From Oxford: Do Birds of a Feather Flock Together?

http://www.ncbi.nlm.nih.gov/pubmed/23881574

Hum Nat. 2013 Jul 24. [Epub ahead of print]

Do Birds of a Feather Flock Together? : The Relationship between Similarity and Altruism in Social Networks.

Curry O, Dunbar RI.

Source

Institute of Cognitive and Evolutionary Anthropology, University of Oxford, 64 Banbury Road, Oxford, OX2 6PN, UK, oliver.curry@anthro.ox.ac.uk.

Abstract

Cooperation requires that individuals are able to identify, and preferentially associate with, others who have compatible preferences and the shared background knowledge needed to solve interpersonal coordination problems. The present study investigates the nature of such similarity within social networks, asking: What do friends have in common? And what is the relationship between similarity and altruism? The results show that similarity declines with frequency of contact; similarity in general is a significant predictor of altruism and emotional closeness; and, specifically, sharing a sense of humor, hobbies and interests, moral beliefs, and being from the same area are the best predictors. These results shed light on the structure of relationships within networks and provide a possible checklist for predicting attitudes toward strangers, and in-group identification.