Friendship transmission and cooperation evolution in highly clustering interactions

Abstract

“Friends of friends are friends, and enemies of friends are enemies” is a well-known friendship transmission effect. In interpersonal interactions, friendship transmission may prompt individuals to imitate one partner’s attitude toward another. Real human interactive networks often show a high degree of clustering and are filled with triangles. In this context, friendship-transmission-based imitation (FI) may be very frequent and play a crucial role in the flourishing of cooperation. Here, we develop an evolutionary pairwise game model and conduct simulations on small-world networks with the aim of revealing exactly how FI affects cooperation. Specifically, we add four forms of FI to a strategy update framework with interactive diversity, using two sets of parameters to control the frequency of each update method. The results show that the different FIs play very different roles. Two of them even conditionally outperform the targeted imitation with reciprocal features. Furthermore, appropriate coexistence of multiple FIs may catalyze more cooperation. This work captures potential factors influencing the evolution of cooperation in real human societies, and contributes to understanding the drivers and the barriers to human cooperation in highly clustering interactions.