Social transmission and the spread of modern contraception in rural Ethiopia

Changes in age at last birth and its determinants in India

In recent years, developing and developed countries are witnessing delayed childbearing among women contributing to the overall decline in fertility rates. The age at which a woman has her last child impacts maternal and child health, especially in a country with high maternal and perinatal mortality rates. This study aims to investigate the trends of age at the last birth among Indian women and to identify the potential factors contributing towards higher maternal age. The present study uses the data from five consecutive rounds (1992-1993, 1998-1999, 2004-2005, 2015-2016, and 2019-2021) of the National Family Health Survey (NFHS). We have used descriptive statistics, bivariate, Cox proportional hazard regression analysis, multiple classification analysis (MCA), Kaplan-Meier curve, life table survival analysis, hierarchical clustered heat map, multivariate decomposition analysis (MDA) and geospatial mapping to fulfill the objective of the study. Results show that the proportion of women with age at last birth before reaching the age of 30 years was less than half (nearly 35%) during NFHS-I while during NFHS-V proportion becomes more than half and reaches 64.3% among 40-49 years women. Within three decades (1992-2021) there has been a decline of 15.8% in median age at last birth among women aged 40-49 years. Additionally, the highest percentage decline in predicted mean age at last birth was noted among individuals from rural area (10.7%, 3.3 years), Hindu religion (10.8%, 3.3 years), poor wealth quantile (12.5%, 4.0 years) and those with mass media exposure (10.6%, 3.2 years) from NFHS-I (1992-1993) to NFHS-V (2019-2021). Although there exists the need to delay age at first childbirth, the age at last childbirth also plays an important role in women's and child health status. Hence, it is important to address the healthcare needs of those delaying their childbirth.

Egocentric social network characteristics and cardiovascular risk among patients with hypertension or diabetes in western Kenya: a cross-sectional analysis from the BIGPIC trial

OBJECTIVES

Management of cardiovascular disease (CVD) is an urgent challenge in low-income and middle-income countries, and interventions may require appraisal of patients' social networks to guide implementation. The purpose of this study is to determine whether egocentric social network characteristics (SNCs) of patients with chronic disease in western Kenya are associated with overall CVD risk and individual CVD risk factors.

DESIGN

Cross-sectional analysis of enrollment data (2017-2018) from the Bridging Income Generation with GrouP Integrated Care trial. Non-overlapping trust-only, health advice-only and multiplex (trust and health advice) egocentric social networks were elicited for each participant, and SNCs representing social cohesion were calculated.

SETTING

24 communities across four counties in western Kenya.

PARTICIPANTS

Participants (n=2890) were ≥35 years old with diabetes (fasting glucose ≥7 mmol/L) or hypertension.

PRIMARY AND SECONDARY OUTCOMES

We hypothesised that SNCs would be associated with CVD risk status (QRISK3 score). Secondary outcomes were individual CVD risk factors.

RESULTS

Among the 2890 participants, 2020 (70%) were women, and mean (SD) age was 60.7 (12.1) years. Forty-four per cent of participants had elevated QRISK3 score (≥10%). No relationship was observed between QRISK3 level and SNCs. In unadjusted comparisons, participants with any individuals in their trust network were more likely to report a good than a poor diet (41% vs 21%). SNCs for the trust and multiplex networks accounted for a substantial fraction of variation in measures of dietary quality and physical activity (statistically significant via likelihood ratio test, adjusted for false discovery rate).

CONCLUSION

SNCs indicative of social cohesion appear to be associated with individual behavioural CVD risk factors, although not with overall CVD risk score. Understanding how SNCs of patients with chronic diseases relate to modifiable CVD risk factors could help inform network-based interventions.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov identifier: NCT02501746; https://clinicaltrials.gov/ct2/show/NCT02501746.

Level and Timing of Implanon Discontinuation and Associated Factors among Women Who Used Implanon in Andabet District, Public Health Facilities, North-West Ethiopia

Background

Implanon discontinuation is unacceptably high in developing countries, including Ethiopia. Furthermore, there is an observed problem of high unintended pregnancy after method discontinuation that strides to program failure. Therefore, the purpose of this study was to assess the level and determinants of Implanon discontinuation among women who used Implanon in Andabet district, public health facilities, North-West Ethiopia, 2017.

Methods

Facility-based cross-sectional study design was employed among 537 women from Feb. 03 to April 28, 2017. Study participants were selected using a systematic random sampling technique. A face-to-face interview was employed to collect data. Epi-Info version 7 was used for data entry and SPSS version 20 for analysis. Both descriptive and analytical statistical analysis was computed. On multivariable binary logistic regression, a p value of less than 0.05 was used to declare statistical significance.

