Osteometric analysis of sexual dimorphism in the sternal end of the rib in a west African population.

This study, and others, are being carried out in order to establish a Forensic Anthropology databank on age estimation and sex determination of skeletonized remains in Ghana. An osteometric study of sexual dimorphism in the sternal end of the right fourth rib on 346 consecutive coroner's autopsy cases (221 males, 125 females) of known age, sex, and race was conducted. The height and width of the sternal end of the rib were measured in each case. The sample was analyzed in three groups: young (< 30 years), old (> or = 30 years), and total sample (total group). Stepwise discriminant function analysis showed that the accuracy of sex determination varied from 80% in the young and 74% in the old groups to 78% for the total group. Statistical analysis of the results obtained when the functions derived from the study were tested using another batch of ribs showed the functions to be effective and reliable in determining sex. When functions derived from a previous study of American Whites were used to determine sex in our study sample, the vast majority of males were misclassified as females. This is the first time, to our knowledge, that a Black African population has been studied osteometrically to evaluate sexual dimorphism in the sternal end of the fourth rib.     

Discriminant function sexing of the mandible of indigenous South Africans

South Africa currently has a high homicide rate. This results in a large number of unidentified bodies being recovered each year, many of which are referred to the forensic examiner. This situation has resulted in considerable growth of forensic anthropological research devoted to devising standards for specific application in South African medico-legal investigations. The standards suitable for Black South Africans now encompass a wide variety of skeletal elements (e.g. cranium, humerus, pelvis, femur, patella, talus, calcaneus), each with differing degrees of accuracy. Apart from a preliminary investigation of the Zulu local population, however, we note that there appears to be no established metric mandible discriminant function standards for sex determination in this population. The purpose of the present study is to undertake a comprehensive analysis of sexual dimorphism in the mandible of Black South Africans, incorporating individuals from a selection of the larger local population groupings; the primary aim is to produce a series of metrical standards for the determination of sex. The sample analyzed comprises 225 non-pathological mandibles of Black South African individuals drawn from the R.A. Dart Collection. Nine linear measurements, obtained from mathematically transformed three-dimensional landmark data, are analyzed using basic univariate statistics and discriminant function analyses. All of the measurements examined are found to be sexually dimorphic; the dimensions of the ramus and corpus lengths are most dimorphic. The sex classification accuracy of the discriminant functions ranged from 70.7 to 77.3% for the univariate method, 81.8% for the stepwise method, and 63.6 to 84% for the direct method. We conclude that the mandible is a very useful element for sex determination in this population.     

Sexual Dimorphism of the First Rib: A Comparative Approach Using Metric and Geometric Morphometric Analyses

This research investigated the sexual dimorphism of the first human rib using geometric morphometric and metric approaches on a sample of 285 specimens containing European Americans and African Americans from the Hamann‐Todd collection. Metric measurements were investigated for sexual dimorphism and ancestral differences using univariate statistics. Four type II landmarks and 40 sliding semi‐landmarks were placed outlining the dorsal and ventral curvatures of the ribs. Landmark data were processed using Generalized Procrustes Analyses with Procrustes distance sliding, and the subsequent coordinates were investigated for sexual dimorphism and ancestral differences using Procrustes ANOVAs. Both geometric morphometric and metric data were analyzed using cross‐validated discriminant function analyses to test the hypothesis that variables from both approaches can be combined to increase sex classification rate. European Americans had sex correctly classified as high as 88.05% and African Americans as high as 70.86% using a combination of metric and geometric morphometric variables.     

Age estimation from the rib by phase analysis: white females

Metamorphosis at the sternal extremity of the rib has already been established as a reliable indicator of age at death. Using a sample of white males, it was shown that an accurate estimation of age can be made by direct examination of the bone itself. However, because of sexual differences in hormonal production and dimorphism in the skeleton, the present study was carried out to develop an appropriate standard for age determination from the sternal rib in white females. The sample consisted of 86 ribs of known age, sex, and race. Observations were made at the costochondral junction with special attention to pit formation (its shape and depth), changes in the walls and rim surrounding it, and overall bone density and texture. Based on changes in these areas, the ribs were separated into nine phases (0 through 8). The most rapid metamorphosis occurred in Phases 1 through 4 (mean ages 14-28) with changes noticeable at 3 to 4 year intervals. After mean age 28, this process slowed, considerably expanding the interval between phases to 10 to 15 years. The female ribs showed both earlier initial pit formation and a different morphologic pattern of aging as compared with males. Statistical analysis revealed that the features chosen to delineate the phases are valid predictors of age. This study has shown that the sternal rib can provide an accurate estimation of age in females spanning a mean age of 14 to 76 years.     

