The need to incorporate human variation and evolutionary theory in forensic anthropology: A call for reform.

In 1992, Norm Sauer called for a language shift in which practitioners would move away from the socially loaded term "race" and replace it with the less provocative term "ancestry." While many heeded the call and moved towards ancestry in their research and reports, the actual approach to research and analysis did not change. In response to this change, there was a large growth in ancestry estimation method development in the early decade of the 2000s. However, the practice of ancestry estimation did not adequately incorporate evolutionary theory in interpretation or trait selection and continued with little critical reflection. In the past decade, there has been an increase in ancestry validation methods with little critique of the "race" concept or discussion of modern human variation or reference samples. To advance, forensic anthropologists need to reckon with the practice of ancestry estimation as it is currently practiced. We are calling for another reform in the axiom focusing on evolutionary theory, population history, trait selection, and population-level reference samples. The practice needs to abandon the terms ancestry and race completely and recalibrate to an analysis of population affinity. Population affinity is a statistical approach based on the underlying population structure that would allow the understanding of how microevolutionary forces act in concert with historical events (e.g., colonization, the Transatlantic Slave Trade, etc.) to shape modern human variation. This is not to be confused with geographic ancestry that all too often can be perceived as interchangeable with social race and as an affirmation of the biological concept of race. It is time to critically evaluate the social and scientific implications of the current practice of ancestry estimation, and re-frame our approach to studying and analyzing modern human variation through a population structure approach.

Morphology of the Homo naledi femora from Lesedi.

OBJECTIVES: The femoral remains recovered from the Lesedi Chamber are among the most complete South African fossil hominin femora discovered to date and offer new and valuable insights into the anatomy and variation of the bone in Homo naledi. While the femur is one of the best represented postcranial elements in the H. naledi assemblage from the Dinaledi Chamber, the fragmentary and commingled nature of the Dinaledi femoral remains has impeded the assessment of this element in its complete state. MATERIALS AND METHODS: Here we analyze and provide descriptions of three new relatively well-preserved femoral specimens of H. naledi from the Lesedi Chamber: U.W. 102a-001, U.W. 102a-003, and U.W. 102a-004. These femora are quantitatively and qualitatively compared to multiple extinct hominin femoral specimens, extant hominid taxa, and, where possible, each other. RESULTS: The Lesedi femora are morphologically similar to the Dinaledi femora for all overlapping regions, with differences limited to few traits of presently unknown significance. The Lesedi distal femur and mid-diaphysis preserve anatomy previously unidentified or unconfirmed in the species, including an anteroposteriorly expanded midshaft and anteriorly expanded patellar surface. The hypothesis that the Lesedi femoral sample may represent two individuals is supported. DISCUSSION: The Lesedi femora increase the range of variation of femoral morphology in H. naledi. Newly described features of the diaphysis and distal femur are either taxonomically uninformative or Homo-like. Overall, these three new femora are consistent with previous functional interpretations of the H. naledi lower limb as belonging to a species adapted for long distance walking and, possibly, running.

Biological sex variation in bone mineral density in the cranium and femur.

OBJECTIVES: Sex and age trends in bone mineral density (BMD) play an important role in the estimation of age-at-death (AAD) of unidentified human remains. Current methodologies lack the ability to precisely estimate age in older individuals. In this study, BMD of the cranium and femur measured by DXA were examined to establish their applicability for age estimation in older adults. BMD as measured by DXA, is most commonly used clinically for prediction of osteoporotic fracture risk. We hypothesized that weight-bearing and non-weight-bearing bones, the femur and cranium, respectively, would provide valuable insights for aging. METHODS: The sample consists of 32 sets of excised cranial fragments from the Regional Forensic Center, Johnson City, Tennessee and 41 associated crania and femora from the North Carolina Office of the Chief Medical Examiner. All crania and femora were scanned using a Hologic (R) DXA scanner and data were analyzed using Student t-tests, Loess regression, and ANOVA. RESULTS: Student t-tests indicate a significant relationship between the sexes and cranial BMD and a significant relationship between age cohorts and femoral neck BMD. The Loess regression showed different aging patterns in the cranium for females and males older than 55. And the ANOVA showed changes in femoral neck after age 55. CONCLUSIONS: These results indicate age and sex dependent changes in BMD especially for individuals over the age of 55, which offers improvement from current aging methods for older individuals. Further research using a larger sample size could improve the predictive capabilities of the model.

Bone mineral density and wounding capacity of handguns: implications for estimation of caliber.

