Auricular Surface Aging: Comparing Two Methods that Assess Morphological Change in the Ilium with Bayesian Analyses

Modern standards in forensic anthropology require rigorous testing and evaluation of methods used for aging skeletal remains. Age estimation has been criticized for bias, inaccuracy, and population specificity; issues which are minimized by the application of Bayesian methodology. Using Bayesian statistics, we compare the Lovejoy et al. (Am J Phys Anthropol, 68, 1985, 15) (original) and Buckberry and Chamberlain (Am J Phys Anthropol, 119, 2002, 231) (revised) auricular surface aging methods. Transition analysis parameters derived from American males (n = 372), in combination with a Thai male (N = 37) informative prior, statistically model age in Portuguese males (n = 221). Cumulative binomial tests assess the accuracy of the generated age ranges. Overall, the application of transition analysis and Bayesian statistics significantly improved age estimation with both methods (also outperforming Suchey‐Brooks pubic symphysis aging). Moreover, the accuracy of the original method was low without statistical modeling, whereas the revised method can be applied accurately without further statistical analysis. Additionally, reference tables for aging Portuguese males are provided.     

Secular Change in Morphological Pelvic Traits used for Sex Estimation

This research evaluates secular change in Phenice's (Am J Phys Anthropol, 30, 1969 and 297) three morphological traits of the pubis, as described by Klales et al. (Am J Phys Anthropol, 149, 2012 and 104): medial aspect of the ischio‐pubic ramus, subpubic contour, and ventral arc. Ordinal scores were collected for these traits and compared between a sample of innominates from the historical Hamann–Todd Collection (n = 170) and modern Bass Donated Collection (n = 129). Using the Freeman–Halton test, significant differences between temporal sample score frequencies were found for all traits in females and for the subpubic contour and ventral arc in males. Despite these findings, classification accuracy using logistic regression between the temporal periods remained low (68.7%). These results suggest that secular changes in trait expression are occurring; however, sex estimation methods using these traits and created with historical samples are still applicable to modern forensic cases. In fact, the secular changes occurring in these traits contribute to better classification accuracy between sexes in modern populations.     

A Test of a Recently Devised Method of Estimating Skeletal Age at Death using Features of the Adult Acetabulum

Estimation of age at death from adult skeletal remains is highly problematic, due in great part to interpopulation variability in skeletal age changes. Thorough testing of aging methods is therefore of key importance. A method recently devised by Calce (Am J Phys Anthropol 148 (2012): 11–23) for placing adult skeletons into three broad age at death classes (17–39, 40–64, 65+ years) on the basis of acetabular morphology is tested on a collection of 18–19th century AD skeletons (N = 185) of documented age at death from London. Results showed that 45% were correctly assigned to age class using this method. This compares with 81% reported by Calce on 20th century North American material. This indicates significant interpopulation differences in the relationship between the Calce acetabular variables and age, even between populations of European ancestry. Until the sources of this variation are better understood, caution should be used before applying this method to estimate age in unknown skeletons.     

Auricular surface aging: a blind test of the revised method on historic Italians from Sardinia

Age determination from human skeletal remains is an important biological parameter in both forensic and bioarchaeological contexts. This study presents the results of a blind test of the revised auricular surface age estimation method proposed by Buckberry and Chamberlain (Am. J. Phys. Anthropol. 119 (2002) 321-329) on a large sample (n=404) of known sex and age from the Sassari collection, housed at the Museum of Anthropology, University of Bologna, Italy. Ilia were scored for five features: transverse organization, surface texture, microporosity, macroporosity, and apical changes, which combined for a composite score. The results indicated that all features and the composite score were positively correlated with known age. Composite scores were significantly different between the sexes, suggesting that males and females should be treated separately. Bias and inaccuracy varied across age intervals. Age tended to be overestimated in individuals under age 59 and underestimated for those over age 60 years. However, the revised method showed improvement over the original auricular surface method (Lovejoy et al., Am. J. Phys. Anthropol. 68 (1985) 15-28), especially for aging older individuals. Considerable variation exists in the age ranges derived from composite scores and few significant differences were found between age stages, suggesting that fewer stages with wider age ranges may be necessary. The independent, quantitative scoring of the surface features makes the revised method substantially easier to apply and the method shows significant improvement for aging older individuals.     

