Quantity-Quality Trade-Offs May Partially Explain Inter-Individual Variation in Psychopathy

ObjectiveThe examination of ultimate factors that maintain genetic (and consequently phenotypic) variance in a behavioral trait represents one of the key goals of evolutionary ecology of personality. One of these factors are adaptive trade-offs: if a trait is involved in a trade-off, than natural selection cannot deplete its genetic variance. We used this theoretical framework to examine psychopathy, a behavioral syndrome consisting of deceitful behavior, emotional coldness and recklessness. Relying on previous research, we assumed that psychopathy elevates fertility but diminishes offspring quality, thus contributing to quantity-quality trade-off.MethodThe research sample was consisted of 635 individuals with at least one child, who were at the end of their reproductive phase. We examined psychopathy traits of these individuals, together with parental investment via their offspring ratings. Furthermore, we collected the measures of offspring Covitality (combined physical and mental health) and Residual reproductive value (expected future fitness in offspring) as the measures of offspring quality. We used parental reproductive success as an indicator of offspring quantity.ResultsResearch results confirmed the hypotheses. Psychopathic traits had small positive relations with the number of children and negative associations with parental investment, Covitality and residual reproductive value in offspring. Mediation model that depicted parental investment as the mediator of the psychopathy-offspring quality link had a good fit to the data.ConclusionsResearch findings have high heuristic potential because they provide an insight in how natural selection can preserve variation in psychopathy.