Results

About 37% of Implanon users have discontinued the method before the intended time. About 86% of them discontinued Implanon before two years of insertion. Women who had no live child (AOR = 2.17, 95% CI: 1.25-3.77), women who did not receive preinsertion counseling (AOR = 1.85, 95% CI: 1.15-2.97), women who developed Implanon-related side effect (AOR = 5.17, 95% CI: 3.18-8.40), and women who did not satisfy by the service provided (AOR = 5.40, 95% CI: 3.04-9.57) had higher odds of Implanon discontinuation. On the other hand, women who received appointment follow-up (AOR = 0.23, 95% CI: 0.13-0.41) had lower odds of Implanon discontinuation.

Conclusions

The level of Implanon discontinuation before its intended time was high in the district. Hence, strengthening preinsertion counseling and appointment follow-up as well as improving the clients' level of service satisfaction could increase Implanon's continuation.

Using Trellis software to enhance high-quality large-scale network data collection in the field

Trellis is a mobile platform created by the Human Nature Lab at the Yale Institute for Network Science to collect high-quality, location-aware, off-line/online, multi-lingual, multi-relational social network and behavior data in hard-to-reach communities. Respondents use Trellis to identify their social contacts by name and photograph, a procedure especially useful in low-literacy populations or in contexts where names may be similar or confusing. We use social network data collected from 1,969 adult respondents in two villages in Kenya to demonstrate Trellis' ability to provide unprecedented metadata to monitor and report on the data collection process including artifactual variability based on surveyors, time of day, or location.

Reproductive health decision making among nomadic pastoralists in North Eastern Kenya: a qualitative social network analysis

BACKGROUND

To our knowledge, no studies exist on the influence of nomadic pastoralist women's networks on their reproductive and sexual health (RSH), including uptake of modern family planning (FP).

METHODS

Using name generator questions, we carried out qualitative egocentric social network analysis (SNA) to explore the networks of four women. Networks were analyzed in R, visuals created in Visone and a framework approach used for the qualitative data.

RESULTS

Women named 10-12 individuals. Husbands were key in RSH decisions and never supported modern FP use. Women were unsure who supported their use of modern FP and we found evidence for a norm against it within their networks.

CONCLUSIONS

Egocentric SNA proves valuable to exploring RSH reference groups, particularly where there exists little prior research. Pastoralist women's networks likely change as a result of migration and conflict; however, husbands make RSH decisions and mothers and female neighbors provide key support in broader RSH issues. Interventions to increase awareness of modern FP should engage with women's wider networks.

Men's social networks, social norms, & family planning in Benin

To address low family planning (FP) use and high unmet need in West Africa, attention has been paid to addressing FP-related social networks and norms. Most work focuses on women. This analysis assesses men's FP-related social networks and norms and their relation to FP use in Benin using data from baseline surveys from the Tékponon Jikuagou intervention. We descriptively analysed men's egocentric FP-related social networks and norms at the village level. Multivariable logistic regression analyses (N = 885) examined the relationship between FP-related social networks, norms, and men's current and future FP use. Twenty-three percent of men reported current modern contraception use and 47% reported intended future use. Most had few network members. While most believed it was acceptable to discuss FP, few talked with peers about FP and most did not discuss FP with their partner(s). In multivariable analyses, neither networks nor norms were significantly related to men's FP use. Men's networks being small and men rarely discussing FP indicate an opportunity for village-based approaches to engage men in FP discussions and spark FP dialogue within couples, between men, and within villages. Future work should further explore the relationship between men's social networks, norms, and FP use.

Effects of family planning on fertility behaviour across the demographic transition

The adoption of contraception often coincides with market integration and has transformative effects on fertility behavior. Yet many parents in small-scale societies make decisions about whether and when to adopt family planning in an environment where the payoffs to  have smaller families are uncertain. Here we track the fertility of Maya women across 90 years, spanning the transition from natural to contracepting fertility. We first situate the uncertainty in which fertility decisions are made and model how childbearing behaviors respond. We find that contraception, a key factor in cultural transmission models of fertility decline, initially has little effect on family size as women appear to hedge their bets and adopt fertility control only at the end of their reproductive careers. Family planning is, however, associated with the spread of lower fertility in later cohorts. Distinguishing influences on the origin versus spread of a behaviour provides valuable insight into causal factors shaping individual and normative changes in fertility.

Association of Effective Spousal Family Planning Communication with Couples' Modern Contraceptive Use in Harar, Eastern Ethiopia

BACKGROUND

Spousal family planning communication plays an important role in making better reproductive health decisions and in increasing the use of modern contraceptive methods. The objective of the current study is to examine the association of spousal family planning communication in its broader context with current modern contraceptive use among couples.

METHODS

A community based cross-sectional survey was conducted in twelve kebeles of Harar Urban Health and Demographic Surveillance System. A total of 2700 currently married couples of whose wives were in the reproductive age participated in the study. The selection of the study participants was made using simple random sampling and data were collected using an interviewer administered structured questionnaire and analyzed using Stata version 12.

