Schizophrenia Research Trends

Evolution and Schizophrenia 125individual selection or kin selection models – no matter how inapplicable or contorted thelogic. The near complete dismissal of the idea for so long is a testament to how dogmatic andunquestioning the culture of science can be. In 1994, Wilson and Sober’s seminal paper,“Reintroducing group selection to the human behavioral sciences” clarified the concept andestablished group selection as a plausible evolutionary mechanism to explain certain humancognitive-behavioral traits [73]. To those perhaps interested in the topic, the history of thegroup selection controversy is briefly reviewed in Sober and Wilson’s, “Unto Others – theevolution and psychology of unselfish behavior” [74].Stevens and Price were the first to consider the evolutionary mechanism of groupselection to explain the schizophrenia phenotype although their model does not exclude thepossible influence of individual and kin selection [53,75]. Their group splitting hypothesispresumes that proliferating tribal communities must eventually split to maintain optimumnumbers. Schizotypal traits in certain prominent individuals may be necessary to ensuresurvival of the offshoot group. Stevens and Price argue that schizotypal traits are frequentlyfound in charismatic leaders; namely Adolph Hitler, Joan of Arc, and Charles Manson. Theseshaman-like individuals use paranoia, delusions, religious themes and even neologisms, tofraction disaffected individuals and form new groups. They propose that this type ofleadership is essentially altruistic and thus maintained by group selection.Polimeni and Reiss, unaware of the work of Stevens and Price, developed a similarhypothesis although with a distinctly different emphasis – schizophrenia represents a onceadaptivevestigial phenotype that facilitated spiritual rituals conducted by shamans in huntingand gathering societies [76-77]. In our formulation, spirituality and religion are adaptivefunctions propagated by psychosis-prone shamans. We also question the classic diseasemodel of schizophrenia and view psychosis-prone shamans as group-level adaptivespecialists. Analogous to the polyethism of honeybee colonies, schizophrenia could be themost convincing example of behavioral specialization in humans [78]. The two majorcornerstones of this hypothesis involve a familiarity with the concepts of group selection andshamanism. In the next section, we review the precursory ideas that led us to this seeminglyunusual conclusion.A Closer Look at Group Selection and ShamanismGroup SelectionGroup selected traits exist because they provide some advantage to delimited groups ofliving organisms competing with other similar groups. The quintessential group selectedcreatures are ants, bees, wasps and termites. The level of social cooperation in these creaturesis astounding and has translated into significant dominance compared to solitary insectsoccupying similar environmental niches – eusocial insects constitute half of all living insectswhile only representing 2% of the total number of insect species [79]. The Darwinian benefitsof group-selected traits are formidable – so much so that they more than counterbalance thedisadvantages created for the individual. The integrity of the group becomes so important thatexpelled individuals are unable to survive and procreate on their own. Consequently, the