Dyadic inter-group cooperation in shotgun hunting activities in a Congo Basin village.

Understanding the dynamics of inter-group cooperation in human adaptation has been the subject of recent empirical and theoretical studies in evolutionary anthropology, beginning to fill gaps in our knowledge of how interactions across political, economic and social domains can - and often do - lead to stable, large-scale cooperation. Here we investigate dyadic intergroup cooperation in shotgun hunting in the Republic of the Congo. In the Congo Basin, inter-group cooperation between foragers and farmers is at the centre of an exchange system maintained by traditional norms and institutions such as fictive kinship. Here, we focused on what factors predict cooperative shotgun hunting exchanges between BaYaka and Yambe. We conducted structured interviews with 48 BaYaka hunters and 18 Yambe men who organise hunts in a village along the Motaba River. We used Bayesian multilevel regression models to investigate the influence of Yambe and BaYaka attributes on probability of dyadic cooperation. We found that BaYaka men's reputations as skilled hunters and their family size each predicted cooperation in shotgun hunting, whereas there was no effect of Yambe attributes (status, wealth, family size). We discuss the results in terms of evolutionary models of men as hunters and inter-group cooperation, as well as biodiversity conservation implications

Human preferences for sexually dimorphic faces may be evolutionarily novel

A large literature proposes that preferences for exaggerated sex typicality in human faces (masculinity/femininity) reflect a long evolutionary history of sexual and social selection. This proposal implies that dimorphism was important to judgments of attractiveness and personality in ancestral environments. It is difficult to evaluate, however, because most available data come from large-scale, industrialized, urban populations. Here, we report the results for 12 populations with very diverse levels of economic development. Surprisingly, preferences for exaggerated sex-specific traits are only found in the novel, highly developed environments. Similarly, perceptions that masculine males look aggressive increase strongly with development and, specifically, urbanization. These data challenge the hypothesis that facial dimorphism was an important ancestral signal of heritable mate value. One possibility is that highly developed environments provide novel opportunities to discern relationships between facial traits and behavior by exposing individuals to large numbers of unfamiliar faces, revealing patterns too subtle to detect with smaller samples

Women’s subsistence strategies predict fertility across cultures, but context matters

While it is commonly assumed that farmers have higher, and foragers lower, fertility compared to populations practicing other forms of subsistence, robust supportive evidence is lacking. We tested whether subsistence activities—incorporating market integration—are associated with fertility in 10,250 women from 27 small-scale societies and found considerable variation in fertility. This variation did not align with group-level subsistence typologies. Societies labeled as “farmers” did not have higher fertility than others, while “foragers” did not have lower fertility. However, at the individual level, we found strong evidence that fertility was positively associated with farming and moderate evidence of a negative relationship between foraging and fertility. Markers of market integration were strongly negatively correlated with fertility. Despite strong cross-cultural evidence, these relationships were not consistent in all populations, highlighting the importance of the socioecological context, which likely influences the diverse mechanisms driving the relationship between fertility and subsistence

Women's subsistence strategies predict fertility across cultures, but context matters.

While it is commonly assumed that farmers have higher, and foragers lower, fertility compared to populations practicing other forms of subsistence, robust supportive evidence is lacking. We tested whether subsistence activities-incorporating market integration-are associated with fertility in 10,250 women from 27 small-scale societies and found considerable variation in fertility. This variation did not align with group-level subsistence typologies. Societies labeled as "farmers" did not have higher fertility than others, while "foragers" did not have lower fertility. However, at the individual level, we found strong evidence that fertility was positively associated with farming and moderate evidence of a negative relationship between foraging and fertility. Markers of market integration were strongly negatively correlated with fertility. Despite strong cross-cultural evidence, these relationships were not consistent in all populations, highlighting the importance of the socioecological context, which likely influences the diverse mechanisms driving the relationship between fertility and subsistence

Observations of Cooperative Pond Fishing by the Bayaka and Bantu People in the Flooded Forest of the Northern Republic of Congo