RESULTS

The level of current modern contraceptive use was 57.1% (95% CI: 0.53, 3.39). Effective spousal family planning communication was significantly associated with current modern contraceptive use even after controlling for socio-economic and demographic variables. Socio-economic and demographic variables such as religion of couples, number of couples' living children, household monthly income, couples' family planning approval and women's counseling about family planning by health workers were significantly associated with current modern contraceptive use.

CONCLUSION

Policies and programs aimed at increasing contraceptive prevalence should properly address the importance of spousal communication about family planning and integrate men into family planning programs to facilitate and enhance couples communication skills.

Modern contraceptive utilization and associated factors among married and cohabiting women in Papua New Guinea: a population-based cross-sectional study

BACKGROUND

Universal access to family planning has been emphasized by the international development agenda, as evident in the Sustainable Development Goal 3.7. This notwithstanding, the use of modern contraceptives has been minimal in low- and middle-income countries, especially in Papua New Guinea. In view of this, we investigated the factors associated with the use of modern contraceptives and the associated factors among married and cohabiting women in Papua New Guinea.

METHODS

The study utilised the Demographic and Health Survey data of 2345 women in sexual unions in Papua New Guinea. We employed a descriptive and binary logistic regression analyses. We presented the results as crude Odds Ratios (COR) and adjusted Odds Ratios (AOR), with 95% confidence intervals (CI) signifying level of precision. Level of statistical significance was set at p < 0.05.

RESULTS

We found that 74.4% of the women were using modern contraceptives ranging from injectables (44.5%) to other modern methods (0.23%). Women aged 15-19 [AOR = 7.425, 95% CI = 2.853, 19.32], residents of the Highland region [AOR = 1.521, 95% CI =1.086, 2.131], self-employed women in the agricultural sector [AOR = 1.710, 95% CI = 1.218, 2.400], and women who listened to radio at least once a week [AOR = 1.409, 95% CI = 1.048, 1.895] had higher odds of modern contraceptive usage. However, women in the Islands region [AOR = 0.291, 95% CI = 0.224, 0.377], women whose husbands had higher education [AOR = 0.531,95%CI = 0.318,0.886], women in professional/technical/managerial work [AOR = 0.643, 95% CI = 0.420, 0.986], and those with no child [AOR = 0.213, CI = 0.0498,0.911] had lower odds of modern contraceptive use.

CONCLUSION

Out of the 2345 participants, we found that majority of them were using modern contraceptives and the commonly used modern contraceptive was injectables. Age, region of residence, partner's education, employment, partner's desire for children, and frequency of listening to radio are associated with modern contraceptive usage. Tailored reproductive healthcare should be developed for women who are disadvantaged when it comes to the usage of modern contraceptives in order to boost modern contraceptive use among them. Further investigation is needed to unravel the motivation for the high usage of injectables among married and cohabiting women in Papua New Guinea.

Adoption of outgroup norms provides evidence for social transmission in perinatal care practices among rural Namibian women

Background and objectives

How do new ideas spread in social groups? We apply the framework of cultural evolution theory to examine what drives change in perinatal care norms among Himba women in the Kunene region of Namibia. Access to formal medical care is on the rise in this region, and medical workers regularly visit communities to promote WHO-recommended perinatal care practices. This study investigates how various forms of social transmission affect women's uptake of medical recommendations concerning perinatal care.

Methodology

Based on interviews with one hundred Himba mothers, we used Bayesian multi-level logistical regression models to examine how perceptions of group preferences, prestige ascribed to outgroup conformers, interaction with the outgroup and access to resources affect norm adoption.

Results

Women who perceive medical recommendations as common in their group prefer, plan and practice these recommendations more often themselves. We observed a shift toward medical recommendations regarding birth location and contraception use that was in line with conformity bias predictions. Practices that serve as cultural identity markers persist in the population.

Conclusions and implications

Norm changes, and the cultural evolutionary processes that can lead to them, are not uniform, either in process or pace. Empirical studies like this one provide important examples of how these changes reflect local culture and circumstance and are critical for better understanding the models that currently predominate in cultural evolution work. These cases can also help bridge the gap between evolutionary anthropology and public health by demonstrating where promotion and prevention campaigns might be most effective.

Lay Summary

The recent promotion of WHO-recommended perinatal care practices in Namibia provides an opportunity to empirically study norm change using a cultural evolution framework. We found women adopt medical recommendations when they believe these are common in their social group. Local norms that were not discouraged persisted in the study group.

