Infant feeding practice in medieval Japan: Stable carbon and nitrogen isotope analysis of human skeletons from Yuigahama-minami

Co-Evolution of Breast Milk Lipid Signaling and Thermogenic Adipose Tissue

Breastfeeding is a unique and defining behavior of mammals and has a fundamental role in nourishing offspring by supplying a lipid-rich product that is utilized to generate heat and metabolic fuel. Heat generation from lipids is a feature of newborn mammals and is mediated by the uncoupling of mitochondrial respiration in specific fat depots. Breastfeeding and thermogenic adipose tissue have a shared evolutionary history: both have evolved in the course of homeothermy evolution; breastfeeding mammals are termed “thermolipials”, meaning “animals with warm fat”. Beyond its heat-producing capacity, thermogenic adipose tissue is also necessary for proper lipid metabolism and determines adiposity in offspring. Recent advances have demonstrated that lipid metabolism in infants is orchestrated by breast milk lipid signals, which establish mother-to-child signaling and control metabolic development in the infant. Breastfeeding rates are declining worldwide, and are paralleled by an alarming increase in childhood obesity, which at least in part may have its roots in the impaired metabolic control by breast milk lipid signals.

Cribra orbitalia is correlated with the meningo-orbital foramen and is vascular and developmental in nature

Cribra orbitalia is a phenomenon with interdisciplinary interest. However, the etiology of cribra orbitalia remains unclear. Recently, the appearance of cribra orbitalia was identified as vascular in nature. This study assessed the relationship between anatomical variation of vasculature, as determined by the presence of meningo-orbital foramina, and the presence of cribra orbitalia in 178 orbits. Cribra orbitalia was identified in 27.5% (49:178) of orbits (22.7%, 35:154 adult orbits and 58.3%, 14:24 subadult orbits) and meningo-orbital foramina were identified in 65.8% (100:152) of orbits. Among the 150 total intact adult orbits (i.e., orbital roof and posterior orbits both intact), cribra orbitalia was found in 35 (23.3%). Of these 35 occurrences of cribra orbitalia, 32 (91.4%) had the concurrent finding of a meningo-orbital foramen. However, in the absence of the meningo-orbital foramen, cribra orbitalia was only found in three sides out of the total sample of intact orbits (3:150; 2.0%). Fisher's exact test revealed that the presence of cribra orbitalia and the meningo-orbital foramen were statistically dependent variables (p = .0002). Visual evidence corroborated statistical findings-vascular impressions joined cribra orbitalia to meningo-orbital foramina. This study identifies that individuals who possess a meningo-orbital foramen are anatomically predisposed to developing cribra orbitalia. Conversely, cribra orbitalia is unlikely to occur in an individual who does not possess a meningo-orbital foramen. Thus, the antecedent of cribra orbitalia is both vascular and developmental in nature. This report represents an important advancement in the understanding of cribra orbitalia-there is an anatomical predisposition to the development of cribra orbitalia.

Toward a bioarchaeology of urbanization: Demography, health, and behavior in cities in the past

Urbanization is one of the most important settlement shifts in human history and has been the focus of research within bioarchaeology for decades. However, there have been limited attempts to synthesize the results of these studies in order to gain a broader perspective on whether or how urbanization affects the biology, demography, and behavior of humans, and how these potential effects are embodied in the human skeleton. This paper outlines how bioarchaeology is well-suited to examine urbanization in the past, and we provide an overview and examples of three main ways in which urbanization is studied in bioarchaeological research: comparison of (often contemporaneous) urban and rural sites, synchronic studies of the variation that exists within and between urban sites, and investigations of changes that occur within urban sites over time. Studies of urbanization, both within bioarchaeology and in other fields of study, face a number of limitations, including a lack of a consensus regarding what urban and urbanization mean, the assumed dichotomous nature of urban versus rural settlements, the supposition that urbanization is universally bad for people, and the assumption (at least in practice) of homogeneity within urban and rural populations. Bioarchaeologists can address these limitations by utilizing a wide array of data and methods, and the studies described here collectively demonstrate the complex, nuanced, and highly variable effects of urbanization.

