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.
Keywords: psychopathy, nepotism, kin discrimination, dispersal, mental disorder
Citation: Krupp DB, Sewall LA, Lalumière ML, Sheriff C and Harris GT (2012) Nepotistic patterns of violent psychopathy: evidence for adaptation? Front. Psychology 3:305. doi: 10.3389/fpsyg.2012.00305
Received: 17 January 2012; Accepted: 03 August 2012;
Published online: 28 August 2012.
Edited by:Paul J. Watson, University of New Mexico, USA
Reviewed by:Paul J. Watson, University of New Mexico, USA
Copyright: © 2012 Krupp, Sewall, Lalumière, Sheriff and Harris. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.
*Correspondence: Daniel Brian Krupp, Department of Mathematics and Statistics, Queen’s University, Jeffery Hall, Kingston, ON, Canada K7L 3N6. e-mail: firstname.lastname@example.org