Social networks for health communication in rural Uganda: A mixed-method analysis of Dekabusa Trading Centre, Luwero County

To reach the most vulnerable individuals in under-resourced countries, health communication interventions increasingly move towards the community level. However, little is known about how health information spreads through local social networks. This paper maps the health information network of a rural trading centre in Uganda. As part of a five-year ethnographic study of sustainable community health resources, ego networks were obtained for 231 village residents in March 2014. Using both ethnographic and social network data, we analyze how the village social network is structured, and how this structure may influence the transmission of health information. Results show a network with low average proximity, with a small number of individuals, notably key administrative officials, much closer connected to many other community members than average. However, because of social partitioning in the village network, a number of people are outside the social clusters in which the top influencers are located.

The Examination of Diffusion Effects on Modern Contraceptive Use in Nigeria

This study uses data gathered for an evaluation of a Bill & Melinda Gates Foundation–funded initiative designed to increase modern contraceptive use in select urban areas of Nigeria. When the initiative was conceived, the hope was that any positive momentum in the cities would diffuse to surrounding areas. Using a variety of statistical methods, we study three aspects of diffusion and their effects on modern contraceptive use: spread through mass communications, social learning, and social influence. Using a dynamic causal model, we find strong evidence of social multiplier effects through social learning. The results for social influence and spread through mass communications are promising, but we are unable to identify definitive causal impacts.

Market integration reduces kin density in women's ego-networks in rural Poland

It is widely assumed that as populations become more market integrated the 'inner circles' of people's social networks become less densely connected and family-oriented. This 'loosening' of kin networks may fundamentally alter the social dynamics of reproduction, facilitating demographic transitions to low fertility. Few data exist to test this hypothesis. Previous research in urbanized populations has not explicitly measured kin density in ego-networks, nor assessed how market integration influences network structure at different levels of aggregation. Here I analyze the ego-networks of ~2000 women in 22 rural Polish communities transitioning from subsistence farming to market-dependence. I compare how ego-network size, density and kin density co-vary with household and community-level market integration. Market integration is associated with less kin-dense networks, but not necessarily less dense ones, and is unrelated to network size. Declining kin density during economic transitions may be a critical mechanism for the broader cultural transmission of low fertility values.

Exploratory, cross-sectional social network study to assess the influence of social networks on the care-seeking behaviour, treatment adherence and outcomes of patients with tuberculosis in Chennai, India: a study protocol

INTRODUCTION

Poor treatment adherence and outcomes among patients with tuberculosis (TB) lead to drug resistance, and increased risk of morbidity, mortality and transmission of the disease in the community. Individual patient-level psychological and behavioural risk factors and structural-level social and health system determinants of treatment adherence and outcomes had been studied widely in India and other countries. There is an evidence gap on how care-seeking behaviour, treatment adherence and outcomes of patients with TB are influenced by their social network structure and the different support they received from social network members.

METHODS AND ANALYSIS

We propose an exploratory, cross-sectional social network study to assess the social network structure of patients with TB in Chennai who recently completed their treatment under the Revised National Tuberculosis Control Program in India. We will employ egocentric personal social network survey to 380 patients with TB to generate their social network relationships and will retrospectively assess the types of support they received from different network members. Support received will be categorised as emotional support, resources support, appraisal support, informational support, spiritual support, occupational support and practical support. Social network size, composition, density, centrality and cohesion for individual patients with TB will be calculated and sociograms will be developed. Multinomial logistic regressions will be used to assess the relationship between the 'structure of social network members' and 'social network supports' and the differential treatment-seeking behaviour, treatment adherence and outcomes among patients with TB.

ETHICS AND HUMAN PROTECTION

The proposal was approved by the Institutional Review Board and Ethics Committee of the School of Public Health, SRM University in Kancheepuram. Confidentiality and privacy of participants will be protected. Duty of care for patients who have not completed treatment will be ensured by taking all possible measures to bring them back for treatment.

Gene-Culture Coinheritance of a Behavioral Trait

Many physical and behavioral traits in animals, including humans, are inherited both genetically and culturally. The presence of different inheritance systems affecting the same trait can result in complex evolutionary dynamics. Here, we present a general model that elucidates the distinct roles of cultural and genetic inheritance systems and their interaction in driving the evolution of complex phenotypes. In particular, we derive a Price equation that incorporates both cultural and genetic inheritance of a phenotype where the effects of genes and culture are additive. We then use this equation to investigate whether a genetically maladaptive phenotype can evolve under dual transmission. We examine the special case of altruism using an illustrative model and show that cultural selection can overcome genetic selection when the variance in culture is sufficiently high with respect to genes. We also show that the presence of cultural transmission can modify genetic selection itself, making genetic selection more favorable to a trait than under purely genetic inheritance. Last, we consider the effect of different timescales of genetic and cultural transmission. We discuss the implications of our results for understanding the evolution of important coinherited behaviors, including how our framework can be used to generate quantitative estimates of selection pressures required for a genetically maladaptive trait to evolve.

