Female subsistence strategies among Ache hunter-gatherers of Eastern Paraguay

Anthropologists have frequently proposed that sexual division of labor is produced by childcare constraints on women's subsistence work. We present data on the forest activities of Ache women that show that differences in parental investment partially account for variation in food acquisition among individual women. Data also suggest that childcare constraints are important in understanding the sexual division of labor.     

Fathers matter: Intrahousehold responsibilities and children's wellbeing during the COVID-19 lockdown in Italy

The lockdown imposed during the spring of 2020 as a result of the COVID-19 pandemic upset families lives, in addition to the health consequences of the virus, forcing parents to completely reorganize their labor, domestic work and childcare time. At the same time, school closures forced children to rearrange their lives and learning processes: in Italy, schools and nurseries were closed for four months, and the incidence and quality of distance learning activities was heterogeneous across education levels and among schools. Using real-time survey data on families with under-16 children collected in April 2020, which include information on parents’ market and household work, and their perception of their children's wellbeing, we estimate how the lockdown has affected children's use of time, their emotional status and their home learning, and whether the reallocation of intrahousehold responsibilities during the lockdown played a role in this process. Changes in the parental division of household tasks and childcare, mostly induced by the labor market restrictions imposed during the lockdown, point to a greater involvement of fathers in childcare and homeschooling activities. This positive variation in fathers’ involvement is accompanied by an increase in children's emotional wellbeing and by a reduction in TV and passive screen time. On the other hand, the quality of children's home learning does not appear to depend on which parent is overseeing their work, but rather on the type of distance learning activities proposed by their teachers.     

The public health implications of maternal care trade-offs

The socioeconomic and ethnic characteristics of parents are some of the most important correlates of adverse health outcomes in childhood. However, the relationships between ethnic, economic, and behavioral factors and the health outcomes responsible for this pervasive finding have not been specified in child health epidemiology. The general objective of this paper is to propose a theoretical approach to the study of maternal behaviors and child health in diverse ethnic and socioeconomic environments. The specific aims are: (a) to describe a causal pathway between the utility that women obtain through work outside the home and through child care and disease hazard rates in childhood using an optimization model; (b) to specify the influence of ethnic and socioeconomic factors on model constraints; (c) to use the model as a tool to learn about how different combinations of maternal wage labor and child care time might influence child health outcomes in diverse social contexts; (d) to identify parameters that will require measurement in future research; (e) to discuss research strategies that will enable us to obtain these measurements; and (f) to discuss the implications of the model for biostatistical modeling and public health intervention. Optimization models are powerful heuristic tools for understanding how ethnic, environmental, family, and personal characteristics can place important constraints on both the quality and quantity of care that women can provide to their children. They provide a quantitative appreciation for the difficult trade-offs that most women face between working in order to purchase basic goods that children cannot do without (e.g., food, clothing, shelter, health insurance), and increasing offspring well-being through child care (e.g., training in social skills, affection, protection from environmental hazards, help with homework). The research was funded by a Faculty Scholars Award from the William T. Grant Foundation to A. Magdalena Hurtado. A. Magdalena Hurtado, Ph.D., is an associate professor in the Department of Anthropology, University of New Mexico. Her research interests include the origins of the sexual division of labor, epidemiology of indigenous peoples, disease susceptibility, the development and intergenerational transmission of antigens and immune defense, immune function and allergic sensitization, and trauma. She also works on public health interventions, biological capital and poverty, and land tenure and human rights in native communities of South America. Carol Lambourne, M.Sc., is a doctoral candidate in the Department of Anthropology, University of New Mexico. Her research interests are evolutionary models of child and adolescent development, life history theory, family composition and investment patterns, pubertal timing and psychosexual maturation, juvenile stress, and infanticide. Kim Hill, Ph.D., is a professor in the Department of Anthropology, University of New Mexico. His research interests are modern hunter-gatherers, including extensive fieldwork in lowland South America. Current topics of interest include human evolution, economic strategies, life history theory, the evolution of cooperation, and the emergence of social norms enforced by punishment. He is also involved in economic development, health and education projects with lowland South American native populations. Karen Kessler received her M.S. in Anthropology from the University of New Mexico in 1996. Her research interests are the application of mathematical modeling to the prevention of diabetes and other causes of morbidity and mortality in historical populations.     

