The Effect of Behavioral Assortment on Selection Dynamics: Externalities, Information Processing and Subjective Commitment

The role of group selection in the evolution of social adaptations is a contentious issue. It is unclear whether all adaptations for social interaction should be considered group selected or whether the title ‘group selection’ should be confined to cases in which selection acts at the level of the group (i.e. interdemic selection). No matter what definition of group selection one uses, it is nevertheless clear that social evolution often involves selection at various levels of organization. The focus of this paper is on the roles of externalities, information processing and subjective commitment in creating situations in which multilevel selection and social evolution take place. Many of the mechanisms through which social evolution occurs require the processing of information about the behavior of others and the ability to selectively interact with individuals based on that information. This can enable agents to assort based upon behavior, which opens up the possibilities for group selection at the level of the behaviorally formed group. The thesis of this paper is that behavioral assortment (particularly assortment according to behavioral strategies) can change the dynamics of selection, making group selection more likely. However, there are some difficulties with the view that behavioral grouping results in group selection. Groups that are formed behaviorally are often temporary, lasting shorter than the lifetime of an individual (not long enough for there to be differences in productivity between groups). Nevertheless, the cumulative effect of temporary behavioral grouping on productivity can be essentially the same as it would be in multigenerational groups. It is unclear exactly how groups of this nature fit within the framework of group selection. However, it is apparent that behavioral grouping can create circumstances that favor interdemic selection. By grouping based on behavior, significant between-group differences in cooperativeness can result. It is suggested in this paper, that group selection probably played a role in shaping the capacity for subjective commitment. Individual level selection for ability to detect genuine commitment can cause behavioral assortment that can result in group selection favoring groups made up of individuals capable of commitment. Commitment can be thought of as internalization of some of the social externalities associated with an action. Modeling the evolution of commitment might be possible by allowing for the coupling of utility functions of agents in dyads or larger groups. Computer simulations that model such mechanisms and their role in social evolution should be helpful in understanding adaptations for social interaction in humans and other species.