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

Exploring cranial macromorphoscopic variation and classification accuracy in a South African sample

To date South African forensic anthropologists are only able to successfully apply a metric approach to estimate population affinity when constructing a biological profile from skeletal remains. While a non-metric, or macromorphoscopic approach exists, limited research has been conducted to explore its use in a South African population. This study aimed to explore 17 cranial macromorphoscopic traits to develop improved methodology for the estimation of population affinity among black, white and coloured South Africans and for the method to be compliant with standards of best practice. The trait frequency distributions revealed substantial group variation and overlap, and not a single trait can be considered characteristic of any one population group. Kruskal-Wallis and Dunn's tests demonstrated significant population differences for 13 of the 17 traits. Random forest modelling was used to develop classification models to assess the reliability and accuracy of the traits in identifying population affinity. Overall, the model including all traits obtained a classification accuracy of 79% when assessing population affinity, which is comparable to current craniometric methods. The variable importance indicates that all the traits contributed some information to the model, with the inferior nasal margin, nasal bone contour, and nasal aperture shape ranked the most useful for classification. Thus, this study validates the use of macromorphoscopic traits in a South African sample, and the population-specific data from this study can potentially be incorporated into forensic casework and skeletal analyses in South Africa to improve population affinity estimates.

Estimation of population affinity using proximal femoral measurements based on computed tomographic images in the Japanese and western Australian populations

The present study analyzes morphological differences femora of contemporary Japanese and Western Australian individuals and investigates the feasibility of population affinity estimation based on computed tomographic (CT) data. The latter is deemed to be of practical importance because most anthropological methods rely on the assessment of aspects of skull morphology, which when damaged and/or unavailable, often hampers attempts to estimate population affinity. The study sample comprised CT scans of 297 (146 females; 151 males) Japanese and 330 (145 females; 185 males) Western Australian adult individuals. A total of 10 measurements were acquired in two-dimensional CT images of the left and right femora; two machine learning methods (random forest modeling [RFM]) and support vector machine [SVM]) were then applied for population affinity classification. The accuracy of the two-way (sex-specific and sex-mixed) model was between 71.38 and 82.07% and 76.09-86.09% for RFM and SVM, respectively. Sex-specific (female and male) models were slightly more accurate compared to the sex-mixed models; there were no considerable differences in the correct classification rates between the female- and male-specific models. All the classification accuracies were higher in the Western Australian population, except for the male model using SVM. The four-way sex and population affinity model had an overall classification accuracy of 74.96% and 79.11% for RFM and SVM, respectively. The Western Australian females had the lowest correct classification rate followed by the Japanese males. Our data indicate that femoral measurements may be particularly useful for classification of Japanese and Western Australian individuals.

Estimation of sex assigned at birth using dental crown and cervical measurements in a modern global sample

Despite developing prior to the appearance of secondary sexual characteristics of the skeleton, the permanent dentition exhibits sexual dimorphism. Therefore, teeth can serve as a means to estimate sex assigned at birth even in young individuals. This project takes a large global sample of maximum dimensions of the crown as well as measurements of the crown at the cervix to explore sexual dimorphism. Dimorphism is noted in teeth throughout the dental arcade, particularly in the canines. We provide sectioning points as well as the probability of correct classification (ranging from 50.9% to 81.3%) for each measurement to aid the practitioner in sex estimation from the dentition. This research provides a method to estimate sex without arbitrary population specifications. We argue for a global approach that incorporates more population variation to remove the need to estimate "ancestry," (which in actuality is translated to a social race category) and therefore does not force sexual dimorphism-related variation into these mutable and ambiguous categories. Further, this paper demonstrates the utility of the dentition as an additional indicator to aid with the estimation of sex assigned at birth in forensic anthropology. The goal of this research is to better understand the expression of sexual dimorphism across the skeleton in a global context.