Pubic bone age estimation in adult women

In recent years, numerous physical anthropologists have pointed out the need for regional standards for estimating age in various world populations. While investigating aging methods for East European populations, dramatic changes were noted in the pubic symphyseal morphology and structure of older adult female individuals. These changes were not captured in the typically used pubic symphysis aging methods. This paper defines and tests the need for a new phase, phase VII, that follows the Suchey-Brooks phase VI. In addition, Suchey-Brooks phases V and VI are redefined. Phase definitions, decision-making rules, and comparison graphics for the new method are presented. Balkan (n = 85) and Eastern Tennessee (n = 104) samples, totaling 189 individuals, were used in the analysis. Pearson correlation coefficients between four observers and a control seriation were strong, indicating ease of replicability between investigators. No statistically significant intra-observer error was detected. Summary statistics show that individuals in phase V were on average in the early 50s, while individuals in phase VI were in their mid 50s to mid 60s, and individuals in phase VII were in their mid 70s. Since linear regression models tend to under-age the elderly and over-age the young, transition analysis, using an unrestricted cumulative probit model, was undertaken to evaluate the phases and to produce point estimates for the ages-at-transition for the Balkan sample. The highest posterior density region point estimates with their associated upper and lower bounds can be used for predicting age for unknown forensic cases related to the Balkan sample. Further, the mean ages and standard deviations for phases V-VII for the Tennessee sample are presented for use in American forensic cases.     

Evaluation of the Suchey-Brooks method for aging skeletons in the Balkans

This study has been carried out to examine whether the Suchey-Brooks (S&B) methods could be successfully applied in age assessment of populations from the Balkans. The known-age sample consists of 33 females and 52 males pairs of pubic bones collected from the autopsy cases. Age estimation by S&B method showed an accuracy of 89.74% in males and 72.0% in females. Statistical analysis showed a positive correlation between the actual age of the investigated individuals and age phases obtained by the S&B method, although the mean values of the sixth age category differed significantly compared with the original model. The most reliable indicators in both sexes were the relief of the symphyseal surface, lipping, symphyseal rim, and dorsal margin. The discriminating power of these indicators was the least reliable in distinguishing S&B phases 2 and 3. Based on these results, the appropriate recommendations for aging Serbian populations are made. There was a good agreement between two observers (kappa=0.726).     

A Bayesian approach to estimate skeletal age-at-death utilizing dental wear

In the forensic context, teeth are often recovered in mass disasters, armed conflicts, and mass graves associated with human rights violations. Therefore, for victim identification, techniques utilizing the dentition to estimate the first parameters of identity (e.g., age) can be critical. This analysis was undertaken to apply a Bayesian statistical method, transition analysis, based on the Gompertz-Makeham (GM) hazard model, to estimate individual ages-at-death for Balkan populations utilizing dental wear. Dental wear phases were scored following Smith's eight-phase ordinal scoring method and chart. To estimate age, probability density functions for the posterior distributions of age for each tooth phase are calculated. Transition analysis was utilized to generate a mean age-of-transition from one dental wear phase to the next. The age estimates are based on the calculated age distribution from the GM hazard analysis and the ages-of-transition. To estimate the age-at-death for an individual, the highest posterior density region for each phase is calculated. By using a Bayesian statistical approach to estimate age, the population's age distribution is taken into account. Therefore, the age estimates are reliable for the Balkan populations, regardless of population or sex differences. The results showed that a vast amount of interpersonal variation in dental wear exists within the current sample and that this method may be most useful for classifying unknown individuals into broad age cohorts rather than small age ranges.     

