A five-point framework for the collapse of societies was proposed by Diamond (2005):
• Damage that people inadvertently inflict on their environment
• Climate change
• Society’s responses to its problems
• Hostile neighbors
• Decreased support by friendly neighbors
Essentially the first three relate, directly or indirectly, to water resources.
Other civilizations that collapsed in ancient Mesoamerica, the Mayans, and in the southwestern United States, the Hohokams and the Chaco Anasazis, have interesting histories. The ancient Maya lived in a vast area covering parts of present-day Guatemala, Mexico, Belize, and the western areas of Honduras and El Salvador. Mayans settled in the last millennium B. C. and their civilization flourished until around A. D. 870. The environment that the Mayans lived in was less fragile than that of the semiarid lands where the Anasazi and Hohokam lived.
Centuries before the Spanish arrived, the collapse of many other great Mayan cities occurred within a fairly short time period. Several reasons have emerged as to why these cities collapsed, including overpopulation and the consequential exhaustion of land resources possibly coupled with a prolonged drought. A drought from A. D. 125 until A. D. 250 caused the pre-classic collapse at El Mirador and other locations. A drought around A. D. 600 caused a decline at Tikal and other locations. Around A. D. 760 a drought started that resulted in the Mayan classic collapse in different locations from A. D. 760 to 910.
The soil of the rain forest is actually poor in nutrients so that crops could be grown for only two or three years, then to go fallow for up to 18 years. This required ever-increasing destruction of the rain forest (and animal habitat) to feed a growing population. Other secondary reasons for the collapse include increased warfare, a bloated ruling class requiring more and more support from the working classes, increased sacrifices extending to the lower classes, and possible epidemics. The Maya collapsed as a result of four of the five factors in Diamond’s (2005) framework. Trade or cessation of trade with friendly societies was not a factor for the Maya. Water resources sustainability was likely a factor in the collapse of the Maya.
In A. D. 899 a flood caused decentralization and widespread population movement of the Hohokams from the Salt-Gila River Basin to areas where they had to rely upon dry farming. The dry farming provided a more secure subsistence base. Eventual collapse of the Hohokam regional system resulted from a combination of several factors, which included: flooding in the 1080s, hydrologic degradation in the early 1100s, and larger communities forcibly recruiting labor or levying tribute from surrounding populations (Crown and Judge, 1991). In 1358, a major flood ultimately destroyed the canal networks, resulting in the depopulation of the Hohokam area. Culturally drained, the Hohokam faced obliteration in about 1450. Parts of the irrigation system had been in service for almost 1500 years, which may have fallen into disrepair, canals silted in need of extensive maintenance, and problems with salt.
Chaco Canyon, situated in the San Juan Basin in northwestern New Mexico, had limited surface water, most of which was discharged from ephemeral washes and arroyos. The Chacoans developed a method of collecting and diverting runoff as discussed in Chapter 9. The diversion of water from the mesas (see Fig. 11.2) into the canals combined with the clearing of vegetation resulted in the eroding (cutting) of deep arroyos to depths below the fields being irrigated. By A. D. 1000 the forests of pinon and juniper trees had been deforested completely to build roofs, and even today the area remains deforested as shown in Fig. 11.2. Between A. D. 1125 and 1180, very little rain fell in the region. After 1180, rainfall briefly returned to normal. Another drought occurred from 1270 to 1274, followed by a period of normal rainfall. In 1275, yet another drought began which lasted 14 years.
Of the five-factor framework for social collapse suggested by Diamond (2005), the only factor that did not play a role in the collapse of the Anasazi was hostile neighbors. Water resources sustainability was affected by the deforestation, the erosion (cutting) of the arroyos from the diversion of water resulting in lowering the groundwater levels and the supply source to the irrigated fields, and finally, the repeated periods of drought caused the final collapse.
What relevance does the collapse or decline of ancient civilizations have upon modern societies? Learning from the past and discovering the reasons for the
Fig. 11.2 Chaco Canyon (copyright with L. W. Mays)
Success and failure of other societies seems very logical. We certainly are a much more advanced society than those of the ancient societies, but will we be able to overcome the obstacles to survival before us? The collapse of some civilizations may have been the result of the very processes that had been responsible for their success (e. g. the Mayans and Romans and others).
World History
