Sex determination in subadults using auricular surface morphology: a forensic science perspective.

The determination of sex in subadult skeletons remains a problem for several areas of biological anthropology. To date, univariate and multivariate assessments of sex in the young using adult indicators have failed to produce reliable results. However, research in this area continues. In 1980, Weaver proposed a modification of adult differences in auricular surface morphology as an effective means for sex determination in subadult remains. His method was indirectly evaluated by Hunt through a comparison of the sex ratios produced by this technique and the expected 1:1 ratio. The present investigation expands upon both studies by using a sample of subadults of known sex, and by evaluating Weaver's method from two perspectives: 1) what percentage of individuals can be correctly sexed using Weaver's criteria? and 2) what is the probability that an individual case will be correctly sexed based on the presence or absence of auricular surface elevation? The first is of interest to those reconstructing population patterns, while the second is critical to the forensic investigator faced with the diagnosis of an individual case. The sample used in this study consisted of 58 ilia from subadults of known sex ranging in age from birth through 18. In each case, sufficient soft tissues were present to allow absolute sex diagnosis. Each ilium was subjected to a blind examination using Weaver's criteria for auricular surface elevation. Weaver's technique proved most effective on the males in our sample, with an overall accuracy of 85.3%; however, accuracy in sexing females was only slightly better than chance at 58.3%. Our results corresponded closely to Weaver's own values of 85.4 and 57.7% respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sex determination in the subadult ilia: an indirect test of Weaver's nonmetric sexing method

The sexing of subadult remains has been an ongoing problem in physical anthropology for many years. This is due in part to the scarcity of subadult collections of known age and sex which are large enough to be used to develop and test analytical methods. Several methods have been devised but few have produced reliable results. In 1980, Weaver presented a method for sexing subadult ilia using a nonmetric trait (the raised versus nonraised auricular surface), which has an accuracy of 75% in fetal females and 92% in fetal males. His method has not been tested for reliability on a different subadult sample. An indirect test of Weaver's method was made on a sample of subadult South Dakota Arikara Indian ilia by comparing the ratio of raised to nonraised auricular surfaces with an expected 1:1 sex distribution. Bimodal sex distributions in the Arikara formed unrealistic sex ratios, following an age-related shift from a 6:1 raised/nonraised ratio in newborns to a 1:4 ratio in young adolescence. Significant age correlations were found both in the present study and in Weaver's published results. The age-to-sex correlations indicated no confounding in the present study. The results of this test suggest that auricular surface morphology is not sex specific in subadult ilia, but may be related to aspects of shape and morphology in pelvic growth.     

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%.     

A Method for Estimating Sex Using the Clavicle,Humerus, Radius,and Ulna

Sex estimation from skeletal remains can be an important part of preliminary identification. The best source of information for estimating sex is the pelvis but it is not always available for analysis. For these cases, a probabilistic sex estimation method is presented using combinations of standard and alternative measurements of the clavicle, humerus, radius, and ulna. Various equations are developed that are not population specific and that are applicable in various recovery scenarios. The equations were tested using four independent samples (n > 370), including a forensic sample. Allocation accuracies vary by test sample and equation and are consistently good (87.4–97.5%) except for a sample of very small males that show the extreme effects of poverty and mortality bias. For many of the cases where allocation was incorrect, the probabilistic approach indicated that no confidence should be placed in the incorrect allocation and the unknown should be classified as sex indeterminate.     

Age Estimation of Infants Through Metric Analysis of Developing Anterior Deciduous Teeth

This study provides regression equations for estimation of age of infants from the dimensions of their developing deciduous teeth. The sample comprises 97 individuals of known sex and age (62 boys, 35 girls), aged between 2 days and 1,081 days. The age‐estimation equations were obtained for the sexes combined, as well as for each sex separately, thus including “sex” as an independent variable. The values of the correlations and determination coefficients obtained for each regression equation indicate good fits for most of the equations obtained. The “sex” factor was statistically significant when included as an independent variable in seven of the regression equations. However, the “sex” factor provided an advantage for age estimation in only three of the equations, compared to those that did not include “sex” as a factor. These data suggest that the ages of infants can be accurately estimated from measurements of their developing deciduous teeth.     