Evolutionary demography of age at last birth: integrating approaches from human behavioural ecology and cultural evolution

Cultural evolutionary theory and human behavioural ecology offer different, but compatible approaches to understanding human demographic behaviour. For much of their 30 history, these approaches have been deployed in parallel, with few explicit attempts to integrate them empirically. In this paper, we test hypotheses drawn from both approaches to explore how reproductive behaviour responds to cultural changes among Mosuo agriculturalists of China. Specifically, we focus on how age at last birth (ALB) varies in association with temporal shifts in fertility policies, spatial variation and kinship ecologies. We interpret temporal declines in ALB as plausibly consistent with demographic front-loading of reproduction in light of fertility constraints and later ages at last birth in matrilineal populations relative to patrilineal ones as consistent with greater household cooperation for reproductive purposes in the former. We find little evidence suggesting specific transmission pathways for the spread of norms regulating ALB, but emphasize that the rapid pace of change strongly suggests that learning processes were involved in the general decline in ALB over time. The different predictions of models we employ belie their considerable overlap and the potential for a synthetic approach to generate more refined tests of evolutionary hypotheses of demographic behaviour.This article is part of the theme issue 'Bridging cultural gaps: interdisciplinary studies in human cultural evolution'.

Support for new mothers and fertility in the United Kingdom: Not all support is equal in the decision to have a second child

Low fertility across Europe highlights the need to understand reproductive decisions in high-income countries better. Availability of support may be one factor influencing reproductive decisions, though within high-income countries availability varies between environments, including socio-economic environments. We test whether receiving higher levels of support, from different sources (informal and formal) and of different types (practical and emotional), is positively correlated with second births in the United Kingdom (UK) Millennium Cohort Study, and whether these relationships differ by socio-economic position (SEP). Our hypothesis is only partially supported: receiving emotional support correlates with higher likelihood of second birth, but the opposite is true for practical support. Availability of different types of support varies across SEP, but relationships between support and fertility are similar, with one exception: kin-provided childcare increases the likelihood of birth only among lower-SEP women. Our results highlight that not all support is equal in the decision to have a second child.

Modernizing Evolutionary Anthropology : Introduction to the Special Issue

Evolutionary anthropology has traditionally focused on the study of small-scale, largely self-sufficient societies. The increasing rarity of these societies underscores the importance of such research yet also suggests the need to understand the processes by which such societies are being lost-what we call "modernization"-and the effects of these processes on human behavior and biology. In this article, we discuss recent efforts by evolutionary anthropologists to incorporate modernization into their research and the challenges and rewards that follow. Advantages include that these studies allow for explicit testing of hypotheses that explore how behavior and biology change in conjunction with changes in social, economic, and ecological factors. In addition, modernization often provides a source of "natural experiments" since it may proceed in a piecemeal fashion through a population. Challenges arise, however, in association with reduced variability in fitness proxies such as fertility, and with the increasing use of relatively novel methodologies in evolutionary anthropology, such as the analysis of secondary data. Confronting these challenges will require careful consideration but will lead to an improved understanding of humanity. We conclude that the study of modernization offers the prospect of developing a richer evolutionary anthropology, by encompassing ultimate and proximate explanations for behavior expressed across the full range of human societies.

Evolutionary contributions to the study of human fertility

Demography, lacking an overarching theoretical framework of its own, has drawn on theories in many other social sciences to inform its analyses. The aim of this paper is to bring to the demographic community's attention research in the evolutionary sciences on fertility, and to demonstrate that evolutionary theory can be another useful tool in the demographer's toolkit. I first dispel some myths which impede the incorporation of evolutionary theory into demography: I make it clear that evolutionary explanations do not assume that all human behaviour is hardwired and functions to maximize genetic fitness; that they are able to explain variation in human behaviour; and that they are not necessarily alternatives to social science explanations. I then describe the diversity of work on fertility by evolutionary researchers, particularly human evolutionary ecologists and cultural evolutionists, and illustrate the usefulness of the evolutionary approach with examples of its application to age at first birth and the fertility transition.

The cultural evolution of fertility decline

Cultural evolutionists have long been interested in the problem of why fertility declines as populations develop. By outlining plausible mechanistic links between individual decision-making, information flow in populations and competition between groups, models of cultural evolution offer a novel and powerful approach for integrating multiple levels of explanation of fertility transitions. However, only a modest number of models have been published. Their assumptions often differ from those in other evolutionary approaches to social behaviour, but their empirical predictions are often similar. Here I offer the first overview of cultural evolutionary research on demographic transition, critically compare it with approaches taken by other evolutionary researchers, identify gaps and overlaps, and highlight parallel debates in demography. I suggest that researchers divide their labour between three distinct phases of fertility decline--the origin, spread and maintenance of low fertility--each of which may be driven by different causal processes, at different scales, requiring different theoretical and empirical tools. A comparative, multi-level and mechanistic framework is essential for elucidating both the evolved aspects of our psychology that govern reproductive decision-making, and the social, ecological and cultural contingencies that precipitate and sustain fertility decline.

