Search

Objectives: Biological mortality bias is the idea that individuals who perish (non‐survivors) are biologically distinct from those who survive (survivors). If biological mortality bias is large enough, bioarchaeological studies of nonsurvivors (skeletal samples) cannot accurately represent the experiences of the survivors of that population. This effect is particularly problematic for the study of juvenile individuals, as growth is particularly sensitive to environmental insults. In this study, we test whether biological mortality bias exists in one dimension of growth, namely dental development. Materials and methods: Postmortem computed tomography scans of 206 children aged 12 years and younger at death were collected from two institutions in the United States and Australia. The sample was separated into children dying from natural causes as proxies for non‐survivors and from accidental causes as proxies for survivors. Differences in the timing of dental development were assessed using sequential logistic regressions between dental formation stages and residual analysis of dental minus chronological age. Results: No consistent delay in age of attainment of dental stages was documented between survivors and non‐survivors. Delays between survivors and non‐survivors in dental relative to chronological age were greatest for infants, and were greater for females than for males. Discussion Lack of biological mortality bias in dental development reinforces confidence in juvenile age estimates and therefore in skeletal growth profiles and growth studies. As dental development is known to be less environmentally sensitive than skeletal growth and development, further studies should examine biological mortality bias in long bone length. [ABSTRACT FROM AUTHOR]

Objectives: Previous studies have demonstrated the need for regionally specific stature estimation formulae due to the geographical specificity of limb proportionality related to the effects of environmental pressures on growth and development. High‐altitude Andean populations have often been neglected in the creation of these formulae. This study uses a hybrid approach to create linear regression formulae for stature estimation and test their accuracy when compared previously published formulae traditionally used in Andean bioarchaeology. Materials and Methods: We studied a sample from a high‐altitude Andean population to create linear regression formulae based on anatomical estimates of stature from the femur, tibia, and calcaneus and compare the newly created formulae with those traditionally employed in Andean bioarchaeology. We also examine the reliability of calcanei in stature estimation by creating and testing regression formulae based on metrics from that element. Results: We include specific formulae accurate to within 1 cm of anatomical stature estimates using femoral, tibial, and calcaneal metrics. These formulae provide estimates that are closer to anatomical stature than those traditionally used in the Andes. ANOVA results were statistically significant for differences between Andean‐derived and Mesoamerican‐derived formulae. Discussion: Although regionally proximate (mid‐altitude) formulae provide estimates approximating population‐specific formulae, those created from geographically distant populations from sites at or near sea‐level are inappropriate in high‐altitude studies. Like some previous studies on stature, we found that the most accurate estimates were based on the tibia rather than the femur and that the calcaneus can be used reliably in stature estimation when no other element is present or measurable. [ABSTRACT FROM AUTHOR]

