Some people are especially physically adept, others carry dangerous pathogens, some have valuable and rare knowledge, and still others cheat or deceive those around them. Because of these differences, and the costs and benefits they pose, natural selection has crafted mechanisms of partner choice that are selective: some people are chosen as social partners, others are not. When people are not chosen as partners—when they are socially excluded—they lose access to important fitness benefits. Thus, the mind should have adaptations to recapture these benefits by regaining inclusion. Is there one best way to regain inclusion? This is unlikely because there are multiple causes of exclusion; a single response is unlikely to be successful across all possible causes. Instead, distinct causes of exclusion might require adaptively tailored responses. We test whether there are tailored responses to five possible causes of exclusion from a cooperative group: inability to contribute, pathogen infection, free riding, disrupting group coordination, and exit from the group. Our results show that different causes of exclusion lead to distinct profiles of emotions and behavior. Each emotion and behavior profile is adaptively specialized to reverse or mitigate its specific cause of exclusion. Our research shows how taking an evolutionary view of human sociality can help map the psychology of cooperation and exclusion.
Some people are especially physically adept, others carry dangerous pathogens, some have valuable and rare knowledge, and still others cheat or deceive those around them. Because of these differences, and the costs and benefits they pose, natural selection has crafted mechanisms of partner choice that are selective: Some people are chosen as social partners; others are not (Cottrell et al., 2007, Delton and Robertson, 2012, Goffman, 1963, Kurzban and Leary, 2001 and Neuberg et al., 2000).
The flip side of selectivity is that some people are not chosen; they are socially excluded. Exclusion can range from subtle avoidance to outright expulsion (Kurzban & Leary, 2001). Regardless, excluded people may lose access to the benefits of sociality and cooperation, like food sharing, aid in health crises (Sugiyama, 2004), and defense from predators (both human and nonhuman; Wrangham & Peterson, 1996). Given these costs, there may be psychological mechanisms that respond to or defend against exclusion (e.g., Maner, DeWall, Baumeister, & Schaller, 2007).
Past empirical research on the psychology of social exclusion has frequently treated exclusion as a unitary phenomenon: Exclusion is a single thing and, therefore, there is a single normatively correct way to respond. Here we challenge these assumptions. Different causes of exclusion each create their own, unique adaptive problems. Thus, a mind well-designed to respond to exclusion should have a menu of possible responses; for each ancestrally common cause of exclusion, there should be an adaptively tailored response.
