Forensic Anthropology Research Articles

Sexual dimorphism of the twelfth thoracic vertebra for sex determination in the Central Thai population

Analyzing skeletal remains is crucial for identifying individuals, and forensic anthropologists use this analysis to determine biological characteristics, particularly sex, aiding criminal investigations. Among thoracic vertebrae, the twelfth thoracic vertebra (T12) is highly sexually dimorphic in various populations. This study aims to establish a discriminant function equation (DFE) for sex determination based on T12 in the Central Thai population. A total of 15 parameters of T12 were examined in 69 bone samples (43 males and 26 females). Among the 15 parameters, 14 were significantly different between males and females. The discriminant function equation (DFE) was generated as DFE = -19.578 + 0.376(i) BDsm + 0.254(l) PW + 0.081TDm, with a cutoff value of -0.296 for males and females, showing 92.8% accuracy. The evaluation of the DFE using 10 blind samples showed 90% accuracy. These findings may offer an additional method for sex determination through T12, complementing the examination of other skeletal elements.

Morphometric analysis of the mastoid process using cone beam computed tomography

The sexual dimorphism of the mastoid process, as demonstrated by cone beam computed tomography (CBCT), is not well examined in forensic anthropology or clinical diagnostics. The mastoid region can be precisely imaged in three dimensions using CBCT, which reveals minute anatomical variations between males and females. These characteristics can help forensic professionals identify the sex of unidentified human remains, helping to solve crimes and aid in the search for missing persons. Moreover, recognising sexual dimorphism in the mastoid process in clinical settings can help with precise patient identification and individualised medical treatments, highlighting the important function of CBCT in both the forensic and medical areas.

Uncovering Forensic Evidence: A Path to Age Estimation through DNA Methylation

Age estimation is a critical aspect of reconstructing a biological profile in forensic sciences. Diverse biochemical processes have been studied in their correlation with age, and the results have driven DNA methylation to the forefront as a promising biomarker. DNA methylation, an epigenetic modification, has been extensively studied in recent years for developing age estimation models in criminalistics and forensic anthropology. Epigenetic clocks, which analyze DNA sites undergoing hypermethylation or hypomethylation as individuals age, have paved the way for improved prediction models. A wide range of biomarkers and methods for DNA methylation analysis have been proposed, achieving different accuracies across samples and cell types. This review extensively explores literature from the past 5 years, showing scientific efforts toward the ultimate goal: applying age prediction models to assist in human identification.

What we see is what we touch? Sex estimation on the skull in virtual anthropology.

The increased use of virtual bone images in forensic anthropology requires a comprehensive study on the observational errors between dry bones and CT reconstructions. Here, we focus on the consistency of nonmetric sex estimation traits on the human skull. We scored nine nonmetric traits on dry crania and mandibles (n = 223) of archaeological origin and their CT reconstructions. Additionally, we 3D surface scanned a subsample (n = 50) and repeated our observations. Due to the intricate anatomy of the mental eminence, we split it into two separate traits: the bilateral mental tubercles and the midsagittal mental protuberance. We provide illustrations and descriptions for both these traits. We obtained supreme consistency values between the CT and 3D surface modalities. The most consistent cranial traits were the glabella and the supraorbital margin, followed by the nuchal crest, zygomatic extension, mental tubercles, mental protuberance, mental eminence, mastoid process and ramus flexure, in descending order. The mental tubercles show higher consistency scores than the mental eminence and the mental protuberance. The increased interchangeability of the virtual modalities with each other as compared to the dry bone modality could be due to the lack of tactility on both the CT and surface scans. Moreover, tactility appears less essential with experience than a precise trait description. Future studies could revolve around the most consistent cranial traits, combining them with pelvic traits from a previous study, to test for accuracy.

Way forward in the involvement of forensic anthropology in the identification of human remains

ABSTRACT Forensic anthropology should not continue to be the last resource in the identification of a forensic case. The methods to be applied in a forensic case are dictated by the state of preservation of the human remains. Forensic anthropologists (and other forensic stakeholders) should be aware of a broad spectrum of methods, their scope and limitations, to be able to perform or recommend all approaches necessary for a successful identification. The value of the so-called secondary identifiers, best designated as biological identifiers, should be reconsidered. The importance of objectivity, and impartiality will be emphasized. During a death investigation, forensic anthropologists should always formulate deductions on the biological aspects of the body before acquiring antemortem information of missing persons to avoid bias in conclusions. To illustrate our arguments, a case study is presented, where expertise in forensic anthropology has been crucial for the identification of a body in advanced state of decomposition. In this case, interdisciplinary collaborative efforts and use of multiple identifiers have led to a positive identification.

