Some extreme variants are associated with the deviations of psychological function that we describe as psychosis. These states are seen as boundaries of the distribution of personality variation, including the capacity for language and emotional expression. In particular, those with the earliest manifestations (i.e. schizophrenia, Asperger’s syndrome and autism) have the greatest impairments of communication and social ability, and also demonstrate a failure to develop anatomical asymmetry. In summary, key features of the theory are that the psychoses are disorders of specifically human evolution, arising from variation in the genes controlling hemispheric asymmetry that has led, by the mechanism of sexual selection, through progressive delay in maturation (neoteny) to increased brain size and intelligence. The most readily testable prediction is that the gene for asymmetry (and by implication contributing to predispostion to psychosis) should be X-Y homologous (p. 24). Crow, T. J. (1995). A Darwinian approach to the origins of psychosis. British Journal of Psychiatry, 167(1), 12-25.
Professor Tim Crow’s work offers a powerful evolutionary explanation for autism by concentrating on neoteny’s connection to cerebral symmetry. Crow mostly works on schizophrenia. His works seems relatively little cited when it comes to autism. Combining Crow’s insights regarding neoteny with Geschwind and Galaburda’s understanding of the influence of testosterone on cerebral lateralization with Annett’s discovery of random handedness relationship with lateralization, the foundation for an evolutionary understanding of autism is evident in the neuropsychological literature.