Improving Nonmetric Sex Classification for Hispanic Individuals

Current techniques used by forensic anthropologists for the identification of unknown human skeletal remains have largely been created using U.S. Black and White samples. When applied to Hispanics, these techniques perform poorly and can lead to misclassifications; consequently, there is an imperative need for population‐specific standards for Hispanics. This research examines the classification accuracies obtained by the original Walker (Am J Phys Anthropol, 136, 2008) and Klales et al. (Am J Phys Anthropol, 149, 2012) methods for nonmetric sex estimation and provides recalibrated regression equations specifically for Hispanics. Ordinal data were collected for five skull and three pelvic traits from a sample of 54 modern Hispanic individuals. Recalibration of the Klales et al. equation improved accuracy (90.3% vs. 94.1%), while recalibration of the Walker method equation decreased accuracy (81.5% vs. 74.1%), but greatly improved sex bias (22.2% vs. ?7.4%), thereby making the recalibrated equations more appropriate for use with Hispanics.     

Pronasale Position: An Appraisal of Two Recently Proposed Methods for Predicting Nasal Projection in Facial Reconstruction

This study examines two recently proposed methods for predicting nose projection from the skull, those developed by Stephan et al. (Am J Phys Anthropol 122, 2003, 240) and Rynn et al. (Forensic Sci Med Pathol 6, 2010, 20). A sample of 86 lateral head cephalograms of adult subjects from Central Europe was measured, and the actual and predicted dimensions were compared. Regarding nose projection (the anterior and vertical position of the pronasale), in general, the method of Rynn et al. (Forensic Sci Med Pathol 6, 2010, 20) was found to perform better and with less error variance than the method of Stephan et al. (Am J Phys Anthropol 122, 2003, 240), but the mean difference between the actual and predicted values did not exceed 2.2 mm (6.5% of the actual dimension) in most of the variables tested. The vertical dimensions of the nose were predictable with greater accuracy than the horizontal dimensions. Although the mean error of both methods is not great in practice and thus both methods could be considered to be “accurate,” the real variance of error should not be overlooked.     

New formulae for estimating stature in the Balkans

Recent studies of secular change and allometry have observed differential limb proportions between the sexes, among and within populations. These studies suggest that stature prediction formulae developed from American Whites may be inappropriate for European populations. The purpose of this investigation is to present more appropriate stature prediction equations for use in the Balkans to aid present-day identifications of the victims of genocide. The reference sample totals 545 white males obtained from World War II data. The Eastern European sample totals 177 males and includes both Bosnian and Croatian victims of the recent war. Mean stature for Eastern Europeans was obtained from the literature. Results show that formulae based on Trotter and Gleser systematically underestimate stature in the Balkans. Because Eastern Europeans are taller than American Whites it is appropriate to use this as an "informative prior" that can be applied to future cases. This informative prior can be used in predictive formulae, since it is probably similar to the sample from which the Balkan forensic cases were drawn. Based on Bayes' Theorem new predictive stature formulae are presented for Eastern Europeans.     

Estimation and evidence in forensic anthropology: age-at-death

A great deal has previously been written about the use of skeletal morphological changes in estimating ages-at-death. This article looks in particular at the pubic symphysis, as it was historically one of the first regions to be described in the literature on age estimation. Despite the lengthy history, the value of the pubic symphysis in estimating ages and in providing evidence for putative identifications remains unclear. This lack of clarity primarily stems from the fact that rather ad hoc statistical methods have been applied in previous studies. This article presents a statistical analysis of a large data set (n = 1766) of pubic symphyseal scores from multiple contexts, including anatomical collections, war dead, and victims of genocide. The emphasis is in finding statistical methods that will have the correct "coverage."Coverage" means that if a method has a stated coverage of 50%, then approximately 50% of the individuals in a particular pubic symphyseal stage should have ages that are between the stated age limits, and that approximately 25% should be below the bottom age limit and 25% above the top age limit. In a number of applications it is shown that if an appropriate prior age-at-death distribution is used, then "transition analysis" will provide accurate "coverages," while percentile methods, range methods, and means (+/-standard deviations) will not. Even in cases where there are significant differences in the mean ages-to-transition between populations, the effects on the stated age limits for particular "coverages" are minimal. As a consequence, more emphasis needs to be placed on collecting data on age changes in large samples, rather than focusing on the possibility of inter-population variation in rates of aging.     