Correlations between Dental Age, Skeletal Age, and Mandibular Morphologic Index Changes in Turkish Children in Eastern Anatolia and Their Chronological Age during the Pubertal Growth Spurt Period: A Cross-Sectional Study

In age determination, different methods aiming to obtain the closest result to chronological age have been investigated so far. The most commonly used one among these is the radiological method, which is usually used to evaluate the developmental stages of wrist bones or teeth. In our study, we assessed bone age estimations using the Gilsanz–Ratib atlas (GRA), which has recently become commonly used for children aged 9 to 15 years; evaluated the dental age, determined with Cameriere’s European method; conducted morphometric measurements of the mandibular bone; and then examined their relationships with chronological age. The results of our study reveal that, in children during the puberty growth spurt, Cameriere’s EU formula might have higher accuracy in estimating chronological age in younger age groups, while the GRA might be more accurate for older ages. Additionally, we conclude that of the mandibular morphometric measurements, condylar height and tangential ramus height show strong positive correlations with age. As a result, we conclude that the morphometric measurements evaluated in the present study can be used as auxiliary methods in forensic anthropology and forensic dentistry.

The taphonomic effects of long-term burial in the South African Highveld.

Taphonomy studies the environmental effects on remains from the time of deposition to the time of recovery and has been integrated into the field of forensic anthropology. The changes to skeletal remains are dependent on the method of disposal and the surrounding environment. This study focused on buried remains where the type and chemical composition of the soil and the microorganisms present need to be considered. The aim was to investigate the type, frequency, and correlations of the taphonomic alterations of buried domestic pigs. Six taphonomic alterations were observed which included depositional staining, adipocere formation, bone weathering, acidic soil corrosion, and plant, and animal activity. Depositional staining, weathering and plant activity were the most common alterations followed by adipocere which was present on 92.3% of the remains. The bones were mostly stained dark brown and brown; however, the trunk region was the only region to present with black staining. The right sides were darker than the left due to the body positioning as most pigs were placed on their right sides and thus were in direct contact with the cadaver decomposition island. Additionally, the right sides presented with more adipocere as well as increased plant activity suggesting that the soil retained water. Darker stains were correlated with a more complete skeleton as adipocere provides some protection. The study confirms that there are various complicated relationships between different taphonomic alterations. A good understanding of them is needed in forensic anthropology to assist in reconstructing the events that occur after death.

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.

Rastros documentales de la (des)aparición de cuerpos: inhumaciones irregulares y antropología forense en un cementerio público de Córdoba

This article reflects on the extensive use of irregular burials in public cemeteries as a method of disappearance/elimination of bodies during the last civic-military dictatorship in Argentina. Drawing on a historical-anthropological perspective, it investigates a paradigmatic case: the discovery of one of the largest mass graves in Latin America, located in the San Vicente Cemetery in the city of Córdoba, Argentina. The underlying assumption guiding the analysis is that irregular burial involved the intervention of bureaucratic-administrative instances linked to the regular handling of corpses—hospitals, morgues, and public cemeteries—resulting in the existence of documentary traces that currently account for its use and extent. The article begins with the description of a letter written in 1980 by morgue workers and a newspaper article about the first identification in Córdoba, serving as temporal markers of a lengthy search process. The geographical and historical reconstruction of San Vicente and its burial practices configure it as a territory of marginalities and impurities, as a receiver of bodies of the sick, the poor, and also “subversive delinquents.” Analyzed as cultural artifacts, the morgue's entry books and the 1980 letter reveal different aspects of the irregular burial practice and how the bodies of the murdered were incorporated into the routines of state agencies. Such records were crucial in the forensic anthropological work of searching for and locating the large mass grave. The article is framed among studies focusing on the “legal” and “administrative” forms of state repression and terror. It seeks to highlight the importance of preliminary investigation and interdisciplinarity in the application of forensic anthropology, not only in the analyzed geographical area but also in clarifying the multiple violences that permeate the region.

