Culture and Ecology of Chaco Canyon and the San Juan Basin

Explaining Pueblo Social Organization 279(1992) proposed that the downturn in small-site populationnoted by Windes (1987[1], 1993) couldrepresent movement from these sites to great houseswhere workers expended energy in construction, craftspecialties, etc., in return for food. It is possible thatleaders could have extracted surplus from the populationunder the guise of ritual metaphor; communalstores in McElmo structures would accumulate forredistribution. The decreased rainfall could havesignaled decreased power, so that leaders may haveworked harder to show devotion to the dieties. Orpatrons could take advantage of ties with kin oralliance partners to move away from the canyon. Theinterpretation of the next pattern would depend onhow evidence from the last two decades of theeleventh century was viewed. Sebastian (1992:131)stressed the role of competition during this period-inacquisition and display, and even in conspicuousconsumption. She extended this to regional competitionbetween Chaco Canyon and the new centersthat were being established along the San Juan Riverand its tributaries to the north.Although interpretations of pattern III (A.D.1100 to 1130) vary, Sebastian (1992) observed that allagree that the period was an unusually good one foragriculture. In Judge's interpretation, this periodrepresents a delayed reaction to earlier climaticdownturns leading to the transference of leadershipfrom Chaco to the San Juan Valley. For H. Toll(1985), the earlier downturn could have resulted in ashift, but it also could have decreased the need forintense reliance on other areas as a coping strategy.On the other hand, Lekson (1984a) saw the increasedvariability in architecture as evidence for more complexsociopolitical interaction-a time during whichChaco is the central place for the San Juan Basin. Itsdifferent buildings had different functions.The northern San Juan Basin would havebenefited from the changes in precipitation during theearly twelfth century, and, following Irwin-Williamsand Shelley (1980), Sebastian (1992: 134) thought thatit may represent expansion of the system. Althoughthere is still importation of ceramics, lithics, and otherprestige items into Chaco Canyon, she suggested thata cessation of use of imported wood, lack of depositionon trash mounds, and a dependence on localsmall mammals indicate a cessation of populationinfluxes. That no new great houses were built afterA.D. 1115 could be interpreted in two ways: as afailure by the leaders, or the possibility that patronscould have used control of food as their new powerbase. If the former, there would be a contraction inthe scope of power that did not return once conditionsimproved. The expansion in the northern San JuanBasin, and the Aztec complex as documented by Steinand McKenna (1988), suggest these leaders were ableto successfully compete for leadership positions. Onthe other hand, if control of food during scarcitybecame the new power base within the canyon, thencompetition in construction and ritual events may haveended among groups in the canyon. Competitionwould exist among secondary regions, and Chacowould have transferred more information and lessmatter and energy. Because the downturns during theA.D. 1090s were severe enough to wipe out surpluses,Sebastian (1992: 138) preferred the first scenario, inwhich the leadership lost credibility with its followers.The evolution of power, therefore, remains unknown,but the collapse during the long dry period after A.D.1130 was clear.Dual Social OrganizationThe presence of two distinct groups living inChaco Canyon had been proposed by several previousinvestigators; e.g., Judd (1964:41), within one greathouse, Pueblo Bonito, vs. Kluckhohn (1939a), whoviewed differences between large and small sites asevidence for two different popUlations based onmasonry styles. Based on McElmo-style architectureand pottery types, Gordon Vivian and Mathews (1965)suggested that three distinct Pueblo traditions mayhave been present from around A.D. 1050 to 1150.The dichotomy between site size, agricultural practices,and topography on the north and south sides ofthe canyon led Gwinn Vivian (1989, 1990) to revisitthe proposal that two distinct cultural traditions werepresent in the canyon from ca. A.D. 800, and thatthese traditions are still visible in contemporaryPueblo societies.Gwinn Vivian (1989, 1990:430-434) wasfamiliar with G. Johnson's (1978, 1982) evaluation oforganizational models. Johnson noted that decisionmakingunits were usually composed of no more than15 people and more often at around six. When highernumbers are reached, units either fission or form oneof two types of hierarchies: In a simultaneous hier-