British epidemiologists Richard Wilkenson and Kate Pickett's book The Spirit Level: Why Greater Equality Makes Societies Stronger reveals the widespread effects of a country's inequality of income. Greater income inequality is related to a wide range of harmful effects including many related to health such as life expectancy, obesity, drug use, and mental illness, and to social measures such violence, bullying and conflict in schools, rates of imprisonment, happiness, levels of trust, children's well being, educational performance, and teen pregnancy.
Wilkenson and Pickett based their book on research that used statistics from first world nations and from states in the U.S. Following are two videos from a longer talk that they gave in 2010.
"Can an Unequal Society Become Sustainable?"
Epidemiologist Kate Pickett from the University of York addresses this question and more. See the 6 minute video and transcript
"Why Cubans Live Longer than Americans" - Kate Pickett explains that the systemic problems of inequality penetrate the entire social hierarchy, giving wealthy societies like the U.S., greater health problems and shorter life expectancies than many, less economically developed, nations. The video is not actually about Cuba, but part of a broader discussion of countries' wealth and their life expectancy. See the 3 minute video.
A cross cultural research project in 2009 found the U.S. to be the most dysfunctional society in comparison to 16 other wealthy countries on measures of social cohesiveness from the Successful Societies Scale. In fact, David Strand remarked in the August 3 Aitken Independent Age that the U.S. was a remarkable outlier, lagging other nations by a wide margin. Strand wrote, "our poor standing on the Successful Society Scale is not surprising considering three decades of public policies promoting economic and social insecurity. The middle and lower classes have been under attack for 30 years." Read his column summarizing the study.