Income and wealth inequality can be measured by Gini statistics, and in fact nations have been evaluated by the degree of inequality existing in their economies. Japan scores pretty low in income inequality (under 30), and we see that despite the stress and long the Japanese workman suffers, Japan still has one of the longest average life expectancies. Countries with the highest inequality are located in sub-Saharan Africa and Latin America, and it is no surprise that life expectancies in these countries are low. The US is the most unequal of the developed nations, with the exception of two city-states Singapore and Hong Kong.

Another problem with gross inequality besides health is that it can undermine our political system. Very rich people can contribute to politicians while ordinary folks can't.