Combining historical and archaeological data with crop models to estimate agricultural productivity in past societies
Carrying capacity, population pressure, and agricultural productivity are of central importance to understanding key innovations in human social and cultural evolution. In this paper we outline how crop yield models can be combined with the historical and archaeological information about past societies compiled by Seshat: Global History Database to infer how agricultural productivity and potential have changed over time in different parts of the world. To aid comparative research we focus on developing a method for calculating the carrying capacity of a particular region based on a number of simplifying assumptions. Here we present two case studies demonstrating the calculation of ancient crop yields and carrying capacity for the regions of Latium (Italy) and Oaxaca (Mexico); regions selected to illustrate a number of different features of past agricultural systems, as well as different staple crops. We outline the strengths and weaknesses of this approach and discuss ways in which it could be adapted to address a range of research questions, e.g. relating to archaeological demography and anthropogenic change. Comparison of our reconstructed carrying capacity series with independent estimates of ancient population from these regions demonstrate broadly good agreement with some notable mismatches as well, highlighting a fruitful area of focus for future studies exploring the gap between achieved population and potential carrying capacity.