Sex estimation research trends in forensic anthropology between 2000 and 2022 in five prominent journals

In forensic anthropology, osteological sex estimation methods are continuously reevaluated and updated to improve classification accuracies. Therefore, to gain a comprehensive understanding of recent trends in sex estimation research in forensic anthropology, a content analysis of articles published between 2000 and 2022 in Forensic Science International, the Journal of Forensic Sciences, the International Journal of Legal Medicine, the American Journal of Biological Anthropology, and Forensic Anthropology, was performed. The main goals of this content analysis were to (1) examine trends in metric versus morphological research, (2) examine which areas of the skeleton have been explored, (3) examine which skeletal collections and population affinities have been most frequently utilized, and (4) determine which statistical methods were commonly implemented. A total of 440 articles were coded utilizing MAXQDA and the resulting codes were exported for analysis. Statistical analyses were conducted utilizing the Cochran-Armitage and Jonckheere-Terpstra tests for trends, as well as Fisher-Freeman-Halton tests. The results demonstrate that sex estimation research published in these journals has prioritized metric over morphological methods. Further, the most utilized skeletal regions continue to be the skull and pelvis, while the most popular classification statistics continue to be discriminant function analysis and logistic regression. This study also demonstrates that a substantial portion of research has been conducted utilizing U.S. and Europe-based collections and limited populations. Based on these results, future sex estimation research must continue exploring the use of long bones and other postcranial elements, testing newer methods of analysis, as well as developing population-inclusive methods.

Utilizing augmented reality for reconstruction of fractured, fragmented and damaged craniofacial remains in forensic anthropology

Forensic anthropologists are often confronted with human remains that have been damaged due to trauma, fire, or postmortem taphonomic alteration, frequently resulting in the fracture and fragmentation of skeletal elements. The augmented reality (AR) technology introduced in this paper builds on familiar 3D visualization methods and utilizes them to make three dimensional holographic meshes of skeletal fragments that can be manipulated, tagged, and examined by the user. Here, CT scans, neural radiance fields (NeRF) artificial intelligence software, and Unreal Engine production software are utilized to construct a three-dimensional holographic image that can be manipulated with HoloLens™ technology to analyze the fracture margin and reconstruct craniofacial elements without causing damage to fragile remains via excessive handling. This allows forensic anthropologists a means of assessing aspects of the biological profile and traumatic injuries without risking further damage to the skeleton. It can also be utilized by students and professional anthropologists to practice refitting before reconstructing craniofacial fragments if refitting is necessary. Additionally, the holographic images can be used to explain complicated concepts in a courtroom without the emotional response related to using bony elements as courtroom exhibits.

Forensic anthropologists and estimates of skeletal completeness: The impacts of training and experience

Forensic anthropologists engage with numerous and diverse stakeholders in their casework. Regarding the recovery of human remains, these stakeholders may be interested in quantifying or qualifying the amount of remains recovered. How forensic anthropologists respond to such questions, whether verbally or in written reporting, has the potential to impact the trajectory of a case. However, communications about skeletal completeness are rarely discussed within the field. Current data-collection procedures recommend the use of inventories. This approach may be less feasible for complicated assemblages involving commingling or high degrees of fragmentation. Numerous methods exist to quantify the amount of skeletal remains present in complex or larger assemblages, but it remains unclear to what extent forensic anthropologists utilize these methods and whether factors like degree of expertise influence analysts' ability to report skeletal completeness consistently and precisely. A study was designed to examine differences between public and professional perceptions of skeletal completeness, presenting images of incomplete bones and skeletal remains. Survey participants were asked to assess the completeness of the remains in each image. Few patterns were observed regarding photographs of skeletal assemblages, but distinct differences were observed among individual bones between respondents with different degrees of expertise. These responses reflect potentially unexamined assumptions underlying assessments of incomplete bones and skeletal assemblages. This highlights the necessity of standardizing how we report estimates of completeness within the forensic anthropology community and how we discuss these results with external stakeholders. Completeness estimates must be either removed from reports and bench notes or annotated and cited clearly, as is standard with other aspects of forensic anthropological analysis. Several methods are summarized, with recommendations for integrating them into casework.

On the persistence of race: Unique skulls and average tissue depths in the practice of forensic craniofacial depiction

The (re-)surfacing of race in forensic practices has received plenty of attention from STS scholars, especially in connection with modern forensic genetic technologies. In this article, I describe the making of facial depictions based on the skulls of unknown deceased individuals. Based on ethnographic research in the field of craniofacial identification and forensic art, I present a material-semiotic analysis of how race comes to matter in the face-making process. The analysis sheds light on how race as a translation device enables oscillation between the individual skull and population data, and allows for slippage between categories that otherwise do not neatly map on to one another. The subsuming logic of race is ingrained - in that it sits at the bases of standard choices and tools - in methods and technologies. However, the skull does not easily let itself be reduced to a racial type. Moreover, the careful efforts of practitioners to articulate the individual characteristics of each skull provide clues for how similarities and differences can be done without the effect of producing race. Such methods value the skull itself as an object of interest, rather than treat it as a vehicle for practicing race science. I argue that efforts to undo the persistence of race in forensic anthropology should focus critical attention on the socio-material configuration of methods and technologies, including data practices and reference standards.

