Non‐zero‐sum collaboration,reciprocity, and the preference for similarity: Developing an adaptive model of close relational functioning

An evolutionary framework was used to develop a model of relational functioning among friends. The proposed model focuses on the collaborative nature of close friendships and attempts to highlight two adaptive mechanisms important in creating non‐zero‐sum outcomes among highly interdependent parties. The model emphasizes the importance of reciprocity in creating mutually beneficial outcomes through social exchange, and it articulates how the preference for similarity is useful when creating non‐zero‐sum rewards through synergistic coordination. In particular, the focus is on the unique role that shared interests and mutual knowledge play when individuals attempt to pursue common goals through joint activity. The implications of the model are discussed with respect to a host of issues ranging from deceptive communication to relational satisfaction and commitment.