March 27, 1827 and what happened later--the impact of psychiatry on evolutionary theory.

In the interaction between Psychiatry and evolutionary theory the force of the impact has not always been in one direction. The Brownes, father and son, had an influence on the development of Darwin's theory at different points in the nineteenth century. The crystallization by Miskolczy in 1933 of the concept that schizophrenia is a disorder that is specific to Homo sapiens is another example. In 1964 the formulation of the central paradox of psychosis by Huxley, Mayr and co-authors and the subsequent critique by Kuttner et al. of the solution Huxley et al. had offered opened up evolutionary approaches to aetiology. Here it is argued that a resolution of this paradox requires identification of the speciation event for modern H. sapiens and elucidation of its neuroanatomical and physiological consequences. It necessitates a saltational account of species transitions and the recognition of species-specific genetic variation. Pursuit of these objectives leads to the hypothesis that speciation events occur selectively on the heterogametic chromosome (the Y in mammals) and are followed by a phase of sexual selection to establish a new specific mate recognition system. In H. sapiens the core component of this system is the capacity for language; the nuclear symptoms of schizophrenia are necessary clues to its neural structure.