Group Structure and Female Cooperative Networks in Australia’s Western Desert

The division of labor has typically been portrayed as a complementary strategy in which men and women work on separate tasks to achieve a common goal of provisioning the family. In this paper, we propose that task specialization between female kin might also play an important role in women’s social and economic strategies. We use historic group composition data from a population of Western Desert Martu Aborigines to show how women maintained access to same-sex kin over the lifespan. Our results show that adult women had more same-sex kin and more closely related kin present than adult men, and they retained these links after marriage. Maternal co-residence was more prevalent for married women than for married men, and there is evidence that mothers may be strategizing to live with daughters at critical intervals—early in their reproductive careers and when they do not have other close female kin in the group. The maintenance of female kin networks across the lifespan allows for the possibility of cooperative breeding as well as an all-female division of labor.     

Sexual Division of Labor in African Agriculture: A Network Autocorrelation Analysis

A model of causes and consequences of sexual division of labor in agriculture is tested using a sample of African societies. Crop type and the presence or absence of slavery are shown to be effective predictors of the degree of female contribution to agricultural subsistence, and the degree of polygyny is shown to be affected by female agricultural contribution and the form of residence. Autocorrelation effects are found and are shown to be a consequence of Bantu societies having higher female participation in agriculture than would otherwise be expected. This effect is an example of one of the kinds of phenomena that anthropologists have referred to as Galton's problem . [sexual division of labor, cultural ecology, Galton's Problem, Africa]     

Environmental constraints upon locomotion and predator-prey interactions in aquatic organisms: an introduction

Environmental constraints in aquatic habitats have become topics of concern to both the scientific community and the public at large. In particular, coastal and freshwater habitats are subject to dramatic variability in various environmental factors, as a result of both natural and anthropogenic processes. The protection and sustainable management of all aquatic habitats requires greater understanding of how environmental constraints influence aquatic organisms. Locomotion and predator-prey interactions are intimately linked and fundamental to the survival of mobile aquatic organisms. This paper summarizes the main points from the review and research articles which comprise the theme issue 'Environmental constraints upon locomotion and predator-prey interactions in aquatic organisms'. The articles explore how natural and anthropogenic factors can constrain these two fundamental activities in a diverse range of organisms from phytoplankton to marine mammals. Some major environmental constraints derive from the intrinsic properties of the fluid and are mechanical in nature, such as viscosity and flow regime. Other constraints derive from direct effects of factors, such as temperature, oxygen content of the water or turbidity, upon the mechanisms underlying the performance of locomotion and predator-prey interactions. The effect of these factors on performance at the tissue and organ level is reflected in constraints upon performance of the whole organism. All these constraints can influence behaviour. Ultimately, they can have an impact on ecological performance. One issue that requires particular attention is how factors such as temperature and oxygen can exert different constraints on the physiology and behaviour of different taxa and the ecological implications of this. Given the multiplicity of constraints, the complexity of their interactions, and the variety of biological levels at which they can act, there is a clear need for integration between the fields of physiology, biomechanics, behaviour, ecology, biological modelling and evolution in both laboratory and field studies. For studies on animals in their natural environment, further technological advances are required to allow investigation of how the prevailing physico-chemical conditions influence basic physiological processes and behaviour.     

Synergy from reproductive division of labor and genetic complexity drive the evolution of sex

Computer experiments that mirror the evolutionary dynamics of sexual and asexual organisms as they occur in nature were used to test features proposed to explain the evolution of sexual recombination. Results show that this evolution is better described as a network of interactions between possible sexual forms, including diploidy, thelytoky, facultative sex, assortation, bisexuality, and division of labor between the sexes, rather than a simple transition from parthenogenesis to sexual recombination. Diploidy was shown to be fundamental for the evolution of sex; bisexual reproduction emerged only among anisogamic diploids with a synergistic division of reproductive labor; and facultative sex was more likely to evolve among haploids practicing assortative mating. Looking at the evolution of sex as a complex system through individual-based simulations explains better the diversity of sexual strategies known to exist in nature, compared to classical analytical models.     

Sexual dimorphism in human lower limb bone structure: relationship to subsistence strategy and sexual division of labor

Cross-sectional geometric properties of the human femur and tibia are compared in males and females in a number of recent and archaeological population samples extending back to the Middle Paleolithic. There is a consistent decline in sexual dimorphism from hunting-gathering to agricultural to industrial subsistence strategy levels in properties which measure relative anteroposterior bending strength of the femur and tibia in the region about the knee. This trend parallels and is indicative of reductions in the sexual division of labor, in particular differences in the relative mobility of males and females. Sexual dimorphism in mediolateral bending strength near the hip shows no consistent temporal trend, probably reflecting relatively constant sex differences in pelvic structure related to the requirements of childbirth. Upper and Middle Paleolithic samples are indistinguishable in terms of sexual dimorphism from modern huntergatherers, suggesting a similar sexual division of labor. The results illustrate the utility of cross-sectional geometric parameters of long bone diaphyses in reconstructing behavioral differences within and between past populations. Some variations in the accuracy of sexing techniques based on diaphyseal measurements of the lower limb long bones may also be explained by these behavioral and structural factors.     

