Evaluating osteological ageing from digital data

Mapping the landscape: Analysis of publication trends in forensic anthropology. Insights from Poland

Academic research in forensic anthropology is a crucial aspect for the development of this highly applied science, especially considering its social impact. The interdisciplinary character of forensic anthropology and very diversified caseload create a context in which theoretical and practical challenges emerge. This requires a swift response from the scientific community to develop new solutions or improve existing approaches. Although much is being produced worldwide in the field of forensic anthropology, there are only a few countries that lead this trend. In this article, the authors attempted to critically examine academic research within forensic anthropology in Poland by analysing its knowledge production over the last decades. A meticulous bibliographic analysis resulted in the discovery of 220 relevant academic records published between 1952 and 2023. Almost 70 % of identified papers were published in national journals and 58 % appeared in Polish. In total, 36 different institutions participate in knowledge production in this field. International collaboration is very low (∼6 %) and over 50 % of records did not involve any academic partnership. The most common type of paper is case report, primarily related to mass grave exhumations of war and totalitarian crimes. We conclude that Polish forensic anthropology research is derivative rather than original (with case reports and review papers as most frequent) and Poland remains a relatively insignificant actor when considering the overall knowledge production in forensic anthropology. In the discussion we try to understand these outcomes in the light of Polish historical context and current academic, and socio-political conjuncture.

Gender-Specific Biases in Age Estimation Methods: A Comparative Analysis of Chaillet and Morris Methods in Forensic Anthropology

Background

Accurate age estimation is crucial in various fields, particularly in forensic and anthropological contexts, where it aids in identification and legal proceedings. However, discrepancies and biases may exist in age estimation methods, necessitating comprehensive evaluation, especially across gender groups.

Materials and Methods

This study used ANOVA and t-tests to analyze age estimation data obtained from the Chaillet and Morris methods, alongside actual ages, across male and female groups. Descriptive statistics including mean, median, standard deviation, and range were calculated to provide detailed insights into the distribution of age estimates.

Results

ANOVA revealed significant differences in age estimates between the Chaillet and Morris methods, as well as actual ages, for both males and females (P < 0.05). However, t-tests did not indicate statistically significant gender differences in age estimates from either method. Notably, a significant difference was observed in actual ages, with males having lower ages on average than females. Descriptive statistics showed consistent underestimation of actual ages by both estimation methods, with females exhibiting higher actual ages compared with males.

Conclusion

This study underscores the importance of considering gender-specific biases and variations in age estimation methods. Although the Chaillet and Morris methods may not show significant gender disparities in estimates, they consistently underestimate actual ages, with females having higher actual ages on average. These findings highlight the need for continued refinement and validation of age estimation techniques to ensure accuracy and fairness across diverse populations.

Evaluation of age estimation using alveolar bone images

OBJECTIVE

The purpose of this study is to examine the time-related changes of alveolar bone in 2D images quantitatively and to estimate age groups based on the change index.

MATERIALS AND METHODS

The 238 panoramic X-ray images and 140 CT panoramic reconstructed images of the permanent dentition period were used to examine age-related changes. Comparisons between the younger age group and each of the other age groups were calculated using the landmark method of Procrustes analysis. As aging changes were observed in each age group, age estimation was performed using antemortem panoramic X-ray images and postmortem CT images so that they could be used in practice. The CT images used in the age estimation were performed using forty-two postmortem CT panoramic reconstructed images of known age submitted to the judicial autopsy.

RESULTS

Both panoramic and CT images showed changes in the alveolar bone over time. Age estimation using postmortem CT images provided a certain assessment.

CONCLUSION

In this study, clinically observed changes in alveolar bone over time were quantified on the images. Furthermore, the possibility of age estimation by alveolar bone was also suggested. The use of an updatable clinical database that can be stored in coordinate values offers the potential for age estimation in line with the times.

