The British Journal of Psychiatry
Psychosis: the price Homo Sapiens pays for language – in 100 words
Tim Crow

Age- and sex-dependent uniformity across populations of the psychotic continuum reflects ontogeny of the cerebral torque. This sapiens-specific evolutionary innovation identified four compartments of association cortex as the language circuit: perceived speech > meaning > thought > speech production. Symptoms (due to directional asynchronies of callosal myelination) represent `leakages' – negative anterior, positive posterior, linguistic to left, affective to right. The speciation event occurred 160KYA in the Y copy (PCDHY) of the ProtocadherinXY homologous gene pair with subsequent sequence change in PCDHX. Thus, language, H. sapiens & predisposition to psychosis resulted from a single chance event in a male, selected by females.