Biological and Climatic Factors (IMAGE) Chinese Academy of Sciences Headquarters Caption These are frequency-dependent effects of biological and climatic factors on prevalence of human epidemics in ancient China. Credit IOZ Usage Restrictions None 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.