of wild plants and animals was available for food, with woodlands also providing timber for construction and firewood.

The Chacoans initially lived in pit houses constructed partially underground, as was characteristic of their compatriots. But in 700 AD, they began constructing one-story stone structures. In Pueblo Bonito, the largest Chacoan site, these structures reached two stories and eventually 4-5 stories, with intervening ceilings supported by logs up to 16 feet long. (These heights were not exceeded anywhere in North America for another eight centuries, until the discovery of a process for inexpensively mass-producing steel, followed by the incorporation of steel girders in the construction of buildings beginning in Chicago in the 1880s.) At its peaks, this settlement included about 600 rooms.

Over a period of 600 years, population growth in the Canyon led to a society of increasing sophistication, complexity, and interdependence, as was apparent from their long-distant supply network of roads, their multistory construction, and the imported goods and luxuries they left behind (pottery, high quality stones for tool making, turquoise, macaws, and shell jewelry). But this increase in population also created a demand for more food, as well as for timber for housing and firewood. Their growing difficulty in locally meeting these demands highlighted the fragility of the environment that had attracted them there in the first place:

• Poor water management led to erosion of irrigation canals during downpours, creating deep gullies, lowering groundwater levels, and thereby making irrigation impossible during the dry season.
• By the 11th century, the Canyon floor had been stripped bare of forests, as its regeneration could not keep up with the rate of logging. Also, with the loss of forests, deer disappeared from their diet, replaced by rabbit and mice.

By exceeding the carrying capacity of their local environment, local resources declined and the Chacoans became more dependent on neighboring villages. Eventually, food (corn) had to be imported from several areas 50-60 miles away. Logs necessary for their multi-story construction ultimately were also transported from several of these same areas. In the absence of draft animals, humans alone bore the burden of transporting an estimated two hundred thousand timbers, each weighing up to 700 pounds, this long distance.

In spite of these difficulties, the population continued to increase, with spurts coinciding with periods of increased rain and food production, when times of food scarcity during the dry periods were forgotten. The society subsequently weathered several droughts, but by 1130 AD, the burgeoning population was left with no unoccupied land into which to expand agriculture and with an excessive dependence on neighboring villages.

Then toward the end of the 12th century, a more serious drought was the final event that pushed the Chacoans over the edge. Climate change and excessive population prevented them from maintaining their society. As their society collapsed and the Canyon was abandoned, indications of civil unrest, warfare, and cannibalism have been found.

Today, the Canyon is devoid of virtually all flora, fauna, and human life. It provides a reminder of what happens when a society fails to rein in unbridled population growth and instead relies, misguidedly and in vain, on technological fixes—in this case, irrigation—to meet an ever-expanding demand for food created by a burgeoning population. Today, we are witnessing a similar population growth and climate change on a global scale, increasing competition with emerging economies for food, and increasingly fewer "neighboring villages" to bail us out when we fall short.

It may seem impossible to imagine that a technologically advanced society could choose, in essence, to destroy itself, but that is what we are now in the process of doing.**

Despite the centuries separating the experiences of the Chacoan and of our contemporary society, evidence indicates that mankind today may well be following in the footsteps of the Chacoans, toward its impending demise. While this may sound alarming, contemporary trends lend themselves to few other interpretations.

That an essential requirement for the survival of any society—Chacoan or contemporary—is the production of adequate food to sustain its people cannot be disputed. Without food and water, life is impossible. But then as now, agricultural production is implemented in a fragile and risky environment, sensitive to both human and natural interventions. To overcome the obstacles it encounters as it tries to keep up with food production, mankind has developed a variety of technological fixes. For the Chacoan, this included irrigation. Today, our mastery of science and technology has permitted us to expand the range of options to include, for example, genetic modification of crops, use of oil-based fertilizers, and deep-well pump irrigation.

But our short-term technological successes in agriculture have made us oblivious of the fact that we, like the Chacoans, are losing the battle for increased sustainable food production.

• In the U.S. and overseas, growing urban demand for water is reducing the amount of land that can be cultivated.
• Aquifers are being overdrawn, further depriving farmers of water.
• Poorly managed irrigation is leading to salinization and waterlogging of the land, forcing more of it out of cultivation.
• Urban migration is leading to the conversion of productive land into building lots and highways.
• Reliance on a few high-yielding commercial varieties of plants is eroding biodiversity and increasing their vulnerability to pests and diseases.
• Increasing diversion of grain for such ends as meat and ethanol production further decreases effective agricultural yield.
• Over reliance on oil-based fertilizers, herbicides, pesticides, and fuel for farm machinery and transportation is placing production in jeopardy due to the increasing cost and impending shortage of oil, as the diminishing reserves are drained.
• And increasing temperatures, such as those due to global warming, have been shown to considerably reduce crop pollination and yield.