Methodologies that improve estimation of caliber from cranial bone defects are necessary to meet the ever increasing admissibility standards. The relationship between caliber, wound diameter, and bone mineral density (BMD) was examined. The formation of the permanent cavity is influenced by bullet yaw, velocity, distance, and tissue properties. The hypothesis was that including BMD, wound diameter could be explained by differences in caliber. The sample consists of 68 autopsy sections and 101 specimens from Phelps (1898). A subsample of 18 was scanned using dual energy x-ray absorptiometry (DEXA) for BMD measurement to test whether an increase in BMD affects wound diameter. Pearson product-moment correlations of the subsample indicate the strongest correlation is between BMD and minimum diameter (r = 0.7101), followed by a correlation between minimum diameter and caliber (r = 0.6854). Despite the previous use of thickness as a proxy for BMD, no correlation was found between BMD and thickness (r = 0.0143). A multivariate analysis of variance (MANOVA) detected a significant influence of BMD and minimum diameter on caliber size (Prob > F = 0.0003). The logistic regression shows that caliber can be estimated from minimum diameter. Using the subsample, the results show that the inclusion of BMD strengthens the model for estimating caliber from entrance gunshot defects.

Sex, Ancestral, and pattern type variation of fingerprint minutiae: A forensic perspective on anthropological dermatoglyphics.

OBJECTIVES: The majority of anthropological studies on dermatoglyphics examine the heritability and inter-population variation of Level 1 detail (e.g., pattern type, total ridge count), while forensic scientists concentrate on individual uniqueness of Level 2 and 3 detail (e.g., minutiae and pores, respectively) used for positive identification. The present study bridges the gap between researcher-practitioner by examining sex, ancestral, and pattern type variation of Level 2 detail (e.g., minutiae). MATERIALS AND METHODS: Bifurcations, ending ridges, short ridges, dots, and enclosures on the right index finger of 243 individuals (n = 61 African American ♀; n = 61 African American ♂; n = 61 European American ♀; n = 60 European American ♂) were analyzed. The overall effect of sex, ancestry, and pattern type on minutiae variation was assessed using a MANCOVA. ANOVA was used to identify Level 2 detail variables responsible for the variation. Logistic regression was used to classify individuals into groups. RESULTS: The effect of sex is insignificant. Ancestry is significant (Wilks' λ = 0.053 F value = 2.98, DF = 4,224, P value = 0.02), as is pattern type (Wilks' λ = 0.874 F value = 2.57, DF = 12,592.94, P value = 0.003). The ANOVA reveals that bifurcations are responsible for the variation between ancestral groups, while bifurcations and ending ridges vary between patterns. Logistic regression results suggest that total bifurcations can predict the ancestry of an individual (ChiSq = 6.55, df = 1, Prob > ChiSq = 0.01). DISCUSSION: Significant minutiae variation between ancestral groups yields information that is valuable in both a forensic and anthropological setting. Am J Phys Anthropol 160:625-632, 2016. © 2015 Wiley Periodicals, Inc.

Establishing Standards for Side-by-Side Radiographic Comparisons.

The objectives of this research were to evaluate the use of various anatomical features that are visible in standard radiographs and to develop a standard system of assessing concordant features for making positive identifications through radiographic comparison.The radiographs used in the study include craniofacial (n = 41), chest (n = 100), and proximal femur (n = 49), which were made available by the North Carolina Office of the Chief Medical Examiner. Radiographs were scored for number of concordant features and were analyzed using classification decision trees. The accuracy of the classification tree models was evaluated using a receiver operating characteristic.Two or more points of concordance are required in lateral cranial radiographs for a 97% probability of a positive identification. If more than 1 concordant feature exists on the cervical vertebrae, there is a 99% probability of correct identification. For thoracic and lumbar vertebrae, 4 or more concordant features are required for a 98% probability of correct identification. If there are 1 or more femoral head and neck concordant features, the probability of a correct identification is 94% and 97%, respectively. This study established the minimum number of concordant areas needed to confirm positive identifications in 3 standard radiographic views.

Skeletal and radiological manifestations of child abuse: Implications for study in past populations.

