Lack of biological mortality bias in the timing of dental formation in contemporary children: Implications for the study of past populations.

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.

One size does not fit all. How universal standards for normal height can hide deprivation and create false paradoxes.

Public health practitioners and social scientists frequently compare height against one-size-fits-all standards of human growth to assess well-being, deprivation, and disease risk. However, underlying differences in height can make some naturally tall populations appear well-off by universal standards, even though they live in severe states of deprivation. In this article, I describe the worldwide extent of these population differences in height and illustrate how using a universal yardstick to compare population height can create puzzling disparities (eg, between South Asia and sub-Saharan Africa) while also underestimating childhood stunting in specific world regions (eg, West Africa and Haiti). I conclude by discussing potential challenges of developing and implementing population-sensitive standards for assessing healthy development.

A comparison of subadult skeletal and dental development based on living and deceased samples.

OBJECTIVES: A fundamental assumption in biological anthropology is that living individuals will present with different growth than non-survivors of the same population. The aim is to address the question of whether growth and development data of non-survivors are reflective of the biological consequences of selective mortality and/or stress. MATERIALS AND METHODS: The study compares dental development and skeletal growth collected from radiographic images of contemporary samples of living and deceased individuals from the United States (birth to 20 years) and South Africa (birth to 12 years). Further evaluation of deceased individuals is used to explore differential patterns among manners of death (MOD). RESULTS: Results do not show any significant differences in skeletal growth or dental development between living and deceased individuals. However, in the South African deceased sample the youngest individuals exhibited substantially smaller diaphyseal lengths than the living sample, but by 2 years of age the differences were negligible. In the US sample, neither significant nor substantial differences were found in dental development or diaphyseal length according to MOD and age (>2 years of age), though some long bones in individuals <2 years of age did show significant differences. No significant differences were noted in diaphyseal length according to MOD and age in the SA sample. DISCUSSION: The current findings refute the idea that contemporary deceased and living individuals would present with differential growth and development patterns through all of ontogeny as well as the assumptions linking short stature, poor environments, and MOD.

P > .05: The incorrect interpretation of "not significant" results is a significant problem.

Statistically nonsignificant (p > .05) results from a null hypothesis significance test (NHST) are often mistakenly interpreted as evidence that the null hypothesis is true-that there is "no effect" or "no difference." However, many of these results occur because the study had low statistical power to detect an effect. Power below 50% is common, in which case a result of no statistical significance is more likely to be incorrect than correct. The inference of "no effect" is not valid even if power is high. NHST assumes that the null hypothesis is true; p is the probability of the data under the assumption that there is no effect. A statistical test cannot confirm what it assumes. These incorrect statistical inferences could be eliminated if decisions based on p values were replaced by a biological evaluation of effect sizes and their confidence intervals. For a single study, the observed effect size is the best estimate of the population effect size, regardless of the p value. Unlike p values, confidence intervals provide information about the precision of the observed effect. In the biomedical and pharmacology literature, methods have been developed to evaluate whether effects are "equivalent," rather than zero, as tested with NHST. These methods could be used by biological anthropologists to evaluate the presence or absence of meaningful biological effects. Most of what appears to be known about no difference or no effect between sexes, between populations, between treatments, and other circumstances in the biological anthropology literature is based on invalid statistical inference.

Reliability of Physiological Responses Induced by Basic Emotions: A Pilot Study.

