ABSTRACT
This chapter explains abnormal behaviour and internal states of human. Darwinian medicine and evolutionary psychiatry are concerned with understanding illness and abnormal behaviour from an ultimate perspective. Abnormal psychology is concerned with the causes and treatments of mental dysfunction and in particular with mental illnesses. The term psychopathology is often used as a synonym for abnormal psychology, but is a narrower term since it implies a disease process is occurring. The Diagnostic and Statistical Manual of Mental Disorders (DSM) is the generally accepted worldwide manual used for diagnosing mental health disorders. The British Psychological Society (BPS) has suggested that the DSM medicalizes natural and normal responses to life experiences. Enduring negative emotional states that are seen as mental illnesses: depression and anxiety disorders may be due, in part, to the fact that the ability to experience unpleasant states was necessary for the survival of ancestors.
