Cooperation In Human Societies Research Articles

Who is a Leader in the Leading Eight? Indirect Reciprocity under Private Assessment

Indirect reciprocity is a mechanism that explains large-scale cooperation in human societies. In indirect reciprocity, an individual chooses whether to cooperate with another based on reputation information, and others evaluate the action as good or bad. Under what evaluation rule (called “social norm”) cooperation evolves has long been of central interest in the literature. It has been reported that if individuals can share their evaluations (i.e., public reputation), social norms called “leading eight” can be evolutionarily stable. On the other hand, when they cannot share their evaluations (i.e., private assessment), the evolutionary stability of cooperation is still in question. To tackle this question, we create a novel method to analyze the reputation structure in the population under private assessment. Specifically, we characterize each individual by two variables, “goodness” (what proportion of the population considers the individual as good) and “self-reputation” (whether an individual thinks of him or herself as good or bad), and analyze the stochastic process of how these two variables change over time. We discuss the evolutionary stability of each of the leading-eight social norms by studying the robustness against invasions of unconditional cooperators and defectors. We identify key pivots in those social norms for establishing a high level of cooperation or stable cooperation against mutants. Our finding gives an insight into how human cooperation is established in a real-world society. Published by the American Physical Society 2024

Reputation and reciprocity.

Reputation and reciprocity are key mechanisms for cooperation in human societies, often going hand in hand to favor prosocial behavior over selfish actions. Here we review recent researches at the interface of physics and evolutionary game theory that explored these two mechanisms. We focus on image scoring as the bearer of reputation, as well as on various types of reciprocity, including direct, indirect, and network reciprocity. We review different definitions of reputation and reciprocity dynamics, and we show how these affect the evolution of cooperation in social dilemmas. We consider first-order, second-order, as well as higher-order models in well-mixed and structured populations, and we review experimental works that support and inform the results of mathematical modeling and simulations. We also provide a synthesis of the reviewed researches along with an outlook in terms of six directions that seem particularly promising to explore in the future.

Emergence of Punishment in Social Dilemma with Environmental Feedback

Altruistic punishment (or punishment) has been extensively shown as an important mechanism for promoting cooperation in human societies. In AI, the emergence of punishment has received much recent interest. In this paper, we contribute with a novel evolutionary game theoretic model to study the impacts of environmental feedback. Whereas a population of agents plays public goods games, there exists a third-party population whose payoffs depend not only on whether to punish or not, but also on the state of the environment (e.g., how cooperative the agents in a social dilemma are). Focusing on one-shot public goods games, we show that environmental feedback, by itself, can lead to the emergence of punishment. We analyze the co-evolution of punishment and cooperation, and derive conditions for their co-presence, co-dominance and co-extinction. Moreover, we show that the system can exhibit bistability as well as cyclic dynamics. Our findings provide a new explanation for the emergence of punishment. On the other hand, our results also alert the need for careful design of implementing punishment in multi-agent systems, as the resulting evolutionary dynamics can be somewhat complex.

Testosterone administration modulates inequality aversion in healthy males: evidence from computational modeling

Fairness concerns play a prominent role in promoting cooperation in human societies. Social preferences involving fairness concern have been associated with individual testosterone levels. However, the causal effects of testosterone administration on fairness-related decision making remain to be elucidated. Here, we used a randomized, double-blind, between-participant design and administered testosterone or placebo gel to 120 healthy young men. Three hours after administration, participants performed a modified Dictator Game from behavioral economics, in which they were asked to choose one of two monetary allocations between themselves and anonymous partners. Participants were either in a position of advantageous inequality (i.e., endowed with more than others) or disadvantageous inequality (i.e., endowed with less than others). Computational modeling showed that inequality-related preferences explained behavior better than competing models. Importantly, compared with the placebo group, the testosterone group showed significantly reduced aversion to advantageous inequality but enhanced aversion to disadvantageous inequality. These findings suggest that testosterone facilitates decisions that prioritize selfish economic motives over fairness concerns, which in turn may boost status-enhancing behaviors.

