Cooperative behaviour and prosocial reputation dynamics in a Dominican village

Communicating the cost of your altruism makes you cool—competitive altruism and sexual selection in a real-life charity situation

Abstract

Maintaining a good reputation is crucial for humans. Altruism, e.g. charity, may serve as a costly signal that enhances reputation based on the real or communicated cost. Fundraising via charity running triggers competitive altruism when potential donors donate in reaction to the reputation increase of the fundraiser. Using real-life data of marathonists and half-marathonists (388 runners) and their 9281 donors, the present research focuses on how the communicated cost and goal of a charity run affected the potential donors. We analysed the introductory texts of the runners presented online according to the cost and the social benefit of the fundraising communicated by them. We have shown that emphasizing more the subjective cost of running and the social benefit of the goal, or writing a longer text, attracted more donors and, even though the average amount of donation per donor did not increase, still lead to a greater amount of donations collected overall by the fundraiser. It was also shown that a higher communicated subjective cost resulted in a higher ratio of opposite-sex donors, both in the case of male and female runners, suggesting that the communication of the cost of an altruistic act might be the object of sexual selection.

Significance statement

A good reputation is crucial for humans, as a reputable person enjoys several benefits. One way to maintain a good reputation is to be altruistic, e.g. doing charity. A seemingly high cost and a socially accepted goal may result in a higher reputation. Using data from a charity running community we demonstrate that fundraisers who emphasize their subjective cost (how difficult to run), and emphasize the good goal of the charity, attract more donors, and even though the average amount of each donation does not increase, a higher number of donors results in a greater amount of donations collected overall. Talking about the difficulties of the charity run results in a higher ratio of opposite-sex donors. Our results may be helpful to plan more successful charity events or to make a human community more altruistic and cooperative in general.

Social Support and Network Formation in a Small-Scale Horticulturalist Population

Evolutionary studies of cooperation in traditional human societies suggest that helping family and responding in kind when helped are the primary mechanisms for informally distributing resources vital to day-to-day survival (e.g., food, knowledge, money, childcare). However, these studies generally rely on forms of regression analysis that disregard complex interdependences between aid, resulting in the implicit assumption that kinship and reciprocity drive the emergence of entire networks of supportive social bonds. Here I evaluate this assumption using individual-oriented simulations of network formation (i.e., Stochastic Actor-Oriented Models). Specifically, I test standard predictions of cooperation derived from the evolutionary theories of kin selection and reciprocal altruism alongside well-established sociological predictions around the self-organisation of asymmetric relationships. Simulations are calibrated to exceptional public data on genetic relatedness and the provision of tangible aid amongst all 108 adult residents of a village of indigenous horticulturalists in Nicaragua (11,556 ordered dyads). Results indicate that relatedness and reciprocity are markedly less important to whom one helps compared to the supra-dyadic arrangement of the tangible aid network itself.

Prioritising well-being and resilience to 'build back better': insights from a Dominican small-scale fishing community

Climate change is increasing the severity of extreme weather events, particularly hurricanes, presenting a significant challenge to Caribbean coastal communities. In the aftermath of a major disaster, government interventions typically prioritise infrastructure, assets, and the economy through rebuilding roads, reviving economic sectors, and providing financial compensation. This is driven by a focus on macro-level quantitative indicators rather than by local, multidimensional subjective and relational factors, closer to lived experiences and livelihoods. Using frameworks outlining social well-being and agency, this paper explores strategies used by a fisheries-dependent community in Dominica to recover from Hurricane Maria in 2017 and pursue well-being. The findings highlight the importance of multidimensional well-being, particularly relational and subjective dimensions, including existing social networks, and personal relationships critical for recovery after Maria. Furthermore, the paper demonstrates how recovery initiatives that concentrate solely on material well-being, such as employment, can undermine agency in the capacity of a community to recover and build resilience.

Four Puzzles of Reputation-Based Cooperation : Content, Process, Honesty, and Structure

Research in various disciplines has highlighted that humans are uniquely able to solve the problem of cooperation through the informal mechanisms of reputation and gossip. Reputation coordinates the evaluative judgments of individuals about one another. Direct observation of actions and communication are the essential routes that are used to establish and update reputations. In large groups, where opportunities for direct observation are limited, gossip becomes an important channel to share individual perceptions and evaluations of others that can be used to condition cooperative action. Although reputation and gossip might consequently support large-scale human cooperation, four puzzles need to be resolved to understand the operation of reputation-based mechanisms. First, we need empirical evidence of the processes and content that form reputations and how this may vary cross-culturally. Second, we lack an understanding of how reputation is determined from the muddle of imperfect, biased inputs people receive. Third, coordination between individuals is only possible if reputation sharing and signaling is to a large extent reliable and valid. Communication, however, is not necessarily honest and reliable, so theoretical and empirical work is needed to understand how gossip and reputation can effectively promote cooperation despite the circulation of dishonest gossip. Fourth, reputation is not constructed in a social vacuum; hence we need a better understanding of the way in which the structure of interactions affects the efficiency of gossip for establishing reputations and fostering cooperation.

