Darwinian dynamics of depression.

Darwin's theory of sexual selection offers a challenge to psychology and psychiatry. We select each other, and have been doing so since social life first evolved. But who is selected and what happens to those who are not selected? What social structures have evolved to contain the unselected? What behaviours have evolved to manage the selection process? How do the selected relate to the unselected and what behaviours have evolved to manage this asymmetry in social relations? What mental states have evolved to characterize the selected and the unselected? These questions should be kept in mind when we observe and study the social structures, behaviours and mental states that we see displayed before us in all the variety of nature. It is suggested that a significant amount of current psychiatric disorder, especially depressive states and both social and generalized anxiety disorder, have evolved because they managed the processes of being unselected and de-selected, and maintained the unselected in that social role without loss of life or physical incapacity, and enabled the unselected to contribute to general social well-being.