Metrical and non-metrical assessment of population affinity from the calcaneus

To date, there are no metric standards for differentiating between population groups from measurements of the calcaneus in South Africa. Previously, some of the measurements of the calcaneus have been used for sex determination in Americans, Europeans, Italians and South Africans. However, the variations in the number of articular facet present on the superior surface of the calcaneus have been observed in different population groups. This study aims at investigating the potentials of measurements of the calcaneus in diagnosing population affinity and observes population variations of the number of articular facet present on its superior surface in indigenous South Africans and those of European descent. Nine measurements were taken from 180 non-pathological left calcanei in a sample of known sex and population affinity obtained from the Raymond A. Dart Collection of Human Skeletons. Three articular facet types were observed. A significantly higher incidence of type A was observed in South Africans of European descent (SAED) population group while type B predominated in the indigenous South African (ISA) population group. Type C even though rare was found only in ISA group. The metrical data were subjected to discriminant function analyses. The average accuracy in correct classification (81-89%) obtained for the discriminant function equations derived in this study may assist in the determination of population affinity when the calcaneus is present for analysis in forensic cases.     

Sex determination from the talus and calcaneus measurements

Several studies have demonstrated that discriminant function equations used to determine the sex of a skeleton are population-specific. The purpose of the present research was to develop discriminant function equations for sex determination on the basis of 18 variables on the right and left talus and calcaneus in a modern northern Italian sample. The sample consisted of 118 skeletons (62 males and 56 females) from the Frassetto Collection (University of Bologna). The ages of the individuals ranged from 19 to 70 years. The results indicated that metric traits of the talus (in particular) and calcaneus are good indicators of sexual dimorphism. The percentage of correct classification was high (87.9-95.7%). In view of the differences among current Italian populations, we tested the validity of the discriminant function equations in an independent sample of individuals of different origin (northern and southern Italy). The accuracy of classification was high only for the northern Italians. Most southern Italian males were misclassified as females, confirming the population-specificity of discriminant function equations.     

Articular surfaces of the pectoral girdle: sex assessment of prehistoric New Zealand Polynesian skeletal remains

Prehistoric Polynesian skeletal remains are frequently being recovered in New Zealand due to the increasing pace of urbanisation. Since such material must often be reinterred quickly, it is important that the sex of individuals be determined from the remains in a relatively short time. For this purpose, discriminant function analysis was utilised for sex determination of prehistoric adult New Zealand Polynesian clavicles (31 male and 31 female) and scapulae (33 male and 38 female). Diameters of the acromial and sternal ends of the clavicle and the height and breadth of the scapular glenoid cavity were measured and subjected to Statistical Package for the Social Sciences (SPSS) direct discriminant function analysis. For the single discriminant function derived, accuracy of sex determination was 97.7% and reduction in error over random assignment by sex was 95%. This discriminant function will be a useful tool in the assessment of human remains in the forensic and archaeological context because it incorporates measurements which can be taken on incomplete bones.     

