Seven dimensions of personality pathology are under sexual selection in modern Spain

Abstract

Personality variation is increasingly thought to have an adaptive function. This is less clear for personality disorders (PDs)—extreme variants of personality that cause harm in most aspects of life. However, the possibility that PDs may be maintained in the population because of their advantages for fitness has been not convincingly tested. In a sample of 959 outpatients, we examined whether, and how, sexual selection acts on the seven main dimensions of personality pathology, taking into account mating success, reproductive success, and the mediating role of status. We find that, to varying extents, all personality dimensions are under sexual selection. Far from being predominantly purifying, selective forces push traits in diverging, often pathological, directions. These pressures differ moderately between the sexes. Sexual selection largely acts in males through the acquisition of wealth, and through the duration (rather than the number) of mates. This gives a reproductive advantage to males high in persistence–compulsivity. Conversely, because of the decoupling between the number of mates and offspring, the promiscuous strategy of psychopaths is not so successful. Negative emotionality, the most clinically detrimental trait, is slightly deleterious in males but is positively selected in females, which can help to preserve variation. The general picture is that at least some PDs form part of high-risk alternative strategies, although a sole evolutionary mechanism is unlikely to apply to all traits. An evolutionary perspective on PDs can provide a better understanding of their nature and causes than we have achieved to date by considering them as illnesses.