Richard Wilkinson and Kate Pickett, academic epidemiologists at Nottingham and York universities respectively, are authors of The Spirit Level: Why More Equal Societies Almost Always Do Better.
They explain why relatively unequal societies such as Britain and the United States are more likely to suffer from a range of problems, including low life expectancy, illiteracy, stress, and a high crime rate. Even climate change is less of a challenge for a society with a narrow gap between rich and poor.