Dimensional accuracy of structured light scans and 3D prints of various human skeletal elements

Three-dimensional (3D) structured light scanning is a beneficial documentation technique in forensic anthropology because such models facilitate continued analysis and data sharing; they can also be 3D printed for demonstrative purposes in legal proceedings and training, without risk of damage to the original skeletal material. As its application in forensic anthropology is relatively novel, the aim of the present study is to statistically evaluate the dimensional accuracy of 3D structured light scans and 3D prints for ten bone types, including the cranium, mandible, 2nd cervical vertebra (C2), clavicle, scapula, capitate, 2nd metacarpal, os coxae, femoral head, and patella. Standard linear measurements are acquired in each physical bone, 3D virtual model, and 3D print of the same bone specimen. Variances between measurements of physical, virtual, and printed bones are quantified using the technical error of measurement (TEM), relative TEM (rTEM), and coefficient of reliability (R). Measurements acquired in the virtual models and prints were found to be within ±2 mm average of the same measurements in the physical bones, with a tendency to underestimate true value. rTEM and R values for the virtual clavicle, capitate, scapula and C2, and rTEM for the printed clavicle and capitate, were comparatively less reliable than for other bone types; although all bones were reproduced to within acceptable anthropological error standards (rTEM≤5 %; R≥0.95). This study reaffirms the use of 3D structured light scanning and 3D printing to complement traditional skeletal documentation in forensic anthropology.

Human identification: an investigation of 3D models of paranasal sinuses to establish a biological profile on a modern UK population

Medical imaging is a valuable source for facilitating empirical research and provides an accessible gateway for developing novel forensic anthropological methods for analysis including 3D modelling. This is especially critical for the United Kingdom (UK), where methods developed from modern UK populations do not currently exist. This study introduces a new approach to assist in human identification using 3D models of the paranasal sinuses. The models were produced from a database of 500 modern CT scans provided by University College London Hospital. Linear measurements and elliptic Fourier coefficients taken from 1500 three-dimensional models across six ethnic groups assessed by one-way ANOVA and discriminant function analysis showed a range of classification rates with certain rates reaching 75-85.7% (p < 0.05) in correctly classifying age and sex according to size and shape. The findings offer insights into the potential for employing paranasal sinuses as an attribute for establishing the identification of unknown human remains in future crime reconstructions.

Comparison of measurements made on dry bone and digital measurements in Anatomage for the sacral bone in a Spanish population

The use of osteometry for human identification is a key element in the field of forensic sciences. Currently, the osteometry focuses on the use of digital techniques such as photography or 3D scans, to study and measure bones, offering advantages like easy access, preservation of bones, and worldwide collaboration possibilities. The study aims to analyze whether digital tools such as Anatomage can be used to collect reliable data. The study compares measurements of the sacral bone from 41 individuals from Orgiva Collection using both traditional and digital methods. The variables analyzed were described previously, including landmarks and positions, and were coded by differentiating the measurements between dry bone (caliper) and digital measurement (Anatomage). Results indicate minimal differences between digital and dry bone measurements, with only one variable showing a significant differences in the effect size analysis (d > 0.80). The TEM analysis showed four variables as non-acceptable (rTEM > 1.5), possibly due to the landmark location or the experience using the tool to locate landmarks. Digital resources are valuable for morphometric evaluations and human identification within forensic sciences. However, caution is necessary to ensure accurate landmark localization and validate these tools across various bone types and larger sample sizes.

Automated age-at-death estimation from 3D surface scans of the facies auricularis of the pelvic bone

This work presents an automated data-mining model for age-at-death estimation based on 3D scans of the auricular surface of the pelvic bone. The study is based on a multi-population sample of 688 individuals (males and females) originating from one Asian and five European identified osteological collections. Our method requires no expert knowledge and achieves similar accuracy compared to traditional subjective methods. Apart from data acquisition, the whole procedure of pre-processing, feature extraction and age estimation is fully automated and implemented as a computer program. This program is a part of a freely available web-based software tool called CoxAGE3D. This software tool is available at https://coxage3d.fit.cvut.cz/ Our age-at-death estimation method is suitable for use on individuals with known/unknown population affinity and provides moderate correlation between the estimated age and actual age (Pearson's correlation coefficient is 0.56), and a mean absolute error of 12.4 years.