Child abuse in its various types such as physical, emotional, sexual, and neglect has been document throughout history. However, before the mid-20th century, inflicted injuries to children was overlooked in part because children were often viewed as property. According to the World Health Organization, 57,000 children were the victims of homicide in the year 2000. In this paper we present the skeletal and radiological manifestation of physical abuse and fatal neglect and provide recommendations to assess child maltreatment from past populations. Pediatric biomechanical factors and healing are discussed as it is important to keep in mind that children are not just small adults. Skeletal and radiological indicators of nonaccidental or inflicted injuries are reviewed from the literature. Inflicted injuries are presented based on specificity to identify child abuse. In addition, skeletal indicators that could help assess fatal starvation are also reviewed and metabolic diseases are proposed as potential evidence of neglect. A recent child homicide is presented and used to illustrate the difficulty in assessing child maltreatment. Present-day clinical child abuse protocols are used to provide recommendations to assess child abuse in a bioarchaeological context. Clin. Anat. 29:844-853, 2016. © 2016 Wiley Periodicals, Inc.

Cribra orbitalia: Prevalence in contemporary populations.

The prevalence of cribra orbitalia (CO) is often used as an indicator of the general health status of past populations. Although debates as to its exact etiology are still ongoing, cribra is generally accepted to be the result of an anemic condition. Cribra has been reported to be declining in modern populations or even to be absent. The aim of this study was to compare modern, historic, and prehistoric prevalences of CO to assess whether it has changed through time and if it still occurs in contemporary populations. CO in skeletons (n = 844) from two widely different regions, the northeastern US and the central Gauteng area of South Africa, were compared in order to evaluate temporal trends. The sample comprised 245 prehistoric, 381 historic, and 218 modern skeletons. In adult skeletons the prevalence was found to be lower in historic South Africans (2.23%) than in historic North Americans (6.25%). It was lower in modern North Americans than in modern South Africans (12.35 and 16.8%, respectively). Its prevalence in prehistoric North Americans (11.86%) was also not much different from that of modern North Americans (12.35%). The frequency of CO in historic South African juveniles was higher (10.71%) than in historic North American juveniles (1.35%). Modern South African children had a lower frequency (25.14%) than modern American juveniles (40%), although the sample in the North American group was small. It seems that CO is still present in modern populations, and that health may indeed have declined for some groups in recent times. Clin. Anat. 29:823-830, 2016. © 2016 Wiley Periodicals, Inc.

Sex estimation from the tarsal bones in a Portuguese sample: a machine learning approach.

Sex estimation is extremely important in the analysis of human remains as many of the subsequent biological parameters are sex specific (e.g., age at death, stature, and ancestry). When dealing with incomplete or fragmented remains, metric analysis of the tarsal bones of the feet has proven valuable. In this study, the utility of 18 width, length, and height tarsal measurements were assessed for sex-related variation in a Portuguese sample. A total of 300 males and females from the Coimbra Identified Skeletal Collection were used to develop sex prediction models based on statistical and machine learning algorithm such as discriminant function analysis, logistic regression, classification trees, and artificial neural networks. All models were evaluated using 10-fold cross-validation and an independent test sample composed of 60 males and females from the Identified Skeletal Collection of the 21st Century. Results showed that tarsal bone sex-related variation can be easily captured with a high degree of repeatability. A simple tree-based multivariate algorithm involving measurements from the calcaneus, talus, first and third cuneiforms, and cuboid resulted in 88.3% correct sex estimation both on training and independent test sets. Traditional statistical classifiers such as the discriminant function analysis were outperformed by machine learning techniques. Results obtained show that machine learning algorithm are an important tool the forensic practitioners should consider when developing new standards for sex estimation.

Secular trends in Cherokee cranial morphology: Eastern vs Western bands.

BACKGROUND: The research objective was to examine if secular trends can be identified for cranial data commissioned by Boas in 1892, specifically for cranial breadth and cranial length of the Eastern and Western band Cherokee who experienced environmental hardships. MATERIALS AND METHODS: Multiple regression analysis was used to test the degree of relationship between each of the cranial measures: cranial length, cranial breadth and cephalic index, along with predictor variables (year-of-birth, location, sex, admixture); the model revealed a significant difference for all craniometric variables. Additional regression analysis was performed with smoothing Loess plots to observe cranial length and cranial breadth change over time (year-of-birth) separately for Eastern and Western Cherokee band females and males born between 1783-1874. RESULTS: This revealed the Western and Eastern bands show a decrease in cranial length over time. Eastern band individuals maintain a relatively constant head breadth, while Western Band individuals show a sharp decline beginning around 1860. CONCLUSIONS: These findings support negative secular trend occurring for both Cherokee bands where the environment made a detrimental impact; this is especially marked with the Western Cherokee band.

A geometric morphometric validation study of computed tomography-extracted craniofacial landmarks.