Discriminant function sexing of the calcaneus of the South African whites

The skull and some postcranial elements, such as the humerus, femur, and tibia, have been used in their intact states for sex determination in forensic and archaeological cases. But, in practice, these bones are often recovered in fragmented states, which render them unsuitable for use in sex determination. The calcaneus is a compact bone that is able to withstand high tensile forces. Some of its parameters have been used for sex determination in American whites and blacks (1) and Italians (2). This bone has not been used for sex determination in the South African white population. Therefore, the aim of this study was to assess the degree of sexual dimorphism of the calcaneus of the South African white population sample, derive discriminant function score equations for use in sex determination, and determine the level of accuracy of its sex-determining ability. Nine parameters were measured on each pair of 53 male and 60 female calcanei of known South African white skeletons, obtained by a random sampling technique from the Raymond A. Dart Collection of Human Skeletons, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg. Basic statistic and discriminant function analysis was performed on the acquired data. The basic statistics showed that all measured parameters were sexually dimorphic. Discriminant function score equations were generated for use in sex determination. The average accuracy of sex classification ranged from 73 to 86% for the univariate method, 81 to 91% for the stepwise method, and 82 to 92% for the direct method. It is concluded that the calcaneus is useful for sex determination in the South African white population.     

A Method for Estimating Sex Using Metric Analysis of the Scapula*

Abstract: The most accurate and precise methods for the assessment of age and stature often require knowledge of sex. Thus, being able to correctly identify sex from skeletal remains is critical in the forensic context. The presence of the os coxae or skull can never be guaranteed, making the development of reliable methods of sex estimation using other skeletal elements necessary. Using a 724 individual calibration sample from the Hamann‐Todd collection, this study identifies sexual dimorphism in the human scapula, and presents a new five‐variable discriminant function for sex estimation. The overall accuracy of this method proved to be 95.7% on the cross‐validated calibration sample, 92.5% on an 80 individual test sample from the Hamann‐Todd collection, and 84.4% on a 32 individual test sample from the skeletal collection of the Wichita State University Biological Anthropology Laboratory. Additionally, a slightly less accurate two‐variable model was developed and has cross‐validated accuracy of 91.3%.     

Quantitative Assessment of the Sternal Rib End Morphology and Implications for Its Application in Aging Human Remains

Intercostal and age differences in the sternal rib end morphology of documented female skeletons from Spitalfields and St. Bride's are examined. The morphology was captured using three‐dimensional morphometrics and the statistical analyses employed included parametric and nonparametric MANOVA, discriminant analysis, and multilinear regressions. It was found that the quantified morphology of the sternal rib end was statistically significantly different between rib four and all other ribs except for the third one and that the morphological characteristics of all ribs varied with age. However, due to the inherent variability in sternal rib end morphology, nonstatistically significant results were obtained among the various age groups and neither disciminant nor multilinear regression analysis could be used for the estimation of the age of an individual based on digitized coordinates of the sternal rib end of individuals of known age, raising some concern as to the rigorousness of the fourth rib aging method.     

Sex determination from the distal part of the femur in a French contemporary population

Until now, determining the sex of a recently deceased individual using the measurement of the bicondylar breadth of the femur (also known as condylar width, epicondylar breadth and distal epiphyseal breadth) raised some concerns as to accuracy because no sample of contemporary French subjects was available. In this study, a sample of 88 female and male femurs taken from recently deceased elderly French people was studied. The bones were collected from subjects who had donated their bodies to the Medical School of Nice. The mean value of the male bicondylar breadth was found to be greater than that of females (84.3mm versus 74.8mm), confirming the sexual dimorphism of this parameter. Furthermore, the results showed a 95.4% accuracy rate for sexing individuals. To date, in the French population, as in some other samples, epicondylar breadth is the single most accurate measurement of sex determination, ahead even of head diameter. A discriminant function is presented to allow sex determination from remains of the distal femur. With regard to the data available in the literature, sexual dimorphism is probably the result of both genetic and environmental factors. The comparison of our results with those of other populations shows that there are inter-population variations of the bicondylar breadth, and also intra-population variations that account for the differences in the accuracy rate of this variable for the purposes of sex determination. These findings underscore the need to re-evaluate bone measurements within various contemporary populations.     

