A practical guide to cross-cultural and multi-sited data collection in the biological and behavioural sciences.

Researchers in the biological and behavioural sciences are increasingly conducting collaborative, multi-sited projects to address how phenomena vary across ecologies. These types of projects, however, pose additional workflow challenges beyond those typically encountered in single-sited projects. Through specific attention to cross-cultural research projects, we highlight four key aspects of multi-sited projects that must be considered during the design phase to ensure success: (1) project and team management; (2) protocol and instrument development; (3) data management and documentation; and (4) equitable and collaborative practices. Our recommendations are supported by examples from our experiences collaborating on the Evolutionary Demography of Religion project, a mixed-methods project collecting data across five countries in collaboration with research partners in each host country. To existing discourse, we contribute new recommendations around team and project management, introduce practical recommendations for exploring the validity of instruments through qualitative techniques during piloting, highlight the importance of good documentation at all steps of the project, and demonstrate how data management workflows can be strengthened through open science practices. While this project was rooted in cross-cultural human behavioural ecology and evolutionary anthropology, lessons learned from this project are applicable to multi-sited research across the biological and behavioural sciences.

Religious Involvement Is Associated With Higher Fertility and Lower Maternal Investment, but More Alloparental Support Among Gambian Mothers.

OBJECTIVES: Human childrearing is cooperative, with women often able to achieve relatively high fertility through help from many individuals. Previous work has documented tremendous socioecological variation in who supports women in childrearing, but less is known about the intracultural correlates of variation in allomaternal support. In the highly religious, high-fertility setting of The Gambia, we studied whether religious mothers have more children and receive more support with their children. METHODS: We randomly sampled 395 mothers and 745 focal children enrolled in the Kiang West (The Gambia) Longitudinal Population Study cohort. Structured interviews asked mothers who and how often people invest in their children, and about their religious practices. Data were collected at participants' homes on electronic tablet-based long-form surveys and analyzed using the Bayesian hierarchical models. RESULTS: Religiosity was weakly associated with women's higher age-adjusted fertility. Maternal religiosity was negatively related to maternal investment in focal children, but positively associated with total allomaternal support. Specifically, a woman's religiosity was positively associated with allomaternal support from matrilineal kin, other offspring, and affinal kin, but unrelated to paternal, patrilineal, and non-kin investment. CONCLUSIONS: These results suggest that higher fertility among religious mothers may be supported by high levels of investment from biological and affinal kin. Matrilineal kin, other siblings, and affinal kin seem to be the most responsive to a woman's religiosity. Our findings cast doubt on interpretations of women's religious behaviors as signals of fidelity, and instead suggest they may be part of strategies to enable collective allomaternal resources and higher relative fertility.

Economic empowerment and intimate partner violence: a secondary data analysis of the cross-sectional Demographic Health Surveys in Sub-Saharan Africa.

BACKGROUND: Intimate partner violence (IPV) has been recognized as a defining human rights, development and public health issue of our time. Economic empowerment is one of the most promising interventions to reduce IPV in sub-Saharan Africa, yet the evidence around economic factors that are key to ensure a reduction in IPV are still mixed. Furthermore, there is a lack of clarity on what kinds of economic empowerment works for which population group. This paper seeks a more nuanced understanding, by investigating whether the associations between indicators of economic empowerment and physical and/or sexual IPV are similar between the general population of women and among urban versus rural and young, or middle aged women versus older women. METHODS: Using couples data from 25 DHS surveys across 15 countries (n = 70,993 women and men aged 15 and above at time of survey), we analyse how household wealth, men's and women's education and employment status, decision making on women's income, differences in education and employment of women and their partners and women's cash income are associated with physical and/or sexual IPV. We also provide sub-analyses for both urban and rural areas and for women aged, 15 to 24 25 to 34 and 35 to 49. RESULTS: Across all surveys, 20% of women reported physical and/or sexual IPV in the last 12 months. On the one hand, our findings reinforced certain well-established patterns between women's economic empowerment and IPV, with women's and men's higher levels of education and increased household wealth  associated with a decrease in IPV, and women's employment, especially if only the woman worked, and women earning more than her partner associated with an increase in IPV. Most patterns did not differ across urban and rural settings and age groups, but notable differences emerged regarding household wealth, women's and men's employment in the last 12 months and relative employment and education. CONCLUSIONS: Factors relating to women's economic empowerment are  vital in understanding and addressing IPV. Our analysis indicate however that future interventions need to consider the differing needs of urban and rural areas as well as be targeted to different age groups.

