Pack of wolves (IMAGE) Penn State Caption By modeling wolves in Yellowstone National Park, researchers have discovered that how a population is organized into social groups affects the spread of infectious diseases within the population. Credit National Park Service 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.