Expressions like "feeling down" or "feeling low" are more literal than we think, says Lost Connections author Johann Hari. A 30-year field study of wild African baboons by the incredible Stanford University professor Robert Sapolsky has shown that there is a remarkable relationship between depression, anxiety, and social hierarchies. Male baboons—who live in a very strict pecking order—suffer the most psychological stress when their social status is insecure, or when they are on the bottom rung, looking up at the luxuries of others. Does it sound familiar yet? "If you live in the United States... we’re at the greatest levels of inequality since the 1920s," says Hari. "There’s a few people at the very top, there’s a kind of precarious middle, and there’s a huge and swelling bottom." It's no coincidence that mental health gets poorer as the wealth gap continues to widen: depression and anxiety are socioeconomic diseases. The silver lining is that this relationship has been discovered. Could an economic revolution end the depression epidemic? And, most curiously, what can we learn from the Amish on this front? Johann Hari is the author of Lost Connections: Uncovering the Real Causes of Depression – and the Unexpected Solutions.