Friendship, cliquishness, and the emergence of cooperation

Abstract

The evolution of cooperation is a central problem in biology and the social sciences. While theoretical work using the iterated prisoner's dilemma (IPD) has shown that cooperation among non-kin can be sustained among reciprocal strategies (i.e. tit-for-tat), these results are sensitive to errors in strategy execution, cyclical invasions by free riders, and the specific ecology of strategies. Moreover, the IPD assumes that a strategy's probability of playing the PD game with other individuals is independent of the decisions made by others. Here, we remove the assumption of independent pairing by studying a more plausible cooperative dilemma in which players can preferentially interact with a limited set of known partners and also deploy longer-term accounting strategies that can counteract the effects of random errors. We show that cooperative strategies readily emerge and persist in a range of noisy environments, with successful cooperative strategies (henceforth, cliquers) maintaining medium-term memories for partners and low thresholds for acceptable cooperation (i.e. forgiveness). The success of these strategies relies on their cliquishness-a propensity to defect with strangers if they already have an adequate number of partners. Notably, this combination of medium-term accounting, forgiveness, and cliquishness fits with empirical studies of friendship and other long-term relationships among humans. r

Evolution of Decisions in Population Games with Sequentially Searching Individuals

“…Our results are in line with previous models that have incorporated optional interactions or partner choice allowing cooperative individuals to refuse non-beneficial interactions [27][28][29][30][31]. The most notable work is by [31], where, similarly to our study, the coevolution of choosiness and cooperation was examined.…”

“…However, even though previous work has explored various forms of optional interactions and partner choice, particularly in the theory of the evolution of cooperation [25][26][27][28][29][30][31][32], trade-offs arising from sequential search problems have not been studied. In this paper, we address this issue by embedding a mutual choice sequential search problem to an evolutionary game-theoretical framework, and look for decisions that are favored by evolution.…”

Coalitions in theory and reality: a review of pertinent variables and processes

“…As we will see below, coalitions can serve different functions (van Schaik et al, 2006); they can be observed among different sex and age classes (reviewed in Chapais, 1995); they can involve kin (e.g., Riss & Goodall, 1977;Chagnon & Bugos, 1979;Wahaj et al, 2004), non-kin (e.g., Vigilant et al, 2001;Langergraber et al, 2007;Schülke et al, 2010), and friends or acquaintances (Hruschka & Henrich, 2006;Hruschka, 2010). As this brief review makes clear, coalitionary patterns are varied, and understanding this diversity would be greatly enhanced by formal modelling that would allow us to identify the general conditions under which coalition formation is expected to evolve, characterize the degree of variability expected, and predict when coalitions should, and should not, occur.…”

“…Third, the theory of dynamic linking and network formation focuses on dyadic or polyadic games played by individuals in which the outcomes of previous interactions determine who interacts with whom in the future (Skyrms & Pemantle, 2000;Pemantle & Skyrms, 2004a, b;Hruschka & Henrich, 2006;Pacheco et al, 2006Pacheco et al, , 2008Santos et al, 2006;Gavrilets et al, 2008;Aktipis, 2011). We discuss one application of this theory below.…”

The strategy of psychopathy: primary psychopathic traits predict defection on low-value relationships

“…Low-value social partners are potentially profitable targets of exploitation, given that they have few benefits to withhold in the future. The primary psychopathy continuum may correspond to a relative willingness to strategically exploit or invest in others based upon their appraised utility-which might motivate defection if partners are deemed of low-value, including if future interactions are unlikely, but which should motivate cooperation in interactions with valuable, long-term partners [34]. This stands in stark contrast to simplistic rules such as 'always defect' or 'defect whenever possible', the predominant strategies assumed in the psychopathy literature.…”