Objective: This study aims to develop a comparative basis for assessing the developmental stage of KNM‐ER 42700 based on the ontogenetic pattern of the ectocranial surface of the basicranium in modern humans and chimpanzees. Materials and methods: A total of 33 landmarks were collected from an ontogenetic sample of modern humans (80), chimpanzees (51), and 12 individuals classified as Homo erectus s.l. Ontogenetic trajectories were analyzed, and common aspects were extracted for the purpose of discriminating age groups. A regression of size on the extracted shape variables was used to investigate common ontogenetic allometry. Results: The basicranial development of chimpanzees and humans follows different trajectories; however, similarities are also present. The common shape component of development extracted can be used to define age groups in both chimpanzees and modern humans. The extracted shape component presents a similar ontogenetic and static‐allometric pattern in these two species. The developmental stages of H. erectus s.l. specimens were attributed following these common traits. Our analysis correctly assigned developmental stages to those specimens of H. erectus for which developmental ages are known. Discussion: The component used for assessing the developmental stage has an ontogenetic allometric component. However, this shape component can discriminate age group irrespective of size and is no longer related to size when static allometry is considered. Adult H. erectus s.l. specimens were attributed to the adult category. KNM‐WT 15000 fell with the late juvenile age group, whereas D2700 plotted in the region of overlap between the juvenile and adult age groups and Mojokerto with the younger age groups, as predicted by their known developmental ages. KNM‐ER 42700 fell within the adult variability despite its incompletely fused spheno‐occipital synchondrosis. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: Population‐specific growth references are important in understanding local growth variation, especially in developing countries where child growth is poor and the need for effective health interventions is high. In this article, we use mixed longitudinal data to calculate the first growth curves for rural East Timorese children to identify where, during development, deviation from the international standards occurs. Materials and methods: Over an eight‐year period, 1,245 children from two ecologically distinct rural areas of Timor‐Leste were measured a total of 4,904 times. We compared growth to the World Health Organization (WHO) standards using z‐scores, and modeled height and weight velocity using the SuperImposition by Translation And Rotation (SITAR) method. Using the Generalized Additive Model for Location, Scale and Shape (GAMLSS) method, we created the first growth curves for rural Timorese children for height, weight and body mass index (BMI). Results: Relative to the WHO standards, children show early‐life growth faltering, and stunting throughout childhood and adolescence. The median height and weight for this population tracks below the WHO fifth centile. Males have poorer growth than females in both z‐BMI (p = .001) and z‐height‐for‐age (p = .018) and, unlike females, continue to grow into adulthood. Discussion: This is the most comprehensive investigation to date of rural Timorese children's growth, and the growth curves created may potentially be used to identify future secular trends in growth as the country develops. We show significant deviation from the international standard that becomes most pronounced at adolescence, similar to the growth of other Asian populations. Males and females show different growth responses to challenging conditions in this population. [ABSTRACT FROM AUTHOR]

Objectives Dental morphology plays a key role in reconstructing population history and evolutionary relationships at global, regional, and intracemetery scales. At the inter-individual level, it is assumed that close biological kin exhibit greater phenotypic similarity than non-relatives. Heritability estimates provide one measure of phenotypic resemblance but are not easily incorporated into analyses of archaeological samples. In this study we evaluate the assumption that relatives are more similar phenotypically than non-relatives. We compare results for permanent dental morphology to those obtained using deciduous dental morphology in a matched dataset (Paul & Stojanowski, ). Materials and Methods Permanent trait expression was scored from dental casts representing 69 sibling pairs, curated as part of the longitudinal Burlington Growth Study. Simulating a biodistance approach, 22 morphological traits of permanent tooth crowns were used to generate 69 inter-relative and 2,076 non-relative Euclidean distances. Following distance ordination, family-specific dispersion values were calculated from multidimensional scaling coordinates. Output was compared to that of a previous study that focused on deciduous crown variation in the same set of individuals (Paul & Stojanowski, ). Mantel tests were used to evaluate the correlation of a proxy genetic distance matrix to both the permanent and deciduous dental distance matrices. Results On average, inter-relative distances generated from morphological traits of permanent tooth crowns were smaller than expected by chance based on resampling ( p < 0.001). While family-specific dispersion varied greatly for both permanent and deciduous datasets, over 75% of the families exhibited greater dispersion with permanent traits. This suggests that morphological traits of the permanent dentition provide a less faithful reflection of biological relatedness than morphological traits of the deciduous dentition. Mantel tests indicate that both the deciduous and permanent distance matrices are significantly correlated with a matrix of genetic relatedness coefficients; however, the magnitude of the correlations was low. Discussion Overall, morphological traits of permanent tooth crowns perform moderately well in distinguishing relatives from non-relatives, but deciduous crown variations may provide a more direct reflection of the underlying genetic structure of intra-site or intra-cemetery samples. These findings have implications for bioarchaeological research and biodistance practices. In particular, morphological traits of the deciduous dentition should be incorporated into standard data collection protocols because of their stronger signal of relatedness. [ABSTRACT FROM AUTHOR]

