Inequality: The Last 10,000 Years

Abstract.  Despite a long Pleistocene selection for preferences for fairness, cooperation and relative equality with others in our groups, the Holocene was marked by increasing and often cumulative wealth disparities among households within groups as farming and stock-raising permitted storable surpluses and increasing sedentism encouraged population growth. Here I report on a recent project to calculate Gini coefficients from household-size distributions (as a cross-culturally valid proxy for wealth) for a broad cross-section of well-understood archaeological contexts around the world over the last 10K years. In Eurasia, typical Ginis increase in an almost linear fashion from values of less than 0.2 ca. 9000 BC, typical of foragers, to values of around 0.5, typical of contemporary states, by around 1000 BC. In the New World, on the other hand, typical values rarely top 0.3, a level exceeded in Eurasia by 4000 BC. Intriguingly, demographic scale is more strongly related to wealth inequality in Eurasia than in North America and Mesoamerica. I discuss our preferred explanation for the higher levels and earlier development of wealth disparities in Eurasia and their implications for social evolutionary processes in the two hemispheres. I also present evidence that growing wealth disparities were repeatedly violently reversed in at least one well-understood society, that of central Mesa Verde.