Phylogenetic adaptations and the genetics of psychosis

There is evidence that many social skills and responses which are of adaptive value are under a significant degree of genetic control. It is suggested that in states of hyper-arousal these skills are displayed in inappropriate and incomplete forms and that such behaviour constitutes psychosis. Genetic variation in these skills, under polygenic control, appears to be a determinant of the adaptiveness of the personality, with individuals at the extremes of the distribution tending to be maladjusted, chronically overaroused, and vulnerable to psychotic breakdown. Since the individual subjects's psychotic symptomatology will relflect the make-up of his genotype, the hypothesis is consistent with observed familial occurence of the different froms of functional psychosis. The hypothesis explains many of the characteristic manifestations of psychosis, including those in symptomatic psychosis, and also the genetic association with personality disorder. Evidence for the hypothesis and some predictions it generates are briefly reviewed.