BACKGROUND: Although emotion-specific autonomic responses based on the discrete theory of emotion have been widely studied, studies on the reliability of physiological responses to emotional stimuli are limited. In this study, we aimed to assess the reliability of physiological changes induced by the six basic emotions (happiness, sadness, anger, fear, disgust, and surprise) that were measured during 10 weekly repeated experiments. METHODS: Twelve college students participated, and in each experiment, physiological signals were collected before and while participants were watching emotion-provoking film clips. Additionally, the participants self-evaluated the emotions that they experienced during the film presentation at the end of each emotional stimulus. To avoid adaptation of participants to identical stimuli during repeated measurements, we used 10 different film clips for each emotion, and thus a total of 60 film clips over 10 weeks were used. Physiological features, such as skin conductance level (SCL), fingertip temperature (FT), heart rate (HR), and blood volume pulse (BVP), were extracted from the physiological signals. Two reliability indices, Cronbach's alpha and intraclass correlation coefficient, were calculated from the physiological features to assess internal consistency and interrater reliability, respectively. RESULTS: We found that SCL, HR, and BVP measured during the emotion-provoking phase over the 10 weekly sessions were more reliable than those assessed at baseline. Furthermore, SCL, HR, and BVP from the emotion-provoking phase exhibited excellent internal consistency and interrater reliability. CONCLUSIONS: Our findings suggest that these features can be used as reliable physiological indices in emotion studies. The results also support the significance of physiological signals as meaningful indicators for emotion recognition in HCI (human computer interface) area.

Living with observational data in biological anthropology.

The establishment of cause and effect relationships is a fundamental objective of scientific research. Many lines of evidence can be used to make cause-effect inferences. When statistical data are involved, alternative explanations for the statistical relationship need to be ruled out. These include chance (apparent patterns due to random factors), confounding effects (a relationship between two variables because they are each associated with an unmeasured third variable), and sampling bias (effects due to preexisting properties of compared groups). The gold standard for managing these issues is a controlled randomized experiment. In disciplines such as biological anthropology, where controlled experiments are not possible for many research questions, causal inferences are made from observational data. Methods that statisticians recommend for this difficult objective have not been widely adopted in the biological anthropology literature. Issues involved in using statistics to make valid causal inferences from observational data are discussed.

A repeatable geometric morphometric approach to the analysis of hand entheseal three-dimensional form.

OBJECTIVES: The purpose of this study was to put forth a precise landmark-based technique for reconstructing the three-dimensional shape of human entheseal surfaces, to investigate whether the shape of human entheses is related to their size. The effects of age-at-death and bone length on entheseal shapes were also assessed. MATERIALS AND METHODS: The sample comprised high-definition three-dimensional models of three right hand entheseal surfaces, which correspond to 45 male adult individuals of known age. For each enthesis, a particular landmark configuration was introduced, whose precision was tested both within and between observers. The effect of three-dimensional size, age-at-death, and bone length on shape was investigated through shape regression. RESULTS: The method presented high intra-observer and inter-observer repeatability. All entheses showed significant allometry, with the area of opponens pollicis demonstrating the most substantial relationship. This was particularly due to variation related to its proximal elongated ridge. The effect of age-at-death and bone length on entheses was limited. DISCUSSION: The introduced methodology can set a reliable basis for further research on the factors affecting entheseal shape. Using both size and shape, variables can provide further information on entheseal variation and its biomechanical implications. The low entheseal variation by age verifies that specimens under 50 years of age are not substantially affected by age-related changes. The lack of correlation between entheseal shape and bone length or age implies that other factors may regulate entheseal surfaces. Future research should focus on multivariate shape patterns among entheses and their association with occupation.

What have we been looking at? A call for consistency in studies of primate vigilance.

Vigilance functions to detect threats. In primates, these threats emerge from both predators and conspecifics, but a host of other social, demographic, and ecological factors have been shown to influence primate vigilance patterns. The primate vigilance literature is thus characterized by considerable variation in findings, with inconsistent or contradictory results reported not only across different species but also within species and populations across studies. Some of this variation could emerge from fundamental differences in the methods employed, making comparisons across species and groups challenging. Furthermore, identifying consistent behavioral markers for the state of vigilance appears to have proved challenging in primates, leading to a range of definitions being developed. Deviation at this level leads directly into concomitant variation at the level of sampling methodologies. As a result, the primate vigilance literature currently presents a diverse series of approaches to exploring subtly different behaviors and phenomena. This review calls for a greater consistency in studying vigilance, with the aim of encouraging future research to follow similar principles leading to more comparable results. Identifying whether an animal is in a vigilant state is challenging for most field researchers; identifying and recording a more general behavior of "looking" should though be more achievable. Experimental approaches could then be employed to understand the compatibility "looking" has with predator detection (and other threats) in individual study systems. The outcome of this approach will allow researchers to understand the key determinants of looking in their study groups and explore threat detection probabilities given an individual or group's relative level of looking.