Curious about race: Generous methods and modes of knowing in practice

What is race? And how does it figure in different scientific practices? To answer these questions, I suggest that we need to know race differently. Rather than defining race or looking for one conclusive answer to what it is, I propose methods that are open-ended, that allow us to follow race around, while remaining curious as to what it is. I suggest that we pursue generous methods. Drawing on empirical examples of forensic identification technologies, I argue that the slipperiness of race-the way race and its politics inexorably shift and change-cannot be fully grasped as an 'object multiple'. Race, I show, is not race: The same word refers to different phenomena. To grasp this, I introduce the notion of the affinity concept. Drawing on the history of race, along with contemporary work in forensic genetics, the affinity concept helps us articulate how race indexes three different scientific realities: race as object, race as method, and race as theory. These three different, yet interconnected realities, contribute to race's slipperiness as well as its virulence.

Investigating identification disparities in forensic anthropology casework

Forensic anthropology is shifting to reflect on the impact of its practices within the criminal justice context in important ways. Here, we contribute to this essential work by examining how decedent demographics as well as estimations of biological profile components are related to identification trends in forensic anthropology cases. The study uses data from more than 1,200 identified and unidentified forensic anthropology cases from three agencies (together representing a nation-wide sample). We found the following: i) multivariate analyses indicated that decedent sex, age, and race and/or ethnicity are not related to case identification rates in the pooled United States sample, ii) when identification rate differences do occur, they appear to be smaller effects, more agency-specific, and/or related to the context of a particular agency, iii) for the agency-specific sample with available data, there was no consistent evidence for a discrepancy in the duration of an identification investigation based on a decedent's sex, age, or race and/or ethnicity, iv) forensic anthropological estimations of sex, age, and ancestry can improve the odds of identification for decedents, although these are small effects, and v) reporting an ancestry estimation does not appear to impact decedent race representation among resolved unidentified person cases. Although previous studies have identified demographic discrepancies in other areas of the criminal justice system, the results presented here suggest that decedent demographic estimation practices by forensic anthropologists in general do not appear to be related to discrepancies in identification trends, but more research is needed to examine whether these findings hold. Contextual factors and practices specific to each investigative agency likely contribute to identification trends.

Population affinity estimation on a Spanish sample: Testing the validity and accuracy of cranium and mandible online software methods

Population affinity estimation is an important step in the identification of unknown individuals. To ensure accurate results, validation studies of newly developed methods must be performed using different target populations and skeletal elements. This research aimed to determine the accuracy and reliability of population affinity estimation on a modern Spanish sample using two online software applications. The sample consisted of 114 adult individuals (51 males, 63 females) using 38 measurements and one angle from the skull and mandible. AncesTrees was used for craniometric measurements and (hu)MANid for mandibular variables with different classification models and probability thresholds being evaluated. The required parameters were inputted for each individual and statistics were generated to assess the accuracy of the estimation. AncesTrees performed with the greatest accuracy as the program correctly classified the sample as Southwestern European or European, with highest accuracies being 54.56% (trial 1), 86.05% (trial 2), 82.61% (trial 3), 34.55% (trial 4) and 100% (trial 5). (hu)MANid correctly classified the sample as being from white origin with accuracies ranging from 70.59% to 80% without considering correct sex estimation, while accuracy ranged between 62.75% and 80% accounting for estimated sex. Population affinity estimation may determine subsequent methods used in the construction of the biological profile. Our results demonstrated varying accuracy rates depending on the element and method, offering a critical view in relation to software applicability and validity. Reference populations and intrinsic and extrinsic factors can potentially influence the method accuracy and reliability. Future research should focus on the inclusion of underrepresented groups.

