Chronic undernutrition and traditional weaning foods are associated with fat stores in ariaal infants of Northern Kenya

Recent Research on the Human Biology of Pastoralists

Despite encroachment by agricultural systems and globalization, pastoral nomads maintain a robust presence in terms of numbers and subsistence activity. At the same time, increasing concern about climate change has promoted awareness that increased climatic fluctuation may push pastoral population past their capacity for resilience. The response of pastoralists to climate change has important implications for our evolutionary past and our increasingly problematic future. Yet, pastoralists have received less explicit attention than foragers as populations under consistent selective constraints including limited caloric intake, high levels of habitual activity, and high disease burdens. Additional factors include exposure to cold and high temperatures, as well as high altitude. Over the last 20 or so years, the use of new techniques for measuring energetics, including actigraphs and doubly labeled water have built on existing noninvasive sample collection for hormones, immune markers and genes to provide a more detailed picture of the human biology of pastoral populations. Here I consider recent work on pastoralists from Siberia and northern Europe, Africa, Asia, and South America. I survey what is known about maternal milk composition and infant health, childhood growth, lactase persistence, and adult energy expenditure and lactase persistence to build a picture of the pastoralist biological response to environmental conditions, including heat, cold, and high altitude. Where available I include information about population history because of its importance for selection. I end by outlining the impact of milk consumption and climate over the human life cycle and make suggestions for further research.

Perception of uncontrollable mortality risk is associated with food insecurity and reduced economic effort among resource-insecure college students during COVID-19

In the framework of the uncontrollable mortality risk hypothesis, resource scarcity intersects with mortality risk, shaping resource allocation strategies with enduring impacts on human health and wellbeing. Despite rising economic and food insecurity among US college students, little is known about how these insecurities relate to mortality risk, or how scarcity and mortality risk interact to shape college students' resource allocation strategies. We examine perceptions of resource scarcity and mortality risk and their associations with food insecurity and resource allocation strategies among economically insecure college students during COVID-19 lockdowns. Participants were recruited through an economic crisis response center at a major public university in the United States. A total of 118 participants completed an online Qualtrics survey assessing sociodemographic characteristics, perceptions of mortality risk and resource availability, food security, economic effort, and time perspective; a subset (n = 51) also participated in a telephone interview assessing psychological distress. In general, participants reported more environmental adversity and economic effort during COVID-19 lockdowns compared to before. Students experiencing higher levels of uncontrollable (and not controllable) mortality risk report lower levels of economic effort, and the association was strongest among students perceiving the fewest resources. We also found significant associations between uncontrollable mortality risk and food insecurity. Our results highlight uncontrollable mortality risk's influence on human well-being. Public health efforts should target the experiences and root structural causes of uncontrollable mortality risk, which among economically insecure college students increasingly involves food insecurity.

Using syndemic theory to understand food insecurity and diet-related chronic diseases

Syndemic Theory (ST) provides a framework to examine mutually enhancing diseases/health issues under conditions of social inequality and inequity. ST has been used in multiple disciplines to address interacting infectious diseases, noncommunicable diseases, and mental health conditions. The theory has been critiqued for its inability to measure disease interactions and their individual and combined health outcomes. This article reviews literature that strongly suggests a syndemic between food insecurity (FI) and diet-related chronic diseases (DRCDs), and proposes a model to measure the extent of such interaction. The article seeks to: (1) examine the potential syndemic between FI and DRCDs; (2) illustrate how the incorporation of Life History Theory (LHT), into a syndemic framework can help to highlight critical lifeperiods when FI-DRCD interactions result in adverse health outcomes; (3) discuss the use of mixed methods to identify and measure syndemics to enhance the precision and predictive power of ST; and (4) propose an analytical model for the examination of the FI-DRCD syndemic through the life course. The proposed model is more relevant now given the significant increase in FI globally as a result of the ongoing COVID-19 pandemic. The differential impact that the pandemic appears to have among various age groups and by other demographic factors (e.g., race, gender, income) offers an opportunity to examine the potential FI-DRCD syndemic under the lens of LHT.

Weaning practices among pastoralists: New evidence of infant feeding patterns from Bronze Age Eurasia

OBJECTIVES

This paper investigates infant feeding practices through stable carbon (δ¹³ C) and nitrogen (δ¹⁵ N) isotopic analyses of human bone collagen from Kamennyi Ambar 5, a Middle Bronze Age cemetery located in central Eurasia. The results presented are unique for the time period and region, as few cemeteries have been excavated to reveal a demographic cross-section of the population. Studies of weaning among pastoral societies are infrequent and this research adds to our knowledge of the timing, potential supplementary foods, and cessation of breastfeeding practices.

MATERIALS AND METHODS

Samples were collected from 41 subadults (<15 years) and 27 adults (15+ years). Isotopic reference sets from adult humans as well as faunal remains were utilized as these form the primary and complementary foods fed to infants.

RESULTS

Slight shifts in δ¹³ C and δ¹⁵ N values revealed that weaning was a multi-stage process (breastfeeding, weaning, and complete cessation of nursing) that began at 6 months of age, occurred over several years of early childhood, and was completed by 4 years of age.

DISCUSSION

Our results indicate that weaning was a multi-stage process that was unique among late prehistoric pastoralist groups in Eurasia that were dependent on milk products as a supplementary food. Our discussion centers on supporting this hypothesis with modern information on central and east Eurasian herding societies including the age at which complementary foods are introduced, the types of complementary foods, and the timing of the cessation of breastfeeding. Integral to this work is the nature of pastoral economies and their dependence on animal products, the impact of complementary foods on nutrition and health, and how milk processing may have affected nutrition content and digestibility of foods. This research on Eurasian pastoralists provides insights into the complexities of weaning among prehistoric pastoral societies as well as the potential for different complementary foods to be incorporated into infant diets in the past.