Simulation of Group Selection Models

It is often debated whether group selection can explain altruistic behaviors that lower the fitness of individual organisms for the benefit of their group. Several models of group selection are simulated here with more details and fewer simplifying assumptions than previous quantitative studies. The simulated models include island models with selective extinction, selective dispersal, selective migration, outsider exclusion, conformity, altruistic punishment, haystack model, and a new model with floating group territories. The simulations are repeated with different parameter sets in order to map the parameter areas that lead to either fixation of altruism, fixation of egoism, or stable polymorphism. This can help decide whether a particular behavior can be explained by genetic group selection. The conditions for group selection to override counteracting individual selection are found to be very restrictive. These conditions are met for eusocial insects, some parasites, and a few other species. The necessary conditions are unlikely to have been met in the evolutionary history of humans and most other group-living animals. Altruistic behaviors in humans could not have evolved without involving cultural mechanisms, including norms, rewards and punishments, reputation, and leadership. A comprehensive open-source simulation program is provided to facilitate further research.