Bone color changes and interpretation of the temperature/duration of fire exposure to human remains in the forensic context

AbstractIn both the archeological and forensic literature, experimental data have been used to equate the color of burned bone with the temperature to which it was exposed. While this may be applicable in the tightly controlled oxidizing environment of a furnace or crematorium, it is not representative of the more realistic dynamic conditions of fire events involving structures, vehicles, outdoors, and so forth, that are encountered in forensic anthropology casework. In this piece, we review the literature at the cross section of bone color and temperature and compare it to our own observations from experimental burns. We generate a cautionary path forward for future research as well as interpretation in applied contexts. Implying temperature based on burned bone color ignores other significant variables that are related to the degradation of the bone's organic matrix like, the amounts and types of fuels, duration, fluctuations of temperature, oxygen level of the environment, byproducts of combustion, and other variables unique to each scene. Research results on bone color and temperature derived from controlled environments using non‐fleshed bone samples, are not applicable for use in forensic casework involving burned human remains from fleshed bodies. We argue that to do so distracts from other contributing variables and information that can be derived from the analysis of fire patterns on burned human remains and burned bones. Finally, we caution about using bone color alone to estimate temperatures of the fire, which makes incorrect assumptions about fire behavior and could jeopardize court testimony if this method is used as a standard. We raise three issues if a direct correlation between temperature and bone color are used in court: (1) other important factors are ignored, (2) a universal unvaried exposure of the body is assumed, and (3) the expert risks impeachment given conflicting data on the correlation.This article is categorized under: Forensic Medicine > Death Scene Investigation Forensic Anthropology > Taphonomic Changes and the Environment

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.

The Illusion of Truth in Michael Ondaatje’s Anil’s Ghost

Michael Ondaatje's Anil’s Ghost, a literary masterpiece, focuses on the distortion of truth. Set against the backdrop of civil unrest in Sri Lanka, the novel follows forensic anthropologist Anil Tissera as she exposes the complexities of revealing truth in a world rife with political and personal turmoil. This research abstract delves into the multifaceted layers of reality distortion portrayed in Ondaatje's work .At its core; the novel questions the notion of objective reality. Ondaatje masterfully employs fragmented narratives, shifting perspectives, and unreliable memories to diminish the lines between truth and fiction. Through Anil's investigation into the skeletal remains of victims of political violence, Ondaatje exposes the subjective nature of memory and the inherent biases that shape our understanding of past events. Moreover, the novel explores the psychological toll of living in a reality distorted by trauma and political oppression. Characters like Anil and Sarath, haunted by their pasts, grapple with the existential question of whether it is possible to reconcile personal truth with the external realities imposed upon them. Ondaatje's lyrical prose evokes a sense of disorientation, mirroring the characters' internal struggles as they confront the elusive nature of reality. Furthermore, the novel examines how power dynamics influence the construction of reality. Ondaatje exposes the ways in which those in positions of authority manipulate narratives to serve their own agendas, perpetuating falsehoods and suppressing marginalized voices in the process. Through Anil's quest for justice, the novel underscores the importance of bearing witness to the silenced truths obscured by those in power. The novel serves as a profound exploration of the distortion of reality in the face of political upheaval and personal trauma.

Sex determination based on craniometric parameters: a comparative approach between linear and non-linear machine learning algorithms

Introduction: Determining sex based on cranial characteristics is of great relevance in forensic anthropology. Most studies have employed linear methods (such as logistic regression) for this estimation with accuracies around 70%, rarely exceeding 90% accuracy. Several authors have tested non-linear models such as neural networks, support vector machines, and decision trees with good results, surpassing linear models. Objective: To compare linear models (logistic regression, linear regression, and linear discriminant analysis) with non-linear models (neural networks, extreme gradient boosting, support vector machine, naive Bayes, random forest, decision tree, k-nearest neighbors, and adaptive multivariate spline regression). Materials and Methods: 241 skulls used in this study were obtained from the collection of Center for Study and Research in Anatomy and Forensic Anthropology at Tiradentes University, Farolândia campus in Aracaju, Sergipe. Each skull in the collection has secure detailed records. Eighty-nine skulls with signs of craniotomy (n=58) or damage (n=30) and one unidentified were excluded. The 152 eligible skulls underwent cranial measurements. Using the Anaconda platform and Jupyter editor, the data were divided into a training group (80% of the sample) and then were tested (20% of the sample). Eleven machine learning algorithms, including both linear and non-linear models, were applied. Results: The best machine learning algorithm was a neural network with average accuracy of 93%, after 50 runs. The difference to logistic regression, which had an accuracy of 68%, was significantly (p-value of 0.01016). Conclusion: This study demonstrated the potential of the neural network for solving the sex classification problem. The study has a limitation in that neural networks perform better with a large volume of data, and this study used data from a single center. Nevertheless, in the future, more studies should be conducted testing neural networks with larger samples and skulls from other continents.

