A method for sex estimation using the proximal femur

2017

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Forensic Science International, 2017

The estimation of sex is a central step to establish the biological profile of an anonymous skeletal individual. Imaging techniques, including bone densitometry, have been used to evaluate sex in remains incompletely skeletonized. In this paper, we present a technique for sex estimation using the total area (TA) of the proximal femur, a two-dimensional areal measurement determined through densitometry. TA was acquired from a training sample (112 females; 112 males) from the Coimbra Identified Skeletal Collection (University of Coimbra, Portugal). Logistic regression (LR), linear discriminant analysis (LDA), reduce error pruning trees (REPTree), and classification and regression trees (CART) were employed in order to obtain models that could predict sex in unidentified skeletal remains. Under cross-validation, the proposed models correctly estimated sex in 90.2-92.0% of cases (bias ranging from 1.8% to 4.5%). The models were evaluated in an independent test sample (30 females; 30 males) from the 21st Century Identified Skeletal Collection (University of Coimbra, Portugal), with a sex allocation accuracy ranging from 90.0% to 91.7% (bias from 3.3% to 10.0%). Overall, data mining classifiers, especially the REPTree, performed better than the traditional classifiers (LR and LDA), maximizing overall accuracy and minimizing bias. This study emphasizes the significant value of bone densitometry to estimate sex in cadaveric remains in diverse states of preservation and completeness, even human remains with soft tissues.

When the pelvis is unavailable, the skull is widely considered the second best indicator of sex. The goals of this research are to provide an objective hierarchy of sexing effectiveness of cranial and postcranial elements and to test the widespread notion that the skull is superior to postcranial bones. We constructed both univariate and multivariate discriminant models using data from the Forensic Anthropology Data Bank. Discriminating effectiveness was assessed by cross-validated classification, and in the case of multivariate models, Mahalanobis D 2 . The results clearly indicate that most postcranial elements outperform the skull in estimating sex. It is possible to correctly sex 88-90% of individuals with joint size, up to 94% with multivariate models of the postcranial bones. The best models for the cranium do not exceed 90%. We conclude that postcranial elements are to be preferred to the cranium for estimating sex when the pelvis is unavailable.

International Journal of Legal Medicine, 2020

There are several metric and morphological methods available for sex estimation of skeletal remains, but their reliability and applicability depend on the sexual dimorphism of the remains as well as on the availability of preserved bones. Some studies showed that age-related changes on bones can cause misclassification of sex. The purpose of this study was to establish the reliability of pelvic morphological traits and metric methods of sex estimation on relatively old individuals from a modern Italian skeletal collection. The data for this study were obtained from 164 individuals of the Milano CAL skeletal collection and average age of the samples was 75 years. In the pelvic morphological method, the recalibrated regression formula of Klales and colleagues (2012), pre-auricular sulcus, and greater sciatic notch morphology were used for sex estimation. With regard to the metric method, 15 standard measurements from upper and lower limbs were analyzed for sexual dimorphism. The results showed that in pelvic morphological approach, the application of regression formula of the revised Klales and colleague formula (2017) resulted in 100% accuracy. Classification rates of metric methods vary from 75.19 to 90.73% with the maximum epiphyseal breadth of proximal tibia representing the most discriminant parameter. This study confirms that the effect of age on sex estimation methods is not substantial, and both metric and morphological methods of sex estimation can be reliably applied to individuals of Italian descent in middle and late adulthood.

Forensic science international, 2008

Although the assignment of sex to immature skeletal remains is considered problematic, some traits have been considered useful for both forensic and bioarchaeological applications. One such trait is the arch criterion found in subadult ilia, which is defined relative to the greater sciatic notch-auricular surface area. In adults, the composite arch has also been described in relation to this area and has proven relatively successful in sex determination. This study offers an examination of the accuracy of the arch criterion and the composite arch in determining the sex of subadult skeletal remains, and an assessment of intra-and inter-observer scoring error. A sample of 97 skeletons of known sex and age (<15 years) from the Lisbon collection (Portugal) were selected and the traits were scored by three observers on orthogonal photos of each ilium. In general the agreement within (67.7-88.5%) and between (50.5-76.3%) examiners was poor and overall accuracy (26.7-52.6%) did not meet the expectations of that reported in previous studies. The authors suggest that this derives from great variation in morphology, difficulties in interpreting criteria and possibly a lack of association between the expression of the traits and sex. Careful examination of sex-related morphology in the immature skeleton and additional blind tests of so-called useful traits should continue to be carried out. #

International Journal of Osteoarchaeology, 2004

Several studies have presented a variety of sexually dimorphic traits on the skeleton offering possibilities to score these traits for sex determination. However, few have discussed how fragmentation of skeletons affects the reliability of the results, and how to assess sex attribution based on a variety of methods. In the present study sex was determined for 354 skeletons from the medieval Swedish town Sigtuna, using well-recognized sexing techniques on the pelvis, skull and femur. The preservation of the skeletons varied markedly, thus affecting possibilities for sex assessments. An attempt was made to evaluate the result of the sex assessment when weighting of different traits with different scales was used. The resulting estimation for each individual was called total mean value A. In addition, a total mean value B that considers unobservable missing traits was estimated. It can be concluded that both weighting and fragmentation affect sex assessments of incomplete skeletons. Copyright © 2004 John Wiley & Sons, Ltd.

