Mating, sexual selection, and the evolution of schizophrenia

Abstract

this, our research team is trialling a digital therapy called SlowMo that targets problematic fast thinking to modify distressing appraisals of psychotic experiences and thereby reduce paranoia 10 . A SlowMo mobile app (see www.slowmotherapy.co. uk) assists people to slow down for a moment in their daily life to notice new information and develop safer thoughts, thereby aiming to optimize the clinical relevance of adaptive appraisals of psychotic experiences to real life. Mating, sexual selection, and the evolution of schizophrenia For over fifty years, evolutionary theorists have sought to understand the biological roots of our species' vulnerability to schizophrenia -a debilitating disorder that has a relatively high incidence despite being associated with markedly reduced fertility (the so-called "schizophrenia paradox"). While some models treat the entire spectrum of schizophrenia as a manifestation of biological dysfunction, others postulate that psychosis proneness (schizotypy) or even psychotic symptoms may confer adaptive benefits through enhanced survival or reproduction (or they used to do so during our evolutionary history) 1 .Adaptive models of this kind face some formidable challenges. In addition to the low fertility of patients -which is not balanced out by that of their close relatives -and the evidence of reduced IQ and neural integrity in schizophrenia, they need to account for the role played by deleterious de novo mutations (including rare copy number variations), which explain a larger share of schizophrenia risk than common genetic variants 1,2 .Schizophrenia is a heterogeneous category, and any comprehensive explanation is likely to require a combination of models. At the same time, theory and evidence increasingly point to mating as a contributing factor in the evolution of psychosis proneness. The sexual selection model (SSM) was first advanced by Nettle 3 and refined by Shaner et al 4 . According to this model, schizophrenia is a maladaptive condition, but schizotypal traitsin particular positive schizotypal traits such as magical thinking, ideas of reference, and unusual perceptual experiences -are associated with enhanced verbal and artistic creativity and, as a result, lead to increased success in courtship and mating. The hypermentalistic cognitive style of schizotypal individuals involves a heightened focus on others' thoughts and emotions, which may also contribute to courtship success 5,6 . Consistent with this hypothesis, several studies have shown that positive schizotypy is associated with artistic creativity, a larger number of sexual partners, and a preference for uncommitted sexual relatioships 7 . Also, a moderate degree of reduction in white matter integrity has been linked to creative thinking and imagination 8 .But how does this model account for the role of rare mutations in schizophrenia? Most sexually selected traits are fitness indicators in that they correlate with the organism's underlying condition, including good nutrition, absence of parasites, low levels of ...

Rethinking the fast-slow continuum of individual differences

“…On a related note, the major impact of deleterious alleles on schizophrenia risk does not preclude a role for balancing selection , and is consistent with a life history/sexual selection account of this disorder (see Del Giudice, 2017. (Note that schizophrenia is also heterogeneous, and there are still some unanswered questions regarding its overlap with autism; see Del Giudice, 2018, Ch.…”

Interrogating the Evolutionary Paradox of Schizophrenia: A Novel Framework and Evidence Supporting Recent Negative Selection of Schizophrenia Risk Alleles

“…If any of them were affected by psychosis, our findings could be biased. Finally, other evolutionary models, such as the sexual selection and balancing selection model (Nettle, 2001; Del Giudice, 2017), have been proposed to reconcile the evolution paradox in schizophrenia. However, the present study did not empirically evaluate these models because evolutionary markers available are not suitable for testing such evolutionary models.…”

An evolutionary life history approach to understanding mental health

“… 53 56 Recent mounting research validates this hypothesis; for example, schizophrenia is associated with more sexual partners 57 and lower investment in long-term close relationships. 58 Besides, a high level of schizotypal traits is linked to higher aggressiveness 59 and lower agreeableness. Evidence shows that the harsh environment increases the risk of SSDs, 60 61 coinciding with the fast life history strategists.…”