Thursday, April 5, 2012

Human Created environmental Change- The Southwest

Timothy A. Kohler

Prehistoric human impact on the environment in the upland North American Southwest

Population and Environment

Vol. 13, No 4, pages 255-268

In Kohler’s article Prehistoric human impact on the environment in the upland North American Southwest the effects of the intensification of agriculture (in particular maize agriculture) is examined. One of the main changes is that of deforestation due to the clearing of land for field use and the harvesting of firewood. These practices along with depletion of other wild resources lead to a further intensification of agriculture. Kohler goes on to give the example of the Dolores archaeological project (DAP) area in Southwest Colorado near Mesa Verde. The DAP area underwent dramatic increases in population moving from the original colonization of isolated farmsteads to populations of 900 to 1000 people in the site’s peak. This all occurs in a time period of only 300 years with the first half or so being occupied by the small households, so the large periods of growth really occurred over a period of 150 years. Later he explains that even Chaco Canyon fits in this pattern. Kohler concludes with how groups of people like the villages of the DAP area or the large district of Chaco Canyon are formed by the expansion of cooperation among larger groups than a household in order to gain an edge in competition with other groups. This plays a role in explaining why groups of people band together in larger groups when practicing agriculture because this minimizes the risks associated with agriculture while giving additional benefits to those within the group. This article is important because it not only explains the effects of agriculture on the environment but also shows how these changes can lead to a further intensification of agriculture leading to more changes in the environment resulting in a continuation of this cycle. This human created environmental change is particularly harmful because it is a self-propagating cycle that is very difficult to break without a decrease of in the population of people dependent on the agriculture that is part of the cycle.

Florence Hawley Ellis and Andrea Ellis Dodge

The spread of Chaco/Mesa Verde/McElmo black-on-white pottery and the possible simultaneous introduction of irrigation into the Rio Grande drainage

Journal of Anthropological Research

Vol. 45, No.1, pages 47-52

In Florence Hawley Ellis and Andrea Ellis Dodge’s article: The spread of Chaco/Mesa Verde/McElmo black-on-white pottery and the possible simultaneous introduction of irrigation into the Rio Grande drainage a theory is put forward that the refugees of the draught affected areas of Chaco Canyon and Mesa Verde brought not just pottery styles but knowledge of irrigation systems with them. Droughts were traditionally explained by someone or something having done something wrong leading to social breakage and reorganization of groups. This knowledge combined with the traditions of moving south if one needs to move combined to bring groups from Mesa Verde and Chaco Canyon to new areas like the Rio Grande area. Immigrates to these areas had brought along pottery of a certain style and left a trail of the same along the way, however the pottery style quickly dies out in the settlement areas as the refugees become integrated into their new surroundings. Evidence shows that water control systems such as irrigation and reservoirs are first used in these areas after such Black-on-white pottery makes an appearance in the area. This has lead the authors to believe that the groups with Mesa Verdian or Chaco/Mesa Verdian background were bringing pottery with them as they made their way and were perhaps trading knowledge with their hosts for land to farm. This article is important because it provides a theory of how the knowledge of water control systems spread to areas like the Rio Grande. This theory if true provides a reason for the spread of this knowledge to these areas, as well as explaining the disappearance of the pottery styles of the Chaco/Mesa Verdean people. This migration due to drought in their original areas resulted in the transformation of the new areas of settlement that drastically changed the way in which the people of the area could obtain food.

1 comment:

  1. I really like your summary of the Kohler article. It is interesting to think about human modifications leading to a self-propagating cycle. An article that I found also discussed environmental changes, such as deforestation, and how they affect local animal populations (Szuter 1991). The author claimed that as more trees were cut down, the land became a more suitable habitat for jackrabbits, which prefer more open environments. Cottontails, on the other hand, prefer more brush to hide in. Therefore, as groups became more sedentary and agriculture intensified, people consumed more jackrabbits because they were easily accessible. I would imagine that even if they wanted to eat more cottontails, they would not be able to do so because the changes to the environment are not easily reversible. As you said, once they began changing the environment it became a cycle of more and more changes. Once they made a decision to modify the environment, they were pretty much stuck with it.

    Reference Cited:
    Szuter, Christine.
    1991 Hunting by Hohokam Desert Farmers. Kiva 56: 277-291.