Sex estimation from virtual models: exploring the potential of stereolithic 3D crania models for morphoscopic trait scoring

Modern computed tomography (CT) databases are becoming an accepted resource for the practice and development of identification methods in forensic anthropology. However, the utility of 3D models created using free and open-source visualization software such as 3D Slicer has not yet been thoroughly assessed for morphoscopic biological profiling methods where virtual methods of analysis are becoming more common. This paper presents a study that builds on the initial findings from Robles et al. (2020) to determine the feasibility of estimating sex on stereolithic (STL) 3D cranial models produced from CT scans from a modern, living UK population (n = 80) using equation 2 from the Walker's (2008) morphoscopic method. Kendall's coefficients of concordance (KCC) indicated substantial agreement using cranial features scores in an inter-observer test and a video-inter-observer test. Fleiss' Kappa scores showed moderate agreement (0.50) overall between inter-observer sex estimations, and for observer sex estimations in comparison to recorded sexes (0.56). It was found that novice users could virtually employ morphoscopic sex estimation methods effectively on STL 3D cranial models from modern individuals. This study also highlights the potential that digital databases of modern living populations can offer forensic anthropology.

Key points

First example of Walker's (2008) method applied to a living UK population.Open-source software is a valuable resource for crime reconstruction approaches.Male scoring bias was observed in method application.Forensic anthropologists would benefit from virtual anthropology training to use and interpret 3D models.Digital databases offer more ethical, diverse, modern populations for future research.

Forensic age estimation: comparison and validation of the Iscan method in 3D reconstructions using a surface scanner in a Spanish population

When investigating a death, post-mortem identification provides with results of great legal and humanitarian significance. The effectiveness of the methods used to estimate age depends on the reference population, considering variables such as sex and ancestry. The aim of this study was to validate the Iscan method to estimate age in a Spanish forensic population, comparing the estimates obtained in dry bones and 3D reconstructions created with a surface scanner. We carried out a cross-sectional study on 109 autopsied corpses (67% male), scanning the sternal end of the right fourth rib in a 3D mesh, using an EinScan-Pro® surface scanner (precision: 0.05 mm). Two observers estimated the phases in dry bones and 3D images according to the Iscan method and to the sex of the subject. The mean age was 57.73 years (SD = 19.12 years;18-93 years). The intra-observer agreement was almost perfect in bones (κ = 0.877-0.960) and 3D images (κ = 0.954), while the inter-observer agreement was almost perfect in bones (κ = 0.813) and substantial in 3D images (κ = 0.727). The correlation with the Iscan phases was very strong in bones (Rho = 0.794-0.820; p < 0.001) and strong in 3D images (Rho = 0.690-0.691; p < 0.001). Both sex-adjusted linear regression models were significant (dry bones: R2 = 0.65; SEE =  ± 11.264 years; 3D images: R2 = 0.50; SEE =  ± 13.537 years) from phase 4 onwards. An overestimation of age was observed in the first phases, and an underestimation in the later ones. Virtual analysis using a surface scanner in the fourth rib is a valid means of estimating age. However, the error values and confidence intervals were considerable, so the joint use of different methods and anatomical sites is recommended.

Forensic Anthropology and Archaeology in Denmark

In this paper, we provide a brief overview of the status of forensic anthropology and forensic archeology in Denmark, as well as related information about education, research, and skeletal collections. Forensic anthropologists mainly deal with the examination of unidentified skeletal remains. Some special tasks include cranial trauma analysis of the recently deceased, advanced 3D visualization from CT scanning of homicide cases, and stature estimation of perpetrators using surveillance videos. Forensic anthropologists are employed at one of Denmark’s three departments of forensic medicine (in Copenhagen, Odense, and Aarhus) and have access to advanced imaging equipment (e.g., CT and MR scanning, surface scanners, and 3D printers) for use in both their requisitioned work and their research. Extensive research is conducted on different topics, such as the health and diseases of past populations, age estimation, and human morphology. Research is based on skeletal material from the archeological collections housed in Copenhagen and Odense or on CT data from the recently deceased. There is no full degree in forensic anthropology in Denmark, but elective courses and lectures are offered to students at different levels and to people from different professional backgrounds.

