Psychopaths routinely disregard social norms by engaging in selfish, antisocial, often violent behavior. Commonly characterized as mentally disordered, recent evidence suggests that psychopaths are executing a well-functioning, if unscrupulous strategy that historically increased reproductive success at the expense of others. Natural selection ought to have favored strategies that spared close kin from harm, however, because actions affecting the fitness of genetic relatives contribute to an individual’s inclusive fitness. Conversely, there is evidence that mental disorders can disrupt psychological mechanisms designed to (...) protect relatives. Thus, mental disorder and adaptation accounts of psychopathy generate opposing hypotheses: psychopathy should be associated with an increase in the victimization of kin in the former account but not in the latter. Contrary to the mental disorder hypothesis, we show here in a sample of 289 violent offenders that variation in psychopathy predicts a decrease in the genetic relatedness of victims to offenders; that is, psychopathy predicts an increased likelihood of harming non-relatives. Because nepotistic inhibition in violence may be caused by dispersal or kin discrimination, we examined the effects of psychopathy on (1) the dispersal of offenders and their kin and (2) sexual assault frequency (as a window on kin discrimination). Although psychopathy was negatively associated with coresidence with kin and positively associated with the commission of sexual assault, it remained negatively associated with the genetic relatedness of victims to offenders after removing cases of offenders who had coresided with kin and cases of sexual assault from the analyses. These results stand in contrast to models positing psychopathy as a pathology, and provide support for the hypothesis that psychopathy reflects an evolutionary strategy largely favoring the exploitation of non-relatives. (shrink)

Psychopathy represents a unique set of personality traits including deceitfulness, lack of empathy and guilt, impulsiveness, and antisocial behavior. Most often in the literature, psychopathy is described as pathology — a disorder that has been linked to a variety of biological deficits and environmental risk factors. However, from an evolutionary perspective, psychopathy, while it could be a disorder, has been construed in the context of an adaptive strategy. In this article we will examine the strengths and weaknesses of two models (...) suggesting that psychopathy is an adaptive strategy, and one model suggesting that it is a form of pathology resulting from accumulated mutations. Overall, we do not find that there is strong enough evidence to draw firm conclusions about one theory over another, but we highlight some areas where future research may be able to shed light on the issue. (shrink)