Accuracy Rates of Sex Estimation by Forensic Anthropologists through Comparison with DNA Typing Results in Forensic Casework

A common task in forensic anthropology involves the estimation of the biological sex of a decedent by exploiting the sexual dimorphism between males and females. Estimation methods are often based on analysis of skeletal collections of known sex and most include a research‐based accuracy rate. However, the accuracy rates of sex estimation methods in actual forensic casework have rarely been studied. This article uses sex determinations based on DNA results from 360 forensic cases to develop accuracy rates for sex estimations conducted by forensic anthropologists. The overall rate of correct sex estimation from these cases is 94.7% with increasing accuracy rates as more skeletal material is available for analysis and as the education level and certification of the examiner increases. Nine of 19 incorrect assessments resulted from cases in which one skeletal element was available, suggesting that the use of an “undetermined” result may be more appropriate for these cases.     

A Test of the Revised Auricular Surface Aging Method on a Modern European Population

The accurate age estimation of adults is an important step in the construction of the biological profile of skeletonized remains. The auricular surface of the ilium as it was developed in 1985 by Lovejoy et al., is one of the methods employed for age estimation. This study presents the results of a blind test of the revised auricular surface aging method developed by Buckberry and Chamberlain. A sample of 120 individuals from the Athens Collection was used to test this revised aging technique. Almost all features and composite score were positively correlated with known age‐at‐death. The calculation of bias demonstrated no obvious trend for either overestimation or underestimation of age when all individuals were pooled together. Inaccuracy showed that absolute errors of estimated ages against known ages are substantial. The data generated from this study suggest that the revised method can be reliable for age estimation on a modern European population.     

Age estimation from the human os coxa: a test on a documented Italian collection*

Current standards for age at death estimation from the pelvis are based on Americans of European and African ancestry. Our limited understanding of population variability hampers our efforts to apply these techniques to the various skeletal populations around the world, especially in global forensic contexts. However, documented skeletal samples are rare, limiting our ability to test our techniques. This study tested the Suchey-Brooks pubic symphysis aging method and the auricular surface method originally developed by Lovejoy et al. on a large sample (n = 404) of known sex and age from the Sassari Collection, housed at the Museum of Anthropology at the University of Bologna, Italy. The results indicate that for both methods, bias and inaccuracy increased with age and actual age tended to be underestimated over the age of 40. The auricular surface method performed slightly better, exhibiting slightly lower levels of bias and inaccuracy, especially for males.     

A Comparison of Different Age Estimation Methods of the Adult Pelvis

The adult human pelvis is useful to estimate age because it contains three age indicators—the pubic symphysis, auricular surface, and acetabulum. This study tested the accuracy, inaccuracy, and bias of age estimation from the Suchey‐Brooks pubic symphysis, Osborne auricular surface, Rissech and Calce acetabulum aging methods, and a summary age of these indicators. The study sample consisted of 212 White individuals with known age and sex from the William M. Bass Donated Skeletal Collection. The Rissech method performed the best, was the most accurate method with smallest inaccuracy and bias, followed by the Osborne, Suchey‐Brooks, summary age, and then Calce methods. Though the Pearson correlation showed only the Suchey‐Brooks method to correlate significantly with known age, it is likely the Suchey‐Brooks study sample coincidentally reflected the age distribution of this test sample. Results suggested that Bayesian prediction may improve age estimation and should be applied to other age indicators.     