Kin selection favors religious traditions: ancestor worship as a cultural descendant-leaving strategy

ABSTRACT Recent years have seen renewed interest in the role of religious systems as drivers of the evolution of cooperation in human societies. One suggestion is that a cultural tradition of ancestor worship might have evolved as a “descendant-leaving strategy” of ancestors by encouraging increased altruism particularly between distant kin. Specifically, Coe and others have suggested a mechanism of cultural transmission exploiting social learning biases, whereby ancestors have been able to establish parental manipulation of kin recognition and perceived relatedness as a traditional behavior, leading to increased altruism among co-descendants and thereby maximizing the ancestor’s long-term inclusive fitness. Here, we develop a demographically explicit model in order to quantify the resulting increase in altruism and concomitant “ancestor-descendant conflict”, and to determine the evolutionary feasibility of religiously motivated cultural norms that promote altruism among co-descendants. Our analysis reveals that such norms could indeed drive an overall increase in altruism with potential for ancestor-descendant conflict, particularly in low-dispersal settings. Moreover, we find that natural selection can favor traditions encouraging increased altruism towards co-descendants under a range of conditions, with the inclusive-fitness costs of enacting an inappropriately high level of altruism being offset by inclusive-fitness benefits derived from the cultural tradition facilitating kin recognition.

Can monetary incentives overturn fairness-based decisions?

Fairness norms and resulting behaviours are an important prerequisite for cooperation in human societies. At the same time, financial incentives are commonly used to motivate social behaviours, yet it remains unclear how financial incentives affect fairness-based behaviours. Combining a decision paradigm from behavioural economics with hierarchical drift-diffusion modelling, we investigated the effect of different financial incentives on two types of fairness-based decisions in four experimental groups. In two groups, participants divided points between themselves and a disadvantaged person, inciting fairness-based compensation behaviour, in two other groups they divided points between themselves and a fairness violator, inciting fairness-based punishment behaviour. In addition, each group received financial incentives that were either aligned or in conflict with the respective fairness-based behaviour. This design allowed us to directly investigate how different incentives shape the cognitive mechanism of fairness-based decisions and whether these effects are comparable across different fairness domains (fairness-based punishment versus fairness-based compensation). Results showed that offering conflicting incentives diminished fairness-congruent decision behaviour and rendered the fairness-congruent decision process less efficient. These findings demonstrate that financial incentives can undermine fairness-based behaviour, and thus are relevant for the development of incentive schemes aimed at fostering cooperative behaviour.

Fairness, partner choice, and punishment: An ethnographic study of cooperative behavior among children in Helsinki, Finland

AbstractThis article draws upon ethnographic fieldwork among children in Helsinki, Finland, to determine how cooperative behaviors unfold in their everyday lives. Two concepts—fairness and partner choice—emerged as particularly relevant, and related behaviors were examined in the context of ongoing debates regarding cooperation in human societies. Children consistently invoked fairness as an important moral value, and they showed evidence of undergoing a developmental shift from equality‐based to equity‐based fairness by around seven years old. Children mediated disagreements primarily through partner choice strategies (avoidance and disengagement) rather than partner conflict (punishment). Local social values and child‐rearing practices that promote personal autonomy and independence make punishment undesirable and rare in this context. The observed aversion to punishment in Helsinki differs from typical characterizations of so‐called WEIRD societies and demonstrates the value that nuanced ethnographic studies in diverse societies can bring to understandings of human cooperation.

Acceptability of strategy promotes cooperation in a spatial prisoner’s dilemma game

The emotions of individuals are one of the most important factors for affecting cooperation in human society. An individual’s acceptability of her/his own strategy, as one kind of powerful emotion that can be influenced by the neighbors’ strategies, can prompt the individual to adjust her/his strategy in the evolution process of a spatial game. Based on this fact, a spatial prisoner’s dilemma game with acceptability involved is studied in this paper. The average acceptability in the community is introduced to the individual’s fitness in the model. The numerical experiments show that individuals considering average acceptability can greatly facilitate cooperation under certain conditions. Furthermore, when the temptation value is small, rational individuals to blind conformity behavior can promote cooperative behavior, but for a high temptation value, rational individuals are not conducive to cooperation. These results may offer insights to comprehensively understand the mechanism of emotion promoting cooperation.

Ancestral social environments plus nonlinear benefits can explain cooperation in human societies

Human cooperation (paying a cost to benefit others) is puzzling from a Darwinian perspective, particularly in groups with strangers who cannot repay nor are family members. The beneficial effects of cooperation typically increase nonlinearly with the number of cooperators, e.g., increasing returns when cooperation is low and diminishing returns when cooperation is high. Such nonlinearity can allow cooperation between strangers to persist evolutionarily if a large enough proportion of the population are already cooperators. However, if a lone cooperator faces a conflict between the group’s and its own interests (a social dilemma), that raises the question of how cooperation arose in the first place. We use a mathematically tractable evolutionary model to formalise a chronological narrative that has previously only been investigated verbally: given that ancient humans interacted mostly with family members (genetic homophily), cooperation evolved first by kin selection, and then persisted in situations with nonlinear benefits as homophily declined or even if interactions with strangers became the norm. The model also predicts the coexistence of cooperators and defectors observed in the human population (polymorphism), and may explain why cooperators in behavioural experiments prefer to condition their contribution on the contributions of others (conditional cooperation in public goods games).