The subsistence techniques of the Congo Basin peoples are diverse and well-adapted to local ecological and socio-cultural contexts. Besides well-known fishing techniques using dams, nets, barriers, or poison, the BaYaka and Bantu in the northern Republic of Congo use ponds dug by humans, called mosongo. In the flooded forest, the ponds function as fish traps when fish seek refuge there at the end of the dry season. In March 2020, the authors conducted participant observation and interviews with the BaYaka and Bantu who engaged in pond fishing. Some mosongo were inherited from and managed by informants’ grandmothers or mothers. Generally, the Bantu fisher-farmers visit this area once a year to make money with the catch from pond fishing. As in a variety of foraging activities, the Bantu recruit the BaYaka for labor and compensate them with some fish. Much surplus catch is sold in markets. For the BaYaka, pond fishing was one of their important seasonal subsistence activities. Yet, the BaYaka also sold surplus fish to the Bantu. This report provides additional evidence for the diversity in subsistence techniques in the Congo Basin, and reaffirms the importance of inter-ethnic relationships in the subsistence strategies in this region

Evidence for the Adaptive Learning Function of Work and Work-Themed Play among Aka Forager and Ngandu Farmer Children from the Congo Basin

Purpose: Work-themed play may allow children to learn complex skills, and ethno-typical and gender-typical behaviors. Thus, play may make important contributions to the evolution of childhood through the development of embodied capital. Few studies have explored how work and play trade-off throughout childhood among foragers, and how sex, ethnicity, and task complexity influence this trade-off. Using data from Aka foragers and Ngandu farmer children from the Central African Republic, we examine whether children choose ethno- and gender-typical play and work activities, and whether play prepares children for complex work. Methods: Focal follows of 50 Aka and 48 Ngandu children were conducted with the aim of recording children’s participation in 12 categories of work and work-themed play. We then examined how age, sex, ethnicity, and task complexity influences children’s activity choice. Results: We found that as children age, they worked more, and played less across cultures. Sex was a significant predictor for participation in hunting activities, household and other types of activities, while ethnicity was a significant predictor for participation in gathering activities, village activities, and net hunting. Lastly, children worked significantly more than they played at simple activities. Conclusion: Our findings show that ethnic and gender biases are apparent in the play and work behavior of Aka and Ngandu children. We also find the first evidence for the persistence of ethno-typical play within a multi-ethnic community of farmers and foragers. Finally, our results show that play helps both forager and farmer children learn complex skills

Identifying variation in cultural models of resource sharing between hunter-gatherers and farmers: a multi-method, cognitive approach

This book was funded by the EU 7th Framework Programme (7FP), TropicMicroArch 623293 Project (http://cordis.europa.eu/project/rcn/187754_en.html). The book will be Open Access, thanks to FP7 post-grant Open Access (https://www.openaire.eu/postgrantoapilot)

Socialization, Autonomy, and Cooperation: Insights from Task Assignment Among the Egalitarian BaYaka

Across diverse societies, task assignment is a socialization practice that gradually builds children's instrumental skills and integrates them into the flow of daily activities in their community. However, psychosocial tensions can arise when cooperation is demanded from children. Through their compliance or noncompliance, they learn cultural norms and values related to autonomy and obligations to others. Here, we investigate task assignment among BaYaka foragers of the Republic of the Congo, among whom individual autonomy is a foundational cultural schema. Our analysis is based on systematic observations, participant observation, and informal interviews with adults about their perspectives on children's learning and noncompliance, as well as their own learning experiences growing up. We find that children are assigned fewer tasks as they age. However, children's rate of noncompliance remains steady across childhood, indicating an early internalization of a core value for autonomy. Despite demonstrating some frustration with children's noncompliance, adults endorse their autonomy and remember task assignment being critical to their own learning as children. We argue that cross-cultural variation in children's compliance with task assignments must be understood within a larger framework of socialization as constituted by many integrated and bidirectional processes embedded in a social, ecological, and cultural context

Women’s subsistence networks scaffold cultural transmission among BaYaka foragers in the Congo Basin

In hunter-gatherer societies, women’s subsistence activities are crucial for food provisioning and children’s social learning but are understudied relative to men’s activities. To understand the structure of women’s foraging networks, we present 230 days of focal-follow data in a BaYaka community. To analyze these data, we develop a stochastic blockmodel for repeat observations with uneven sampling. We find that women’s subsistence networks are characterized by cooperation between kin, gender homophily, and mixed age-group composition. During early childhood, individuals preferentially coforage with adult kin, but those in middle childhood and adolescence are likely to coforage with nonkin peers, providing opportunities for horizontal learning. By quantifying the probability of coforaging ties across age classes and relatedness levels, our findings provide insights into the scope for social learning during women’s subsistence activities in a real-world foraging population and provide ground-truth values for key parameters used in formal models of cumulative culture.</p