Joint application of A-InDels and miniSTRs for forensic personal, full and half sibling identifications, and genetic differentiation analyses in two populations from China

BackgroundPreviously, a novel multiplex system of 64 loci was constructed based on capillary electrophoresis platform, including 59 autosomal insertion/deletions (A-InDels), two Y-chromosome InDels, two mini short tandem repeats (miniSTRs), and an Amelogenin gene. The aim of this study is to evaluate the efficiencies of this multiplex system for individual identification, paternity testing and biogeographic ancestry inference in Chinese Hezhou Han (CHH) and Hubei Tujia (CTH) groups, providing valuable insights for forensic anthropology and population genetics research.ResultsThe cumulative values of power of discrimination (CDP) and probability of exclusion (CPE) for the 59 A-InDels and two miniSTRs were 0.99999999999999999999999999754, 0.99999905; and 0.99999999999999999999999999998, 0.99999898 in CTH and CHH groups, respectively. When the likelihood ratio thresholds were set to 1 or 10, more than 95% of the full sibling pairs could be identified from unrelated individual pairs, and the false positive rates were less than 1.2% in both CTH and CHH groups. Biogeographic ancestry inference models based on 35 populations were constructed with three algorithms: random forest, adaptive boosting and extreme gradient boosting, and then 10-fold cross-validation analyses were applied to test these three models with the average accuracies of 86.59%, 84.22% and 87.80%, respectively. In addition, we also investigated the genetic relationships between the two studied groups with 33 reference populations using population statistical methods of FST, DA, phylogenetic tree, PCA, STRUCTURE and TreeMix analyses. The present results showed that compared to other continental populations, the CTH and CHH groups had closer genetic affinities to East Asian populations.ConclusionsThis novel multiplex system has high CDP and CPE in CTH and CHH groups, which can be used as a powerful tool for individual identification and paternity testing. According to various genetic analysis methods, the genetic structures of CTH and CHH groups are relatively similar to the reference East Asian populations.

Considerations for age estimation accuracy: Method-derived outcomes and practitioner interpretations.

Recent research observed 92% accuracy for age-at-death estimations by U.S. forensic anthropologists. The present study compares this case report level accuracy to method level accuracy for the most commonly used methods in U.S. casework, drawing from the Forensic Anthropology Database for Assessing Methods Accuracy (FADAMA). Method application rate (i.e., how often a method is used in casework) was analyzed for n = 641 cases and identified 15 methods with an application rate >45 cases, and the present study focused further analyses on these 15 methods. Of the 15, only four yielded accuracies greater than or equal to the 92% documented for case-report level accuracy. The other 11 methods produced accuracy rates ranging from 54% to 91%, with six of these below 70% This disconnect between highly accurate age estimations at the case report level compared to the poor performance at method level suggests that practitioner interpretation and synthesis of the methods' outcomes is a critical step for increasing the accuracy rates of the age estimations as reported on the final case report. This inference was further supported by the study's results which indicated that practitioner interpretations of frequently used method combinations improve accuracy and age range width of age estimation. The study also performed a Fisher's Exact test to assess whether case report-level accuracy differed with the number of aging methods used in a case, and found no significant differences.

Prioritizing a high posterior probability threshold leading to low error rate over high classification accuracy: the validity of MorphoPASSE software for cranial morphological sex estimation in a contemporary population.

An increasing number of software tools can be used in forensic anthropology to estimate a biological profile, but further studies in other populations are required for more robust validation. The present study aimed to evaluate the validity of MorphoPASSE software for sex estimation from sexually dimorphic cranial traits recorded on 3D CT models (n = 180) from three populations samples (Czech, French, and Egyptian). Two independent observers performed scoring of 4 cranial traits (2 of them bilateral) in each population sample of 30 males and 30 females. The accuracy of sex estimation using traditional posterior probability threshold (pp = 0.5) ranged from 85.6% to 88.3% and overall classification error from 14.4% to 11.7% for both observers, and corresponds to the previously published values of the method. The MorphoPASSE method is also affected by the subjectivity of the observers, as both observers show agreement in sex assignment in 83.9% of cases, regardless of the accuracy of the estimates. Applying a higher posterior probability threshold (pp 0.95) provided classification accuracy of 97.9% and 93.3% of individuals (for observer A and B respectively), minimizing the risk of error to 2.1% and 6.7%, respectively. However, sex estimation can only be applied to 54% and 66% of individuals, respectively. Our results demonstrate the validity of the MorphoPASSE software for cranial sex estimation outside the reference population. However, the achieved classification success is accompanied by a high risk of errors, the reduction of which is only possible by increasing the posterior probability threshold.

