DEPRESSION - IMMUNOLOGICAL RESIGNATION OF THE WILL TO LIVE

Evolution is assumed to promote the survival of the fittest by the gre ater success of the reproductive potential of those with the character istics most suited to their environment. Little thought is given to ho w those least adapted fail to survive to reproduce. If the species, ra ther than the individual, has a drive to adaptation and survival, ther e should be a specific mechanism for those least adapted to withdraw f rom life. The immunological changes accompanying depression may facili tate heart disease, infection, parasitic infestation or other ill heal th, so that depression is a mechanism for those least resilient, or fa ced with most adversity, to succumb to illness. If depression is a sta te facilitating withdrawal from competition for reproductive success, major depressive illness may be the inappropriate and spontaneous occu rrence of a mental state which has advantages for the species in allow ing those 'least fit' to fail to survive. This hypothesis gives an emp irically testable challenge to the view that the species has no evolut ionary drive to survival and increased adaptedness to the environment, as well as explaining the more and more frequent occurence of a speci fic mental state and its associated changes in the immune system.