How might psychological disorders have evolved? Why have they not become extinct?

Discussion topic: As hard as it is to define the boundaries between what we call physical and what we call mental, assigning disorders to either domain is even harder. The Diagnostic and Statistical Manual of Mental Disorders avoids the problem by classifying disorders according to their symptoms and not their causes. This is analogous to grouping appendicitis, a stomach ulcer, and intestinal bloating together as Sore Tummy Syndrome.

In sickness behavior, an illness of the body becomes an illness of the mind. An inflammation of the brain becomes schizophrenia or depression. Mental and physical stress both contribute to mental and physical disorders. Can you decide what causes what?

Step 1: Address the following questions in discussion in one paragraph for each of the three question items:

Questions

1. Are we wrong in identifying the mind exclusively with what the brain does? Is “self” more than the brain?

2. How might psychological disorders have evolved? Why have they not become extinct?