The content and structure of reputation domains across human societies: a view from the evolutionary social sciences

Reputations are an essential feature of human sociality and the evolution of cooperation and group living. Much scholarship has focused on reputations, yet typically on a narrow range of domains (e.g. prosociality and aggressiveness), usually in isolation. Humans can develop reputations, however, from any collective information. We conducted exploratory analyses on the content, distribution and structure of reputation domain diversity across cultures, using the Human Relations Area Files ethnographic database. After coding ethnographic texts on reputations from 153 cultures, we used hierarchical modelling, cluster analysis and text analysis to provide an empirical view of reputation domains across societies. Findings suggest: (i) reputational domains vary cross-culturally, yet reputations for cultural conformity, prosociality, social status and neural capital are widespread; (ii) reputation domains are more variable for males than females; and (iii) particular reputation domains are interrelated, demonstrating a structure consistent with dimensions of human uniqueness. We label these features: cultural group unity, dominance, neural capital, sexuality, social and material success and supernatural healing. We highlight the need for future research on the evolution of cooperation and human sociality to consider a wider range of reputation domains, as well as their social, ecological and gender-specific variability. This article is part of the theme issue 'The language of cooperation: reputation and honest signalling'.

The language of cooperation: reputation and honest signalling

Large-scale non-kin cooperation is a unique ingredient of human success. This type of cooperation is challenging to explain in a world of self-interested individuals. There is overwhelming empirical evidence from different disciplines that reputation and gossip promote cooperation in humans in different contexts. Despite decades of research, important details of reputation systems are still unclear. Our goal with this theme issue is to promote an interdisciplinary approach that allows us to explore and understand the evolution and maintenance of reputation systems with a special emphasis on gossip and honest signalling. The theme issue is organized around four main questions: What are the necessary conditions for reputation-based systems? What is the content and context of reputation systems? How can reputations promote cooperation? And, what is the role of gossip in maintaining reputation systems and thus cooperation? This article is part of the theme issue 'The language of cooperation: reputation and honest signalling'.

No good deed goes unpunished: the social costs of prosocial behaviour

Performing costly helpful behaviours can allow individuals to improve their reputation. Those who gain a good reputation are often preferred as interaction partners and are consequently better able to access support through cooperative relationships with others. However, investing in prosocial displays can sometimes yield social costs: excessively generous individuals risk losing their good reputation, and even being vilified, ostracised or antisocially punished. As a consequence, people frequently try to downplay their prosocial actions or hide them from others. In this review, we explore when and why investments in prosocial behaviour are likely to yield social costs. We propose two key features of interactions that make it more likely that generous individuals will incur social costs when: (a) observers infer that helpful behaviour is motivated by strategic or selfish motives; and (b) observers infer that helpful behaviour is detrimental to them. We describe how the cognition required to consider ulterior motives emerges over development and how these tendencies vary across cultures - and discuss how the potential for helpful actions to result in social costs might place boundaries on prosocial behaviour as well as limiting the contexts in which it might occur. We end by outlining the key avenues and priorities for future research.

Scarce and directly beneficial reputations support cooperation

A human solution to the problem of cooperation is the maintenance of informal reputation hierarchies. Reputational information contributes to cooperation by providing guidelines about previous group-beneficial or free-rider behaviour in social dilemma interactions. How reputation information could be credible, however, remains a puzzle. We test two potential safeguards to ensure credibility: (i) reputation is a scarce resource and (ii) it is not earned for direct benefits. We test these solutions in a laboratory experiment in which participants played two-person Prisoner's Dilemma games without partner selection, could observe some other interactions, and could communicate reputational information about possible opponents to each other. Reputational information clearly influenced cooperation decisions. Although cooperation was not sustained at a high level in any of the conditions, the possibility of exchanging third-party information was able to temporarily increase the level of strategic cooperation when reputation was a scarce resource and reputational scores were directly translated into monetary benefits. We found that competition for monetary rewards or unrestricted non-monetary reputational rewards helped the reputation system to be informative. Finally, we found that high reputational scores are reinforced further as they are rewarded with positive messages, and positive gossip was leading to higher reputations.