Oxytocin and the Punitive Hub-Dynamic Spread of Cooperation in Human Social Networks.

Human society operates on large-scale cooperation. However, individual differences in cooperativeness and incentives to free ride on others' cooperation make large-scale cooperation fragile and can lead to reduced social welfare. Thus, how individual cooperation spreads through human social networks remains puzzling from ecological, evolutionary, and societal perspectives. Here, we identify oxytocin and costly punishment as biobehavioral mechanisms that facilitate the propagation of cooperation in social networks. In three laboratory experiments (n = 870 human participants: 373 males, 497 females), individuals were embedded in heterogeneous networks and made repeated decisions with feedback in games of trust (n = 342), ultimatum bargaining (n = 324), and prisoner's dilemma with punishment (n = 204). In each heterogeneous network, individuals at central positions (hub nodes) were given intranasal oxytocin (or placebo). Giving oxytocin (vs matching placebo) to central individuals increased their trust and enforcement of cooperation norms. Oxytocin-enhanced norm enforcement, but not elevated trust, explained the spreading of cooperation throughout the social network. Moreover, grounded in evolutionary game theory, we simulated computer agents that interacted in heterogeneous networks with central nodes varying in terms of cooperation and punishment levels. Simulation results confirmed that central cooperators' willingness to punish noncooperation allowed the permeation of the network and enabled the evolution of network cooperation. These results identify an oxytocin-initiated proximate mechanism explaining how individual cooperation facilitates network-wide cooperation in human society and shed light on the widespread phenomenon of heterogeneous composition and enforcement systems at all levels of life.SIGNIFICANCE STATEMENT Human society operates on large-scale cooperation. Yet because cooperation is exploitable by free riding, how cooperation in social networks emerges remains puzzling from evolutionary and societal perspectives. Here we identify oxytocin and altruistic punishment as key factors facilitating the propagation of cooperation in human social networks. Individuals played repeated economic games in heterogeneous networks where individuals at central positions were given oxytocin or placebo. Oxytocin-enhanced cooperative norm enforcement, but not elevated trust, explained cooperation spreading throughout the social network. Evolutionary simulations confirmed that central cooperators' willingness to punish noncooperation allowed the permeation of the network and enabled the evolution of cooperation. These results identify an oxytocin-initiated proximate mechanism explaining how individual cooperation facilitates network-wide cooperation in human social networks.

Deep ancestry of collapsing networks of nomadic hunter-gatherers in Borneo.

Theories of early cooperation in human society often draw from a small sample of ethnographic studies of surviving populations of hunter-gatherers, most of which are now sedentary. Borneo hunter-gatherers (Punan, Penan) have seldom figured in comparative research because of a decades-old controversy about whether they are the descendants of farmers who adopted a hunting and gathering way of life. In 2018 we began an ethnographic study of a group of still-nomadic hunter-gatherers who call themselves Punan Batu (Cave Punan). Our genetic analysis clearly indicates that they are very unlikely to be the descendants of neighbouring agriculturalists. They also preserve a song language that is unrelated to other languages of Borneo. Dispersed travelling groups of Punan Batu with fluid membership use message sticks to stay in contact, co-operate and share resources as they journey between rock shelters and forest camps. Message sticks were once widespread among nomadic Punan in Borneo, but have largely disappeared in sedentary Punan villages. Thus the small community of Punan Batu offers a rare glimpse of a hunting and gathering way of life that was once widespread in the forests of Borneo, where prosocial behaviour extended beyond the face-to-face community, facilitating successful collective adaptation to the diverse resources of Borneo's forests.

Networks of reliable reputations and cooperation: a review

Reputation has been shown to provide an informal solution to the problem of cooperation in human societies. After reviewing models that connect reputations and cooperation, we address how reputation results from information exchange embedded in a social network that changes endogenously itself. Theoretical studies highlight that network topologies have different effects on the extent of cooperation, since they can foster or hinder the flow of reputational information. Subsequently, we review models and empirical studies that intend to grasp the coevolution of reputations, cooperation and social networks. We identify open questions in the literature concerning how networks affect the accuracy of reputations, the honesty of shared information and the spread of reputational information. Certain network topologies may facilitate biased beliefs and intergroup competition or in-group identity formation that could lead to high cooperation within but conflicts between different subgroups of a network. Our review covers theoretical, experimental and field studies across various disciplines that target these questions and could explain how the dynamics of interactions and reputations help or prevent the establishment and sustainability of cooperation in small- and large-scale societies.This article is part of the theme issue ‘The language of cooperation: reputation and honest signalling’.

