Despite decades of research and many thousands of studies, several important questions continue to plague those who study depression: Why is depression so common? When is depression a mental disorder and when is it a normal response to stress? Why is there genetic variability in depression and what does it mean? What is the best way to treat depression? Depression is an evolutionarily ancient emotional state, yet the implications of this important fact have largely been ignored.

In this lecture, Dr. Paul Andrews discusses how progress in the science and treatment of depression crucially requires an understanding of the evolutionary forces that have shaped the brain.