[Evolution of psychosis].

Psychosis poses a major challenge for natural selection. The heritability of psychotic disorders is considerable and psychosis is associated with decreased reproductive success. Natural selection has not succeeded in eliminating the genes that predispose to the illness. Yet natural selection is considered to prune those features that decrease reproductive success. This paper deals with various evolutionary psychiatric models of major psychoses. According to Burns's model it is argued that psychosis may be the high price that humans have to pay for the evolution of their complex social brains. The same genes that have helped to shape our humanity carry the risk of psychosis. As such the genes would confer an evolutionary advantage, but their incremental effect would increase the risk of psychosis.