Schizotypal Selection

Via John Hawks and the Four Stone Hearth Carnival of Anthropology: The Primate Diaries' explains Sapolsky's theory of selection for schizotypal personalities, possibly in shamans.

Several years ago Robert Sapolsky suggested that genes promoting schizophrenia may have been selected for in human evolution because some of them conferred benefits that outweighed the 1% of people worldwide that were disabled by the disorder. Like the sickle-cell trait that confers resistance to malaria (so long as you don’t receive two recessive alleles and develop full fledged sickle cell anemia) a partial schizophrenia may be beneficial in some way. He observed that relatives of schizophrenics have a high likelihood of “schizotypal personalities,” or a mild form of the disorder that just makes these people a little strange and allows them to see the world in a unique way. What if, he wondered, schizophrenia maintained itself in human populations because of selection for schizotypal personalites? As luck would have it, for a hundred years anthropologists had observed such individuals thriving in nearly every society they encountered: shamans.