Shodagor women cooperate across domains of work and childcare to solve an adaptive problem

High wet-bulb temperatures, time allocation, and diurnal patterns of breastfeeding in Bangladeshi fisher-traders

BACKGROUND

Climate change is a growing threat to population health, with dangerous combinations of heat and humidity increasing in frequency, particularly in South Asia. Evidence suggests that high temperatures and heat stress influence breastfeeding behaviour and may lead to suboptimal infant and young child nutrition.

AIM

Few studies have quantified the relationship between ambient heat and breastfeeding. Here we evaluate associations between wet-bulb temperature and daily breastfeeding patterns in a rural community in Bangladesh.

SUBJECTS AND METHODS

We used 23 months of daily time-diary data from 68 maternal-child dyads and regional wet-bulb temperatures to test the hypothesis that increased heat and humidity negatively influence breastfeeding outcomes among Shodagor fisher-traders.

RESULTS

We found that higher wet-bulb temperatures predicted reduced daily breastfeeding time allocation, particularly among fishers, and drove shifts towards increased night-time and decreased mid/late morning feeding. Maternal occupation and the interaction of child age with heat strongly influenced diurnal breastfeeding patterns.

CONCLUSION

These results highlight an important role of maternal work on infants' vulnerability to environmental stress. Dyads' ability to behaviourally compensate for extreme heat may be constrained by extended heatwaves, humidity, and economic circumstances, suggesting that climate change will likely exacerbate heat-related risks to global child health going forward.

Children's Caregiving and Growth in Northwestern Tanzania: Limited Evidence That Support From Specific Caregivers Is Associated With Better Growth

Receiving care from individuals other than one's mother (i.e., allomothering) is a universal aspect of raising children, but whether and how such care impacts children's health remains subject to debate. Existing studies in low-income societies largely use broad proxies for caregiving behaviors rather than measuring childcare activities, which may mask variation in allomothering and, thus, its impact on children's health. Using data collected to address these limitations we measure, for 808 children under 5 years in Northwestern Tanzania: (a) Maternal residence, (b) receipt of two childcare types from seven caregivers; and (c) children's growth (height-for-age and weight-for-height). We predict that (1) allomothering will be beneficial for children's growth and (2) benefits of allomothering will be most evident within mother nonresident households. We demonstrate that children receive care from a range of allomothers, even when mothers co-reside; and there are associations between care from different relatives. Receiving care from relatives of the same lineage tends to be positively associated, whereas care from fathers is negatively associated with care from maternal relatives. Maternal residence is not associated with child growth. We find little support for our predictions, with few and inconsistent associations between allomothering and child growth. Our findings suggest that our measures of care, while more nuanced than previous proxies, do not fully capture the complexity of caregiving. Pathways between allomothering and child growth may be further elucidated through more comprehensive care indicators, which specifically measure maternal need for help, and whether allomothering is in addition to, or substitutive of, maternal care.

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.

New perspectives on the evolution of women's cooperation

A holistic, evolutionary framework about human cooperation must incorporate information about women's cooperative behaviour. Yet, most empirical research on human cooperation has centered on men's behaviour or been derived from experimental studies conducted in western, industrialized populations. These bodies of data are unlikely to accurately represent human behavioural diversity. To address this gap and provide a more balanced view of human cooperation, this issue presents substantial new data and multi-disciplinary perspectives to document the complexity of women's cooperative behaviour. Research in this issue 1) challenges narratives about universal gender differences in cooperation, 2) reconsiders patrilocality and access to kin as constraints on women's cooperation, 3) reviews evidence for a connection between social support and women's health and 4) examines the phylogenetic roots of female cooperation. Here, we discuss the steps taken in this issue toward a more complete and evidence-based understanding of the role that cooperation plays in women's and girls' lives and in building human sociality. This article is part of the theme issue 'Cooperation among women: evolutionary and cross-cultural perspectives'.

Starting from scratch in a patrilocal society: how women build networks after marriage in rural Bangladesh

Humans rely on both kin and non-kin social ties for a wide range of support. In patrilocal societies that practice village exogamy, women can face the challenge of building new supportive networks when they move to their husband's village and leave many genetic kin behind. In this paper, we track how women from 10 diverse communities in rural Bangladesh build supportive networks after migrating to their husband's village, comparing their trajectories with women who remained in their childhood village (Bengali: n = 317, Santal: n = 36, Hajong: n = 39, Mandi: n = 36). Women who migrated for marriage started with almost no adult close kin (mean 0.1) compared to women who remained in their childhood village (mean 2.4). However, immigrants compensated for the lack of genetic kin by a combination of close affinal kin and close friends. By their late 20s, immigrants reported substantially more non-kin friends than did non-immigrants (mean 1.4 versus 1.1) and a comparable number of supportive partners in several domains. These findings raise questions about the functions and quality of these different social ties and how different composition of supportive networks may provide different opportunities for women in these settings. This article is part of the theme issue 'Cooperation among women: evolutionary and cross-cultural perspectives'.

Thriving together: the benefits of women's social ties for physical, psychological and relationship health

The relationship between social support and well-being is well established in social psychology, with evidence suggesting that these benefits are especially prominent among women. When faced with an environmental stressor, women are more likely to adopt a tend-and-befriend strategy rather than fight-or-flight. Furthermore, female friendships tend to be higher in self-disclosure and more frequently relied on for social support, which is associated with physical and psychological benefits. Women are also more effective at providing social support, further augmenting those benefits. We begin with an overview of the characteristics of women's social ties and how they can be especially useful in times of stress. We then transition to the benefits of female social networks even in the absence of negative events and incorporate research from health and social psychology to consider the positive implications of having strong social bonds and the negative implications of lacking such bonds. Additionally, we consider cross-cultural differences in tendencies to seek out social support and its subsequent benefits, as well as the need for more research with culturally diverse samples. It remains unclear the extent to which patterns of social support benefits for women vary cross-culturally. This article is part of the theme issue 'Cooperation among women: evolutionary and cross-cultural perspectives'.

Sedentarization and maternal childcare networks: role of risk, gender and demography

Women cooperate over multiple domains and while research from western contexts portrays women's networks as limited in size and breadth, women receive help, particularly with childcare, from a diverse range of individuals (allomothers). Nonetheless, little exploration has occurred into why we see such diversity. Wide maternal childcare networks may be a consequence of a lack of resource accumulation in mobile hunter-gatherers-where instead households rely on risk-pooling in informal insurance networks. By contrast, when households settle and accumulate resources, they are able to retain risk by absorbing losses. Thus, the size and composition of mothers' childcare networks may depend on risk-buffering, as captured by mobile and settled households in the Agta, a Philippine foraging population with diverse lifestyles. Across 78 children, we find that childcare from grandmothers and sisters was higher in settled camps, while childcare from male kin was lower, offering little support for risk-buffering. Nonetheless, girls' workloads were increased in settled camps while grandmothers had fewer dependent children, increasing their availability. These results point to gender-specific changes associated with shifting demographics as camps become larger and more settled. Evidently, women's social networks, rather than being constrained by biology, are responsive to the changing socioecological context. This article is part of the theme issue 'Cooperation among women: evolutionary and cross-cultural perspectives'.