Wealth inequality in the prehispanic northern US Southwest: from Malthus to Tyche

Abstract

Persistent differences in wealth and power among prehispanic Pueblo societies are visible from the late AD 800s through the late 1200s, after which large portions of the northern US Southwest were depopulated. In this paper we measure these differences in wealth using Gini coefficients based on house size, and show that high Ginis (large wealth differences) are positively related to persistence in settlements and inversely related to an annual measure of the size of the unoccupied dry-farming niche. We argue that wealth inequality in this record is due first to processes inherent in village life which have internally different distributions of the most productive maize fields, exacerbated by the dynamics of systems of balanced reciprocity; and second to decreasing ability to escape village life owing to shrinking availability of unoccupied places within the maize dry-farming niche as villages get enmeshed in regional systems of tribute or taxation. We embed this analytical reconstruction in the model of an 'Abrupt imposition of Malthusian equilibrium in a natural-fertility, agrarian society' proposed by Puleston et al. (Puleston C, Tuljapurkar S, Winterhalder B. 2014 PLoS ONE 9, e87541 (doi:10.1371/journal.pone.0087541)), but show that the transition to Malthusian dynamics in this area is not abrupt but extends over centuries This article is part of the theme issue 'Evolutionary ecology of inequality'.

Keywords: Neolithic; US Southwest; archaeology; demography; palaeoclimates; wealth inequality.

Figure 1.

Demographic reconstructions and measures of wealth inequality. (a) Crude birth rates estimated from juvenility index, following [38]. Recomputed for the period shown using data from [33] and a loess smoothing with alpha (span) = 0.5. Spatial scope: US Southwest. (b) Two estimates of population size. Spatial scope: VEPIIN area. Reese [39]. (c) Estimate of population size [16]. Spatial scope: VEPIIS area. (d) Estimates for house longevity in small hamlets and villages [14]. Spatial scope: VEPI area. (e) Estimates of wealth inequality. Spatial scope: the central Mesa Verde (CMV), Chuskas, Chaco and the Middle San Juan regions [27]. BMII, Basketmaker II; PI, Pueblo I (etc.).

Figure 2.

Measures of climate relevant to maize productivity, and estimates of declining freedom to relocate through time. (a) Low-frequency estimate of summer temperature derived from pollen [28], relative to modern conditions (preliminary, based on research currently under review). Spatial scope: US Southwest. (b) Inferred low-frequency ENSO phase dominance derived from pollen [28] (preliminary, based on research currently under review). Spatial scope: US Southwest. (c) Proportion of demonstrably occupied cells (having tree-ring dates indicating occupation in the present or any of the previous 3 years) in the maize farming niche [19]. Spatial scope: UUSS as defined in [19]. (d) Room to walk as defined in text. Spatial scope: UUSS as defined in [19]. Series in C and D smoothed using a one-sided moving average of the preceding 11 years. BMII, Basketmaker II; PI, Pueblo I (etc.).

Figure 3.

Grey-shaded columns: population size in the VEPIIN area by subregions as defined in [15]. Data from [39]. Red-shaded column: churn, a measure of degree of mobility at the subregional scale, using data from [15].