The emergence of locally adaptive institutions: Insights from traditional social structures of East African pastoralists

Norm violations and punishments across human societies

Punishments for norm violations are hypothesised to be a crucial component of the maintenance of cooperation in humans but are rarely studied from a comparative perspective. We investigated the degree to which punishment systems were correlated with socioecology and cultural history. We took data from the Standard Cross-Cultural Sample database and coded ethnographic documents from a sample of 131 largely non-industrial societies. We recorded whether punishment for norm violations concerned adultery, religion, food, rape or war cowardice and whether sanctions were reputational, physical, material or execution. We used Bayesian phylogenetic regression modelling to test for culture-level covariation. We found little evidence of phylogenetic signals in evidence for punishment types, suggesting that punishment systems change relatively quickly over cultural evolutionary history. We found evidence that reputational punishment was associated with egalitarianism and the absence of food storage; material punishment was associated with the presence of food storage; physical punishment was moderately associated with greater dependence on hunting; and execution punishment was moderately associated with social stratification. Taken together, our results suggest that the role and kind of punishment vary both by the severity of the norm violation, but also by the specific socio-economic system of the society.

The evolution of peace

While some species have affiliative and even cooperative interactions between individuals of different social groups, humans are alone in having durable, positive-sum, interdependent relationships across unrelated social groups. Our capacity to have harmonious relationships that cross group boundaries is an important aspect of our species' success, allowing for the exchange of ideas, materials, and ultimately enabling cumulative cultural evolution. Knowledge about the conditions required for peaceful intergroup relationships is critical for understanding the success of our species and building a more peaceful world. How do humans create harmonious relationships across group boundaries and when did this capacity emerge in the human lineage? Answering these questions involves considering the costs and benefits of intergroup cooperation and aggression, for oneself, one's group, and one's neighbor. Taking a game theoretical perspective provides new insights into the difficulties of removing the threat of war and reveals an ironic logic to peace - the factors that enable peace also facilitate the increased scale and destructiveness of conflict. In what follows, I explore the conditions required for peace, why they are so difficult to achieve, and when we expect peace to have emerged in the human lineage. I argue that intergroup cooperation was an important component of human relationships and a selective force in our species history beginning at least 300 thousand years. But the preconditions for peace only emerged in the past 100 thousand years and likely coexisted with intermittent intergroup violence which would have also been an important and selective force in our species' history.

The social learning and development of intra- and inter-ethnic sharing norms in the Congo Basin: A registered report protocol

Compared to other species, the extent of human cooperation is unparalleled. Such cooperation is coordinated between community members via social norms. Developmental research has demonstrated that very young children are sensitive to social norms, and that social norms are internalized by middle childhood. Most research on social norm acquisition has focused on norms that modulated intra-group cooperation. Yet around the world, multi-ethnic communities also cooperate, and this cooperation is often shaped by distinct inter-group social norms. In the present study, we will investigate whether inter-ethnic and intra-ethnic social norm acquisition follows the same, or distinct, developmental trajectories. Specifically, we will work with BaYaka foragers and Bandongo fisher-farmers who inhabit multi-ethnic villages in the Republic of the Congo. In these villages, inter-ethnic cooperation is regulated by sharing norms. Through interviews with adult participants, we will provide the first descriptive account of the timing and mechanism by which BaYaka and Bandongo learn to share with out-group members. Children (5–17 years) and adults (17+ years) will also participate in a modified Dictator Game to investigate the developmental trajectories of children’s intra- and inter-ethnic sharing choices. Based on our ethnographic knowledge of the participating communities, we predict that children’s intra-ethnic sharing choices in the Dictator Game will match those of adults at an earlier age than their inter-ethnic sharing choices. We will analyze our data using logistic Bayesian modelling.

Distinguishing Intergroup and Long-Distance Relationships

Intergroup and long-distance relationships are both central features of human social life, but because intergroup relationships are emphasized in the literature, long-distance relationships are often overlooked. Here, we make the case that intergroup and long-distance relationships should be studied as distinct, albeit related, features of human sociality. First, we review the functions of both kinds of relationship: while both can be conduits for difficult-to-access resources, intergroup relationships can reduce intergroup conflict whereas long-distance relationships are especially effective at buffering widespread resource shortfalls. Second, to illustrate the importance of distinguishing the two relationship types, we present a case study from rural Bolivia. Combining ethnography and two different experimental techniques, we find that the importance of intergroup relationships-and the salience of group membership itself-varies across populations and across methods. Although ethnography revealed that participants often rely on long-distance relationships for resource access, we were unable to capture participant preferences for these relationships with a forced-choice technique. Taken together, our review and empirical data highlight that (1) intergroup and long-distance relationships can have different functions and can be more or less important in different contexts and (2) validating experimental field data with ethnography is crucial for work on human sociality. We close by outlining future directions for research on long-distance relationships in humans.

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'.

How small-scale societies achieve large-scale cooperation

For most of our species' history, humans have lived in relatively small subsistence communities, often called small-scale societies. While these groups lack centralized institutions, they can and often do maintain large-scale cooperation. Here, we explore several mechanisms promoting cooperation in small-scale societies, including (a) the development of social norms that encourage prosocial behavior, (b) reciprocal exchange relationships, (c) reputation that facilitates high-cost cooperation, (d) relational wealth, and (e) risk buffering institutions. We illustrate these with ethnographic and psychological evidence from contemporary small-scale societies. We argue that these mechanisms for cooperation helped past and present small-scale communities adapt to diverse ecological and social niches.

Evaluation of rangeland condition in miombo woodlands in eastern Tanzania in relation to season and distance from settlements

Miombo woodlands sustainability in east and south-central Africa is threatened by human activities, including overgrazing. This study investigated seasonal variations in rangeland condition in three grazed areas in miombo woodlands in eastern Tanzania. Transect lines were established across the grazing areas, sampling points were identified and marked at every 10% of the length of transect line. Sampling points were categorised in different distances with respect to settlement. The line intercept method was used to collect data on vegetation cover and forage distribution, while herbaceous forage biomass was estimated using a disc pasture meter. A total of 118 different plant species were observed and grasses comprised 40.6% of all herbaceous species. Bothriochloa pertusa, Cynodon plectostachyus, Hyparrhenia rufa and Urochloa mosambicensis grass species dominated miombo grazed areas in various seasons and distances. These perennial grass species are desirable and indicated moderate grazing activities in miombo. Season affected grass cover, herbaceous forage biomass and nutritional composition. Grass cover and forage biomass were at the lowest during late dry season while forage nutritional quality was best during early dry season. Distance from settlement had no effect on grass cover and herbaceous forage biomass. Rangeland condition was generally fair, livestock stocking rate in continuously grazed drylands should be set at the lowest monthly forage biomass in order to ensure grazing land sustainability.