Testing Discriminant Functions for Sex Determination from Deciduous Teeth*,†

Abstract: Three studies have proposed discriminant functions for sex determination from deciduous tooth crown dimensions, and this study tests the existing functions on a sample of 46 Portuguese immature skeletons of known sex, aged from birth to 10 years. Deciduous teeth were measured in their mesiodistal and faciolingual crown dimensions, and percentage of correct allocation accuracy in determining sex using each specific function was determined. Discriminant functions were also calculated from data collected for this study and tested using cross‐validation. Results show poor overall accuracy (33.3–75%) and poor cross‐validation (46.2–60.0%). This is related to low sexual dimorphism in deciduous tooth crown size, as well as differences in degree of sexual dimorphism and in overall tooth size between different samples. For these reasons, deciduous crown size does not seem to show significant forensic value as discriminator of sex, particularly when methods developed on one population are applied to individuals of another population.     

Sex assessment using measurements of the first lumbar vertebra

Sex determination is a vital part of the medico-legal system but can be difficult in cases where the integrity of the body has been compromised. The purpose of this study was to develop a technique for sex assessment from measurements of the first lumber vertebrate. Twenty-nine linear measurements and five ratios were collected from 113 Chinese adult males and 97 Chinese adult females using digital three-dimensional anthropometry methods. By using discriminant analysis, we found that 23 linear measurements and two ratios identified sexual dimorphism (P<0.01), with predictive accuracy ranging from 57.1% to 86.6%. Using a stepwise method of discriminant function analysis, we found three dimensions predicted sex with 88.6% accuracy: (a) upper end-plate width (EPWu), (b) left pedicle height (PHl), and (c) middle end-plate depth (EPDm). This study shows that a single first lumber vertebra can be used for this purpose, and that the discriminant equation will help forensic determination of sex in the Chinese population.     

Prognosis of sexual dimorphism with unfused hyoid bone: Artificial intelligence informed decision making with discriminant analysis

Depending on the metric and non-metric skeletal features of various bones, forensic experts proposed diverse sex identification methods. The main focus of the present study is to calculate sexual dimorphism in human unfused or disarticulated hyoid bone and compared it with studies conducted by different researchers. For this study, 293 unfused hyoid bones were accumulated and investigated from 173 male and 120 female cadavers of the northwest Indian population from the age of 15 to 80 years. Initially, discriminant analysis was performed on the dataset to predict sex and to get an idea for the crucial variables for sexual dimorphism. Later, significant variables predicted by the discriminant analysis were used for machine learning approaches to improve accuracy for sex determination. The standard scaler method is used for pre-processing of the data before machine learning analysis and to prevent overfitting and underfitting, 70 % of the whole dataset was utilized in the training of the model and the remaining data were used for testing the model. According to the discriminant analysis, body length (BL) and body height (BH) were found to be highly significant for the sex determination and predicted sex with 75.1 % accuracy. However, implementation of machine learning approaches such as the XG Boost classifier increased the accuracy to 83 % with sensitivity, and specificity scores of 0.81 and 0.84, respectively. Moreover, the ROC-AUC score achieved by the XG Boost classifier is 0.89; indicating machine learning investigation can improve the sex determination accuracy up to the appropriate standard.     

Sexual Dimorphism in the 7th Cervical and 12th Thoracic Vertebrae from a Mediterranean Population

Sex determination is an important task in physical anthropology and forensic medicine. The study sample comprised 121 individuals of known sex, age, and cause of death from San Jose cemetery in Granada (Spain). Eight dimensions were analyzed, and discriminant function analysis was performed for each vertebra to obtain discriminating functions and study the percentage of correct assignations of these functions. The percentage accuracy was approximately 80% for both vertebrae, but varied according to the sex, being higher for the 7th cervical in males and higher for the 12th thoracic in females. As reported in other populations, the greatest dimorphism values were found for the length of the inferior surface of the vertebral body and the width and length of the vertebral foramen of the 7th cervical vertebra and for the length of the inferior surface of the vertebral body of the 12th thoracic vertebra.     