The continuing misuse of null hypothesis significance testing in biological anthropology.

There is over 60 years of discussion in the statistical literature concerning the misuse and limitations of null hypothesis significance tests (NHST). Based on the prevalence of NHST in biological anthropology research, it appears that the discipline generally is unaware of these concerns. The p values used in NHST usually are interpreted incorrectly. A p value indicates the probability of the data given the null hypothesis. It should not be interpreted as the probability that the null hypothesis is true or as evidence for or against any specific alternative to the null hypothesis. P values are a function of both the sample size and the effect size, and therefore do not indicate whether the effect observed in the study is important, large, or small. P values have poor replicability in repeated experiments. The distribution of p values is continuous and varies from 0 to 1.0. The use of a cut-off, generally p ≤ 0.05, to separate significant from nonsignificant results, is an arbitrary dichotomization of continuous variation. In 2016, the American Statistical Association issued a statement of principles regarding the misinterpretation of NHST, the first time it has done so regarding a specific statistical procedure in its 180-year history. Effect sizes and confidence intervals, which can be calculated for any data used to calculate p values, provide more and better information about tested hypotheses than p values and NHST.

Applicability of 3D-dental reconstruction in cervical odontometrics.

OBJECTIVES: The objective of this study was to assess the accuracy, reliability, and reproducibility of computed tomography (CT) images in measuring cervical mesiodistal and buccolingual tooth sizes, by comparing the values obtained by 3D virtual models from CT images with those obtained using digital calipers. MATERIALS AND METHODS: In total, 530 maxillary and mandibular teeth of 51 individuals from two Iron Age sites were scanned using a Siemens Somatom sensation 64-slice computed tomography machine, and the images were reconstructed and measured. Values obtained by direct measurement served as the primary reference for cervical measurements. Intra- and inter-observer reliability was assessed by calculating technical error of measurements (TEM), relative technical error of measurements (rTEM), and the coefficient of reliability (R). RESULTS: Results showed that virtual cervical measurements were not significantly different from the actual measurements, and the correlation of the two measurement methods shows that the methods are comparable. Inter- and intra-observer error analysis also indicated high replicability of measurements with both measuring methods (R > 0.99). The rTEM values for all the measurements were below the 5% standards for anthropometric studies. DISCUSSION: CT is a non-invasive technique that allows for an accurate and detailed visualization of morphological features without causing any damage to teeth. Our findings indicate that virtual odontometric analysis is a reliable method, similar to traditional physical odontometric analysis. Currently, the virtual system is likely to be more suitable for fragile specimens, such as archaeological samples.

Error in geometric morphometric data collection: Combining data from multiple sources.

OBJECTIVES: This study compares two- and three-dimensional morphometric data to determine the extent to which intra- and interobserver and intermethod error influence the outcomes of statistical analyses. MATERIALS AND METHODS: Data were collected five times for each method and observer on 14 anthropoid crania using calipers, a MicroScribe, and 3D models created from NextEngine and microCT scans. ANOVA models were used to examine variance in the linear data at the level of genus, species, specimen, observer, method, and trial. Three-dimensional data were analyzed using geometric morphometric methods; principal components analysis was employed to examine how trials of all specimens were distributed in morphospace and Procrustes distances among trials were calculated and used to generate UPGMA trees to explore whether all trials of the same individual grouped together regardless of observer or method. RESULTS: Most variance in the linear data was at the genus level, with greater variance at the observer than method levels. In the 3D data, interobserver and intermethod error were similar to intraspecific distances among Callicebus cupreus individuals, with interobserver error being higher than intermethod error. Generally, taxa separate well in morphospace, with different trials of the same specimen typically grouping together. However, trials of individuals in the same species overlapped substantially with one another. CONCLUSION: Researchers should be cautious when compiling data from multiple methods and/or observers, especially if analyses are focused on intraspecific variation or closely related species, as in these cases, patterns among individuals may be obscured by interobserver and intermethod error. Conducting interobserver and intermethod reliability assessments prior to the collection of data is recommended.