Pathways from education to fertility decline: a multi-site comparative study

Women's education has emerged as a central predictor of fertility decline, but the many ways that education affects fertility have not been subject to detailed comparative investigation. Taking an evolutionary biosocial approach, we use structural equation modelling to examine potential pathways between education and fertility including: infant/child mortality, women's participation in the labour market, husband's education, social network influences, and contraceptive use or knowledge across three very different contexts: Matlab, Bangladesh; San Borja, Bolivia; and rural Poland. Using a comparable set of variables, we show that the pathways by which education affects fertility differ in important ways, yet also show key similarities. For example, we find that across all three contexts, education is associated with delayed age at first birth via increasing women's labour-force participation, but this pathway only influences fertility in rural Poland. In Matlab and San Borja, education is associated with lower local childhood mortality, which influences fertility, but this pathway is not important in rural Poland. Similarities across sites suggest that there are common elements in how education drives demographic transitions cross-culturally, but the differences suggest that local socioecologies also play an important role in the relationship between education and fertility decline.

Understanding variation in human fertility: what can we learn from evolutionary demography?

Decades of research on human fertility has presented a clear picture of how fertility varies, including its dramatic decline over the last two centuries in most parts of the world. Why fertility varies, both between and within populations, is not nearly so well understood. Fertility is a complex phenomenon, partly physiologically and partly behaviourally determined, thus an interdisciplinary approach is required to understand it. Evolutionary demographers have focused on human fertility since the 1980s. The first wave of evolutionary demographic research made major theoretical and empirical advances, investigating variation in fertility primarily in terms of fitness maximization. Research focused particularly on variation within high-fertility populations and small-scale subsistence societies and also yielded a number of hypotheses for why fitness maximization seems to break down as fertility declines during the demographic transition. A second wave of evolutionary demography research on fertility is now underway, paying much more attention to the cultural and psychological mechanisms underpinning fertility. It is also engaging with the complex, multi-causal nature of fertility variation, and with understanding fertility in complex modern and transitioning societies. Here, we summarize the history of evolutionary demographic work on human fertility, describe the current state of the field, and suggest future directions.

Applying evolutionary anthropology

Evolutionary anthropology provides a powerful theoretical framework for understanding how both current environments and legacies of past selection shape human behavioral diversity. This integrative and pluralistic field, combining ethnographic, demographic, and sociological methods, has provided new insights into the ultimate forces and proximate pathways that guide human adaptation and variation. Here, we present the argument that evolutionary anthropological studies of human behavior also hold great, largely untapped, potential to guide the design, implementation, and evaluation of social and public health policy. Focusing on the key anthropological themes of reproduction, production, and distribution we highlight classic and recent research demonstrating the value of an evolutionary perspective to improving human well-being. The challenge now comes in transforming relevance into action and, for that, evolutionary behavioral anthropologists will need to forge deeper connections with other applied social scientists and policy-makers. We are hopeful that these developments are underway and that, with the current tide of enthusiasm for evidence-based approaches to policy, evolutionary anthropology is well positioned to make a strong contribution.

Social network- and community-level influences on contraceptive use: evidence from rural Poland

The diffusion of 'modern' contraceptives-as a proxy for the spread of low-fertility norms-has long interested researchers wishing to understand global fertility decline. A fundamental question is how local cultural norms and other people's behaviour influence the probability of contraceptive use, independent of women's socioeconomic and life-history characteristics. However, few studies have combined data at individual, social network and community levels to simultaneously capture multiple levels of influence. Fewer still have tested if the same predictors matter for different contraceptive types. Here, we use new data from 22 high-fertility communities in Poland to compare predictors of the use of (i) any contraceptives-a proxy for the decision to control fertility-with those of (ii) 'artificial' contraceptives-a subset of more culturally taboo methods. We find that the contraceptive behaviour of friends and family is more influential than are women's own characteristics and that community level characteristics additionally influence contraceptive use. Highly educated neighbours accelerate women's contraceptive use overall, but not their artificial method use. Highly religious neighbours slow women's artificial method use, but not their contraceptive use overall. Our results highlight different dimensions of sociocultural influence on contraceptive diffusion and suggest that these may be more influential than are individual characteristics. A comparative multilevel framework is needed to understand these dynamics.

