No relationship found between dental fluctuating asymmetry, birthweight, and birth term in two modern North American samples

OBJECTIVE

Deciduous dental crowns primarily develop during gestation and early infancy and embody early life stress exposures. Composite measures of dental fluctuating asymmetry (DFA) generated from the deciduous teeth may therefore indicate cumulative gestational stress in developmental origins of health and disease (DOHaD) studies. This study examines whether higher composite measures of deciduous DFA are associated with low birthweight and prematurity, two aspects of birth phenotype consistently associated with increased morbidity and mortality risks in adulthood.

SUBJECTS AND METHODS

We evaluated associations between composite deciduous DFA, birthweight, and birth term in two contemporary North American samples: an autopsy sample from New Mexico (n = 94), and sample from a growth cohort study in Burlington, Ontario (n = 304). Dental metric data for each sample was collected from postmortem CT scans and dental casts, respectively. Composite DFA was estimated using buccolingual (BL) and mesiodistal (MD) crown diameters from paired deciduous teeth.

RESULTS

Contrary to expectations, the results of linear regression indicated no significant relationship between birthweight and DFA, or birth term and DFA, in either sample.

CONCLUSIONS

Deciduous DFA does not predict aspects of birth phenotype associated with gestational stress. Birthweight and birth term are plastic relative to the more developmentally stable deciduous dentition, which may only subtly embody early life stress. We suggest that deciduous DFA should be utilized with caution in DOHaD studies until its relationship with gestational stress is clarified.

The energetics of childhood: Current knowledge and insights into human variation, evolution, and health

How organisms capture and ultimately use metabolic energy-a limiting resource of life-has profound implications for understanding evolutionary legacies and current patterns of phenotypic variation, adaptation, and health. Energetics research among humans has a rich history in biological anthropology and beyond. The energetics of childhood, however, remains relatively underexplored. This shortcoming is notable given the accepted importance of childhood in the evolution of the unique human life history pattern as well as the known sensitivity of childhood development to local environments and lived experiences. In this review, I have three objectives: (1) To overview current knowledge regarding how children acquire and use energy, highlighting work among diverse human populations and pointing to recent advances and remaining areas of uncertainty; (2) To discuss key applications of this knowledge for understanding human variation, evolution, and health; (3) To recommend future avenues for research. A growing body of evidence supports a model of trade-offs and constraint in childhood energy expenditure. This model, combined with advancements on topics such as the energetics of immune activity, the brain, and the gut, provides insights into the evolution of extended human subadulthood and the nature of variation in childhood development, lifetime phenotype, and health.

The pathological anatomical collection of the Natural History Museum Vienna

The pathological anatomical collection Vienna (Pathologisch-Anatomische Sammlung Wien; PASW) is a living and still growing research collection. It was established as early as 1796 as part of the Medical University of Vienna, acquired the status of an independent federal museum in 1971, and was assigned to the Natural History Museum Vienna in 2012. It houses a wide range of human wet and dry specimens and further objects, such as moulages, medical devices, microbiological and histological specimens, and a photo archive (approximately 50,000 objects), which, as a meaningful source, may contribute to disclosing not only aspects of the medical history and the development of corresponding museums in Vienna, but is also considered a collection of cultural and current scientific relevance, quite comparable to today's biobanks. Most of the tissue amassment represents wet organic specimens and human skeletons or skeletal elements representing, e.g., congenital and metabolic disorders, infectious diseases, injuries, neoplasms, or musculoskeletal diseases, basically collected as descriptive anatomical teaching aids. This article reviews the current medical issues on which research has been and is being conducted by including PASW specimens (hereby using the ICD-10 code), and the extent to and ethical conditions under which this important heritage could be used as a reference collection for clinical and bioanthropological (paleopathological and palaeoepidemiological) studies; finally, this article reflects on the value and future research prospects, taking into account different positions and the ongoing discussions in pathological anatomical human tissue collections.

Sexual minority status is associated with earlier recalled age of menarche: Evidence from the 2005-2016 National Health and Nutrition Examination Survey

INTRODUCTION

Menarcheal timing is associated with growth, development, health, wellbeing, and reproduction across the lifespan. Although sexual orientation is a known correlate of health and developmental inequities, relatively little evolutionarily framed research has investigated sexual orientation-based variation in maturational timing. To improve our understanding of menarcheal timing among sexual minority (SM) people, we use a biocultural-evolutionary life history lens that takes into account the stresses of minoritization to examine the relationship between sexual orientation and self-reported age at menarche in a sample of American adults.

METHODS

Using the U.S. National Health and Nutrition Examination Survey (NHANES), a large, nationally representative dataset (n = 9757), we fit multiple logistic regression models and survival curves to evaluate associations between sexual orientation, indicators of somatic and material resources during adolescence (e.g., education, citizenship, upper arm length), and self-reported menarche.

