Social ecology of similarity

Social ecologies shape the way people initiate and maintain social relationships. Settings with much opportunity will lead to more fine-grained similarity among friends; less opportunity leads to less similarity. We compare two ecological contexts—a large, relatively diverse state university versus smaller colleges in the same state—to test the hypothesis that a larger pool of available friendship choices will lead to greater similarity within dyads. Participants in the large campus sample reported substantially more perceived ability to move in and out of relationships compared to participants in the small colleges sample. Dyads were significantly more similar on attitudes, beliefs, and health behaviors in the large campus than in the small colleges sample. Our findings reveal an irony—greater human diversity within an environment leads to less personal diversity within dyads. Local social ecologies create their own “cultures” that affect how human relationships are formed.