Sexual Dimorphism of Anterior Sacral Curvature

Abstract: This study assesses the predictive value of anterior sacral curvature for sex estimation from skeletonized remains. Sacra from a sample of 125 American adults of known age and sex were examined. Nine measurements describing anterior sacral curvature were used in the analysis. Statistical treatment of the data included univariate statistics and discriminant function analysis for sex classification. A bootstrap validation method was employed to assess the classification error rates. Sacral curvature was significantly greater in men than in women at the level of the S2–S3 and S3–S4 articulations (p < 0.05). Correct classification estimates for the discriminant function range from 66–72%. Although sexually dimorphic, metric observations of sacral curvature are not as reliable at predicting sex as other skeletal elements. Anterior sacral curvature should only be used for sex estimation in the absence of other, more reliable, indicators.     

Development and Assessment of Postcranial Sex Estimation Methods for a Guatemalan Population

This study tests whether postcranial sex estimation methods generated from Hispanic, and mainly Mexican samples, can be successfully applied to other increasingly common migrant populations from Central America. We use a sample of postcranial data from a modern (1980s) Guatemalan Maya sample (n = 219). Results indicate a decrease in classification accuracies for previously established univariate methods when applied to the Guatemalan study sample, specifically for males whose accuracies ranged from 30 to 84%. This bias toward inaccuracies for Guatemalan males is associated with the smaller skeletal sizes for the Guatemalan sample as compared to the samples used in the tested sex estimation methods. In contrast, the tested multivariate discriminant function classification yielded less sex bias and improved classification accuracies ranging from 82 to 89%. Our results highlight which of the tested univariate and multivariate methods reach acceptable levels for accuracy for sex estimation of cases where the region of origin may include Guatemala.     

中国汉族人腰椎的性别差异

目的提供体质人类学的数据资料 ,建立中国汉族腰椎性别判别的方法。方法根据人体骨骼测量方法 ,测量 117付 (男 80 ,女 3 7付 ,年龄 17～ 90岁 )中国汉族人腰椎的 10项指标 ;选择性别差异显著的椎测量项目 ,建立腰椎及各腰椎的性别判别方程。结果第一至第五腰椎均有 5个以上的测量项目的数据存在显著意义的性别差异 (P<0 0 5 ) ;建立的 5个腰椎及各腰椎的性别判别方程 ,判别率在 69 4%～ 91 8% ,以 5个腰椎的多项指标的性别判别方程的准确率最高 (91 8% ) ,其次为第一腰椎 (84 5 % )和第二腰椎 (82 1% )。结论中国汉族人腰椎的性别差异以第一和第二腰椎明显 ,腰椎性别判定以多项指标的准确率高     

Evaluation of maxillary sinus dimensions in gender determination using helical CT scanning

Gender determination is an important step in identification in forensic medicine. CT measurements of maxillary sinuses may be useful to support gender identification. This study was undertaken to study the accuracy and reliability of maxillary sinus dimensions measurement in gender classification through the use of reconstructed helical CT images. Eighty-eight patients (43 men and 45 women) with age range from 20 to 49 years were selected in this study. The width, length, and height of the maxillary sinuses in addition to the total distance across both sinuses were measured. Data were subjected to discriminant analysis for gender using multiple regression analysis. Maxillary sinus height was the best discriminant parameter that could be used to study sexual dimorphism with an overall accuracy of 71.6%. Using multivariate analysis, 74.4% of male sinuses and 73.3% of female sinuses were sexed correctly. The overall percentage for sexing maxillary sinuses correctly was 73.9%. It can be concluded that reconstructed CT image can provide valuable measurements for maxillary sinuses and could be used for sexing when other methods of sexing are not conclusive.     

Sex estimation in forensic anthropology: skull versus postcranial elements

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.     

Mastoid Triangle for Sex Determination in Adult Nigerian Population: A Validation Study

In the quest for a simple, reliable technique to estimate the sex of human remains several novel metric skeletal indices have been reported. Only a few have been examined for utility in populations different from those in which they were developed. In this study, the mastoid process was evaluated for sex determination using 102 lateral cephalograms of a Nigerian sample of known age and sex. The asterion‐mastoidale distance and mastoid triangular area were sexually dimorphic with mean values higher in males compared with females (p = 0.02). On analysis of the discriminant function, overall accuracy for sex classification was 55%. On cross‐validation, the triangular area accurately identified 80% of females and 48% of males. The asterion‐mastoidale distance was slightly more accurate at sexing the sample. The practical utility of the mastoid triangle area technique to differentiate sex in Nigerian populations is not supported by the results of this study.     

