THE HIGHLANDS OF Honduras’s Copán region, on the country’s Western border with Guatemala, remain nearly as socially isolated today as when the Mayans built one of their greatest civilizations there thousands of years ago. Far from Facebook, Instagram, or Twitter, however, researchers here are studying social networks, trying to map the true extent to which one’s connectivity can influence behavior and, more importantly, be leveraged to achieve positive outcomes.

The $4 million project, backed by the Gates Foundation, is being led by political scientist James Fowler and physician-sociologist Nicholas Christakis through Yale’s Human Nature Lab. Christakis and Fowler have long been at the vanguard of network science, the idea that one’s social circles can have a ripple effect on behavior, good and bad. In Honduras, the pair hope to overcome one of the most persistent challenges to better global health: Introducing best practices and resources, whether relating to clean water, personal health, or disease, is of little value unless they are systematically adopted by the target community.