“Scientists have long thought that social networks featuring many distant connections, or ‘long ties’—where individuals know a lot of people, but not well—produce large-scale changes most quickly. But in a new study, Damon Centola, an assistant professor of system dynamics and economic sociology at the MIT Sloan School of Management, has reached a different conclusion: People are more likely to acquire new health practices while living in networks with dense clusters of connections—that is, when in close contact with people they already know well.”