That is the controversial theory of one leading psychiatrist.
Professor Tim Crow believes that the difference in the development of the human brain from the primate brain - which allows us to process thought and speech - is linked to why psychotic illnesses occur.
http://news.bbc.co.uk/2/hi/health/4739149.stm
https://www.researchgate.net/publication/13763233_Is_Schizophrenia_the_Price_that_Homo_Sapiens_Pays_for_Language