Cliff-edged fitness functions and the persistence of schizophrenia

Randolph M. Nesse
2004 Behavioral and Brain Sciences  
sistent with modern accounts explaining genetic variation. I suggest that Burns' theory could be substantially strengthened by integrating his insights with recent advances from evolutionary genetics. NOTES 1. "Allele" is used broadly here to include not only genetic variants in the protein-coding regions within loci, but also genetic variants in the regulatory regions that surround loci. 2. In a large, randomly breeding population, the expected frequency (qЈ) for the susceptibility allele
more » ... ibility allele after one generation of selection is given by the recursive equation where q is the frequency of the susceptibility allele before selection, p is the frequency of all other alleles at that locus before selection, and w 1 and w 2 are the fitnesses of those carrying one or two susceptibility alleles, respectively, relative to those carrying no susceptibility alleles. Abstract: Strong recent selection for social cognition may well explain the persistence of genes that predispose to schizophrenia. The specific mechanism responsible may be a skewed fitness function in which selection pushes the mean for advantageous mental traits perilously close to a "fitness cliff" where the system fails catastrophically in some individuals.
doi:10.1017/s0140525x04300191 fatcat:b5pi3ph4sfelfj3arvpnpyhogy