Evaluation of the Enhanced Computational Methods of Estimating Age-at-Death Using the Pubic Symphyses of a White South African Population

To address problems of reproducibility related to current age estimation methods, the enhanced computational Methods (ECM) were previously developed using a sample of white North American male pubic symphyses and showed promise in improving current techniques. However, given the evidence of sex and population differences in the onset of age markers, this study set out to test the ECM on a white South African sample. The sample consisted of 184 well-preserved os coxae from individuals of known age and sex. Pubic symphyseal surfaces were scanned using the Artec Spider 3D scanner, processed using Artec Studio 10 and analyzed using forAge. Point estimates of age were then compared to the true age of each individual. Results indicate that the ECM performed poorly in a white South African population, with consistent underestimation of age-at-death and weak positive correlations with true age. Despite the low correlations, the ECM did, however, reduce observer error.     

Characterization of human control region sequences of the African American SWGDAM forensic mtDNA data set

The scientific working group on DNA analysis Methods (SWGDAM) mitochondrial DNA (mtDNA) population data set is used to infer the relative rarity of control region mtDNA profiles obtained from evidence samples and of profiles used for identification of missing persons. In this study, the African American haplogroup patterns in the SWGDAM data were analyzed in a phylogenetic context to determine relevant single nucleotide polymorphisms (SNPs) and to describe haplogroup distributions for Africans observed in these data sets. Over 200 SNPs (n=217) were observed in the African American data set (n=1148). These SNPs ranged from having 1-39 changes in the phylogenetic tree, with sites 152 and 16519 being the most variable. On average there were 5.8 changes for a character on the tree. The most variable sites (with 19 or more changes each) observed included 16093, 16129, 16189, 16311, 16362, 16519, 146, 150, 152, 189, and 195. These rapidly changing sites are consistent with other published analyses. Only 34 SNPs are needed to identify all clusters containing 10 or more individuals in the African American data set. The results show that the African American SWGDAM mtDNA data set contains variation consistent with that described in continental African populations. Thirteen of the 18 haplogroups previously observed in African populations were observed and include: L1a, L1b, L1c, L2a, L2b, L2c, L3b, L3d, L3e1, L3e2, L3e3, L3e4 and L3f. Haplogroup L2a is the most commonly observed cluster (18.8%) in the African American data set. The next most common haplogroups in the African American data set include the clusters L1c (11.0%), L1b (9.1%), L3e2 (9.0%) and L3b (8.1%). Approximately 8% of the haplogroups observed within African Americans were common in European Caucasians or East Asians; these were H (n=32), J (n=4), K (n=5), T (n=2), U5 (n=6), U6 (n=9 also known from North Africa), A (n=12), B (n=7), C (n=4), and M (n=16), respectively. The European Caucasian and East Asian haplogroups are expected due to admixture between individuals with recent ancestry in Western Eurasia and sub-Saharan Africa. The genetic characterization of these relevant data sets is fully consistent with other published mtDNA genetic variation. The sequence diversity observed in this data set makes it a valuable tool for forensic applications.     

