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There are several evolutionary theories related to schizophrenia spanning time from the when Homo erectus gained control of fire onward to the modern day. The first theory related to schizophrenia is Byproduct theories, which are a specific type of theory put forward by various scientists. These theories portrays the disorder as a consequence of other, separate evolutionary changes. One anthropologist putting forward this theory, Crow, states that schizophrenia is a result from incomplete hemispheric specialization due to selection of genes relating to language. While another scientist, Burns, follows that schizophrenia is related to modified cortical connectivity which is vital for the development fo the 'social brain. Finally Horrobin argues that ancient mutations are what developed linguistic, creative and shamanic ability which in turn can potentially cause deficits in lipid metabolism or as it is termed in modern times Schizophrenia.

Another evolutionary theory which connects with the development of modern day schizophrenia are Balance theories which hypothesizes that schizophrenia's negative aspects are balanced by benefits. These benefits yield valued personality traits or yet again shamanism a desired and mystic ability of the past. Though an evolutionary theory in its own, analysis of balance theory does not show this route as a possibility. Folklore accounts mention wise fools and clever madmen but do not connect such a characteristic to motifs combining psychosis and creativity, aspects believed to be borne from schizophrenia.

A third theory relating to schizophrenia is group selection theory which describes 'psychosis' alleles provide advantages to groups, outweighing any disadvantages. This theory then goes further and states that as a result of this grouping, humans that have specific genes replaced groups that lacked those genes. Additionally, this theory uses elements based on byproduct theories and balance theories. Environmental change theories also rely on schizophrenia-type alleles providing more benefits to our ancestors than to our modern selves. Some who support this theory say that it was modernization which actually generated the disorder itself. While the environmental change theory does explain how the development of schizophrenia survived through to modern times this claim as a whole through historical, anthropological and clinical perspectives the theory has been deemed inconclusive.

Random process theories are another explanation of Schizophrenia. At the center of this idea a polygenic mutation-selection balance theory describes mental disorders as continuous mutational effects on many genes underlying human behavior overtime. This description of all mental disorders, including schizophrenia, implies that when mutations disrupt cognitive processes during evolutionary stages, the functions connected to that process are also affected by those mutations in later eras. This theory not only supplies how mental illness survived through to modern times but also how mental processes are affected as a whole by way of this theory. Additionally, this process theory gives mental disorders a kind of watershed quality where there are varying layers within mental processes that flows to 'downstream' processes which would also be affected by disruptions in cognitive functions 'upstream'.

Other hypotheses relating to schizophrenia include the idea that those with the disorder themselves possess some kind of 'physiological advantage' which includes resistance to injuries, resistance to various infections, enhanced healing abilities and even being less accident prone. These hypotheses are not well supported as any advantages possessed by those with schizophrenia should be found in their behavior not the genotype and the fact of the matter is that selection works on phenotype not genotype. Another suggested hypothesis, the stress-induced neurodevelopment hypothesis, claims that those exposed to pre- and/or early neonatal environmental stress may have developed psychiatric disorders such as schizophrenia and major depressive disorder (MMD). The theory goes on further to explain that these disorders, spurred by stress before and after birth may have evolved and remained in the human genotype as a means of survival against adverse environments. Each of these theories will be explained in further detail in the sections below.