A simple rule for the evolution of contingent cooperation in large groups

Abstract

One contribution of 18 to a theme issue 'The evolution of cooperation based on direct fitness benefits'. Humans cooperate in large groups of unrelated individuals, and many authors have argued that such cooperation is sustained by contingent reward and punishment. However, such sanctioning systems can also stabilize a wide range of behaviours, including mutually deleterious behaviours. Moreover, it is very likely that large-scale cooperation is derived in the human lineage. Thus, understanding the evolution of mutually beneficial cooperative behaviour requires knowledge of when strategies that support such behaviour can increase when rare. Here, we derive a simple formula that gives the relatedness necessary for contingent cooperation in n-person iterated games to increase when rare. This rule applies to a wide range of pay-off functions and assumes that the strategies supporting cooperation are based on the presence of a threshold fraction of cooperators. This rule suggests that modest levels of relatedness are sufficient for invasion by strategies that make cooperation contingent on previous cooperation by a small fraction of group members. In contrast, only high levels of relatedness allow the invasion by strategies that require near universal cooperation. In order to derive this formula, we introduce a novel methodology for studying evolution in group structured populations including local and global group-size regulation and fluctuations in group size.

Correlated pay-offs are key to cooperation

“…There are additional reasons why reciprocity should occur particularly often between relatives (cf. [199]). Closely related individuals interact particularly frequently with each other owing to spatial viscosity [200,201], and groups of relatives are often small (e.g.…”

Evolution of coordinated punishment to enforce cooperation from an unbiased strategy space

“…In our model, the maintenance of pro-social punishment relies on a small minority which supports them, but their robustness stems from the fact that they are constantly challenged by the presence of players that stop cooperating in the absence of pro-social institutions. This combination is empirically prevalent, with resilient public goods often being supported by a minority of contributors [51]. The key to the maintenance of the public good is the observability of institutions: only public knowledge of the presence of punishment institutions allows the conditional strategies that ultimately prevent the rise of anti-social behaviour, either in the form of defection or in the form of coordinated anti-social punishment institutions that never rise to high abundance, but can undermine the public good.…”

“…(Online version in colour.) empirically prevalent, with resilient public goods often being supported by a minority of contributors [51]. The key to the maintenance of the public good is the observability of institutions: only public knowledge of the presence of punishment institutions allows the conditional strategies that ultimately prevent the rise of anti-social behaviour, either in the form of defection or in the form of coordinated anti-social punishment institutions that never rise to high abundance, but can undermine the public good.…”

Trace of pace, place, and space in personal relationships: The chronogeometrics of studying relationships at scale

“…The norm of reciprocity is considered a relatively universal disposition (Gouldner, 1960) and a fundamental organizing process in group formation and maintenance (Fehr, Fischbacher, & Gächter, 2002;Schonmann & Boyd, 2016). Reciprocity is a fundamentally communicative act, motivated through social comparison and aspirational homophily processes (Whitaker, Colombo, Allen, & Dunbar, 2016), and thus, communicative behavior is generally reciprocal in structure and content (Friedman & Singh, 2004), and such links tend to be more stable than nonreciprocated links (Rogers & Kincaid, 1981).…”