Other members of society might treat such individuals as shamans, prophets or other sorts of holy men/women, due to their apparent powers to connect with other realities. Their enhanced social prestige could increase access to vital resources and care. This seems to have been the case in many societies throughout space and time.

Milder forms of schizophrenia tend to exhibit more divergent thinking

Evolutionary psychologists claim that this standard prevalence rate implies that schizophrenia existed when Homo sapiens emigrated out of Africa. So with this long history of the disorder, nature had plenty of time to extinguish this maladaptive disorder. Yet, the mental illness continues to plague the globe at an unwavering rate; even instances in remote populations, such as Australian Aboriginals and Nepali villagers, remain constant. Hence, schizophrenia must have evolved over time for some mysterious purpose or as a negative byproduct of an evolutionary benefit.

Schizophrenia as an evolutionary advantage to the group:

Religious based delusions that enhanced religious rituals ( perhaps justifying the hallucinations of religious prophets)

group-splitting hypothesis of schizophrenia: schizophrenic individuals were usually prominent enough (tended to show signs of leadership) in tribes that their symptoms would result in breaking up the group into smaller units.

Protective function: the symptoms of schizophrenia forces the individual to be in a state of constant alertness, which enhanced territorial instincts.

Schizophrenia as an evolutionary advantage on the individual level:

Reproductive advantage: schizophrenics have a higher resistance to many things: to shock, visceral perforation, high doses of histamine, insulin, thyroxin, and other physiologically active substances, as well as infection and many allergies.

Physiological advantage: As Horribin’s claims, schizophrenia is a whole body disorder demonstrated through the unusual posture, gait, and body shape of diagnosed individuals. The high fever of schizophrenic individuals provides further evidence to Horribin’s theory.

Psychological advantage: there is no evidence that links psychosis, particularly schizophrenia, with creativity (which disproves my hypothesis!)

Schizophrenia as an evolutionary advantage at the kin level:

Schizotypal personality: schizophrenia falls on a genetic continuum where relatives show schizotypal traits and features, even when they are not diagnosed as schizophrenic.

Milder forms of schizophrenia tend to exhibit more divergent thinking

I wonder why milder forms of schizophrenia show signs of divergent thinking. Also, how does that divergent thinking come about? Does it simply come about as a result of their delusions? Perhaps the atmosphere these people live in, which is a solitary mildly depressed atmosphere, is a foundation for a type of creativity. There has been numerous links to depression and creativity. Also, madness and genius has been rumored to be closely linked. If we link mildly schizophrenic people with a "type" in the Meijers Briggs personality type I wonder what the majority of them will have. Will some number get the rare INFJ (Introverted, Intuitive, feeling, judgement)?

Of course there are similarities between some aspects of philosophy and maybe science with schizophrenia.

If I say, for example:

Everything flows nothing stands still (Heraclitus).

Change is impossible, and existence is timeless (Parmenides of Elea)

Physical objects and physical events are "shadows" of their ideal or perfect forms, and exist only to the extent that they instantiate the perfect versions of themselves (Plato).

All things are full of gods (Thales of Mileto).

Am I a mild schizophrenic delusional, or more than mild?

I think the name for the illness is telling. "Schizo" meaning split. "Phrenia" meaning mind. However, the mind itself isn't split. It's split from reality, due to delusions, halucinations, and voices. Listening to a schizphrenic shows that their arguments are logical. It has to make sense of all the information, so the mind stretches itself to the limits to make all abnormalities obedient to a parsimonious theory. Emotions and a faulty intution are in the drivers seat as the imagination buts the theory. These people often use reason, logic, god, gov, philosophy to understand the situation. But how does this all equate to divergent thinking? Obviously, these people are hyper vigilant to their surroundings. Collecting all the information, and struggling to force it into a theory.

This is exactly what a philosopher does, but without the driving force of delusions of persecution. I wonder if schizotypal people often choose as careers... Perhaps theory building comes naturally to them. Philosophers have chosen the contemplative life, and much of that is spent in solitude which schizotypals prefer. Furthermore, if their emotions are undercontrol schizotypal people may be creative individuals. I wonder if the solitary, emotional, yet still logic intact makes them more divergent theories.

Is there any research done on schizophrenics and divergent thinking?

The late David Horrobin wrote a whole book (very readable, but speculative) on this: "The madness of Adam & Eve - How shcizophrenia shaped humanity" (Bantam Press 2001), partly based on human waterside evolution.

Dear Stephen,

What do you mean on mild schizophrenia?

Dear Sachin,

Being a modest entomologist, I do not know how schizophrenia symptoms can force people to be in the state of constant alertness and how can this enhance territorial instincts?

By the way, what are territorial instincts?

Dear All,

Can you list some successful historical personalities with mild schizophrenia?

Hi András

What do you mean by schizophrenia?!

This is not a facetious question. Classification of mental illness is bedevilled by the "box orientated" approach of the 19th century. There is considerable overlap of psychopathology between schizo-, bipolar, depressive, anxiety disorders and the autistic spectrum. Many are linked to Theory of Mind disorders.

While at a genetic level "survival of the fittest" is represented by competition, at the "phenotypic" level survival for mankind has largely resulted from cooperative behaviour with others in a social context. Man's evolutionary success has resulted in large part from genetic competition for success in social cooperation. Over the course of time a complex social problem-solving mechanism has developed. As with machinery, the more complicated something is, the more ways it can go wrong. Psychosis is one of the ways the brain can go wrong.

In the absence of evidence of increasing incidence of psychotic illness (and we have to be careful here because of the interplay between the "true" incidence of psychosis, our ability to detect it, and society's willingness to tolerate it) then the original question should perhaps be rephrased as. "Why, in the absence of obvious evolutionary advantages to psychotic behaviour, does it persist?"

The answer has to lie with a genetic link between psychotic behaviour and development of the human brain, one candidate area being social problem-solving processes.

The issue of persistence of psychosis through evolution is covered in an excellent book by Jonathan Burns: "The Descent of Madness - Evolutionary Origins of Psychosis and the Social Brain" 2007,Routledge ISBN13: 978-1-68391-743-5

Several possibilities include:

1. The very social co-operation that is so successful includes the care of care of affected individuals allowing them to survive.

2. psychotic behaviour is dependent upon a vulnerability to it that only manifests under certain environmental conditions. (But this would still be subject to evolutionary "fitness" mechanisms)

3.  A direct association between the "psychotic" gene and a gene that codes for some essential aspect of human development. In this way the propensity for psychotic illness is passed on because of the importance of the key adaptive gene.

The last is probably the most likely

So in answer to the original question, bearing in mind the issues of "mild" and "schizophrenia", there are adaptive links to psychosis.

Dear Christopher,

It seems that participants and the question owner have abandoned the thread. As you put it above the connotation of this disorder is much more complicated than to arrange it with the expression of “mild schizophrenia”.  By the way, I agree with your rephrasing of the question.