One interesting thing I took from Evolutionary Psychopathology was a better understanding of the diametrical theory of the social brain.

There’s been a lot of discussion over whether schizophrenia is somehow the “opposite” of autism. Many of the genes that increase risk of autism decrease risk of schizophrenia, and vice versa. Autists have a smaller-than-normal corpus callosum; schizophrenics have a larger-than-normal one. Schizophrenics smoke so often that some researchers believe they have some kind of nicotine deficiency; autists have unusually low smoking rates. Schizophrenics are more susceptible to the rubber hand illusion and have weaker self-other boundaries in general; autists seem less susceptible and have stronger self-other boundaries. Autists can be pathologically rational but tend to be uncreative; schizophrenics can be pathologically creative but tend to be irrational. The list goes on.

I’ve previously been skeptical of this kind of thinking because there are many things that autists and schizophrenics have in common, many autistics who seem a bit schizophrenic, many schizophrenics who seem a bit autistic, and many risk factors shared by both conditions. But Del Giudice, building on work by Badcock and Crespipresents the “diametrical model”: schizophrenia and autism are the failure modes of opposing sides of a spectrum from high functioning schizotypy to high functioning autism, ie from overly mentalistic cognition to overly mechanistic cognition.

Schizotypy is a combination of traits that psychologists have discovered often go together. It’s classified as a personality disorder in the DSM. But don’t get too caught up on that term – it’s a disorder in the same sense as narcissistic or antisocial tendencies, and like those conditions, some schizotypals do very well for themselves. Classic schizotypal traits include tendency toward superstition, disorganized communication, and nonconformity (if it sounds kind of like “schizophrenia lite”, that’s not really a coincidence).