The vanishing Black Indian: Revisiting craniometry and historic collections.

OBJECTIVES: This article uses craniometric allocation as a platform for discussing the legacy of Samuel G. Morton's collection of crania, the process of racialization, and the value of contextualized biohistoric research perspectives in biological anthropology. MATERIALS AND METHODS: Standard craniometric measurements were recorded for seven Seminoles in the Samuel G. Morton Crania Collection and 10 European soldiers from the Fort St. Marks Military Cemetery; all individuals were men and died in Florida during the 19th century. Fordisc 3.1 was used to assess craniometric affinity with respect to three samples: the Forensic Data Bank, Howells data set, and an archival sample that best fits the target populations collected from 19th century Florida. Discriminant function analyses were used to evaluate how allocations change across the three comparative databases, which roughly reflect a temporal sequence. RESULTS: Most Seminoles allocated as Native American, while most soldiers allocated as Euro-American. Allocation of Seminole crania, however, was unstable across analysis runs with more individuals identifying as African Americans when compared to the Howells and Forensic Data Bank. To the contrary, most of the soldiers produced consistent allocations across analyses. Repeatability for the St. Marks sample was lower when using the archival sample database, contrary to expectations. For the Seminole crania, Cohen's κ indicates significantly lower repeatability. A possible Black Seminole individual was identified in the Morton Collection. DISCUSSION: Recent articles discussing the merits and weaknesses of comparative craniometry focus on methodological issues. In our biohistoric approach, we use the patterning of craniometric allocations across databases as a platform for discussing social race and its development during the 19th century, a process known as racialization. Here we propose that differences in repeatability for the Seminoles and Euro-American soldiers reflect this process and transformation of racialized identities during 19th century U.S. nation-building. In particular, notions of whiteness were and remain tightly controlled, while other racial categorizations were affected by legal, social, and political contexts that resulted in hybridity in lieu of boundedness.

The reality of virtual anthropology: Comparing digitizer and laser scan data collection methods for the quantitative assessment of the cranium.

OBJECTIVES: The use of geometric morphometry to study cranial variation has steadily grown in appeal over the past decade in biological anthropology. Publication trends suggest that the most popular methods for three-dimensional data acquisition involve landmark-based coordinate data collection using a digitizer. Newer laser scan approaches are seeing increasing use, owing to the benefits that densely sampled data offer. While both of these methods have their utility, research that investigates their compatibility is lacking. The purpose of this project is to compare, quantitatively, craniometrics collected with a digitizer against data extracted from laser scans using the same individuals and laboratory conditions. MATERIALS AND METHODS: Three-dimensional (x,y,z) coordinates and traditional inter-landmark distances (ILDs) were obtained with a Microscribe digitizer and 360° color models produced from NextEngine laser scans for 38 adult crania representing five cemeteries from the ADBOU skeletal collection in Denmark. Variance-based tests were performed to evaluate the disagreement between data collected with a digitizer and from laser scan models. Consideration was given to differences among landmarks by type, between ILDs calculated from landmark coordinates, and in morphology for the cemetery populations. Further, the reliability of laser scan data collection was assessed by intra-observer error tests. RESULTS: Researchers should be aware of the potential error associated with the use of Types II and III landmarks and the limitations on reliability imposed by object-to-scanner placement. DISCUSSION: This project reveals how laser scans can provide a valuable digital archive of cranial material that can be reasonably exploited for the "virtual" collection of coordinates and the calculation of ILDs.

Measurement standards for human metacarpals.

