Smaller saami herding groups cooperate more in a public goods experiment

Group living often entails a balance between individual selfinterest and benefits to the group as a whole. Situations in which an individual’s vested interests conflict with collective interests are known as social dilemmas (Kollock 1998). More formally, a theoretical game becomes a social dilemma when an equilibriumof dominant strategies leads to worse outcomes for all players compared to a more cooperative but nonequilibrium strategy (Zelmer 2003; Cardenas and Carpenter 2008). For example, arms races, climate change, the Cold War, credit markets, eBay, exploitation of fisheries, irrigation scheduling, overpopulation, pollution, price wars, voting, water supply and welfare states all give rise to social dilemmas (Kollock 1998; Wydick 2008). Researchers have identified various mutually inclusive routes to solving social dilemmas, including interacting with kin and/or cooperative individuals, communication, coordination, exclusion, institutions, leadership, legislation, mobility, monitoring, parcelling out cooperation or access to resources, partner choice, partner control, policing, punishment, repeated reciprocalinteractions, rewards, sanctions, and social norms (Trivers 2005; West et al. 2007; Levin 2014; Raihani and Bshary 2015). Social dilemmas pervade the pastoralist way of life. Individual herders must balance their interests (e.g., generating income and managing the inherent risks of pastoralism) with the interests of their herding group and the wider community facing similar challenges (Næss et al. 2012; Næss and Bårdsen 2015). Pastoralists such as Saami reindeer herders in Norway face social dilemmas across a range of scales and have a variety of individual and collective strategies for solving them

Smaller saami herding groups cooperate more in a public goods experiment

Group living often entails a balance between individual selfinterest and benefits to the group as a whole. Situations in which an individual’s vested interests conflict with collective interests are known as social dilemmas (Kollock 1998). More formally, a theoretical game becomes a social dilemma when an equilibriumof dominant strategies leads to worse outcomes for all players compared to a more cooperative but nonequilibrium strategy (Zelmer 2003; Cardenas and Carpenter 2008). For example, arms races, climate change, the Cold War, credit markets, eBay, exploitation of fisheries, irrigation scheduling, overpopulation, pollution, price wars, voting, water supply and welfare states all give rise to social dilemmas (Kollock 1998; Wydick 2008). Researchers have identified various mutually inclusive routes to solving social dilemmas, including interacting with kin and/or cooperative individuals, communication, coordination, exclusion, institutions, leadership, legislation, mobility, monitoring, parcelling out cooperation or access to resources, partner choice, partner control, policing, punishment, repeated reciprocalinteractions, rewards, sanctions, and social norms (Trivers 2005; West et al. 2007; Levin 2014; Raihani and Bshary 2015). Social dilemmas pervade the pastoralist way of life. Individual herders must balance their interests (e.g., generating income and managing the inherent risks of pastoralism) with the interests of their herding group and the wider community facing similar challenges (Næss et al. 2012; Næss and Bårdsen 2015). Pastoralists such as Saami reindeer herders in Norway face social dilemmas across a range of scales and have a variety of individual and collective strategies for solving them

Data from: The narrow gap between norms and cooperative behaviour in a reindeer herding community

Cooperation evolves on social networks and is shaped, in part, by norms: beliefs and expectations about the behaviour of others or of oneself. Networks of cooperative social partners and associated norms are vital for pastoralists, such as Saami reindeer herders in northern Norway. However, little is known quantitatively about how norms structure pastoralists' social networks or shape cooperation. Saami herders reported their social networks and participated in field experiments, allowing us to gauge the overlap between reported and emergent cooperation. We show that individuals' perceptions of reciprocal cooperation within their social networks exceeded actual reciprocity, although both occurred frequently and were concentrated within herding groups. Herders with more extensive cooperation networks received more rewards in an economic game. Although herders overestimated reciprocal helping, cooperation in this community was still extensive, suggesting that perceived norms potentially allow network structures promoting cooperation to emerge and be maintained

Cleaned, processed data

.zip file contains: (1) data about herders; (2) gift giving edgelist; (3) social network edgelist; (4) dyadic data

Supplementary Information for 'The narrow gap between norms and cooperative behaviour in a reindeer herding community'

Supplementary Information for 'The narrow gap between norms and cooperative behaviour in a reindeer herding community

Data from: Kinship underlies costly cooperation in Mosuo villages

The relative importance of social evolution theories such as kin selection, direct reciprocity and needs-based transfers in explaining real-world cooperation is the source of much debate. Previous field studies of cooperation in human communities have revealed variability in the extent to which each of these theories drive human sociality in different contexts. We conducted multivariate social network analyses predicting costly cooperation—labouring on another household’s farm—in 128,082 dyads of Mosuo farming households in southwest China. Through information-theoretic model selection, we tested the roles played by genealogical relatedness, affinal relationships (including reproductive partners), reciprocity, relative need, wealth, household size, spatial proximity, and gift-giving in an economic game. The best-fitting models included all factors, along with interactions between relatedness and (i) reciprocity, (ii) need, (iii) the presence of children in another household, and (iv) proximity. Our results show how a real-world form of cooperation was driven by kinship. Households tended to help kin in need (but not needy non-kin) and travel further to help spatially distant relatives. Households were more likely to establish reciprocal relationships with distant relatives and non-kin but not with closer kin; closer kin cooperated regardless of reciprocity. These patterns of kin-driven cooperation show the importance of inclusive fitness in understanding human social behaviour