Given that income inequality in the United States is pretty bad (see map), this interview with the epidemiologist Richard Wilkinson is...
...we looked at life expectancy, mental illness, teen birthrates, violence, the percent of populations in prison, and drug use. They were all not just a little bit worse, but much worse, in more unequal countries. ... Epidemiologists and people working in public health have been doing this work for some time, not only controlling for relative poverty, but for all the income levels within, for instance, an American state. So once you know the relationship between income and death rates, for example, you should be able to predict what a state's death rate will be. Actually, though, that doesn't produce a good prediction; what matters aren't the incomes themselves but how unequal they are. If you're a more unequal state, the same level of income produces a higher death rate.Wilkinson's explanation? In countries with more income inequality there is fiercer competition for status, and that leads to higher stress, more crime, less trust, and a host of other socially corrosive phenomena.So just keep that in mind next time you hear complaints about Barack "Spread the Wealth Around" Obama.