Scientifically, schizophrenia should not exist. It crushes sexual relationships and reproductive success. Because the illness is genetic, evolution should have eliminated it long ago. Instead, it continues to afflict one in 100 people, too many to be due to just a few kinds of bad genes. A new theory proposes that schizophrenia is an inevitable consequence of courtship behaviors that have evolved expressly to reveal bad genes.
This theory suggests schizophrenia is the low-fitness, unattractive version of a sexually selected fitness indicator that evolved through mutual mate choice. In other words, the disease is evolutionarily analogous to a small, dull peacock tail. The article proposes that all human embryos contain genetic instructions for brain systems specialized for a particular form of courtship, perhaps verbal. Because these systems are designed by evolution for courtship, they function as fitness indicators. Many fitness-reducing mutations and environmental hazards can disrupt their development and reduce the attractiveness of courtship. Such disruptions cause great variation in the trait that correlates with underlying fitness. Severe disruptions result in schizophrenia in place of normal courtship behaviors.
This hypothesis may explain schizophrenia's adolescent and early adult onset; why it slashes rates of marriage and reproduction; why it persists despite reproductive disadvantage; why it affects males earlier and more severely; why neurodevelopmental abnormalities are common; why it is associated with fetal hypoxia, viral infection and famine; why dopamine antagonists are therapeutic; and why affected individuals are socially stigmatized.
Lead investigator is Dr. Andrew Shaner, Department of Psychiatry and Biobehavioral Sciences, UCLA Neuropsychiatric Institute and David Geffen School of Medicine at UCLA; Department of Psychiatry, VA Greater Los Angeles Healthcare System.
Schizophrenia Research (September 2004). See http://www.sciencedirect.com/science/journal/09209964.
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