Why do some innovations spread so swiftly and others so slowly? Read this brilliant article from the New Yorker to find out.

“To create new norms, you have to understand people’s existing norms and barriers to change. You have to understand what’s getting in their way. So what about just working with health-care workers, one by one, to do just that?”

(Photo: LifeNet Nurse Trainer Gabriel Ngambe trains staff at a rural clinic in Burundi)