Use of 2D:4D Digit Ratios to Determine Sex

Second to fourth digit ratios (2D:4D) are sexually dimorphic in human hands and established by the 13th gestational week. Application of 2D:4D for determining sex in living individuals by Kanchan et al. (Forensic Sci Int, 181, 2008, 53.e1) produced classification rates of 80% for males and 74–78% for females. Few studies have explored the use of 2D:4D for sexing skeletal remains. We test estimated finger lengths, phalanx lengths, and 2D:4D derived from hand bones for determining sex. Maximum phalanx length was collected using a mini‐osteometric board from 451 individuals of known age, sex, and ancestry in four skeletal collections. Logistic regression of 2nd and 4th digit finger and phalanx lengths produced classification rates greater than 80%. Digit ratios, however, failed to reach classification rates greater than 59%. Our results support those of Voracek (Forensic Sci Int, 185, 2009, e29) and suggest that 2D:4D may be population‐specific and thus inappropriate for universal application as a means of determining sex.     

Sex Determination Using the Second Cervical Vertebra—A Test of the Method*

Abstract: Sex is one of the critical questions addressed when unidentified skeletal remains are discovered in forensic or archeological contexts. Continuous testing and re‐evaluation of existing techniques is essential to improve accuracy and precision. The Wescott (J Forensic Sci 2000; 45 (2):462–6) method of sex determination from dimensions of the second cervical vertebra was blind‐tested on 153 adult individuals from the Spitalfields documented collection of human skeletal remains held at the Natural History Museum, London. Significant sex differences were determined for all dimensions measured (independent two‐sample t‐test, p < 0.05–0.001). The discriminant functions developed by Wescott were shown to have an overall accuracy of classification of 76.99%. Using stepwise discriminant analysis, a discriminant function based on the Spitalfields data correctly classified sex in 83.3% of individuals and was able to classify males and females with equal accuracy. Additional discriminant functions are presented for use in instances where preservation of the second cervical vertebra is poor.     

Patella sex determination by 3D statistical shape models and nonlinear classifiers

Sex determination is one of the essential steps in personal identification of an individual from skeletal remains. Most elements of the skeleton have been subjected to discriminant function analysis for sex estimation, but little work has been done in terms of the patella. This paper proposes a new sex determination method from the patella using a novel automated feature extraction technique. A dataset of 228 patellae (95 females and 133 males) was amassed from the William M. Bass Donated Skeletal Collection from the University of Tennessee and was subjected to noninvasive high resolution computed tomography (CT). After the CT data were segmented, a set of features was automatically extracted, normalized, and ranked. The segmentation process with surface smoothing minimizes the noise from enthesophytes and ultimately allows our methods to distinguish variations in patellar morphology. These features include geometric features, moments, principal axes, and principal components. A feature vector of dimension 45 for each subject was then constructed. A set of statistical and supervised neural network classification methods were used to classify the sex of the patellar feature vectors. Nonlinear classifiers such as neural networks have been used in previous research to analyze several medical diagnosis problems, including quantitative tissue characterization and automated chromosome classification. In this paper, different classification methods were compared. Classification success ranged from 83.77% average classification rate using labels from a Fuzzy C-Means (FCM) clustering step, to 90.3% for linear discriminant classification (LDC). We obtained results of 96.02% and 93.51% training and testing classification rates, respectively, using feed-forward backpropagation neural networks (NN). These promising results using newly developed features and the application of nonlinear classifiers encourage the usage of these methods in forensic anthropology for identifying the sex of an individual from incomplete skeletons retaining at least one patella.     

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%.     

