Culture and Ecology of Chaco Canyon and the San Juan Basin

244 Chaco Project Synthesisthat the empty spaces on their maps may still havebeen home to a small number of people. Theypropose that the reason for the decreasing populationthroughout this long time span may be related tohaving too few people within the mating population tomaintain population densities.The social changes that would have accompaniedslow reductions in population sizes have not yet beenextensively addressed. The evidence for violence anda few instances of cannibalistic behavior that havebeen documented (e.g., Bustard 2000, White 1992,among others) may have resulted if droughts made itimpossible for late A.D. 1100 populations to eithergrow sufficient food staples or trade for them withgroups or neighbors throughout the region. Severestress lasting for longer periods would have madepeople more dependent on their local groups; if thecooperative aspects of regionwide exchange thatprobably went on during the Classic period no longerproved reliable, the dissension and fissioning thatseems to take place over the 400 years illustrated byHill et al. (2004) is not unexpected. Stuart's (2000)proposal that the settlements of historic populationsthat cover riverine through high-mountain settingsalong the Rio Grande would not be unlikely. Suchsettlements would allow much more independenceamong the historic tribes. Possible explanations willbe further explored in Chapter 9.