This essay is the culmination of forty-five years as a psychiatrist investigating the relationship between severe mental illnesses and human evolution. I have concluded that the most important changes leading to our evolutionary success occurred inside the mind. Upright posture, large molar teeth, opposable thumbs, large brains, and the onset of culture were additive responses to the evolution of what MOTIVATED early humans. The inner experiences of major depression, panic disorder, schizophrenia, and bipolar disorder are shown to derive from the breakdown of normal emotions we all know intimately. These everyday feelings have played a central role in our evolution and thus can be viewed as emotional fossils.