Classification of Malaysian individuals using Fordisc 3 based on four craniofacial measurements

ABSTRACT Fordisc is a discriminant function computer program used to study ancestry, although it lacks representation from a Malaysian sample. Our aim was to evaluate ancestry estimates of Fordisc 3 with Malaysian crania of known sex and ethnicity. A dataset from Hisham and Ibrahim of 300 individuals was included in this study. They had undergone full-body computed tomographic scanning prior to post-mortem examination with scan resolutions of 1.0 mm. Maximum cranial length, maximum cranial breadth, nasal height, nasal breadth, and midorbital width were obtained from these images. Measurements were fed into the Fordisc 3 program and were analysed using the Forensic Anthropology Data Bank (FDB) and Howells’ reference populations according to sex, however midorbital width was excluded in all analyses. Ancestry assessment was evaluated on the basis of percentage of correctly classified individuals. Based on Howells database, 50.67% of the sample are correctly classified into Asian, in contrast to only 32.33% according to FDB. These classification trends are limited by the number of measurements, reference populations available in Fordisc and population history of the sample itself. We need to collect standard anthropological measurements in future research and potentially contribute to the database in Fordisc to improve its performance.

Testing the discrepancy between physical and virtual linear measurements.

Virtual calculations of bone morphology are increasingly becoming the golden standard in anthropological sciences, gradually replacing the performance of direct physical measurements. Nevertheless, the potential discrepancy between the two approaches is rarely addressed. Here, we address this question focusing on the second thoracic vertebrae of 24 well-preserved individuals from the skeletal collection of the Forensic Anthropology Unit of Medical School at the National and Kapodistrian University of Athens, Greece. Following traditional osteometric methods, a series of measurements were taken on the vertebral body, both directly (using a digital caliper) as well as on high-resolution 3D surface models. The arithmetic results of the two measuring techniques were then compared through a number of statistical analyses evaluating inter-method precision (Bland-Altman plots, TEM, %TEM and Wilcoxon test). Moreover, the values obtained from each approach were used to develop discriminant function equations for sex determination to evaluate if both approaches provide the same assessment. Both intraobserver and interobserver tests were performed. Although most statistical analyses showed a significant difference between the two measuring techniques, the discriminant function equations for sex determination provided the same assessment. Overall, the results of this experiment support the use of virtual linear measurements, also suggesting that a refinement of digital measuring protocols could improve their level of agreement with traditional direct osteometry.

Solving cold cases: The importance of new identification techniques in old cases of forensic anthropology

Scientific and technological developments experienced by forensic sciences have increased the possibility of human identification. Forensic anthropology has developed worldwide and has made significant progress in Brazil in the last 10 years. This context has allowed forensic medicine institutes to use new techniques to resolve cold cases of human identification. This work aimed to report the methodology, development, and partial results of the LAFOL Identifies Operation, carried out at the Forensic Anthropology and Forensic Dentistry Laboratory (LAFOL) of the Medico-Legal Institute of Porto Velho. We carried out a multidisciplinary expert approach on human skeletal remains archived over the last 20 years to identify these individuals using current scientific methods. Eighty-one cold cases of skeletonized and/or mummified human skeletal remains were reanalyzed; they were archived in the LAFOL Laboratory collection as unidentified. Anthropological analyses showed that the collection is predominantly composed of adult individuals (86.4%), between 21 and 39 years old (55.6%), and males (62.9%). In the human skeletal remains identified, forensic anthropology played a key role in the case screening process. We expected that the results presented in this work will inspire other Medico-Legal Institutes in Brazil and worldwide to establish task forces for the reanalysis of cold cases in their institutes, promoting new forensic dentistry and anthropological comparisons and collecting biological samples to feed the database of genetic profiles of missing persons.

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.