Theory

Maybe bipolar disorder is actually the most elemental human state, if we define "natural" as something which reflect forces of nature. For as we have seen, especially with the recent tsunami, nature is unpredictable, violent at times, at other times nurturing and peaceful. Its patterns and conduct can, overall, be seen as reflected some sort of cosmological balancing act. Too many people? Disease or natural disaster takes care of that. too much pollution? Kill the polluters through the fruits of their own deeds. So the bipolar person is a more pure human; those who are "normal" have, through evolution, become more removed from the primal world.