Metacarpal sexual determination in a Spanish population

Anthropologists and forensic pathologist determine the sex of skeletons by analyzing quantitative and qualitative characters in the bone remains. Generally, the skull and os coxae are the elements most used, but they are not always preserved. In such cases, the investigator needs to have available other techniques based on different remains. The aim of the present work is to develop and describe discriminating functions for sex determination in a recent Spanish population using metacarpal morphology. A sample of bones corresponding to a contemporary Spanish population deposited at the Complutense University of Madrid (UCM) was analyzed. This sample comprised 697 metacarpals, corresponding to 79 adult individuals (37 men and 42 women). These allowed us to obtain 120 unifactorial discriminant functions. We selected the 10 equations, one for each metacarpal from both hands, that provided the best sexual discrimination. The correct sex classification rank progressed from 81%, for right (R) metacarpals IV and V, to 91%, for left (L) metacarpal II. The results suggest that metacarpals are structures that can be used for sex determination in paleoanthropological and forensic identifications.     

Discriminant function analysis for sex assessment in pelvic girdle bones: sample from the contemporary Mexican population

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.     

Sexual Dimorphism of the Arm Bones in a Modern Greek Population

Abstract: Several studies have shown that sex determination methods based on measurements of the skeleton are population specific. Metric traits of the long bones of the arm have been reported as reliable indicators of sex. This study was designed to determine whether the three long bones of the arm can be used for sex determination on a skeletal population from Greece. The material used consists of the arm bones of 204 adult individuals (111 males and 93 females) coming from the Modern Human Skeletal Collection of the University of Athens. The age range is 19–96 years for males and 20–99 years for females. The maximum lengths and epiphyseal widths were measured in the long bones of the arm (humerus, radius, and ulna). The discriminant analysis of the metrical data of each long bone gave very high discrimination accuracies. The rate of correct sex discrimination based on different long bones ranges from 90.30% (ulna) to 95.70% (humerus). In addition, intra‐ and inter‐observer error tests were performed. These indicated that replication of measurements was satisfactory for the same observer over time and between observers. The results of this study show that metric characteristics of the arm bones can be used for the determination of sex in skeletal remains from Greece and that bone dimensions are population specific.     

Sex Assessment from the Sacral Base by Means of Image Processing

Abstract:  To help improve sex assessment from skeletal remains, the present study considers the diagnostic value of the sacral base (basis osseus sacri) based on its planar image and related metric data. For this purpose, 114 adult sacra of known sex and age from two early 20th century Italian populations were examined, the first from Bologna, northern Italy ( n  = 76), and the second from Sassari, Sardinia ( n  = 38). Digital photos of the sacral base were taken with each bone in a standardized orientation. Technical drawing software was used to trace its profile and to measure related dimensions (area, perimeter, and breadth of S1 and total breadth of the sacrum). The measurements were subjected to discriminant and classification function analyses. The sex prediction success of 93.2% for the Bolognese sample, 81.6% for the Sassarese sample, and 88.3% for the pooled sample indicates that the first sacral vertebra is a good character for sex determination.     

Radiographic age estimation based on degenerative changes of vertebrae

Age estimation is an important component of decedent identification. When assessing adult remains, anthropologists frequently use gross examination of skeletal elements, such as clavicles, ribs, and pubic symphyses. For fleshed bodies, this requires the removal of these elements and maceration prior to analysis. A new method was developed using radiographic imaging to estimate age from degenerative changes of the lower thoracic and upper lumbar vertebrae. This technique will complement anthropological age estimation methods in young and middle-aged adults and may serve as a stand-alone method for older individuals. Digital radiographs from 240 medical examiner cases were evaluated. The sample included 120 females and 120 males between the ages of 18 and 101 years. A 3-phased scoring system was used for the target vertebrae. Transition analysis was conducted on binned average scores and a Bayesian approach was used to assign age intervals. At the 90% credible interval, individuals in Bin 1 were under 36 years of age while those in Bin 3 were over 47 years of age. Individuals in Bin 2 showed too much age variation to be informative. No significant differences were found between males and females. These findings will be especially useful in the age estimation of older adults and may eliminate the need for skeletal sampling in medicolegal cases where advanced degenerative changes are radiographically observed in the lower thoracic and/or upper lumbar vertebrae. This method was developed for use on fleshed individuals but may also be applicable to skeletonized remains.     