"Husband and Wife Do It Together": Sex/Gender Allocation of Labor among the Qhawqhat Lahu of Lancang, Southwest China

In this article, I explore both the diversity and commonality of human labor organization in response to sex difference through an ethnographic study of the sex/gender allocation of labor among the Qhawqhat Lahu of Lancang, China. I argue that the principle of "unity," rather than the more commonly discussed "division," predominantly governs the gendered allocation of labor in Qhawqhat. I demonstrate that the Lahu ideal of gender unity, combined with their practical pursuit of optimal use of household laborers, foster an extraordinarily high degree of joint gender roles in child rearing, as well as in reproductive and productive activities in general. I also show that such an extreme sociocultural system minimizes (although it does not entirely negate) the impact of sex differences. This study may shed some light on the diversity and commonality of human labor organization in response to sex difference by bringing into dialogue more recent approaches to the issue and earlier studies of the "sexual division of labor." [sex/gender allocation of labor, sexual division of labor, anthropology of work, Lahu, China]     

Quantifying division of labor: borrowing tools from sociology,sociobiology, information theory,landscape ecology,and biogeography

How do we quantify division of labor? We review several fields (sociology, landscape ecology, statistics, information theory, and biogeography) that have been cognizant of these questions and been somewhat successful at answering them. We review fourteen indices for quantifying division of labor, sensu lato, which can be categorized into four families: Shannon’s index/entropy, Simpson’s index, geometric mean, and standard/absolute deviation (including coefficients of variation). We argue that those indices using matrix inputs will simultaneously quantify the interplay between all individuals and all tasks and will thus best capture the essence of division of labor. Received 29 March 2006; revised 16 November 2006; accepted 12 February 2007.     

The academic jungle: ecosystem modelling reveals why women are driven out of research

The number of women studying science and engineering at undergraduate and postgraduate levels has increased markedly in recent decades. However females have lower retention rates than males in these fields, and perform worse on average than men in terms of promotion and common research metrics. Two key differences between men and women are the larger role that women play in childcare and house work in most families, and the narrower window for female fertility. Here we explore how these two factors affect research output by applying a common ecological model to research performance, incorporating part‐time work and the duration of career prior to the onset of part‐time work. The model parameterizes the positive feedback between historical research output (i.e. track record) and current output, and the minimum threshold below which research output declines. We use the model to provide insight into how women (and men) can pursue a career in academia while working part‐time and devoting substantial time to their family. The model suggests that researchers entering a tenure track (teaching and research) role part‐time without an established track record in research will spend longer in the early career phase compared to full‐time academics, researchers without teaching commitments, and those who were beyond the early career phase prior to working part‐time. The results explain some of the mechanisms behind the observed difference between male and female performance in common metrics and the higher participation of women in teaching‐focussed roles. Based on this analysis, we provide strategies for researchers (particularly women) who want to devote substantial time to raising their families while still remaining engaged with their profession. We also identify how university leaders can enable part‐time academics to flourish rather than flounder. In particular, we demonstrate that careless application of metrics is likely to further reduce female participation in research, and so reduce the pool of talent available.     

Risky sexual behaviour among unmarried young people in Cameroon: another look at family environment

Most studies of the association between family structure and risky sexual behaviour among adolescents and young adults have employed a risk perspective which assumes that, compared with other types, two-parent families are protective. Drawing from a positive-oriented approach in this study, it is hypothesized that within each family type some influential factors may mitigate such anticipated deleterious effects of non-intact families and decrease sexual risk-taking. The paper examines specifically the effects of risk and protective factors with an emphasis on family processes associated with resilience, using data from a pooled sample of 1025 females and males aged 12-24 years from Bandjoun (West Cameroon). Findings show that the quality of parent/guardian-youth relationships significantly decreases the odds of risky sexual behaviour by 36%, 65% and 50% in neither-, one- and two-parent families, respectively. For two-parent families only, parental control acts as a significant protective factor; it decreased by 41% the odds of risky sexual behaviour. Programmatically, protective family factors such as parent/guardian-youth interactions need to be promoted to improve the efficiency of reproductive health and HIV interventions in sub-Saharan Africa.     