Father absence but not fosterage predicts food insecurity, relative poverty, and poor child health in northern Tanzania.

OBJECTIVES: The importance of fathers in ensuring child health in rural developing populations is questioned by anthropologists and population health scientists. Existing literature focuses on paternal death and child mortality. A relative lack of studies consider alternative forms of father absence and/or more subtle health outcomes. Here we determine the frequency and form of father absence in northern Tanzania, and its relationship to household food security, wealth, and child anthropometric status. METHODS: We conducted a cross-sectional survey of 3136 children under 5 years of age from 56 villages. Using multilevel regression we contrast children residing with both parents to those that (i) have experienced paternal death, (ii) reside with their mother but not their living father and (iii) are fostered apart from both living parents. RESULTS: Of the total, 3.5% of children had experienced paternal death. Thirteen percent resided with their mother but away from their living father. Supporting data indicate such cases primarily reflect parental divorce/separation, extra-marital birth, or polygynous fathers residing with an alternative cowife. Paternal death and residing apart from one's living father was associated with lower food security and/or relative poverty and there is suggestive evidence that children in such circumstances achieve lower height-for-age. Six percent of children were fostered, usually with grandparents, and were comparable to children residing with both parents in terms of household food security, wealth, and anthropometric status. CONCLUSION: Our results highlight diversity in the form and consequences of father absence. We discuss limitations of the current study and wider literature on fatherhood and make suggestions for future research.

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'.

Parent-offspring conflict unlikely to explain 'child marriage' in northwestern Tanzania.

Approximately 40% of women in sub-Saharan Africa marry before their eighteenth birthday1. Within the international development sector, this phenomenon is referred to as 'child marriage', widely equated to forced marriage, and recognized as damaging to multiple dimensions of female well-being1,2. An escalating global campaign to end early marriage typically assumes that its high prevalence is driven by a conflict of interests between parents and daughters, with parents coercing daughters to marry early for the parents' economic benefit3. However, a parent-offspring conflict model of early marriage has not been explicitly tested. Here we present a study of marriage transitions in rural Tanzania, where marriage before or just after 18 years of age is normative. Consistent with parental coercion, we find that bridewealth transfers are highest for younger brides. However, autonomy in partner choice is very common at all ages, relationships between age at marriage and female well-being are largely equivocal, and women who marry early achieve relatively higher reproductive success. We conclude that, in contexts in which adolescents have autonomy in marriage choices and in which marriage promotes economic and social security, early marriage may be better understood as serving the strategic interests of both parents and daughters.

Fathers favour sons, mothers don't discriminate: Sex-biased parental care in northwestern Tanzania.

Variation in parental care by child's sex is evident across cultures. Evolutionary theory provides a functional explanation for this phenomenon, predicting that parents will favour specific children if this results in greater fitness payoffs. Here, we explore evidence for sex-biased parental care in a high-fertility, patriarchal and polygynous population in Tanzania, predicting that both mothers and fathers will favour sons in this cultural setting. Our data come from a cross-sectional study in rural northwestern Tanzania, which included surveys with mothers/guardians of 808 children under age 5. We focus on early childhood, a period with high mortality risk which is fundamental in establishing later-life physical and cognitive development. Examining multiple measures of direct/physical care provision (washing, feeding, playing with, supervising, co-sleeping and caring when sick), we demonstrate that fathers favour sons for washing, feeding and supervising, while maternal care is both more intensive and unrelated to child sex. We find no difference in parental care between girls and boys regarding the allocation of material resources and the duration of breastfeeding; or in terms of parental marital and co-residence status. This bias towards sons may result from higher returns to investment for fathers than mothers, and local gender norms about physical care provision.