Sexual dimorphism in the humerus: a comparative analysis of Chinese, Japanese and Thais

Determination of sex from the skeleton is vital to medicolegal investigations. There is no longer any question that populations differ in size and proportions and these differences affect the metric assessment of sex. The extent of variation in sexual dimorphism among Asian Mongoloids within and between regions has not been quantified by discriminant function analysis, nor have standards for most groups been introduced for the humerus. Therefore, the purpose of this research is to establish metric standards for sex determination from the humerus of Chinese, Japanese and Thais, as well as to compare size and sexual dimorphism in these Asian Mongoloid populations. The database for this study consisted of documented skeletal samples from China (N = 87), Japan (N = 90), and Thailand (N = 104). Six standard dimensions, including maximum length, vertical head diameter, minimum midshaft diameter, maximum midshaft diameter, midshaft circumference, and epicondylar breadth were taken and subjected to stepwise and direct discriminant function analysis. Of dimensions selected by the stepwise function, vertical head diameter and epicondylar breadth were the only elements common to all three groups. Overall, mean accuracies were highest using formulae produced by the stepwise procedure and ranged from 86.8% in the Chinese to 92.4% in the Japanese to 97.1% in the Thais. Group comparisons also revealed that while the Chinese had the largest measurements, they were the least dimorphic. The reverse was true for the Thais and the Japanese were intermediate on both counts. In cross validation tests, classification accuracy decreased in all cases where a formula from one group was applied to another. It was therefore concluded even though all individuals were Asian Mongoloids, these regionally diverse populations exhibited significant metric differences that affect sex determination from the skeleton. These findings confirm those of previous studies that there is a need for group specific metric standards of assessment.     

Age related changes in the human plastron: a roentgenographic and morphologic study

Characteristic changes that can be demonstrated on roentgenograms occur with increasing age in the plastron (chest plate) of humans. These alterations include progressive ossification in the costal cartilages (located characteristically in the sternal rib end, centrichondrally, and peristernally--often with sex and age distinctive patterns), maturation of the newly formed bone with trabeculation formation, loss of the smooth contour of the costo-manubrial junction, cupping of rib ends, osteoporotic changes, and arthritic changes in the sternal head of the clavicles. The sequence of development of these alterations has been examined by X-ray of 1965 cadavers of 15 years of age or over and correlated with the gross bone and cartilage morphology changes in many cases. This technique allows for age determination within 5 years of real age in 55% of cadavers and within 25% of real age in 95% of all cadavers. The greatest departures from real age are in the over-60-year groups. The same roentgenograms can allow for correct sex prediction in 99% of the population.     

Sexual Dimorphism in Ulna: An Osteometric Study from India

Determination of sex constitutes the most important element during the identification process of human skeletal remains. Several sex‐specific features of human skeleton have been exploited for sex determination with varying reliability. This study aims to obtain sexual dimorphic standards for ulnae of the north Indian population. Eight measurements were obtained on a sample of 106 ulnae (males‐80, females‐26) in the age range of 25–65 years. The sexual dimorphism index and demarking points were calculated for all the variables. The data were then subjected to stepwise and direct discriminant function analysis. The best discriminator of sex was the maximum length (84.9%) followed by radial notch width (84%). In stepwise analysis, these two variables were selected and provided an accuracy of 88.7% (M‐87.5%, F‐92.3%). The proximal end provided a classification rate of 81.1% (M‐80%, F‐84.6%) with selection of the notch length and olecranon width.     

颌面数字X线片性别判定指标的研究

目的筛选颌面侧位数字X线片(digital radiology,DR)的骨性定量指标,评估其在法医学性别判定中的应用价值。方法按纳入标准随机抽取颌面DR侧位片220例。对15项骨性指标(S-N,N-Me,Cd-Gn,S-Ns,S-Go(L),S-Gn,Cd-Go(L),SNA,SNB,SN-Npog,SN-MP,Gonial A,SN-RP,SN-NNs,SN-SGn)进行定量测量,采用方差分析方法分析各项指标是否有性别差异,应用逐步判别分析方法筛选出判别力较好的指标、建立判别函数并进行回代检验判别函数。结果200例颌面DR侧位片的15项指标中S-N,N-Me,Cd-Gn,S-Ns,S-Go(L),S-Gn,Cd-Go(L),SN-NNs等8项的性别差异有统计学意义(P<0.001);S-N,Cd-Gn,S-Ns,S-Gn 4项被纳入逐步判别函数。结论颌面DR侧位片中4项骨性指标(S-N,Cd-Gn,S-Ns,S-Gn)可用于性别判定,其判别准确率为95%。