Standards for measuring the metacarpals are absent from commonly used osteometric guides. Perhaps the closest to a set of standard measurements in common use today are those proposed by Scheuer and Elkington (Scheuer and Elkington: J Forensic Sci 38 (1993) 769-788) for forensic sex assessment. They include caliper measurements of interarticular length, base and head width, base and head height, and maximum midshaft diameter. Over the last decade, a new set of measurements that encompass similar dimensions to those used by Scheuer and Elkington, but which are taken with a mini-osteometric board (MOB) have been developed by the lead author. Use of the MOB avoids the need to manipulate both the bone and calipers in three-dimensional space and causes less strain on the hands. However, the question of intra- and interobserver accuracy has not been adequately addressed for either set of measurements. The purpose of this study was to test both the Scheuer/Elkington and MOB measurements on 20 hands from 10 anatomical skeletons for intra- and inter-observer accuracy. The study found that 92% of the MOB measures had a lower intraobserver error, and 88% had a lower interobserver error than did the caliper measurements. It also found that the maximum midshaft diameter measurement used by Scheuer and Elkington is more repeatable than a mediolateral diameter. Overall, 88% of the 25 MOB measurements had median intraobserver error rates of under 1.5%, compared with 60% of the caliper measurements. Furthermore, the MOB measurements as a set were taken 10 to 12% faster than the caliper measurements.

A re-evaluation of the impact of radiographic orientation on the identification and interpretation of Harris lines.

The identification of Harris lines through radiographic analysis has been well-established since their discovery in the late nineteenth century. Most commonly associated with stress, the study of Harris lines has been fraught with inconsistent identification standards, high levels of intra- and interobserver error, and the inevitability of skeletal remodelling. Despite these methodological challenges, the use of Harris lines remains an important contributor to studies of health in archaeological populations. This research explores the radiographic process, specifically orientation and how Harris lines are initially captured for study. Using the Black Friars (13th-mid 17th centuries) skeletal sample from Denmark, 157 individuals (134 adults; 23 subadults) were radiographically analyzed in both an anterior-posterior (A-P) and medial-lateral (M-L) view for the left and right radii and tibiae. Based on the current methodological standards within the literature, it was hypothesized that the A-P view would provide the best resolution and visualization of Harris lines. The results, however, show that the number of lines visible in the M-L view were significantly higher than those visible in the A-P view; inferring that the M-L view is superior for the study of Harris lines.

Physical fitness and anthropometric characteristics in professional soccer players of the United Arab Emirates / Aptitud física y características antropométricas de jugadores profesionales de fútbol de los Emiratos Árabes Unidos

Objetivo. Describir el perfil antropométrico y la aptitud física de los jugadores de fútbol de élite que trabajan en los Emiratos Árabes Unidos. Métodos. Veintisiete jugadores de fútbol de élite que trabajan en los Emiratos Árabes Unidos fueron sometidos a una evaluación antropométrica, un test incremental en un tapiz rodante y Running-Based Anaerobic Test (RAST). Resultados. El índice de masa corporal y el porcentaje de grasa fueron 23,1 ± 2,0 kg.m-2 y 11,6 ± 2,1 %, respectivamente. El consumo máximo de oxígeno (VO2 máx) estimado fue 62,3 ± 5,1 ml.kg-1 .min-1, y la velocidad media de VO2 máx fue 17,6 ± 1,5 km.h-1, y la velocidad media de umbral ventilatorio (UV) fue 13,8 ±0,8 km.h-1. La frecuencia cardíaca del UV fue en media 173,1 ± 8,6 b.min-1, lo que representa 91,2 ± 2,8 % de la frecuencia cardíaca máxima. El test RAST resultó en una potencia máxima absoluta de 551,9 ± 73,0 W, potencia máxima relativa de 7,8 ± 0,4 W.kg-1 , potencia media absoluta de 484,0 ± 7,8 W, y potencia media relativa de 6,8 ± 0,2 W.kg-1. Conclusión. El perfil antropométrico de los jugadores de fútbol que trabajan en los Emiratos Árabes Unidos es similar a otros del resto del mundo. Sin embargo, en cuanto a la aptitud física, los resultados aún no son concluyentes, porque los resultados de otros estudios sugieren que la potencia anaerobia de nuestra muestra es igual o inferior a la de otros jugadores de élite de todo el mundo. Del mismo modo, el VO2max indirecto no es concluyente, teniendo en cuenta las limitaciones reconocidas de obtener indirectamente esta variable. Finalmente, al analizar los jugadores de acuerdo con a la posición táctica, los resultados de este estudio son similares a los estudios anteriores (AU)

