Steven Crane Compiled Section Handouts. Human Behavioral Biology 2012

How do we understand the evolution of schizophrenia?

Is schizophrenia adaptive?

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  Absolutely not. Fewer offspring, shortened life expectancy.
  

What might be adaptive about it?

• Minor point that there might be less cancer in schizophrenics.

• Major point (see religion lecture) that schizotypal personality (having a partial version of schizophrenia) can be quite adaptive.

The Biology of Religion

What tend to be the basic behaviors/experiences of religion? (some are shared, but lots of variability too)

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  Paranormal/meta-magical belief: faith in things that cannot be verified or seen or are outside material human existence
  
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  Ritualism
  
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  Finding of patterns, searching for agency and causality in the patterns of the natural universe
  
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  Emphasis on religious philosophy
  
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  Emphasis on faith
  
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  The point being that many aspects of religion and religious belief have biological explanations just as much as any other human behavior (including non-belief! It's just not studied as much so is less included here).
  

Schizophrenia and meta-magical belief

Back to schizophrenia. How do we explain schizophrenia's evolutionary fitness?

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  NOT that schizophrenia is an adaptation.
  
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  But schizotypalism (an intermediate/partial form of schizophrenia often seen in relatives of schizophrenics) can actually be adaptive. How so?
  

  • Throughout human history, these tend to be the medicine men/women, the shamans wrapped up in meta-magical thought. They hear voices at the right time.

  • In small numbers, they're helpful to society.

  • They tend to leave more offspring

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  And behaviors/features typify schizotypalism?
  
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    Meta-magical thought (converse with the dead)
    
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    Concreteness (he literally did walk on water)
    
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    High degree of religious belief
    
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    Social withdrawal (not so far as isolation as with schizophrenia)
    
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    Do the trances, conduct the ceremonies, fast for 40 days in the desert, etc.
    
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    Perhaps invented some of the more fantastic stories passed down in religious cannon
    

Our Western, US culture is totally rational and beyond all manner of magical thinking, right?

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  Hellz no!
  
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  25% believe in ghosts. 37% in telepathy. 47% in UFOs that have interacted with humans. >50% believe in Satan who plays a role in people's lives.
  
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  Big theme: get your religious/magical thinking at just the right level, and it can take hold in society and even have fitness advantages. Take it too far and it's a cult or schizophrenia. But just right and it's schizotypalism and religion.