Forensic archaeology is a relatively new field of expertise in Denmark, and relevant cases are rare, with only one or two cases per year. No forensic archeologists are officially employed in any of the departments of forensic medicine. Until recently, the Special Crime Unit of the police handled crime scene investigations involving excavations, but with the option of enlisting the help of outside specialists, such as archaeologists, anthropologists, and pathologists. An official excavation work group was established in 2015 under the lead of the Special Crime Unit of the police with the aim of refining the methods and procedures used in relevant criminal investigations. The group is represented by five police officers from the Special Crime Scene Unit, a police officer from the National Police Dog Training center, the two archaeologists from Moesgaard Museum, a forensic anthropologist from the Department of Forensic Medicine (University of Copenhagen), and a forensic pathologist from the Department of Forensic Medicine (University of Aarhus).

Virtual anthropology: a preliminary test of macroscopic observation versus 3D surface scans and computed tomography (CT) scans

Virtual anthropology (VA) is based on applying anthropological methods currently used to analyse bones to 3D models of human remains. While great advances have been made in this endeavour in the past decade, several interrogations concerning how reliable these models are and what their proper use should be remain unanswered. In this research, a fundamental assumption of VA has been investigated: if the way we perceive and apply an anthropological method is truly similar when looking at bones macroscopically and through various 3D media. In order to answer, 10 skulls of known age and sex were scanned using a computed tomography (CT) scanner and a 3D surface scanner. Two observers separately applied a defined staging method to eight suture sites on these skulls, first looking at the bone macroscopically, then at the 3D surface scan, and finally on the CT scan. Two rounds of observation were carried out by each observer. Intra- and inter-observer error were evaluated, and two sample t-tests used to evaluate if the different types of medium used yielded significantly different observations. The results show a high degree of inter-observer error, and that data obtained from 3D surface scans differ from macroscopic observation (confidence level 95%, P ≤ 0.05). CT scans, in these settings, yielded results comparable to those obtained through macroscopic observations. These results offer many possibilities for future research, including indications on the kind of anthropological methods and anatomical landmarks that might be reliably transferable to the virtual environment. All current methods used in traditional anthropology should be tested, and if they prove unreliable, new techniques to analyse bones from virtual models should be developed.

Key points

Large discrepancies between observation on dry bones and computer-generated 3D models (surface scans or CT scans) could lead to the re-evaluation of the suitability of traditional anthropological methods for application on 3D models.

This preliminary study evaluates whether macroscopic, 3D surface scans, and CT scans viewings generate different observations.

The results indicate that the data are not always coherent across all three media of observation.

Explanations include the aspect given to the bone by the 3D software, differences between handling bones in real life versus on a computer, and level of expertise of the observers.

Forensic sex estimation using the vertebrae: an evaluation on two European populations

Sex estimation is one of the primary steps for constructing the biological profile of skeletal remains leading to their identification in the forensic context. While the pelvis is the most sex diagnostic bone, the cranium and other post-cranial elements have been extensively studied. Earlier research has also focused on the vertebral column with varying results regarding its sex classification accuracy as well as the underlying population specificity. The present study focuses on three easily identifiable vertebrae, namely T1, T12, and L1, and utilizes two modern European populations, a Greek and a Danish, to evaluate their forensic utility in sex identification. To this end, 865 vertebrae from 339 individuals have been analyzed for sexual dimorphism by further evaluating the effects of age-at-death and population affinity on its expression. Our results show that T1 is the best sex diagnostic vertebra for both populations reaching cross-validated accuracy of almost 90%, while age-at-death has limited effect on its sexual dimorphism. On the contrary, T12 and L1 produced varying results ranging from 75 to 83% accuracy with the Greek population exhibiting distinctively more pronounced sexual dimorphism. Additionally, age-at-death had significant effect on sexual dimorphism of T12 and L1 and especially in the Greek female and Danish male groups. Our results on inter-population comparison suggest that vertebral sex discriminant functions, and especially those utilizing multiple measurements, are highly population specific and optimally suitable only for their targeted population. An open-source software tool to facilitate classifying new cases based on our results is made freely available to forensic researchers.

