Where in the developed world do people live the longest? Where do people born at the bottom of the economic ladder have the best shot at climbing up? In which nations do children do best in school? Which countries send the most people to prison; have the teenage pregnancies and suffer the most homicides? The answers matter and are indicative of a society's overall health and the quality of life for its citizens.  That is the contention of eminent British epidemiologists Richard Wilkinson and Kate Pickett, authors of The Spirit Level: Why Greater Equality Makes Societies Stronger.