Emergent matriliny in a matrifocal, patrilineal population: a male coalitionary perspective

Daughter-biased parental investment and limited paternal care promote matrifocality and matrilineal descent, both of which are forms of matricentric social organization. However, matrifocality can occur under patrilineal descent. We hypothesize that matrilineal descent could emergently organize social relationships if a society were normatively patrilineal but matrifocal. Furthermore, in matrifocal environments, male and female social lives are envisioned as sex-specific adaptive strategies. Males purportedly form large, flexible social support networks that conflict with conjugal partnership investment owing to a tradeoff in the allocation of effort associated with either investing in male social support or provisioning the conjugal household. However, no quantitative analyses exist about the effect of conjugal partnership formation on male social relations in matrifocal communities. Here we examine whether matrilineal kinship organizes male same-sex social relationships and the effect of conjugal partnerships on male social support in a normatively patrilineal, but matrifocal village. We find that matrilineal kinship influences male social support networks, but not labour cooperation. Consistent with a tradeoff associated with investing in male social support or a conjugal union, we find that labouring with a conjugal partner, but not conjugal partnership itself, reduces male labour and social support outcomes. Our results suggest new insights into men's roles in matricentric social organization: (1) matriliny can emerge in patrilineal systems when household economics shift toward matrifocality in which matrilineal descent is used to organize male social support, and (2) the degree to which this shift occurs depends on the proportion of men who invest in same-sex social networks as opposed to a conjugal partner and offspring. This article is part of the theme issue 'The evolution of female-biased kinship in humans and other mammals'.

Social Evolution: The Force of the Market

Biological market forces shape patterns of cooperation typical of small-scale human societies that are organized by division of labor based on age and gender. Labor specialization promotes trade, while supply and demand affect the amount individuals exchange for commodities.

Revisiting Psychological Mechanisms in the Anthropology of Altruism

Anthropologists have long been interested in the reasons humans choose to help some individuals and not others. Early research considered psychological mediators, such as feelings of cohesion or closeness, but more recent work, largely in the tradition of human behavioral ecology, shifted attention away from psychological measures to clearer observables, such as past behavior, genetic relatedness, affinal ties, and geographic proximity. In this paper, we assess the value of reintegrating psychological measures-perceived social closeness-into the anthropological study of altruism. Specifically, analyzing social network data from four communities in rural Bangladesh (N = 516), we show that perceived closeness has a strong independent effect on helping, which cannot be accounted for by other factors. These results illustrate the potential value of reintegrating proximate psychological measures into anthropological studies of human cooperation.

Multiple reputation domains and cooperative behaviour in two Latin American communities

Reputations are a ubiquitous feature of human social life, and a large literature has been dedicated to explaining the relationship between prosocial reputations and cooperation in social dilemmas. However, humans form reputations in domains other than prosociality, such as economic competency that could affect cooperation. To date, no research has evaluated the relative effects of multiple reputation domains on cooperation. To bridge this gap, we analyse how prosocial and competency reputations affect cooperation in two Latin American communities (Bwa Mawego, Dominica, and Pucucanchita, Peru) across a number of social contexts (Dominica: labour contracting, labour exchange and conjugal partnership formation; Peru: agricultural and health advice network size). First, we examine the behavioural correlates of prosocial and competency reputations. Following, we analyse whether prosocial, competency, or both reputation domains explain the flow of cooperative benefits within the two communities. Our analyses suggest that (i) although some behaviours affect both reputation domains simultaneously, each reputation domain has a unique behavioural signature; and (ii) competency reputations affect cooperation across a greater number of social contexts compared to prosocial reputations. Results are contextualized with reference to the social markets in which behaviour is embedded and a call for greater theory development is stressed.