Multiple stressors affect developing and adult organisms, thereby partly structuring their phenotypes. Determining how stressors influence health, well-being, and longevity in human and nonhuman primate populations are major foci within biological anthropology. Although much effort has been devoted to examining responses to multiple environmental and sociocultural stressors, no holistic metric to measure stress-related physiological dysfunction has been widely applied within biological anthropology. Researchers from disciplines outside anthropology are using allostatic load indices (ALIs) to estimate such dysregulation and examine life-long outcomes of stressor exposures, including morbidity and mortality. Following allostasis theory, allostatic load represents accumulated physiological and somatic damage secondary to stressors and senescent processes experienced over the lifespan. ALIs estimate this wear-and-tear using a composite of biomarkers representing neuroendocrine, cardiovascular, metabolic, and immune systems. Across samples, ALIs are associated significantly with multiple individual characteristics (e.g., age, sex, education, DNA variation) of interest within biological anthropology. They also predict future outcomes, including aspects of life history variation (e.g., survival, lifespan), mental and physical health, morbidity and mortality, and likely health disparities between groups, by stressor exposures, ethnicity, occupations, and degree of departure from local indigenous life ways and integration into external and commodified ones. ALIs also may be applied to similar stress-related research areas among nonhuman primates. Given the reports from multiple research endeavors, here we propose ALIs may be useful for assessing stressors, stress responses, and stress-related dysfunction, current and long-term cognitive function, health and well-being, and risk of early mortality across many research programs within biological anthropology. [ABSTRACT FROM AUTHOR]

ABSTRACT Objectives: A 'dip' in the stable nitrogen isotope ratios (δ15N) of subadults in the late weaning/early post-weaning phase of growth and development has been observed. Speculatively, this is the mechanism of positive nitrogen balance operating among rapidly growing subadults. An alternate hypothesis for δ15N dips is that during weaning, subadults eat lower-15N foods than adults. Methods: This study explores the role of positive nitrogen balance in affecting δ15N variation of growing subadults by comparing growth velocity with stable carbon isotope (δ13C) and δ15N ratios of blood serum from captive rhesus macaques ( Macaca mulatta) ( n = 14) with controlled diets during the first 10 months of life. Results: During the first six months, δ15N values are inversely correlated with growth in some of the anthropometrics (weight and sagittal circumference). Dips in some infants' δ15N values below their mothers' values are observed at the end of the weaning period. However, during this time frame, δ15N values of the infants are not correlated with anthropometric indices. Serum stable isotope ratios of lactating and non-lactating adult females differ significantly. Conclusions: Growth in body mass and size explains some of the variation in infant δ15N values, but are not responsible for dips in the late weaning/early post-weaning phase. It is advised that future research evaluate the extent to which growth in other body systems affects nitrogen balance and δ15N dips during ontogeny, and expand on isotopic differences between lactating and non-lactating females. Am J Phys Anthropol 157:347-357, 2015. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Objectives: A "dip" in the stable nitrogen isotope ratios (δ(15)N) of subadults in the late weaning/early post-weaning phase of growth and development has been observed. Speculatively, this is the mechanism of positive nitrogen balance operating among rapidly growing subadults. An alternate hypothesis for δ(15)N dips is that during weaning, subadults eat lower-(15)N foods than adults., Methods: This study explores the role of positive nitrogen balance in affecting δ(15) N variation of growing subadults by comparing growth velocity with stable carbon isotope (δ(13)C) and δ(15)N ratios of blood serum from captive rhesus macaques (Macaca mulatta) (n = 14) with controlled diets during the first 10 months of life., Results: During the first six months, δ(15)N values are inversely correlated with growth in some of the anthropometrics (weight and sagittal circumference). Dips in some infants' δ(15)N values below their mothers' values are observed at the end of the weaning period. However, during this time frame, δ(15)N values of the infants are not correlated with anthropometric indices. Serum stable isotope ratios of lactating and non-lactating adult females differ significantly., Conclusions: Growth in body mass and size explains some of the variation in infant δ(15)N values, but are not responsible for dips in the late weaning/early post-weaning phase. It is advised that future research evaluate the extent to which growth in other body systems affects nitrogen balance and δ(15)N dips during ontogeny, and expand on isotopic differences between lactating and non-lactating females., (© 2015 Wiley Periodicals, Inc.)