Sex assessment of skeletal remains plays an important role in forensic anthropology. The pelvic bones are the most studied part of the postcranial skeleton for the assessment of sex. It is evident that a population-specific approach improves rates of accuracy within the group. The present study proposes a discriminant function method for the sex assessment of skeletal remains from a contemporary Mexican population. A total of 146 adult human pelvic bones (61 females and 85 males) from the skeletal series pertaining to the National Autonomous University of Mexico were evaluated. Twenty-four direct metrical parameters of coxal and sacral bones were measured and subsequently, sides and sex differences were evaluated, applying a stepwise discriminant function analysis. Coxal and sacra functions achieved accuracies of 99% and 87%, respectively. These analyses follow a population-specific approach; nevertheless, we consider that our results are applicable to any other Hispanic samples for purposes of forensic human identification. Sex estimation using human skeletal remains has long been a major focus of anthropological research, but in forensic science, it is a critical process with legal implications (1,2). Several methods have been developed which provide criteria for sex assessment, focusing on visual (3–10) and morphometric analyses (11–26) of the pelvis bones. A number of studies have been undertaken for the purpose of sex estimation using postcranial and craniofacial discriminant function analysis from Mexican samples (27–32). However, the pelvis has not been studied. Success rates for sex estimation are greater among adult individuals , because sexual differences in the skeleton are better defined than in immature specimens. The male pelvis is longer, robust, and displays more rugged features with marked muscle insertions. Males show a narrower sciatic notch with an acute angle, the ace-tabulum large and the pubis short with a narrower subpubic angle. In contrast, the female pelvis shows a wider sciatic notch with an obtuse angle. It has a preauricular sulcus, a smaller acetabulum, a longer pubis, and a wide subpubic angle (33). The pelvic girdle bones are structurally related to organ support and are functionally articulated to facilitate the erect position, as well as permitting the bipedal locomotion of the human body (34– 36). A particular characteristic of the pelvis is the configuration of an obstetrical ring, which is the main source of variation between sexes (37). The implication is that pelvic morphology has considerable potential for sex assessment, and for this purpose, in the present study, discriminant functions were developed. Materials and Methods The sample examined here derives from the Osteological Collection of the Anthropology Section, One hundred and forty-six human skeletons were examined (42% females and 58% males), ranging in age from 21 to >67 years old; all well-preserved and without any osteo-pathologies or postmortem modifications caused by peeling. The series corresponds to contemporary skeletons from unclaimed bodies recovered in diverse public health facilities (38). Following an agreement between the School of Medicine (UNAM), the Health Ministry and the Mexico City Government, the authors received permission to study the skeletons from the chief of the Anatomy Department who is officially responsible for the collection and has authorization from the Health Ministry. Using sliding and spreading calipers and an osteometric board; 24 direct metrical parameters relating to both coxal and sacrum bones were measured (Tables 1 and 2; Figs 1 and 2).

2014

Physical secular changes in the human skeleton may interfere with the reliability of metric methods so these should be monitored from time to time to make sure that they are still up to date. In this research, sex estimation methods conventionally applied to the Portuguese population and developed on a collection from the 19th and early 20th centuries were tested in a sample of recently deceased individuals (N = 82) with the same ancestry composed of skeletons exhumed from the civil cemetery of Prado do Repouso (Porto). Referenced sex discriminating cut-off points were applied to the latter and the percentage of correct classification resulting from this procedure was calculated. A positive secular trend was found for the dimensions of most features that were investigated with clear implications for metric sex estimation. In comparison with the published values, the correct classification rates obtained on the modern sample were smaller in most cases. In particular, the results indicated that the use of established references for tarsal bones to sex estimate recent individuals is unadvisable. Therefore, new metric references developed on modern individuals are needed for the evaluation of remains from recent forensic contexts. Alternatively, when those are not available, more conservative interpretations of the results obtained through the application of outdated references are required when applied to modern individuals.