A violent structure. Southern perspective on the practice of forensic anthropology as a public service

Global South perspective rarely reaches the academic vanguard. While they represent over 80% of the world population, the voices from less developed regions often are ignored in academic debate. This fact produces an important disequilibrium in relation to the dissemination of knowledge, sharing of expe­riences and exchange of thoughts and, consequently, undermines and hinders the development of scientific disciplines. Forensic anthropology is no exception in this trend. The present article brings up the subject of the context of forensic anthropology in Brazil to demon­strate the interconnection of the professional situation of this discipline, its structural and bureaucratic limitations and their effect on the perpetuation of human rights violation. Various aspects of daily practice of forensic anthropology in a context devoid of basic resources generate a setting that affects both the vic­tims and their families. Despite an outstanding performance and dedication of professionals, structural limitations often substantially affect the effectiveness of their service. The present article discusses these aspects in a conceptual framework of the relation between the practice of forensic anthropology and human rights violation. In this research, Brazil serves as a case-study, an intensively studied subject that brings interpretations that can be applied in a broader context. The article aims at opening a broader, international debate that would increase the visibility of the relationship between the practice of forensic anthropology and the structure generating and/or maintaining violence in a specific economic and legislative context especially present in the countries of the so-called global South.

Operationalizing a Structural Vulnerability Profile for forensic anthropology: Skeletal and dental biomarkers of embodied inequity

Human societies create and maintain structures in which individuals and groups experience varying degrees of inequity and suffering that may be skeletally and dentally embodied. It is necessary to foreground these social and structural impacts for forensic anthropologists to eschew biologically deterministic interpretations of human variation and overly individualistic interpretations of health and disease. We thus propose a 'Structural Vulnerability Profile' (SVP), akin to the Structural Vulnerability Assessment Tool of medical anthropology [1], to be considered along with the traditional 'biological' profile estimated by forensic anthropologists. Assembling an SVP would involve examining and assessing skeletal/dental biomarkers indicative of embodied social inequity-the lived experiences of social marginalization that can get 'under the skin' to leave hard-tissue traces. Shifting our emphasis from presumably hereditary variation to focus on embodied social marginalization, the SVP will allow forensic anthropologists to sensitively reconstruct the lived experiences of the people we examine.

Twenty-first century bioarchaeology: Taking stock and moving forward

This article presents outcomes from a Workshop entitled "Bioarchaeology: Taking Stock and Moving Forward," which was held at Arizona State University (ASU) on March 6-8, 2020. Funded by the National Science Foundation (NSF), the School of Human Evolution and Social Change (ASU), and the Center for Bioarchaeological Research (CBR, ASU), the Workshop's overall goal was to explore reasons why research proposals submitted by bioarchaeologists, both graduate students and established scholars, fared disproportionately poorly within recent NSF Anthropology Program competitions and to offer advice for increasing success. Therefore, this Workshop comprised 43 international scholars and four advanced graduate students with a history of successful grant acquisition, primarily from the United States. Ultimately, we focused on two related aims: (1) best practices for improving research designs and training and (2) evaluating topics of contemporary significance that reverberate through history and beyond as promising trajectories for bioarchaeological research. Among the former were contextual grounding, research question/hypothesis generation, statistical procedures appropriate for small samples and mixed qualitative/quantitative data, the salience of Bayesian methods, and training program content. Topical foci included ethics, social inequality, identity (including intersectionality), climate change, migration, violence, epidemic disease, adaptability/plasticity, the osteological paradox, and the developmental origins of health and disease. Given the profound changes required globally to address decolonization in the 21st century, this concern also entered many formal and informal discussions.

Investigation of the relationship between corpse age and microscopic morphometric indices of the fourth and sixth rib bones

This study was performed to estimate the corpse age using histological examinations of the fourth and sixth ribs by a morphometric method. One hundred samples of referred bodies of the Legal Medicine Organization of Lorestan province, Iran, were examined. The sampling was performed from the fourth and sixth ribs. The transverse sections of the samples were prepared, in which various variables such as the diameter of the haversian system (DHC), haversian system perimeter (PHS), haversian system area (AHS), and the thickness of the haversian lamellae (TH) were measured using a Motic microscope video system and the Motic Image Plus 2 software. To predict age from sex and the morphometric parameters a stepwise multiple linear regression was used. Accordingly, AHS in rib 4, DHC with lens 10 in rib 4, DHC with lens 10 in rib 6 and TH in rib 6 remained in the model at significance level 0.05 (R square = 0.1654). Although age was associated with some of the studied parameters, the obtained equation was not fit enough to predict the exact age. Further parameters should be studied for prediction of age in corpse.