The article titled “Creation, Evolution, and Dissolution of Social Groups,” by James Flamino, Boleslaw K. Szymanski, Ashwin Bahulkar, Kevin Chan, and Omar Lizardo” appeared today in Scientific Reports, 11, September 1, 2021.

The article titled “Creation, Evolution, and Dissolution of Social Groups,” by James Flamino, Boleslaw K. Szymanski, Ashwin Bahulkar, Kevin Chan, and Omar Lizardo” appeared today in Scientific Reports11, September 1, 2021. The article aims at understanding why people join, stay, or leave social groups that is a central question in the social sciences, including computational social systems. Modeling such processes is a challenge in complex networks. Yet, the current empirical studies rarely focus on group dynamics for lack of data relating opinions to group membership. In the NetSense data, we find hundreds of face-to-face groups whose members make thousands of changes of memberships and opinions. We developed a model of utility of group interactions for group members and validated it on NetSense groups. Our study offers two broad conclusions. Agreement on values shared by people with whom we regularly interact (called homophily in the social sciences) is the basis for successful relationships in groups. Accordingly, we introduced a model of the person’s enjoyment (utility) of the group’s interactions that increases with the level of sharing of this person’s values with other members. In a quest for such enjoyment, people are willing to leave some groups to join others. In doing so, they unintentionally make the groups they spend most of their time like-minded and therefore polarized in values and opinions across groups. This happens even when people make such changes altruistically, by considering how their decisions will affect the enjoyment of the other group members. The second important conclusion is relevant for people joining a new university, a workplace, or an organization. We found that a person holding opinions that are unpopular in the new environments limits how much enjoyment this person can derive from group interactions there. Accordingly, we found that holders of minority opinions change friends more frequently than others. This is especially important for young people choosing a university to attend. Making such a choice, not only professors, but also peer students and their views, are important considerations.