The role of alliance cooperation in spatial public goods game

Assistance and aiding partners exploited by defectors could be essential to avoid being exploited and expanding the payoff. The research on of human behaviors has suggested that organizations and alliances play an important role in promoting cooperation between humans. Therefore, this article studies the evolution of cooperation in spatial public goods games with alliance strategy on square lattice network where, in addition to the classical strategies of cooperation (C) and defection (D), alliance cooperators (A) are considered as an additional strategy. Alliance players will provide a portion of their payoff to aid their allies in the same group, who have been exploited by defectors. Apparently, alliance players demonstrate a remarkable ability sweep out defectors through network reciprocity. However, by analyzing the parameters, as influenced by cooperators, the cooperation level is a non-monotonic function of aid intensity and synergy factor. The results presented in this article can help to understand the role of alliance strategies, organizations, and taxes in promoting and maintaining cooperation in human society.

Evolutionary dynamics in the spatial public goods game with tolerance-based expulsion and cooperation

Altruistic sanctions for free riders are among the most valuable approaches for promoting cooperation in human society. As a new form of punishment, expulsion allows individuals to expel defectors from their neighborhoods, which is considered an effective mechanism to promote the evolution of cooperation. Inspired by the fact that people often evaluate their surrounding environment before making decisions, we introduce a tolerance-based expulsion mechanism into the spatial public goods game. The condition for expulsion to be triggered is the number of defectors in the group exceeding the tolerance threshold. Unlike the traditional expulsion mechanism that requires the immediate removal of free rides from the group, tolerance provides a way for players to switch between pure cooperation and expulsion. Apparently, tolerance reduces the frequency of costly expulsions, providing a way for expellers to balance payoff and expulsion costs. Our simulations successfully reveal that tolerance-based expulsion can significantly foster cooperation and stabilize pure cooperation under negative conditions. Moreover, the optimal threshold for implementing expulsion is determined. By drawing the formation process of an effective resistance alliance, we prove that unselfish expellers can assist other pure cooperators in removing defection and using vacant sites to form an isolated layer. Interestingly, a pure cooperation cluster might provide a special shield for defection that result in poor expulsion performance. We also observe in the phase diagrams the continuous and discontinuous phase transitions between frozen and dynamical stationary states of the system. Our work extends the form of expulsion to a realistic perspective, and the results might help enhance the understanding of the expulsion mechanism.

Improving environment drives dynamical change in social game structure.

The development of cooperation in human societies is a major unsolved problem in biological and social sciences. Extensive studies in game theory have shown that cooperative behaviour can evolve only under very limited conditions or with additional complexities, such as spatial structure. Non-trivial two-person games are categorized into three types of games, namely, the prisoner's dilemma game, the chicken game and the stag hunt game. Recently, the weight-lifting game has been shown to cover all five games depending on the success probability of weight lifting, which include the above three games and two trivial cases (all cooperation and all defection; conventionally not distinguished as separate classes). Here, we introduce the concept of the environmental value of a society. Cultural development and deterioration are represented by changes in this probability. We discuss cultural evolution in human societies and the biological communities of living systems.

Дележ ограниченными ресурсами у детей и подростков охотников-собирателей (хадза) и земледельцев (ираку) в контексте представлений об эволюционных основах альтруизма у человека

The study of the evolution of altruism and cooperation in human society is one of the central topics of modern anthropology. A promising approach to solving this problem is a comparative study of the behavior of cooperation and sharing of limited resources in a cross-cultural and ontogenetic perspective. The aim of this study was to analyze the principles of sharing the limited resources among children in two traditional African societies: Hadza and Iraqw. A statistical assessment of the contribution of a number of factors to the adoption of prosocial, egoistic and altruistic decisions in the direction of members of own group and strangers is presented. The sample was represented by 240 children and adolescents (130 Hadza and 110 Iraqw). Studies were conducted in rural areas of Northern Tanzania. The current results, along with the data on Meru children, obtained by us earlier, revealed that positive social selectivity (friendship) has an important stimulating role in making decisions of a prosocial and altruistic nature in children and adolescents in traditional African societies. For hunter-gatherers, the percentage of individuals focused on selfish and mixed sharing strategies, both in direction of friends and strangers, was higher compared with farmers. Along with that, we demonstrated a positive association between the adoption of altruistic decisions about sharing and the subjective happiness. Presumably, such association is a human universal.