Evolution of individual versus social learning on social networks

A number of studies have investigated the roles played by individual and social learning in cultural phenomena and the relative advantages of the two learning strategies in variable environments. Because social learning involves the acquisition of behaviours from others, its utility depends on the availability of 'cultural models' exhibiting adaptive behaviours. This indicates that social networks play an essential role in the evolution of learning. However, possible effects of social structure on the evolution of learning have not been fully explored. Here, we develop a mathematical model to explore the evolutionary dynamics of learning strategies on social networks. We first derive the condition under which social learners (SLs) are selectively favoured over individual learners in a broad range of social network. We then obtain an analytical approximation of the long-term average frequency of SLs in homogeneous networks, from which we specify the condition, in terms of three relatedness measures, for social structure to facilitate the long-term evolution of social learning. Finally, we evaluate our approximation by Monte Carlo simulations in complete graphs, regular random graphs and scale-free networks. We formally show that whether social structure favours the evolution of social learning is determined by the relative magnitudes of two effects of social structure: localization in competition, by which competition between learning strategies is evaded, and localization in cultural transmission, which slows down the spread of adaptive traits. In addition, our estimates of the relatedness measures suggest that social structure disfavours the evolution of social learning when selection is weak.

Predictors of condom use among peer social networks of men who have sex with men in Ghana, West Africa

Ghanaian men who have sex with men (MSM) have high rates of HIV infection. A first step in designing culturally relevant prevention interventions for MSM in Ghana is to understand the influence that peer social networks have on their attitudes and behaviors. We aimed to examine whether, in a sample of Ghanaian MSM, mean scores on psychosocial variables theorized to influence HIV/STI risk differed between peer social networks and to examine whether these variables were associated with condom use. We conducted a formative, cross-sectional survey with 22 peer social networks of MSM (n = 137) in Ghana. We assessed basic psychological-needs satisfaction, HIV/STI knowledge, sense of community, HIV and gender non-conformity stigmas, gender equitable norms, sexual behavior and condom use. Data were analyzed using analysis of variance, generalized estimating equations, and Wilcoxon two sample tests. All models were adjusted for age and income, ethnicity, education, housing and community of residence. Mean scores for all psychosocial variables differed significantly by social network. Men who reported experiencing more autonomy support by their healthcare providers had higher odds of condom use for anal (AOR = 3.29, p<0.01), oral (AOR = 5.06, p<0.01) and vaginal (AOR = 1.8, p<0.05) sex. Those with a stronger sense of community also had higher odds of condom use for anal sex (AOR = 1.26, p<0.001). Compared to networks with low prevalence of consistent condom users, networks with higher prevalence of consistent condom users had higher STD and HIV knowledge, had norms that were more supportive of gender equity, and experienced more autonomy support in their healthcare encounters. Healthcare providers and peer social networks can have an important influence on safer-sex behaviors in Ghanaian MSM. More research with Ghanaian MSM is needed that considers knowledge, attitudes, and norms of their social networks in the development and implementation of culturally relevant HIV/STI prevention intervention strategies.

Social networks and health: a systematic review of sociocentric network studies in low- and middle-income countries

In low- and middle-income countries (LMICs), naturally occurring social networks may be particularly vital to health outcomes as extended webs of social ties often are the principal source of various resources. Understanding how social network structure, and influential individuals within the network, may amplify the effects of interventions in LMICs, by creating, for example, cascade effects to non-targeted participants, presents an opportunity to improve the efficiency and effectiveness of public health interventions in such settings. We conducted a systematic review of PubMed, Econlit, Sociological Abstracts, and PsycINFO to identify a sample of 17 sociocentric network papers (arising from 10 studies) that specifically examined health issues in LMICs. We also separately selected to review 19 sociocentric network papers (arising from 10 other studies) on development topics related to wellbeing in LMICs. First, to provide a methodological resource, we discuss the sociocentric network study designs employed in the selected papers, and then provide a catalog of 105 name generator questions used to measure social ties across all the LMIC network papers (including both ego- and sociocentric network papers) cited in this review. Second, we show that network composition, individual network centrality, and network structure are associated with important health behaviors and health and development outcomes in different contexts across multiple levels of analysis and across distinct network types. Lastly, we highlight the opportunities for health researchers and practitioners in LMICs to 1) design effective studies and interventions in LMICs that account for the sociocentric network positions of certain individuals and overall network structure, 2) measure the spread of outcomes or intervention externalities, and 3) enhance the effectiveness and efficiency of aid based on knowledge of social structure. In summary, human health and wellbeing are connected through complex webs of dynamic social relationships. Harnessing such information may be especially important in contexts where resources are limited and people depend on their direct and indirect connections for support.

Community-level education accelerates the cultural evolution of fertility decline

Explaining why fertility declines as populations modernize is a profound theoretical challenge. It remains unclear whether the fundamental drivers are economic or cultural in nature. Cultural evolutionary theory suggests that community-level characteristics, for example average education, can alter how low-fertility preferences are transmitted and adopted. These assumptions have not been empirically tested. Here, we show that community-level education accelerates fertility decline in a way that is neither predicted by individual characteristics, nor by the level of economic modernization in a population. In 22 high-fertility communities in Poland, fertility converged on a smaller family size as average education in the community increased-indeed community-level education had a larger impact on fertility decline than did individual education. This convergence was not driven by educational levels being more homogeneous, but by less educated women having fewer children than expected, and more highly educated social networks, when living among more highly educated neighbours. The average level of education in a community may influence the social partners women interact with, both within and beyond their immediate social environments, altering the reproductive norms they are exposed to. Given a critical mass of highly educated women, less educated neighbours may adopt their reproductive behaviour, accelerating the pace of demographic transition. Individual characteristics alone cannot capture these dynamics and studies relying solely on them may systematically underestimate the importance of cultural transmission in driving fertility declines. Our results are inconsistent with a purely individualistic, rational-actor model of fertility decline and suggest that optimization of reproduction is partly driven by cultural dynamics beyond the individual.

