Crop Productivity Estimates for Past Societies in the World Sample-30 of Seshat: Global History Databank

This article reports the results of a collaborative research project that aims to estimate agricultural productivities of the past societies in the Seshat World Sample-30. We focus on 30 Natural Geographic Areas (NGAs) distributed over 10 major world regions (Europe, Africa, Southwest Asia, South Asia, Southeast Asia, East Asia, Central Eurasia, North America, South America, and Oceania). The conceptual framework that we use to obtain these estimates combines the influences of the production technologies (and how they change with time), climate change, and effects of artificial selection into a Relative Yield Coefficient, indicating how agricultural productivity changed over time in each NGA between the Neolithic and Industrial Revolutions. We then use estimates of historical yield in an NGA to translate the Relative Yield Coefficient into an Estimated Yield (tons per hectare per year) trajectory. We tested the proposed methodology in two ways. For eight NGAs, in which we had more than one historical yield estimate, we used the earliest estimate to anchor the trajectory and compared the ensuing trajectory to the remaining estimates. We also compared the end points of the estimated NGA trajectories to the earliest (the 1960s decade) FAO data on crop productivities in the modern countries encompassing Seshat NGAs.