Stress mechanism is sex-specific: Female amelioration or escape from stress to avoid compromising reproduction contrasts with male utilisation or in effect manufacture of stress to fulfill male 'genetic filter' function

Steve Moxon

Abstract


Research into stress response has exploded in the wake of findings of major sex differences, to show, further, that mechanism is genetically and epigenetically underpinned non-overlapping neuro-hormonal pathway specific to each sex: that is, it is not merely sex-dimorphic but sex-dichotomous; sexspecific. A general principle now appears to emerge of a still more fundamental distinction in stress mechanism than the generally accepted conceptualisation of female ‘tend and befriend’ vis-a-vis male ‘fight or flight’. Stress for the female essentially is a problem because of its negative impact on reproduction, and hence females have evolved to escape stressors through easily registering them in order to be motivated to escape; if need be through profound inactivity (major depression). By contrast, stress for males not only is not the problem it is for females, but it usefully drives intra-sexual competition, which males require so as to achieve rank indicating genetic quality – and the stress entailed in contesting and maintaining rank makes it ‘honest signalling’. With male ranking determining sexual selection by females, then it is in the service of purging accumulated gene replication error (the fundamental problem for all biological systems): the ‘genetic filter’ [Atmar (1991)] / ‘mutational cleanser’ [West-Eberhard (2005)] key function of the male. Consequently, males tend not to try to escape stressors but to live with and to utilise, and even, in effect, to ‘manufacture’ stress; and thus have evolved a higher threshold to register stress and can attenuate and override it. Sex-specific stress mechanism appears, as would be anticipated, to be a manifestation of the foundational distinction in function between the sexes.

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