The role of third parties in norm enforcement in customary courts among the Enga of Papua New Guinea

Cultural norms are key to cooperation in human societies. How they are regulated, maintained, and adapted to the change remains a matter of debate. Humans have dispositions for both retributive and restorative justice; recent focus has been on third-party punishment, punitive sanctions by those not directly harmed, as key for norm enforcement. However, punishment does not engage the essential proficiencies and emotions critical to cooperation in small-scale societies with high dependence on collective action, sharing, and exchange. Third-party participation in norm enforcement is examined with data from a 10-y study among the Enga of Papua New Guinea. The Enga have a plural justice system with formal courts practicing retributive justice and customary courts applying restorative measures. Most cases are brought to customary courts. Drawing on observations from 333 village customary court cases concerning assault, marriage, land, and property violations, third-party engagement outside of and during customary court hearings is analyzed. Results show that all sides are heard, restoration is prioritized, and third-party punishment is rare; rather, third parties help with compensation to reintegrate wrongdoers and resolve conflicts. Repeated offenders and free riders receive ever less community support. Third parties contribute substantially both during and outside of customary court sessions to help kin, pursue economic agendas, or gain reputation. They also act generously to build a strong community. Emphasis is on amends to the victim for fairness, not punishment of the offender. Broad third-party participation is maintained throughout times of rapid change to adapt while supporting essential structures of society.

The emergence and implementation of pool exclusion in spatial public goods game with heterogeneous ability-to-pay

Exploring the conditions and mechanisms for the emergence of cooperation in human society has important theoretical and practical significance. Social exclusion has been considered a powerful sanction for promoting and sustaining cooperation. However, whether the heterogeneity of the ability-to-pay of individuals can still favor cooperation when exclusion is introduced remains unclear. On the basis of this consideration, the dynamic cost of pool exclusion is taken into account in the public goods game, which focuses on the evolution process of each strategy in a square lattice. Specifically, we describe the cost of exclusion behavior as a function of payoff, while the probability of exclusion depends on the former. Through conducting Monte Carlo simulations, the effects of parameters on the evolution of cooperation are investigated. The results indicate that pool exclusion can promote cooperative behaviors within a wide range of parameters. Moreover, structured populations can form an effective alliance to sweep out defection, which requires a few excluders. This alliance continues to function even under strong dilemma strength. We further confirm that overinvestment in exclusion is unwanted. These results may help researchers better understand the emergence and implementation of social exclusion, and provide new insight into the analysis of the origin of cooperation for further exploration.

Effect of memory, intolerance, and second-order reputation on cooperation.

The understanding of cooperative behavior in social systems has been the subject of intense research over the past few decades. In this regard, the theoretical models used to explain cooperation in human societies have been complemented with a growing interest in experimental studies to validate the proposed mechanisms. In this work, we rely on previous experimental findings to build a theoretical model based on two cooperation driving mechanisms: second-order reputation and memory. Specifically, taking the donation game as a starting point, the agents are distributed among three strategies, namely, unconditional cooperators, unconditional defectors, and discriminators, where the latter follow a second-order assessment rule: shunning, stern judging, image scoring, or simple standing. A discriminator will cooperate if the evaluation of the recipient's last actions contained in his memory is above a threshold of (in)tolerance. In addition to the dynamics inherent to the game, another imitation dynamics, involving much longer times (generations), is introduced. The model is approached through a mean-field approximation that predicts the macroscopic behavior observed in Monte Carlo simulations. We found that, while in most second-order assessment rules, intolerance hinders cooperation, it has the opposite (positive) effect under the simple standing rule. Furthermore, we show that, when considering memory, the stern judging rule shows the lowest values of cooperation, while stricter rules show higher cooperation levels.

The demography of human warfare can drive sex differences in altruism.

Recent years have seen great interest in the suggestion that between-group aggression and within-group altruism have coevolved. However, these efforts have neglected the possibility that warfare - via its impact on demography - might influence human social behaviours more widely, not just those directly connected to success in war. Moreover, the potential for sex differences in the demography of warfare to translate into sex differences in social behaviour more generally has remained unexplored. Here, we develop a kin-selection model of altruism performed by men and women for the benefit of their groupmates in a population experiencing intergroup conflict. We find that warfare can promote altruistic, helping behaviours as the additional reproductive opportunities winners obtain in defeated groups decrease harmful competition between kin. Furthermore, we find that sex can be a crucial modulator of altruism, with there being a tendency for the sex that competes more intensely with relatives to behave more altruistically and for the sex that competes more intensely with non-relatives in defeated groups to receive more altruism. In addition, there is also a tendency for the less-dispersing sex to both give and receive more altruism. We discuss implications for our understanding of observed sex differences in cooperation in human societies.