Map Pacific (IMAGE) Max Planck Institute of Geoanthropology Caption Distribution of intensive agriculture ('landesque capital') and high social stratification in the societies analyzed. Each filled circle represents one of the 155 societies in the sample, and its color corresponds to which traits are present in that society. Credit Sheehan et al. Coevolution of intensive agriculture and sociopolitical hierarchy. <i>PNAS</i> (2018). Usage Restrictions With appropriate credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.