Evolutionary Hypotheses of Mental Disorder and Their Limitations

Park, Hanson

Abstract

Like the body of Hominin, mind is the result of natural selection. Therefore, an evolutionary approach in the biological aspects is essential for an intrinsic understanding of mental disorders. However, the evolutionary medical approach to mental disordershas not been well researched because evolutionary psychiatry is not widely accepted, and the conceptual paradigm has not been unified. Nevertheless, some evolutionary hypotheses about some mental disorders have been proposed, including the following: 1) thesimple disease argument that mental disorder is a mere disease, 2) the genomic lag hypothesis that current genes are incompatible with evolutionary environmental changes, 3) the developmental mismatch hypothesis that brain development cannot reflect entire-information of surrounding environment, 4) the trade-off hypothesis that costs are offset by other adaptive benefits, 5) the by-product hypothesis that mental disorders are inevitable outcome of evolutionary design, 6) the cliff-edge model that the encephalizationin the Hominin caused mental disorders, 7) the inclusive fitness hypothesis that costs of individual are compensated by benefits of kinship, 8) the antagonistic polymorphism hypothesis that differential costs and benefits according to sex or age cause ofpolymorphic psychological traits 9) the heterozygote advantage hypothesis that the heterozygous genotypes have higher relative fitness, so they can persist even though homozygous genotypes cause mental disorders, and 10) a genomic imprinting hypothesis that conflicts between maternal genes and paternal genes cause mental disorders. I will summarize and compare the evolutionary hypotheses of mental disorders and present the lim itations of each hypothesis.