Revista Argentina de Antropología Biológica, 2022

In bioarchaeology and forensic anthropology the most reliable skeletal element for sex estimation is the pelvis; nevertheless, when it is missing, other postcranial elements must be used. The main goal of this research is to provide sectioning points for sex assessment from humeral and femoral head diameters for three prehispanic and two contemporary Mexican populations. Using a sliding caliper, a total of 386 (45.3% female and 54.6% male) humeral and femoral head diameters were recorded. The sectioning point was calculated as the mean between sexes, and univariate independent sample t-tests were performed to test significant differences between sexes. The results demonstrate significant sexual differences in all populations and high percentages of correct sex classification (90%-94%). We conclude that the proposed cut-off points can be used as an alternative for sex estimation in Mexican populations, in contexts with incomplete skeletons and/or fragmented bones.

Journal of Forensic and Legal Medicine, 2017

La Revue de Médecine Légale, 2017

Journal of the Canadian Society of Forensic Science, 2021

ABSTRACT The estimation of sex is an important part of building the biological profile for unknown human remains. Many of the bones traditionally used for the estimation of sex are often found fragmented or incomplete in forensic and archaeological cases. The goal of this research is to derive population-specific discriminant functions from the talus, a preservationally favoured bone, for estimation of sex from a contemporary adult Chilean population. Nine parameters were measured from 220 individuals (113 males and 107 females) with age ranges from 15 to 78 years old. All nine tali variables were sexually dimorphic. Population-specific discriminant function equations were generated for use in sex estimation. Overall, the accuracy of sex classification ranged from 64.1% to 79.7% for the univariate analysis, 79.1% to 84.7% for the direct method, and 82.8% for the stepwise method. Comparisons to other populations were made and the results demonstrated the need for population-specific discriminant functions. Overall, the cross-validated accuracies ranged from 50% to 78%. The talus was shown to be useful for sex estimation in the modern Chilean population. RÉSUMÉ L’estimation du sexe est un élément important de la construction du profil biologique de restes humains non-identifiés. Dans les contextes médico-légaux et archéologiques, les ossements traditionnellement utilisés pour l’estimation du sexe sont le plus souvent retrouvés fragmentés ou incomplets. L’objectif de cette recherche est, pour une population spécifique, d’utiliser des analyses discriminantes basées sur le talus, généralement bien conservé, afin d’estimer le sexe sur une population chilienne adulte contemporaine. Neuf paramètres ont été mesurés sur un échantillon constitué de 220 individus (113 hommes et 107 femmes) âgés de 15 à 78 ans. Les neuf variables ont montré un dimorphisme sexuel. Des équations basées sur ces analyses discriminantes ont été générées pour être utilisées pour l’estimation du sexe. Dans l’ensemble, la précision de la classification par sexe variait de 64,1% à 79,7% pour l’analyse univariée, de 79,1% à 84,7% pour la méthode directe et était de 82,8% pour la méthode par étapes. Des comparaisons avec d’autres populations ont été réalisées et les résultats ont démontré la nécessité d’employer des analyses discriminantes spécifiques à la population. Globalement, les précisions obtenues par validation croisée variaient de 50% à 78%. Le talus s’est avéré utile pour l’estimation du sexe dans la population chilienne moderne.

Sex determination of human skeletal and dental remains is a very important step in palaeodemographic reconstructions. This information can be easily obtained if skeletons are complete and well preserved, but problems arise when the sample contains fragmented and/or commingled remains. In these cases alternative methodological procedures must be achieved, taking into account the population-specific variability in sexual dimorphism and the degree of robustness of the skeletal sample. In this chapter an unconventional methodology applied to a sample of removed human remains from the Chenque I site (Lihué Calel National Park, La Pampa province, Western Pampean Region, Argentina) is described and analyzed. This site is a prehistoric cemetery used by hunter-gatherer societies during the Final Late Holocene, throughout 700 years. It has two clearly defined units with very different characteristics. The Superior Unit (0-30 cm depth) contains thousands of bony and dental remains with different degrees of fragmentation, comminglement, arrangement and anatomic association. In the Inferior Unit (below 30 cm) 42 burials were detected, many of them associated with subsuperficial stone structures. To this moment a preliminary MNI of 216 was estimated.

International Journal of Legal Medicine, 2014

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.

2014

"Recent forensic studies have shown that the hyoid bone is a sexually dimorphic element of the human skeleton. Given the advanced techniques of collecting human remains in archeological and forensic contexts, the recovery of hyoid bones is now more frequent in skeletal samples. For that reason the authors propose a new method for estimating sex based on hyoid bodies from archeological sites. The study has been conducted on well-preserved hyoids of skeletal remains of 64 adult individuals (44 males and 20 females) dated from the pre-Roman to the medieval periods. The authors considered 10 linear measurements of the hyoid body. The most significant measurements showing sexual dimorphism are the body height, body length, and the maximum and minimum diameter of the articular facet for the greater horn. Discriminant function analysis achieved the allocation accuracy between 75.0% and 88.0%, depending on the measurement collected. This method represents a new, useful and easy way for increasing biological information when assessing the sex of adult human remains from an archeological sample."