Evolution of psychopathy in the public goods game with institutional redistribution of resources

Following the model of Testori et al. (2022), we examined the dynamics of the evolution of psychopathy in the public goods game that incorporates both punishing psychopaths (selfish/manipulative risk-taking agents) and rewarding cooperators (generous, risk-averse agents). We systematically varied the mortality of psychopathic phenotypes, and the community cost they inflict on society in an abundant or harsh environment in order to check how they affect population size and the proportion of psychopathic agents in the population. Our aim was to determine which combination of mechanisms for the redistribution of resources enables the model to converge to the solution where the percentage of psychopathic individuals in the population is very low, consistent with empirical estimates on human populations. Model simulations revealed several notable results. Firstly, a low frequency of psychopathy emerges: 1) if psychopathic phenotypes have a high mortality rate; and 2) if society not only punishes psychopaths but actively rewards generous individuals. Secondly, psychopathy showed higher fitness in scarce environments and small-sized populations; the latter result is incongruent with existing theories about the association between population size and the adaptive potential of psychopathy. Hence, the proposed model highlights, in addition to punishment of psychopaths, the societal reward for cooperative individuals as the crucial socioecological condition that maintains the frequency of psychopathic phenotypes at a low level.