Archaeological sites are brimming with valuable information on the local ecosystems contemporary with their occupation. For instance, charcoal fragments from archaeological sites are taken to botanists who identify the carbonized seeds and plant remains that formed that ancient charcoal. Those seeds and plant remains, in tandem with the bones of animals found in the sites, provide us with a dynamic background of plant and animal life from which to interpret human adaptation and provide us with a measure of human impact on past environments. As an example of the ultimate impact, archaeologists traced the evolution of corn from plant remains found in the rock shelters of the valley of Mexico.

Other information on environmental change is found in soils and tree ring data from archaeological sites. In southern New Mexico, where my research takes place, the combined environmental evidence clearly shows that the last 10,000 years have seen a slow, steady warming trend. The Chihuahuan Desert has slowly advanced northward, bringing with it mesquite and other plant and animal species native to that desert. Now, when it seems equally clear that humans have contributed to this warming trend, it is important to recognize that we are simply speeding up an existing process. Archaeological time capsules of past environments suggest that we have been dealing with global warming for 10,000 years, resulting in tumultuous human migrations and social reorganizations.

While environmental fluctuations have certainly affected the actions of humans, archaeology also documents the effect of human activities on the environment. The Hohokam farmers in southern Arizona unwittingly salinized their field areas through intensive irrigation, the Chaco Canyon pueblos deforested the remnant stands of timber in that dry canyon before going farther and farther afield in search of building materials, and the people of the Mimbres River cleared their floodplain of riparian species, leaving it susceptible to erosion from floods that destroyed their floodgates and, quite possibly, their way of life.

In the long-running debate over land use and environment in the Southwest, archaeology has much evidence to share. Although there is little doubt that overgrazing by cattle has contributed significantly to the spread of mesquite, archaeology suggests that mesquite was more widely distributed than generally believed. In 1976, I excavated several fire pits on the Lordsburg Mesa in southwestern New Mexico, and these pits were full of charcoal chunks that were identified as mesquite and radiocarbon- dated to more than 1,000 years ago. Since then numerous archaeological sites in the New Mexico desert have yielded mesquite charcoal dating as early as 2,000 years ago, long before the introduction of cattle.

But archaeological data do not play favorites. On the other side of the coin, ranchers have adamantly opposed the reintroduction of the wolf. When wolf reintroduction was proposed for the San Andres Mountains of south-central New Mexico, opponents argued that the San Andres Range had never been wolf habitat. A review of bones from archaeological sites revealed that wolves were indeed present in the prehistoric past. This is not the only case where archaeological data have been key in determining the historic suitability of habitat for a threatened species.

Although these examples are from the southwestern U.S., archaeological sites around the world are furnishing invaluable clues to their local environmentās past·and future. Unfortunately, archaeological sites, unlike trees or wolves, are nonrenewable. Once they are destroyed by unthinking artifact-collectors or simply allowed to erode through lack of appropriate management, they, and their environmental time capsules, are gone forever. It is an unfortunate reality that archaeological sites do not always receive the protection by landowners and conservancy organizations that they deserve. Given the range and time span of the environmental information that they contain, isnāt it time that archaeological sites receive the same consideration and protection that we give biological reserves?

Karl Laumbach is associate director of research and public education for Human Systems Research, a nonprofit corporation for anthropological research, and co-leader of Prehistoric Pueblos. During the past 26 years, he has directed hundreds of archaeological projects in southern New Mexico, where he has served as a catalyst for preservation of archaeological sites on private land. His most recent publication is a book on the history of an Apache Wars battlefield (in press).

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