This study investigates the variation between craniofacial landmarks extracted from computed tomographic (CT) scans and those collected from direct digitization of dry skulls. Thirteen traditional craniofacial landmarks were obtained from each CT scan using the coordinate option in the software Aviso. These coordinates were then compared with the coordinates digitized directly from the dry skulls as 2 separate samples and individually. Similarities were found between the 2 coordinate samples, with the first principal component representing only 23.97% of the total variation associated with the data acquisition methods, and were found to be statistically significant (P = 0.0223). Differences were more prevalent along the midline landmarks. In contrast, the individual specimen comparisons exhibited the largest amount of variation within the symmetric landmarks with the bilateral landmarks that were more medially located in the CT sample, but no individual specimens were significantly different (eg, P = 0.9883) when comparing both data acquisition modalities. The bilateral coordinates were not found to be significantly different for either analysis (P = 0.4165). The significant differences found for the entire data set suggest that the combination of CT-extracted and digitized individuals needs to be further explored with respect to the reference frames and sample composition. However, the individual specimen comparison results of this study validate the utility of CT-extracted landmarks when used for putative identifications in a forensic setting and when clinically applied.

A brief history of fatal child maltreatment and neglect.

Child abuse encompasses four major forms of abuse: physical abuse, sexual abuse, psychological abuse, and neglect. The United States retains one of the worst records of child abuse in the industrialized world. It has also been determined that a large portion of these cases are missed and go undocumented in state and federal reporting agencies. In addition, disparate risk factors have been identified for physical abuse and neglect cases, but substance abuse has been found to be a significant factor in all forms of abuse. Fatal child maltreatment and neglect investigations require a multi-pronged and multidisciplinary approach requiring the coordination and information gathering from various agencies. A major difficulty in determining the accidental or non-accidental nature of these cases is that the account surrounding the events of the death of child is acquired from the caretaker. In this review, we outline common diagnostic characteristics and patterns of non-accidental injuries and neglect as a result of nutritional deprivation.

Investigating the Timing and Extent of Juvenile and Fetal Bone Diagenesis in a Temperate Environment.

It is well understood that intrinsic factors of bone contribute to bone diagenesis, including bone porosity, crystallinity, and the ratio of organic to mineral components. However, histological analyses have largely been limited to adult bones, although with some exceptions. Considering that many of these properties are different between juvenile and adult bone, the purpose of this study is to investigate if these differences may result in increased degradation observed histologically in fetal and juvenile bone. Thirty-two fetal (n = 16) and juvenile (n = 16) Sus scrofa domesticus femora subject to different depositions over a period of two years were sectioned for histological observation. Degradation was scored using an adapted tunneling index. Results showed degradation related to microbial activity in both fetal and juvenile remains across depositions as early as three months. Buried juvenile remains consistently showed the greatest degradation over time, while the blanket fetal remains showed more minimal degradation. This is likely related to the buried remains' greater contact with surrounding soil and groundwater during deposition. Further, most of the degradation was seen in the subendosteal region, followed by the subperiosteal region, which may suggest the initial microbial attack is from endogenous sources.

Identifying Blunt Force Traumatic Injury on Thermally Altered Remains: A Pilot Study Using Sus scrofa.

In forensic scenarios involving homicide, human remains are often exposed to fire as a means of disposal and/or obscuring identity. Burning human remains can result in the concealment of traumatic injury, the creation of artifacts resembling injury, or the destruction of preexisting trauma. Since fire exposure can greatly influence trauma preservation, methods to differentiate trauma signatures from burning artifacts are necessary to conduct forensic analyses. Specifically, in the field of forensic anthropology, criteria to distinguish trauma from fire signatures on bone is inconsistent and sparse. This study aims to supplement current forensic anthropological literature by identifying criteria found to be the most diagnostic of fire damage or blunt force trauma. Using the skulls of 11 adult pigs (Sus scrofa), blunt force trauma was manually produced using a crowbar and flat-faced hammer. Three specimens received no impacts and were utilized as controls. All skulls were relocated to an outdoor, open-air fire where they were burned until a calcined state was achieved across all samples. Results from this experiment found that blunt force trauma signatures remained after burning and were identifiable in all samples where reassociation of fragments was possible. This study concludes that distinct patterns attributed to thermal fractures and blunt force fractures are identifiable, allowing for diagnostic criteria to be narrowed down for future analyses.

Recent Advances in Forensic Anthropological Methods and Research.

This Special Issue, "Recent Advances in Forensic Anthropological Methods and Research", with thirteen articles covers a wide range of highly diverse topics within forensic anthropology [...].

Ethical dilemmas in skeletal collection utilization: Implications of the Black Lives Matter movement on the anatomical and anthropological sciences.