髂骨耳状面的人类学个体识别

本文综述了髂骨耳状面在人类学个体识别中的应用,髂骨耳状面对年龄、身高和性别的推断,具有简单、准确的特点,在人类学个体识别中具有重要意义。     

Sex Estimation from Human Cranium: Forensic and Anthropological Interest of Maxillary Sinus Volumes

Sex estimation is a key objective of forensic science. We aimed to establish whether maxillary sinus volumes (MSV) could assist in estimating an individual's sex. One hundred and three CT scans were included. MSV were determined using three‐dimensional reconstructions. Two observers performed three‐dimensional MSV reconstructions using the same methods. Intra‐ and interobserver reproducibility were statistically compared using the intraclass correlation coefficient (ICC) (α = 5%). Both intra‐ and interobserver reproducibility were perfect regarding MSV; both ICCs were 100%. There were no significant differences between right and left MSV (p = 0.083). No correlation was found between age and MSV (p > 0.05). We demonstrated the existence of sexual dimorphism in MSV (p < 0.001) and showed that MSV measurements gave a 68% rate of correct allocations to sex group. MSV measurements could be useful to support sex estimation in forensic medicine.     

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.     

Morphoscopic Trait Expression in “Hispanic” Populations

This study evaluates population variation of eight cranial morphoscopic traits using samples of known southwest Hispanics (n = 72), Guatemalans (n = 106), American Blacks (n = 146), and American Whites (n = 218). We applied the support vector machine (SVM) method to build a prediction model based on a subsample (20%) of the data; the remainder of the data was used as a test sample. The SVM approach effectively differentiated between the four groups with correct classification rates between 72% (Guatemalan group) and 94% (American Black group). However, when the Guatemalan and southwest Hispanic samples were pooled, the same model correctly classified all groups with a higher degree of accuracy (American Black = 96%; American White = 77%; and the pooled Hispanic sample = 91%). This study also identified significant differences between the two Hispanic groups in six of the eight traits using univariate statistical tests. These results speak to the unique population histories of these samples and the current use of the term “Hispanic” within forensic anthropology. Finally, we argue that the SVM can be used as a classification model for ancestry estimation in a forensic context and as a diagnostic tool may broaden the application of morphoscopic trait data for the assessment of ancestry.     

Sex Determination from the Frontal Bone: A Geometric Morphometric Study

Sex estimation in human skeletal remains when using the cranium through traditional methods is a fundamental pillar in human identification; however, it may be possible to incur in a margin of error due because of the state of preservation in incomplete or fragmented remains. The aim of this investigation was sex estimation through the geometric morphometric analysis of the frontal bone. The sample employed 60 lateral radiographs of adult subjects of both sexes (30 males and 30 females), aged between 18 and 40 years, with mean age for males of 28 ± 4 and 30 ± 6 years for females. Thin‐plate splines evidenced strong expansion of the glabellar region in males and contraction in females. No significant differences were found between sexes with respect to size. The findings suggest differences in shape and size in the glabellar region, besides reaffirming the use of geometric morphometrics as a quantitative method in sex estimation.     

Evaluation of the (hu)MANid program for sex and ancestry estimation in a diverse,contemporary CT scan-based sample

Human remains from forensic and bioarcheological contexts are often fragmentary, requiring methods for estimating a forensic profile that are based upon limited skeletal features. In 2017, Berg and Keryhercz created an online application, (hu)MANid, that provides sex and ancestry estimation from mandibular morphoscopic traits and linear measurements. In this study, we examine the utility of the (hu)MANid application in a diverse, urban US adult sample (aged 20–45; n = 143) derived from computed tomography (CT) scans. We secondarily conduct a preliminary analysis of the program's utility in a sample of adolescents (aged 15–17; n = 40). Six morphoscopic, and eleven morphometric traits were recorded as directed by the literature associated with the (hu)MANid program. Percent correct classification and posterior predictive values were calculated for the sex and ancestry estimations output by the program; chi-squared tests were employed to compare self-reported and predicted ancestry. In the adult sample, sex was accurately predicted for 75.52% of the sample. Ancestry prediction, however, was less favorable ranging from 19.3% to 50% correct. For the adolescent sample, correct sex estimation (45%) did not surpass what could occur by chance alone, though ancestry prediction fared better than in the larger adult sample (percent correct prediction overall average: 47.5%, range 35.71%–71.43%). The (hu)MANid application shows utility for use with CT scan-derived adult samples for sex estimation, but caution is warranted for ancestry estimation and use with samples that may not have reached full adult maturity.     

