Culture and Ecology of Chaco Canyon and the San Juan Basin

272 Chaco Project SynthesisCanyon represent Pueblo ancestors. Intermediate Uto­Aztecan-speaking groups could have facilitated thepassage of information about successful adaptations tosimilar problems, goods, or some people throughoutthe American Southwest and Mexico (Wilcox 1986).How ideas, information, and goods moved amongthese people has become clearer through time(Carpenter and Sanchez 1996), but our understandingof the cultures of northern and western Mexico willrequire much more research before this issue iscompletely resolved. Those who support models ofindigenous development, however, must incorporatewhy, how, and when the concepts and objects fromthe south appear in the archaeological record.Indigenous Development ModelsDuring the 1970s, a number of models focusedon an explanation of a Chaco "system" between A.D.900 and 1200, when developments in the canyon wereunique when compared with the rest of the Southwest.Grebinger (1973, 1978) introduced the concept ofChaco as an indigenous ranked society, and Altschul(1978) considered the development of a Chaco interactionsphere. Allan and Broster (1978) applied theChristaller model to then-recognized Chaco greathouses and roads data to conclude that the spacingbetween major sites supported an interpretation ofthem as redistribution centers. These models stimulatedquestions that Judge (1976b [published in 1979],1977a) recognized needed to be addressed. Amongthem were the extent of the system, how it wasorganized, whether it was stratified, population trends,interaction among site residents, seasonal use, regionaldependence or independence, responses to changes inmoisture, and cause of the system's collapse.Because Judge (1977 a) relied heavil y on conceptsfrom cultural ecology and systems theory, humanswere considered part of an ecosystem that conformedto principles of energy distribution, diversity, tropiclevels, and succession stability. It was assumed thathumans would react to any stimulus that threatenedtheir security within a perceived stable system. Eithershort-term or sustained stimuli included social,demographic, or environmental elements; they couldhave both positive (impetus) or negative (stress)effects. With regard to social stimuli, Judge (1976b,1979) preferred not to address outside influence,especially from Mesoamerica, until he understoodlocal conditions and their effects on culturaldevelopment.Once analyses of survey and excavation datawere completed and numerous Chaco structures andcommunities within the San Juan Basin had beenidentified, Judge's (1976a, 1977a, 1977b, 1979) earlymodel was expanded to encompass the San Juan Basin(e.g., Judge 1981a, 1983a [published in 1989], 1991;Judgeetal. 1981). Data used for the evaluation of hismodel included that gathered by Chaco Projectpersonnel, as well as by colleagues undertaking newsurvey and excavations in the San Juan Basin. Thesecolleagues (e.g., Breternitz et al. 1982; Irwin­Williams and Shelley 1980; Pippin 1979, 1989;Gwinn Vivian 1990), too, based much of theirtheoretical approaches on cultural ecology. Mostagreed that some type of leadership was necessary todirect the construction of Chacoan great houses androads and integrate the many Chacoan communitiesthroughout the region, but whether or not this was astratified society has not been resolved.The Chaco Project ModelThe initial Chaco Project model (Judge 1977a)outlined how aspects of moisture availability (relativeabundance as measured by annual precipitation,seasonal dominance, and periodicity) would affectstability of the system; what cultural responses toenvironmental stress (mobility or investment in energysubsidies such as importation of foodstuffs or intensificationof agriculture) might be expected; howperceptions of group security (e.g., the amount offood surplus on hand) would affect response time; andhow the population growth rate would increase if theadopted responses continued to be successful. Ademographic stimulus would occur when popUlationgrowth (or immigration) exceeded carrying capacity.Using Hayes's (1981) data, Judge recognized thatmobility options would probably have remained openbeyond the Late Pueblo II period due to increasingrainfall and recognition that the San Juan Basin wasnot completely filled during Early Pueblo II (Marshallet al. 1979; Powers et al. 1983). The Bis sa'ani communityis an example of a short-lived late communityduring the early A.D. 1100s in a period of higherprecipitation (Breternitz et al. 1982)