Weaning and stunting affect nitrogen and carbon stable isotope natural abundances in the hair of young children

Natural abundances of stable nitrogen and carbon isotopes (δ¹⁵N and δ¹³C) can vary with both dietary intake and metabolic (specifically catabolic) state. In low-income countries, weaning is a period of dietary transition from milk to plant-based foods and a high-risk period for malnutrition. We explored how diet and malnutrition impact hair δ¹⁵N and δ¹³C in young children by an observational, cross-sectional study in Cox’s Bazar District, Bangladesh [255 children, 6–59 months with 19.6% wasted (7.1% severely) and 36% stunted (9.8% severely)]. Hair δ¹⁵N and δ¹³C exhibited exponential decreases with age, with the loss of one trophic level (3.3‰ and 0.8‰, respectively) from 6 to 48 months, which we associate with the shift from exclusive breastfeeding to complete weaning. After adjustment for age and breastfeeding status, hair isotopic values were unaffected by wasting but lower in severe stunting (−0.45‰ to −0.6‰, P < 0.01). In this population of young children, whose isotopic values in hair primarily depended on age, we failed to observe any effect of wasting, likely due to opposite, compensating effects between dietary and metabolic changes involved. In contrast, we evidenced low δ¹⁵N and δ¹³C values in severely stunted children that likely indicate chronic exposure to diets low in animal products.

Post-weaning diet in archaeological human populations: A meta-analysis of carbon and nitrogen stable isotope ratios of child skeletons

OBJECTIVES

Childhood is a unique stage in human life history, in which subadults have completed their weaning process but are still dependent on older individuals for survival. Although the importance of food provisioning during childhood has been intensively discussed, childhood diet in the past has rarely been studied in a systematic manner.

METHODS

In this study, a meta-analysis of carbon and nitrogen stable isotope ratios of post-weaning children (PWC) in Holocene human populations around the world is presented. The isotope ratios of PWC were standardized with those of adult females and males in the same population, and they were analyzed in terms of the difference in subsistence.

RESULTS

Results of this study indicate that diets of PWC and adults were generally similar (most differences were within the range of ±1‰), which is consistent with the universal feature of food provisioning to PWC in humans. In hunter-gatherer populations, there is no significant difference between PWC and adult isotope ratios. In non-hunter-gatherer populations, however, PWC probably consumed significantly larger proportions of foods from lower trophic levels than did the adults, and such foods would be terrestrial C₃ plants.

CONCLUSIONS

Potential factors relating to the dietary differences among PWC and adults are presented from a perspective of balance between food provisioning and self-acquisition by PWC. Significant isotopic differences between PWC and adults in non-hunter-gatherer populations revealed in this study have implications for declined health during the subsistence transition in Holocene, isotopic studies using human tooth enamel, and "δ¹⁵ N dip" of subadults after weaning.

Breastfeeding over two years is associated with longer birth intervals, but not measures of growth or health, among children in Kilimanjaro, TZ

OBJECTIVES

Breastfeeding has been associated with numerous health and well-being benefits for both children and their mothers, including prolonging the birth interval to the subsequent sibling. The clearest associations between breastfeeding and health outcomes, per se, reflect exclusive breastfeeding in the first months of postnatal life and are most evident during infancy. Fewer studies explore the consequences of breastfeeding for multiple years. In this article, we ask whether breastfeeding for more than 2 years is associated with discernible health and well-being benefits to children.

METHODS

Data were collected from 315 children, aged 2 to 7, and their caretakers residing in Kilimanjaro, Tanzania. Basic demographic and health information was solicited, and anthropometric and blood markers of health were evaluated.

RESULTS

Our results indicate a strong positive relationship between breastfeeding for 2 or more years and interbirth interval, but little evidence for a relationship between prolonged breastfeeding and several indicators of child growth and health.

CONCLUSIONS

We suggest that these relationships may support the recently rekindled birth spacing hypothesis, positing selection for longer interbirth intervals, rather than, or in addition to, more direct health benefits associated with breastfeeding for 2 or more years. Our results may indicate attenuating health benefits associated with longer breastfeeding.