Culture and Ecology of Chaco Canyon and the San Juan Basin

336 Chaco Project SynthesisOnce the packing threshold is reached, subsistencediversity decreases and group 2 size decreases.The pattern of minimizing group size to reducemobility is no longer important; the daily laborrequired increases as the group works within a smallerhome range. Group size is further reduced as a functionof decreases in subsistence diversity and thesplintering of groups into new residential units that aresituated adjacent to the resources upon which eachgroup focuses. Splintering accompanies a concentrationof labor upon those resources that respond best toincreased labor with increased net returns. A segmentedsocial organization may result among those forwhom the adoption of horticulture progresses slowly.For those who change subsistence strategies at a rapidrate, organization became complex and exhibited internalsocial ranking. Inherited leadership also appearsamong some elite segments.As a result of his detailed modeling and comparisonsagainst frames of reference, Binford derived aset of packing thresholds that indicate the populationdensities at which system state organizations wouldchange (Table 11.2). The first threshold (line 0, orminus 0.57 persons per 100 km 2 ) represents theminimum number of people that must be present inorder to sustain themselves in a habitat.The second threshold (line 1, or 1.57 persons per100 2km) represents the popUlation density at whichthose who specialize in obtaining either aquaticresources or terrestrial animals in settings with relativelynarrow niche breadth change their subsistencestrategy. Aquatic specialists tend to expand theirniche to include plant foods. Terrestrial hunters willeither begin to utilize plants or they will extensify.Mounted hunters of the Great Plains are one exampleof an extensification strategy, which is considered oneroute to ranked social organization. The introductionof the horse allowed former semi sedentary horticulturdliststo utilize a new ecological niche-thebison. The sizes of their smallest residential groupsand their seasonal aggregated groups increased dramaticallywhile the population density decreased to3.69 per 100 km 2 • The response was reflected in asocial scale in which larger dispersed and aggregatedgroups responded to the need for cooperative labor.All remaining nonpacked hunter-gatherers areorganized in terms of networks, for which the familyis the basic decisionmaking unit. Because there isseasonal segmentation and rejoining into larger groupsand these larger groups are not necessarily made up ofthe same composition as previous ones, networksallow broad contacts within the ethnic unit, but theaggregated residential units have much fluidity.The third threshold (line 2, or 9.098 persons per100 km 2 ) is the packing threshold where there ismaximum diversification in niche breadth. Mobilitydisappears and many new patterns emerge as populationscontinue to increase. Binford (2001:435-437)calls this the point of self-organized criticality, wherethere is a transition from a relatively stable generichunter-gatherer pattern to one with greater instabilitythat former subsistence tactics cannot arrest. Abovethis point, there are complex hunter-gatherers (rankedsocieties with elite, or ranked societies with wealthdifferentiation); mutualists (who rely on exchange oftheir specialized products with neighboring groups toobtain sufficient food); or those who domesticateeither plants or animals.Those who become specialists often developranked societies. Those who had been primarily dependenton terrestrial animals had responded tointensification by reducing dependence on largerterrestrial animals and shifting to terrestrial animalshaving smaller body size. In warmer temperate zones,they increased dependence on plants; in cool to coldenvironments, this shift was to aquatic resources,which was their only option (Binford 2001:368).Once the packing threshold is reached and populationsare focused on the use of patches, institutionalizationof leaders of groups who own the most productivepatches occurs when those in less productive patchesmeet with insufficiencies and become indebted to thosewho have surplus to share in return for labor or craftitems. The craft items eventually mount up, andleaders with wealth differentials emerge.For those dependent on plants, when mobility isno longer an option and no aquatic resources areavailable, they can either expand their diet breadth tospecies that increase net return but that are less efficientto obtain, or they can increase their laborinputs for processing and storage. Major changes totheir social organization can thus be delayed as theygain time and space utility through the use of residentialpatches. Thus, not all hunter-gatherer groups