Reciprocal Exchange Patterned by Market Forces Helps Explain Cooperation in a Small-Scale Society

Social organisms sometimes depend on help from reciprocating partners to solve adaptive problems [1], and individual cooperation strategies should aim to offer high supply commodities at low cost to the donor in exchange for high-demand commodities with large return benefits [2, 3]. Although such market dynamics have been documented in some animals [4-7], naturalistic studies of human cooperation are often limited by focusing on single commodities [8]. We analyzed cooperation in five domains (meat sharing, produce sharing, field labor, childcare, and sick care) among 2,161 household dyads of Tsimane' horticulturalists, using Bayesian multilevel models and information-theoretic model comparison. Across domains, the best-fit models included kinship and residential proximity, exchanges in kind and across domains, measures of supply and demand and their interactions with exchange, and household-specific exchange slopes. In these best models, giving, receiving, and reciprocating were to some extent shaped by market forces, and reciprocal exchange across domains had a strong partial effect on cooperation independent of more exogenous factors like kinship and proximity. Our results support the view that reciprocal exchange can provide a reliable solution to adaptive problems [8-11]. Although individual strategies patterned by market forces may generate gains from trade in any species [3], humans' slow life history and skill-intensive foraging niche favor specialization and create interdependence [12, 13], thus stabilizing cooperation and fostering divisions of labor even in informal economies [14, 15].

Hwæt!: adaptive benefits of public displays of generosity and bravery in Beowulf

Costly signalling — along with other adaptive mechanisms, including reciprocity and kin selection — supports altruism in human societies. Because literary works can reflect the lives, motivations and ideals of real cultures, the same adaptive forces governing the actions of actual persons may drive the interactions depicted in these stories. Based on this reasoning, we analysed the interactions in the Old-English poem Beowulf, asking whether the beneficent behaviour exhibited by the characters functions as costly signalling or as exchange-based interactions. We found that both mechanisms play a role but costly signalling provides benefits beyond those from relationships based on exchange. Specifically, gift exchange promoted comrade allegiance but costly signalling additionally provided status increase to the signaller. Furthermore, boasting about oneself forged alliances whereas telling tales about the exploits of others increased speaker status. We show that hypotheses derived from evolutionary theory can be explored through quantitative text analyses of period-specific literature.

Selective Cooperation in the Supermarket : Field Experimental Evidence for Indirect Reciprocity

Numerous laboratory experiments suggest that mechanisms of indirect reciprocity might account for human cooperation. However, conclusive field data supporting the predictions of indirect reciprocity in everyday life situations is still scarce. Here, we attempt to compensate for this lack by examining the determinants of cooperative behavior in a German supermarket. Our methods were as follows: Confederates of the experimenter lined up at the checkout, apparently to buy a single item. As an act of cooperation, the waiting person in front (the potential helper) could allow the confederate to go ahead. By this means, the potential helper could take a cost (additional waiting time) by providing the confederate with a benefit (saved waiting time). We recorded the potential helpers' behavior and the number of items they purchased as a quantitative measure proportional to the confederate's benefit. Moreover, in a field experimental design, we varied the confederates' image by manipulating the item they purchased (beer vs. water). As predicted, the more waiting time they could save, the more likely the confederates were to receive cooperation. This relationship was moderated by the confederates' image. Cost-to-benefit ratios were required to be more favorable for beer-purchasing individuals to receive cooperation. Our results demonstrate that everyday human cooperation can be studied unobtrusively in the field and that cooperation among strangers is selective in a way that is consistent with current models of indirect reciprocity.

Lethal coalitionary aggression and long-term alliance formation among Yanomamö men

Some cross-cultural evidence suggests lethal coalitionary aggression in humans is the product of residence and descent rules that promote fraternal interest groups, i.e., power groups of coresident males bonded by kinship. As such, human lethal coalitions are hypothesized to be homologous to chimpanzee (Pan troglodytes) border patrols. However, humans demonstrate a unique metagroup social structure in which strategic alliances allow individuals to form coalitions transcending local community boundaries. We test predictions derived from the fraternal interest group and strategic alliance models using lethal coalition data from a lowland South American population, the Yanomamö. Yanomamö men who kill an enemy acquire a special status, termed unokai. We examine the social characteristics of co-unokais or men who jointly kill others. Analyses indicate co-unokais generally are (i) from the same population but from different villages and patrilines, (ii) close age mates, and (iii) maternal half-first cousins. Furthermore, the incident rate for co-unokai killings increases if men are similar in age, from the same population, and from different natal communities. Co-unokais who have killed more times in the past and who are more genetically related to each other have a higher probability of coresidence in adulthood. Last, a relationship exists between lethal coalition formation and marriage exchange. In this population, internal warfare unites multiple communities, and co-unokais strategically form new residential groups and marriage alliances. These results support the strategic alliance model of coalitionary aggression, demonstrate the complexities of human alliance formation, and illuminate key differences in social structure distinguishing humans from other primates.