The Authors

Nicholas A. Christakis, MD, PhD, MPH, is a professor at Harvard University with appointments in the Departments of Health Care Policy, Sociology, and Medicine. He was trained both as a physician and social scientist. Until recently, his clinical practice focused on the care of seriously ill patients receiving hospice care. His research has for over a decade focused on how social networks form and operate. In 2009, he was named one of Time magazine's 100 most influential people in the world.

James H. Fowler, PhD, is a social scientist who conducts research on social networks, political participation, the evolution of cooperation, and genopolitics (the study of the genetic basis of political behavior). He is a Professor of Genetics in the Department of Medicine and a Professor of Political Science in the Division of Social Sciences at the University of California, San Diego. He holds graduate degrees from both Harvard and Yale, and he also served for two years as a Peace Corps Volunteer in Ecuador.