Quantitative Analysis of the Morphological Changes of the Pubic Symphyseal Face and the Auricular Surface and Implications for Age at Death Estimation

Age estimation methods are often based on the age‐related morphological changes of the auricular surface and the pubic bone. In this study, a mathematical approach to quantify these changes has been tested analyzing the curvature variation on 3D models from CT and laser scans. The sample consisted of the 24 Suchey–Brooks (SB) pubic bone casts, 19 auricular surfaces from the Buckberry and Chamberlain (BC) “recording kit” and 98 pelvic bones from the Terry Collection (Smithsonian Institution). Strong and moderate correlations between phases and curvature were found in SB casts (ρ 0.60–0.93) and BC “recording kit” (ρ 0.47–0.75), moderate and weak correlations in the Terry Collection bones (pubic bones: ρ 0.29–0.51, auricular surfaces: ρ 0.33–0.50) but associated with large individual variability and overlap of curvature values between adjacent decades. The new procedure, requiring no expert judgment from the operator, achieved similar correlations that can be found in the classic methods.     

Sex Estimation of Infants Between Birth and One Year Through Discriminant Analysis of the Humerus and Femur

Estimation of sex when investigating subadult skeletal remains is largely problematic because of unreliable and inaccurate results. Despite the limitations encountered with skeletal material, the medical literature clearly demonstrates differences between males and females in utero that persist through life. The current study investigates sexual dimorphism in the long bones of the humerus and femur for individuals between birth and 1 year of age. A radiographic sample amassed from Erie County Medical Examiner's office includes 85 femoral and 45 humeral images for analysis in relation to sex. Measurements for lengths and breadths were collected through tpsDig software. Discriminant analysis proved to be the most successful method, with error rates of 3% when utilizing maximum breadth at midshaft of the femur and 11% with humerus maximum distal breadth. This research demonstrates that it is possible to correctly classify sex of unknown subadult remains when comparing them to a known sample.     

The Use of Femoral Neck Axis Length to Estimate Sex and Ancestry

Having multiple reliable methods of estimating sex and ancestry from various skeletal features increases the likelihood of identifying skeletal remains. Femoral neck axis length (FNAL), as measured in living individuals, has been shown to vary by sex and ancestry. FNAL has not, however, been previously measured directly from skeletonized remains and investigated for its potential use in forensic anthropological applications. This research proposes a method for measuring FNAL from skeletal remains, determines the reliability and repeatability of the measurement, and assesses the validity of FNAL in sex and ancestry estimation. Results showed low interobserver error in the measurement of FNAL (TEM = 0.33 mm, R = 0.99). Significant differences in FNAL were found between sexes as well as between American Black, American White, and Native American groups. FNAL can correctly classify sex in ~86% of all cases and is considered valuable to sex estimation. The value of FNAL to ancestry estimation, however, is considered limited.     

A Comparative Assessment of the Chen et al. and Suchey‐Brooks Pubic Aging Methods on a North American Sample, ,

Accurately estimating the age‐at‐death of adult human skeletons is fundamental in forensic anthropology. This study evaluates the accuracy of two pubic bone age estimation methods—Chen et al. and Suchey‐Brooks. Specimens were obtained from a known collection of modern pubic bones curated at the Maricopa County Forensic Science Center in Phoenix, Arizona. A sample of 296 left male pubic bones of European ancestry was statistically evaluated via bias, absolute mean error, and intra‐ and inter‐observer error. Results indicate that the two methods are similar; the Suchey‐Brooks method is the most accurate for aging young adults (error c. 7 years), while the Revised Chen et al. method is most accurate for aging middle‐age adults (error c. 6 years). Thus, the Chen et al. method is an important contribution to forensic anthropology for aging older adult skeletal remains. There are, however, some limitations such as subjectivity and the intricate scoring system of Chen et al. method.