Why is America so rich and powerful? The answer lies in our genes, according to psychologist John Gartner. Hypomania, a genetically based mild form of mania, endows many of us with unusual energy, creativity, enthusiasm, and a propensity for taking risks. America has an extraordinarily high number of hypomanics--grandiose types who leap on every wacky idea that occurs to them, utterly convinced it will change the world. Market bubbles and ill-considered messianic crusades can be the downside. But there is an enormous upside in terms of spectacular entrepreneurial zeal, drive for innovation, and material success. Why is America so hypomanic? It is populated primarily by immigrants. This self-selection process is the boldest natural experiment ever conducted. Those who had the will, optimism, and daring to take the leap into the unknown have passed those traits on to their descendants. --From publisher description.