重点生态功能区农户生计对环境资源的依赖性——以甘南高原为例

重点生态功能区承担着重要的生态系统服务供给功能,农户作为该区主要的经济活动主体,其对环境资源过度依赖会严重影响该区的生态环境质量,从而使生态系统服务功能受损。当前亟需深入探索重点生态功能区农户生计对环境资源的依赖性及其影响因素,为制定环境友好型区域发展政策提供借鉴。本研究以甘南高原为例,基于581份农户调查数据,分析了农户生计对环境资源的依赖度,并利用有序多分类Logistic回归模型识别了影响农户环境资源依赖度的因素。结果表明: 甘南高原农户生计对环境资源的依赖度较高,其主要体现在食物自给、生活用能、收入来源3个方面,依赖度分别为57.3%、56.9%和37.4%;不同类型农户生计对环境资源的依赖性存在显著差异,劳动力受教育水平较高及非农化水平较高的农户,对环境资源的依赖度较低,而抚养比系数较高的农户对环境资源的依赖度较高;家庭抚养比、劳动力受教育水平、家庭成员领导能力、外出打工人数占劳动力比重、生态政策、海拔等因素均对农户的环境资源依赖度有显著影响。其中,家庭抚养比、海拔对其具有正向影响,而外出打工人数占劳动力比重、劳动力受教育水平、家庭成员领导能力、生态政策等因素对其表现为负向影响。     

Household extension and reproductive behaviour in Taiwan

The inflence of household type on reproductive behavior is examined for a national probability sample of Taiwanese women. Data were derived from a 1980 national household survey of the labor force in Taiwan, focusing on 10,624 couples. Reproductive variables include measures of current and prospective fertility as well as cumulative fertility. In spite of remarkable social and economic development over the past 3 decades, extended families are still widely found in Taiwan. Women in extended households have only slightly higher fertility preferences and current fertility than women in nuclear families once marital duration is controlled. Although women in extended households marry earlier and receive more family help with child care than women in nuclear families, such factors are no longer considered sufficient to produce major differentials in reproductive behavior. Residence and husband's class of work are the strongest correlates of whether a household is currently extended or nuclear. In general, the husband's characteristics are more strongly related to family type than the wife's. Findings suggest that preferences for smaller families and low fertility need not await a transformation to a nuclear family structue.     

Showing off: Tests of an hypothesis about men's foraging goals

It is widely assumed that among hunter-gatherers, men work to provision their families. However, men may have more to gain by giving food to a wide range of companions who treat them favorably in return. If so, and if some resources better serve this end, men's foraging behavior should vary accordingly. Aspects of this hypothesis are tested on observations of food acquisition and sharing among Ache foragers of Eastern Paraguay. Previous analysis showed that different Ache food types were differently shared. Resources shared most widely were game animals. Further analysis and additional data presented here suggest a causal association between the wide sharing of game and the fact that men hunt and women do not. Data show that men preferentially target resources in both hunting and gathering which are more widely shared, resources more likely to be consumed outside their own nuclear families. These results have implications for 1) the identification of male reproductive trade-offs in human societies, 2) the view that families are units of common interest integrated by the sexual division of labor, 3) current reconstructions of the evolution of foraging and food sharing among early hominids, and 4) assessments of the role of risk and reciprocity in hunter-gatherer foraging strategies.     

The domestic context of production and reproduction in a Guatemalan community

This paper investigates the relationship between fertility and domestic adjustments that people have made to changing conditions of production and consumption in a rural community in western Guatemala. Present and past systems of production and the domestic factors affecting the timing of family formation and the incidence of sexual activity within unions are described. Analyses of variance for demographic variables among three productive sectors reveals that the greatest changes in fertility over time have occurred in the families of labor-intensive garlic producers and in those of poor basketmaking specialists. The results are discussed as direct and indirect outcomes of earlier family formation due to recurrent labor crises and chronic subsistence stress.     

