Modeling the Mechanisms of Friendship Network Formation

The formation of friendships and alliances is a ubiquitous feature of human life. It is likely a crucial component of the cooperative hunting and child-rearing practices that helped our early ancestors survive.

Research on contemporary human beings typically finds that strong-tie social networks are fairly small. It reveals a high degree of physical (e.g., age) and social-structural (e.g., educational attainment) homophily. Yet, existing works all too often underestimate or even ignore, the importance of abstract, symbolic homophily (such as shared identities or worldviews) as a driver of friendship formation.

Here the research team employs agent-based modeling to identify the optimal variable weights influencing friendship formation to best replicate the results of existing empirical work. The team includes indicators of physical and social-structural homophily, in addition to symbolic homophily.

Results suggest that the optimization values that best replicate existing empirical work include strong variable weightings of kinship, shared worldview, and outgroup suspicion.