Running title: Group-splitting Hypothesis of Schizophrenia

Submitted to Ethology and Sociobiology, April 1996

The schizophrenic genotype facilitates group selection: an examination of the group-splitting hypothesis of schizophrenia

by John Price and Anthony Stevens

Summary

We suggest that the adaptive behaviour which becomes disordered in the schizophrenic and affective psychoses is concerned with two vital emergent properties of groups. The capacity for mood change which underlies affective disorders was important for group cohesion and homeostasis, while the capacity for delusional thinking and hallucinatory perceptions was important for group splitting. This analysis supports the diagnostic distinction between the two major groups of psychoses. The suggestion depends for its validity on the importance of group selection in human evolution, and we review various aspect of human behaviour which are consistent with this premise.

Key words: Schizophrenia, group selection, sociobiology, adaptation, group dynamics, cults