The ‘Fate’ of the The Anasazi

Anasazi Native Americans The Anasazi ("Ancient Ones"), thought to be ancestors of the modern Pueblo Indians They inhabited the Four Corners country of southern Utah, southwestern Colorado, northwestern New Mexico, and northern Arizona from about A.D. 200 to A.D. 1300 They practiced a wandering, hunting, and food-gathering life-style from about 6000 B.C. until some of them began to develop into the distinctive Anasazi culture in the last millennium B.C. By A.D. 1200, horticulture (growing maize) had assumed a significant role in the economy. Anasazi society collapsed suddenly around 1200 AD – WHY?

Chaco Canyon: Greatest Site of Anasazi Culture Pueblo Bonita Hungo pavi

Why did the Ansazi Societies Collapse? Environmental damage Climate change Hostile Neighbors Friendly trade partners (5th is always a significant factor:) Societies response to its environmental problems. Read More: http://www.time.com/time/2002/greencentury/endiamond.html

Irrigation and Salinzation Non-irrigated types of agriculture remained vastly dominant throughout the Anasazi era (700-1200 A.D.), but as the culture flourished, irrigation and diversion systems were developed by some of the more advanced Anasazi groups. Chaco Canyon, the epicenter of Anasazi culture throughout the tenth to twelfth centuries, is characterized by one of the best examples of pre-Anglo water diversion systems.

Evidence suggests that these irrigation systems were constructed in the tenth or eleventh centuries and, over time, degraded the area’s soils. The high evaporation rate and alkaline nature of the soils of the arid San Juan Basin eventually caused salinization and nutrient depletion as a result of prolonged irrigation. Because of the degradation of the canyon’s soils, irrigation was largely abandoned toward the end of Anasazi occupation of Chaco Canyon, during the twelfth century, in favor of floodwater farming in outlying reaches of the canyons. Read more: http://cpluhna.nau.edu/Change/waterdevelopment2.htm

What is Salinization? Read more: http://www.fao.org/docrep/r4082e/r4082e08.htm

Why is Salinization Harmful? Aldine Lab on Turgor Pressure: Place potatoes and celery in tap water vs. salt water for 20 minutes. Have the students feel the samples to determine if they are crispy or soggy. Because of the water moving out of the cell into the salt water, the samples would feel soggy. Because the samples are regulating internal water pressure in the tap water, they would feel crispy. Instructional and Laboratory: Formative / or Summative Questions * What would a graph of the negative feedback system look like? (example – sweating, increased demand for oxygen) * How can you demonstrate control of blood glucose by a flow chart? * How can you demonstrate thermal regulation by use of a diagram? Why is Salinization Harmful? Read more: http://www.fao.org/docrep/r4082e/r4082e08.htm The top plants are not salt tolerant, the bottom ones are. http://www.treehugger.com/files/2009/07/scientists-make-progress-salt-tolerant-gm-crops.php

Plant Cells and Salty Water: Osmosis Turgor pressure in plant cells immersed in solutions with different salt concentrations (hypertonic = high concentration; hypotonic = low concentration)

Conclusion/Summary “Over the six centuries the human population of Chaco Canyon grew, its demands on the environment grew, its environmental resources declined, and people came to be living increasingly close to the margin of what the environment could support. That was the ultimate cause of abandonment. The proximate cause…was the drought that finally pushed the Chacoans over the edge, a drought that a society living at a lower population density could have survived.”