腰椎的个体识别

腰椎是人体躯干骨中的主要承重骨,其形态受多种因素影响。腰椎的研究对白骨、碎尸等类型案件尸源的寻找和古人类的体征复原均有重要意义。本文着重从身高推算、性别判定和年龄判定三个方面综述了近年来腰椎在法医人类学领域的研究进展。     

Generating a Vertebrae‐based Method to Discriminate between Korean and U.S. White Male Casualties from the Korean War,

Low recovery rate of intact crania in conflict‐related contexts necessitates the use of postcranial elements for ancestry estimation. This study aimed to develop a new method to discriminate between Korean and U.S. White casualties from the Korean War using vertebrae. Maximum body heights of C2 through L5 were measured from 75 Korean and 51 U.S. males to generate discriminant functions. U.S. vertebral heights were statistically greater than Koreans in 18 out of 23 vertebrae (C2, C4‐6, T3‐6, and T8‐L5). The functions with lumbar vertebrae tended to yield higher correct classification ratios (CCR) than those with cervical or thoracic vertebrae. Inclusion of the femur and tibia lengths in the vertebrae‐involved functions enhanced the CCR's. Discriminant functions using the femur and tibia length were also presented. The results of this study are expected to complement the current practices of the Defense POW/MIA Accounting Agency and the Ministry of National Defense Agency for KIA Recovery and Identification, which are primarily based on cranial and dental morphology.     

Sex estimation in a modern American osteological sample using a discriminant function analysis from the calcaneus

Reliable methods for sex estimation during the development of a biological profile are important to the forensic community in instances when the common skeletal elements used to assess sex are absent or damaged. Sex estimation from the calcaneus has potentially significant importance for the forensic community. Specifically, measurements of the calcaneus provide an additional reliable method for sex estimation via discriminant function analysis based on a North American forensic population. Research on a modern American sample was chosen in order to develop up-to-date population specific discriminant functions for sex estimation. The current study addresses this matter, building upon previous research and introduces a new measurement, posterior circumference that promises to advance the accuracy of use of this single, highly resistant bone in future instances of sex determination from partial skeletal remains. Data were collected from The William Bass Skeletal Collection, housed at The University of Tennessee. Sample size includes 320 adult individuals born between the years 1900 and 1985. The sample was comprised of 136 females and 184 males. Skeletons used for measurements were confined to those with fused diaphyses showing no signs of pathology or damage that may have altered measurements, and that also had accompanying records that included information on ancestry, age, and sex. Measurements collected and analyzed include maximum length, load-arm length, load-arm width, and posterior circumference. The sample was used to compute a discriminant function, based on all four variables, and was performed in SAS 9.1.3. The discriminant function obtained an overall cross-validated classification rate of 86.69%. Females were classified correctly in 88.64% of the cases and males were correctly classified in 84.75% of the cases. Due to the increasing heterogeneity of current populations further discussion on this topic will include the importance that the re-evaluation of past studies has on modern forensic populations. Due to secular and micro evolutionary changes among populations, the near future must include additional methods being updated, and new methods being examined, both which should cover a wide population spectrum.     

Estimating Sex Using Metric Analysis of the Scapula by Postmortem Computed Tomography

Postmortem computed tomography (CT) has been extensively used in the last decade for identification purposes and in various anthropologic studies. Postmortem CT measurements of scapulae, analyzed using logistic discriminant function developed in this study, showed 94.5% accuracy in estimating sex. Data analyzed using the Dabbs and Moore‐Jansen (2010) discriminant function and the discriminant function generated in this study provided nearly identical results with disagreement in only one case. Height and weight were not statically significant in sex prediction. The results of this study show that data obtained from volume rendered postmortem CT images can be considered reliable and treated as a practical option to standard anthropological methods, especially in mass fatalities as a rapid triage tool for sex determination.     

Misclassification probability of dental discrimination functions for sex determination

Misclassification probability of dental discriminant functions for sexing American whites was evaluated using three verification procedures. These validation techniques involved sample resubstitution, jackknife classification, and use of a holdout sample. Resulting discriminant score distributions yielded correct classifications ranging between 65 and 81% depending upon the particular tooth combinations selected. Dental discriminant functions are applicable to forensic science cases if used with caution.