Evolution, depression and the interplay between chance and choices

Abstract

Depression is a common and disabling mental disorder that affects people of all ages, cultures and ethnic backgrounds (Hendersonet al., 2000; Matherset al., 2001; Kessleret al., 2005; Princeet al., 2007). Its presence has been recorded throughout history (Berrios, 1985), which suggests that the signs and symptoms of depression are not simply a product of our time. However, given the overwhelmingly negative consequences of depression (Broadheadet al., 1990; Ellis and Gordon, 2004), it may seem surprising that depression is so ubiquitous and that evolution by means of natural selection has not eliminated it from our midst.