RESULTS

SM respondents were more likely to report earlier (by 4-5 months) ages of menarche (p < .001). Post-hoc tests revealed that these differences were driven by bisexual (p < .001) and same-sex experienced (p < .001) relative to heterosexual and lesbian/gay respondents. Earlier menarcheal timing among SM respondents persisted after adjusting for socio-demographic factors and proxies of developmental conditions.

DISCUSSION

Our findings reveal that SM status is associated with earlier ages of menarche, an important social and reproductive milestone. We argue that uniting life history theory with the minority stress hypothesis better explains differences in menarcheal timing by sexual orientation than previous paradigms. Investigators should attend to sexual orientation-based variation in maturational timing using holistic, inclusive approaches.

Prediction model for gestational diabetes mellitus using the XG Boost machine learning algorithm

OBJECTIVE

To develop the extreme gradient boosting (XG Boost) machine learning (ML) model for predicting gestational diabetes mellitus (GDM) compared with a model using the traditional logistic regression (LR) method.

METHODS

A case-control study was carried out among pregnant women, who were assigned to either the training set (these women were recruited from August 2019 to November 2019) or the testing set (these women were recruited in August 2020). We applied the XG Boost ML model approach to identify the best set of predictors out of a set of 33 variables. The performance of the prediction model was determined by using the area under the receiver operating characteristic (ROC) curve (AUC) to assess discrimination, and the Hosmer-Lemeshow (HL) test and calibration plots to assess calibration. Decision curve analysis (DCA) was introduced to evaluate the clinical use of each of the models.

RESULTS

A total of 735 and 190 pregnant women were included in the training and testing sets, respectively. The XG Boost ML model, which included 20 predictors, resulted in an AUC of 0.946 and yielded a predictive accuracy of 0.875, whereas the model using a traditional LR included four predictors and presented an AUC of 0.752 and yielded a predictive accuracy of 0.786. The HL test and calibration plots show that the two models have good calibration. DCA indicated that treating only those women whom the XG Boost ML model predicts are at risk of GDM confers a net benefit compared with treating all women or treating none.

CONCLUSIONS

The established model using XG Boost ML showed better predictive ability than the traditional LR model in terms of discrimination. The calibration performance of both models was good.

More voices are always better: Tackling power differentials in knowledge production and access in human biology

OBJECTIVE

Academic human biology seeks to characterize and explain human biocultural variation in terms of adaptations to local environments. Understanding and educating about such variation, if not carried out thoughtfully, can reinforce power asymmetries around who can produce and access the knowledge, and in what ways and places. One of many factors contributing to power inequities in knowledge production and access concerns histories of state-driven colonization, with people(s) dispossessed of land through colonization generally having relatively less power. Because human biologists disproportionately work with communities/sub-populations living in marginal environments, most of which have been moved, dispossessed, and/or reconfigured through colonization, we are prone to reproducing these land-related power imbalances but we are also well-situated to level them.

METHODS

Here, we do three things we hope will move us toward research and teaching practices that recognize and begin to disrupt colonial power inequities in human biology knowledge production and access.

RESULTS

First, after defining terms core to understanding the power matrices at stake, we outline likely benefits to human biologists of using anticolonial approaches. Second, we highlight two frameworks offering anticolonial tools (community-based participatory research and "two-eyed seeing"). Third, we suggest several practical, behavioral changes to make and skills to develop for human biologists looking to shift power balances.

CONCLUSION

We conclude by reflecting on our own positions along the colonially rooted power gradients structuring human biology. We argue that doing so constitutes an essential early step toward creating anticolonial spaces for more ethical and just production, consumption, and application of knowledge.

Heterogeneous frailty and the expression of linear enamel hypoplasia in a genealogical population

OBJECTIVES

Linear enamel hypoplasia (LEH) is a common skeletal marker of physiological stress (e.g., malnutrition or illness) that is studied within and across populations, without reference to familial risk. We examine LEH prevalence in a population with known genealogical relationships to determine the potential influence of genetic heritability and shared environment.

METHODS

LEH data of 239 individuals from a single population were recorded from the Ohio State University Menegaz-Bock collection dental casts. All individuals were of known age, sex, and genealogy. Narrow-sense heritability estimates were obtained for LEH presence and count data from all unworn, fully erupted teeth (excluding third molars) using SOLAR (v.8.1.1). Age, sex, and age-sex interaction were included as covariates. Models were re-run with a household effect variable.

RESULTS

LEH persists across generations in this study population with moderate, significant heritability estimates for presence in four teeth, and count in four teeth (three teeth were significant for both). When a household effect variable was added, no residual heritability remained for LEH count on any tooth. There was no significant household effect for three of the four teeth that had significant heritability estimates for LEH presence. Age was a significant covariate. Further analyses with birth year data revealed a secular trend toward less LEH.

CONCLUSIONS

This study provides evidence for familial risk of LEH (genetic and environmental) that has consequences for the broad use of this skeletal marker of stress. These results have repercussions for archaeological assemblages, or population health studies, where genetic relatives and household groups might be heavily represented.