Strengthening the role of forensic anthropology in personal identification: Position statement by the Board of the Forensic Anthropology Society of Europe (FASE)

In this position statement, the Board members of the Forensic Anthropology Society of Europe (FASE) argue that forensic anthropology methods can be used as means of personal identification, particularly in situations with limited availability of traditional identification methods (i.e. dactyloscopy, odontology, and molecular genetic analysis). This statement has been issued taking into account the international migration crises related to thousands of deaths worldwide, in which the utility of these traditional means of identification has been sporadic to non-existent. The statement is however not limited to deaths related to the migration crises, as similar problems may occur in fatalities en masse such as in natural disasters and armed conflicts, and on a smaller scale in cases of homeless or otherwise socioeconomically disadvantaged persons. The number of reports on personal identification based on sound anthropological methodology is increasing in the scientific literature. However, more research is needed to develop evidence-based standard operating procedures and statistical frameworks. It remains essential to raise awareness among forensic practitioners, law enforcement, and judiciary professionals on the utility of forensic anthropology in cases where it can provide sufficient information for identification.

A validation study of the Stoyanova et al. method (2017) for age-at-death estimation quantifying the 3D pubic symphyseal surface of adult males of European populations

The age-at-death estimation thresholds have recently been shifted towards a more objective assessment of the aging process. Such a non-subjective approach offers quantitative methods of age estimation; for instance, the method relating to the surfaces of pubic symphyses of males published by Stoyanova et al. (J Forensic Sci 62:1434-1444, 2017). A validation study was conducted to test the method performance in European samples. The sample consisted of 96 meshes of pubic symphyses of male individuals (known sex and age) that came from four different samples (two Portuguese collections, one Swiss, and one Crete). Stoyanova's method based on five regression models (three univariate and two multivariate models) performed worse in our sample, but only when the whole sample (without age limitation) was included. A sample limited to individuals under 40 years of age achieved better results in our study. The best results were reached through the thin plate spline algorithm (TPS/BE) with a root mean square error of 5.93 years and inaccuracy of 4.47 years. Generally, the multivariate regression models did not contribute to better age estimation. In our sample in all age categories, age was systematically underestimated. The quantitative method tested in this study works best for individuals under 40 years of age and provides a suitable basis for further research.

The Sommersdorf mummies-An interdisciplinary investigation on human remains from a 17th-19th century aristocratic crypt in southern Germany

Sommersdorf Castle (Bavaria, Germany) is a medieval castle complex which has been inhabited by the aristocratic family von Crailsheim. The deceased were entombed in a crypt located in the parapets underneath the castle’s church, resulting in mummification of the bodies. Based on the family chronicle and oral history, identities have been ascribed to the mummies. The aim of the study is therefore to test the accuracy of the historical records in comparison to archaeological, anthropological and genetic data. Today, the crypt houses eleven wooden coffins from the 17^th to 19^th century AD. In ten of these, mummified and scattered human remains were found. Archive records were studied in order to identify names, ancestry, titles, occupation, date of birth and death, and place of interment of the individuals. The coffins were visually inspected and dated by typo-chronology, and the mummified and scattered skeletal remains were subjected to a physical anthropological examination. In total, the crypt contains the remains of a minimum number of nine individuals, among them three adult males, five adult females and one infant. A detailed scientific examination, including prior conservation, ancient DNA analyses, and computed tomography (CT), was performed on five mummies. By means of the CT data age at death, sex, body height, pathologies, and anatomical variants were investigated. CT analysis further showed that the bodies were naturally mummified. Mitochondrial DNA analyses revealed that the tested individuals are not maternally related. In addition, health, living conditions and circumstances of death of the entombed individuals could be highlighted. Being confronted with the strengths, weaknesses and limitations of each methodological approach, probable identification was achieved in two cases.