A synthetic biosocial model of fertility transition: testing the relative contribution of embodied capital theory, changing cultural norms, and women's labor force participation

This article presents a biosocial model of fertility decline, which integrates ecological-economic and informational-cultural hypotheses of fertility transition in a unified theoretical framework. The model is then applied to empirical data collected among 500 women from San Borja, Bolivia, a population undergoing fertility transition. Using a combination of event history analysis, multiple regression, and structural equation modeling, we examine the pathways by which education responds to birth cohort, parental education and network ties, and how age at first birth and total fertility, in turn, respond to birth cohort, social network ties, education, expectations about parental investment, work, and contraceptive use. We find that in addition to secular trends in education, respondent's education is associated with the education of parents, the investment she received from them, and the education of older siblings. Total fertility has dropped over time, partly in response to increased education; moreover, the behavior of other women in a woman's social network predicts both initiation of reproduction and total fertility, while expected parental investment in offspring negatively predicts total fertility. Involvement in paid work that is incompatible with childcare is associated with a later age of first reproduction, but not subsequent fertility. Contraceptive use partially mediates the effect of education and birth cohort on total fertility, but is not a mediator of the effect of social network or expected parental investment on total fertility. Overall, the empirical results provide support for a biosocial model of fertility decline, particularly the embodied capital and cultural pathways.

Rural to urban migration is an unforeseen impact of development intervention in Ethiopia

Rural development initiatives across the developing world are designed to improve community well-being and livelihoods. However they may also have unforeseen consequences, in some cases placing further demands on stretched public services. In this paper we use data from a longitudinal study of five Ethiopian villages to investigate the impact of a recent rural development initiative, installing village-level water taps, on rural to urban migration of young adults. Our previous research has identified that tap stands dramatically reduced child mortality, but were also associated with increased fertility. We demonstrate that the installation of taps is associated with increased rural-urban migration of young adults (15-30 years) over a 15 year period (15.5% migrate out, n = 1912 from 1280 rural households). Young adults with access to this rural development intervention had three times the relative risk of migrating to urban centres compared to those without the development. We also identify that family dynamics, specifically sibling competition for limited household resources (e.g. food, heritable land and marriage opportunities), are key to understanding the timing of out-migration. Birth of a younger sibling doubled the odds of out-migration and starting married life reduced it. Rural out-migration appears to be a response to increasing rural resource scarcity, principally competition for agricultural land. Strategies for livelihood diversification include education and off-farm casual wage-labour. However, jobs and services are limited in urban centres, few migrants send large cash remittances back to their families, and most return to their villages within one year without advanced qualifications. One benefit for returning migrants may be through enhanced social prestige and mate-acquisition on return to rural areas. These findings have wide implications for current understanding of the processes which initiate rural-to-urban migration and transitions to low fertility, as well as for the design and implementation of development intervention across the rural and urban developing world.

Contraception Use among Egyptian Women: Results from Egypt Demographic and Health Survey in 2005

BACKGROUND

THE REPORTS OF A RISE IN CONTRACEPTIVE PRACTICES HAVE NOT BEEN MATCHED BY A SIMILAR DECREASE IN POPULATION: therefore, there is a need to look into the causes of this discrepancy. The objectives of this study were to determine the prevalence of different methods of contraception used by Egyptian women, to compare different contraception methods used among various socio-demographic groups and, finally, to identify the main decision makers of contraception use within Egyptian families.

METHODS

The 2005 Egypt Demographic and Health Survey (EDHS) is a nationally representative household survey of 18134 married women aged 15-49 years. The 2005 EDHS provides a wealth of information on fertility, family planning, maternal and child health and nutrition, and violence against women. The study sample was selected using a multistage sampling technique. A face-to-face structured interview was conducted with each of the selected women. The response rate was 99.5% for completing the questionnaires.

RESULTS

The prevalence of contraception was 57.5%, nearly one third of the participants (33.1%) used IUD as a method of contraception. Both male and female were responsible for decision making regarding the use of contraception among different educational levels. Most women reporting use of contraceptive methods were 30-39 years old, were employed, were rich, educated and belonged to urban governorates.

CONCLUSION

More than half of the participants used contraception while IUDs and pills were the most commonly used methods. Whatever the level of education, the majority of women thought that family planning decisions should be made by both partners.