Objective. To describe the anthropometric and physical fitness profiles of elite soccer players acting in the United Arab Emirates. Method. Twenty seven elite soccer players acting in the United Arab Emirates were underwent to an anthropometric evaluation, an incremental test in treadmill and performed the Running-Based Anaerobic Test (RAST). Results. Body mass index and body fat percentage of the athletes were 23.1 ± 2.0 kg.m-2 11.6 ± 2.1 %, respectively. Indirect maximum oxygen uptake (VO2max) was 62.3 ± 5.1 ml.kg-1.min-1, mean velocity at VO2max was 17.6 ± 1.5 km.h-1, ventilatory threshold (VT) of 13.8 ± 0.8 km.h-1, heart rate at VT of 173.1 ± 8.6 b.min-1, which represents of 91.2 ± 2.8 % of maximum heart rate. RAST resulted in a maximum absolute power of 551.9 ± 73.0 W, maximum relative power of 7.8 ± 0.4 W.kg-1, mean absolute power of 484.0 ± 57.8 W, and mean relative power of 6.8 ± 0.2 W.kg-1. Conclusion. The anthropometric profile of soccer players that act in the United Arab Emirates is similar to others around the world. However, regarding the physical fitness, results are still inconclusive, since findings from other studies suggest that the anaerobic power of our sample is alike or lower than other elite players throughout the world. Likewise indirect VO2max, especially given the acknowledged limitations of obtaining indirectly this variable. In addition, making an analysis by playing position, the results of this study are similar to previous research (AU)

Cross-sectional reference values for BMI among Khasi tribal adolescents of Meghalaya, India.

Body mass index (BMI) is a useful tool to assess nutritional status and may be applied to study undernutrition and overweight/obesity in distinct ethnic populations like Khasi tribal children to derive cross sectional reference values for undernutrition, overweight and obesity. Cross-sectional methods of anthropometric measurements in 957 Khasi children (467 boys, 490 girls) of age 11 to 17 years were used to derive BMI (kg/m2), which were compared with national and international standards. Smoothed Khasi specific BMI percentiles were generated by the LMS method and International Obesity Task Force (IOTF) criteria were applied as for Asian children. Mean BMI in Khasi children were below those of national and international reference standards. Girls achieved higher BMI in late adolescence, but boys remained thin throughout. Smoothed percentile charts were constructed for boys and girls and IOTF criteria for undernutrition, overweight and obesity were applied corresponding to 11, 77.4 and 90.5 percentiles for boys and 13.4, 74 and 91.2 percentiles for girls, respectively. Undernutrition was more prevalent in boys than in girls, particularly at age 14 and 15 years (p < 0.001). There was a small prevalence of obesity, 5.1% in boys and 9.5% in girls at age 17 years. BMI values in pubertal Khasi boys and girls are different from commonly used standards. BMI percentiles specific to Khasi children in puberty are advocated to track changing trends over time.

Technical note: comparing von Luschan skin color tiles and modern spectrophotometry for measuring human skin pigmentation.

Prior to the introduction of reflectance spectrophotometry into anthropological field research during the 1950s, human skin color was most commonly classified by visual skin color matching using the von Luschan tiles, a set of 36 standardized, opaque glass tiles arranged in a chromatic scale. Our goal was to establish a conversion formula between the tile-based color matching method and modern reflectance spectrophotometry to make historical and contemporary data comparable. Skin pigmentation measurements were taken on the forehead, inner upper arms, and backs of the hands using both the tiles and a spectrophotometer on 246 participants showing a broad range of skin pigmentation. From these data, a second-order polynomial conversion formula was derived by jackknife analysis to estimate melanin index (M-index) based on tile values. This conversion formula provides a means for comparing modern data to von Luschan tile measurements recorded in historical reports. This is particularly important for populations now extinct, extirpated, or admixed for which tile-based measures of skin pigmentation are the only data available.