The Black Lives Matter (BLM) movement has brought to the public eye longstanding issues of social and racial injustice which have permeated the experiences of individuals of African ancestry in the United States and abroad for centuries. Motivated by a desire to disassemble a framework of systemic racism, the BLM movement has infiltrated numerous social and political arenas including the sciences, demanding change. The impact of the BLM movement is evident in the attention recently garnered by protests of museum skeletal collections' acquisition and handling of African/African American human remains. It is from this vantage point that we explore the ethical issues pervasive within United States skeletal collections and forensically relevant issues surrounding the unclaimed decedents of marginalized populations; colonial/imperial ideological formations, which construct and sustain power differentials in anatomization; and conceive of a path forward that prioritizes personhood.

Midfacial Morphology and Neandertal-Modern Human Interbreeding.

Ancient DNA from, Neandertal and modern human fossils, and comparative morphological analyses of them, reveal a complex history of interbreeding between these lineages and the introgression of Neandertal genes into modern human genomes. Despite substantial increases in our knowledge of these events, the timing and geographic location of hybridization events remain unclear. Six measures of facial size and shape, from regional samples of Neandertals and early modern humans, were used in a multivariate exploratory analysis to try to identify regions in which early modern human facial morphology was more similar to that of Neandertals, which might thus represent regions of greater introgression of Neandertal genes. The results of canonical variates analysis and hierarchical cluster analysis suggest important affinities in facial morphology between both Middle and Upper Paleolithic early modern humans of the Near East with Neandertals, highlighting the importance of this region for interbreeding between the two lineages.

Ancestry Studies in Forensic Anthropology: Back on the Frontier of Racism.

One of the parameters forensic anthropologists have traditionally estimated is ancestry, which is used in the United States as a proxy for social race. Its use is controversial because the biological race concept was debunked by scientists decades ago. However, many forensic anthropologists contend, in part, that because social race categories used by law enforcement can be predicted by cranial variation, ancestry remains a necessary parameter for estimation. Here, we use content analysis of the Journal of Forensic Sciences for the period 2009-2019 to demonstrate the use of various nomenclature and resultant confusion in ancestry estimation studies, and as a mechanism to discuss how forensic anthropologists have eschewed a human variation approach to studying human morphological differences in favor of a simplistic and debunked typological one. Further, we employ modern geometric morphometric and spatial analysis methods on craniofacial coordinate anatomical landmarks from several Latin American samples to test the validity of applying the antiquated tri-continental approach to ancestry (i.e., African, Asian, European). Our results indicate groups are not patterned by the ancestry trifecta. These findings illustrate the benefit and necessity of embracing studies that employ population structure models to better understand human variation and the historical factors that have influenced it.

Craniofacial growth, maturation, and change: teens to midadulthood.

Despite the attainment of several adult cranial dimensions relatively early in childhood, skeletal maturity and, by consequence, adult form are typically defined by the eruption of the third molars around 17 years of age. This in turn serves as the division between subadults and adults, which is then applied to population studies of biological variation. Specifically, comparative data sets of adult measurements are not directly applied to individuals who do not have complete skeletal growth, as it is believed that the confounding effects of allometry may skew the results. The present study uses geometric morphometrics techniques to investigate the appropriateness of this division with respect to three-dimensional anatomical landmarks. Twenty-six landmarks were collected from a single population of 24 crania partitioned into 4 age groups spanning late adolescence to midadulthood. Generalized Procrustes and multivariate statistical analyses were performed on the landmark data. Results showed no significant morphological differences between the teen and young adult age groups, whereas significant shape and size differences were found in older adults relative to their younger cohorts. Moreover, no growth-related shape variation (ie, allometry) was detected within the sample. These findings suggest that adult form is attained several years earlier than commonly thought and corroborate other research that suggest that subtle changes in cranial morphology continue throughout adulthood.

Faces Divulge the Origins of Caribbean Prehistoric Inhabitants.

The origins of the first peoples to colonize the Caribbean Islands have been the subject of intense debate for over 30 years. Competing hypotheses have identified five separate migrations from the mainland with a separate debate concerning the colonization of The Bahamas. Significant differences in the facial morphology of the pre-Columbian inhabitants of Hispaniola and Cuba led to the present study of Lucayan skulls from The Bahamas. The goal was to determine which group the native Lucayans more closely resembled to resolve this long-standing dispute. The results indicate that they are related to groups from Hispaniola and Jamaica and not to Cuban inhabitants. This study clarified the larger picture of Caribbean migrations and supports evidence for a Carib invasion of the Greater Antilles around AD 800.