Marked Variability in the Extent of Protein Disorder within and between Viral Families

Intrinsically disordered regions in eukaryotic proteomes contain key signaling and regulatory modules and mediate interactions with many proteins. Many viral proteomes encode disordered proteins and modulate host factors through the use of short linear motifs (SLiMs) embedded within disordered regions. However, the degree of viral protein disorder across different viruses is not well understood, so we set out to establish the constraints acting on viruses, in terms of their use of disordered protein regions. We surveyed predicted disorder across 2,278 available viral genomes in 41 families, and correlated the extent of disorder with genome size and other factors. Protein disorder varies strikingly between viral families (from 2.9% to 23.1% of residues), and also within families. However, this substantial variation did not follow the established trend among their hosts, with increasing disorder seen across eubacterial, archaebacterial, protists, and multicellular eukaryotes. For example, among large mammalian viruses, poxviruses and herpesviruses showed markedly differing disorder (5.6% and 17.9%, respectively). Viral families with smaller genome sizes have more disorder within each of five main viral types (ssDNA, dsDNA, ssRNA+, dsRNA, retroviruses), except for negative single-stranded RNA viruses, where disorder increased with genome size. However, surveying over all viruses, which compares tiny and enormous viruses over a much bigger range of genome sizes, there is no strong association of genome size with protein disorder. We conclude that there is extensive variation in the disorder content of viral proteomes. While a proportion of this may relate to base composition, to extent of gene overlap, and to genome size within viral types, there remain important additional family and virus-specific effects. Differing disorder strategies are likely to impact on how different viruses modulate host factors, and on how rapidly viruses can evolve novel instances of SLiMs subverting host functions, such as innate and acquired immunity.     

Variation and covariation among life-history traits in Rumex acetosella from a successional old-field gradient

In this study morphological variation and the potential for competition to affect biomass and seedling selection of the families of five populations of Rumex acetosella L. sampled along a successional old-field gradient have been investigated. Seeds from 25 families were submitted to four competitive regimes: no competition (one plant per pot), medium competition (two plants/ pot taking plants from the same population), high within-population competition (four individuals from the same population in a pot) and high between-population competition (four individuals from two different populations in a pot). Eight traits were analysed after 3 months of growth for variation among families within populations. A significant difference among families within the two older populations was recorded for sexual biomass and related components. High sensitivity of these traits to density was observed in all populations except the youngest, suggesting specialization to particular environmental conditions in late successional populations, and a good adaptive capacity to buffer environmental variation in the pioneer population. Little significant interaction between competitive regimes and families within populations was found, i.e. genotypes within each population showed little variation in their response to environmental variation. Genotypic variance decreased with increasing competitive conditions for the majority of the traits. However, the percentage of variance in sexual reproduction explained by family was stable among treatments. Tradeoffs between vegetative reproduction and sexual reproduction were recorded at the population level along the successional gradient, with increasing competitive conditions. As succession proceeds, we observed a decrease in sexual reproduction and an increase in vegetative reproduction. At the family level, correlation among traits were similar when plants were grown in the absence of competition and at high density, with a significant negative correlation between sexual reproduction and vegetative reproduction. For both sprout number and sexual biomass, the performance of families grown under all the treatments was positively correlated. Together these results indicate allocational constraints on the reproductive biology of R. acetosella that may be favoured by natural selection and have influenced population differentiation along the successional gradient. However, they also revealed that the potential exists for evolutionary specialization through plasticity, in response to variation in environmental conditions.     

The evolutionary ecology of testicular function: size isn't everything

Larger testes are considered the quintessential adaptation to sperm competition. However, the strong focus on testis size in evolutionary research risks ignoring other potentially adaptive features of testicular function, many of which will also be shaped by post‐mating sexual selection. Here we advocate a more integrated research programme that simultaneously takes into account the developmental machinery of spermatogenesis and the various selection pressures that act on this machinery and its products. The testis is a complex organ, and so we begin by outlining how we can think about the evolution of testicular function both in terms of the composition and spatial organisation of the testis (‘testicular histology’), as well as in terms of the logical organisation of cell division during spermatogenesis (‘testicular architecture’). We then apply these concepts to ask which aspects of testicular function we can expect to be shaped by post‐mating sexual selection. We first assess the impact of selection on those traits most strongly associated with sperm competition, namely the number and kind of sperm produced. A broad range of studies now support our contention that post‐mating sexual selection affects many aspects of testicular function besides gross testis size, for example, to maximise spermatogenic efficiency or to enable the production of particular sperm morphologies. We then broaden our focus to ask how testicular function is affected by fluctuation in sperm demand. Such fluctuation can occur over an individual's lifetime (for example due to seasonality in reproduction) and may select for particular types of testicular histology and architecture depending on the particular reproductive ecology of the species in question. Fluctuation in sperm demand also occurs over evolutionary time, due to shifts in the mating system, and this may have various consequences for testicular function, for example on rates of proliferation‐induced mutation and for dealing with intragenomic conflict. We end by suggesting additional approaches that could be applied to study testicular function, and conclude that simultaneously considering the machinery, products and scheduling of spermatogenesis will be crucial as we seek to understand more fully the evolution of this most fundamental of male reproductive traits.