Quantification of Pubic Symphysis Metamorphosis Based on the Analysis of Clinical MDCT Scans in a Contemporary Malaysian Population

Forensic age estimation methods are biased to sex and population; in general, accuracy is reduced when applied to foreign populations. This study assessed the accuracy of the Suchey–Brooks method in contemporary Malaysian individuals and aimed to formulate population‐specific standards. Multi‐detector computed tomography scans of 355 individuals (165 male; 190 female) of 15–83 years of age were reconstructed using 3D‐volumetric rendering in RadiAnt. Pubic symphyseal phase, bias, inaccuracy, and percentage correct age classifications are examined. Transition analysis was used to develop age estimation standards. High observer agreement (κ = 0.763–0.832) and a positive relationship between age and pubic symphyseal phase (r = 0.884–0.90) were demonstrated. Mean inaccuracies were 8.62 and 8.95 years for males and females, respectively; overall correct classification was 97.8%. Transition ages between phases in males were 18.79, 23.29, 28.85, 43.64, and 61.15 years; in females, the corresponding data were 19.77, 22.53, 32.62, 41.85, and 57.39 years.     

Third molar development according to chronological age in populations from Spanish and Magrebian origin

Spain is frequently the entrance country into the European Union for undocumented immigrants, especially those from the Magreb (Northern Africa). Forensic age estimates for these persons are difficult because systematic studies of dental maturity are lacking. Three different populations were analyzed to determine the pattern of development of third molars as a tool for age estimation in people of different ethnic and geographic origin. Orthopantomograms from two different populations of Spanish origin (Galicia in northwestern continental Spain, and Ceuta, a Spanish province in Northern Africa) were compared to radiographs of molars from a Magrebian population (Northern Africa) resident in Ceuta. Orthopantomograms were obtained from a private dental clinic (n=344) in Galicia and from the Public Oral Health Services (n=228) in Ceuta. We looked for differences in third molar mineralization (determined with the Demirjian scale) that might serve as age indicators (older versus younger than 18 years). Differences in maturation patterns were found between sexes and populations of origin. Mineralization of tooth 38 was more advanced in males than females among subjects 18 years of age and older in all three populations. Moreover, mineralization of tooth 38 in subjects aged 18 years and older was significantly slower in the Spanish-Galicia population than in the Magrebian-Ceuta population. We found no significant differences between Magrebian and Spanish individuals from Ceuta. We conclude that differences in tooth 38 mineralization may be related more with socio-geographical than ethnic origin (ancestry), and thus constitute evidence of the relevance of socio-geographic rather than genetic factors in third molar development. We used ROC analysis to determine the accuracy of the examiner's ability to correctly estimate age as younger or older than 18 years. The results suggest that Demirjian stage for tooth 38 can be considered a good indicator of age in all three populations.     

A re-examination of cremains weight: sex and age variation in a Northern California sample

The reduction of modern commercially cremated remains into a fine powder negates the use of traditional methods of skeletal analysis. The literature on the use of cremains weight for estimating aspects of the biologic profile is limited, often with conflicting results. This study re-evaluates the value of weight in the assessment of biologic parameters from modern cremated remains. A sample of adults was collected in northern California (n = 756), with a cremains weight averaging 2737.1 g. Males were significantly heavier than females (mean = 3233.2 g versus mean = 2238.3 g, respectively; p<0.001). Comparison of this sample with other previously reported samples from southern California, Florida, and Tennessee indicates a consistent sex difference, with the most similar mean values to the Tennessee study. Although cremains weight decreases with age as expected, the relationship is weak; thus, cremains weight cannot accurately predict age-at-death. While sex estimation shows considerable accuracy (86.3% for males and 80.9% for females), sectioning points may be population specific.     

A Geometric Morphometric Approach to Sex Determination of the Human Adult Os Coxa

Abstract: Sex determination of the human skeleton is best assessed from the os coxa. The present study explored the possibility of using three‐dimensional landmark coordinate data collected from various landmarks located over the entire bone to determine whether there were significant sex differences local to the landmarks. Thirty‐six landmarks were digitized on 200 African American and European American male and female adult human os coxae. MANCOVA results show that sex and size have a significant effect on shape for both European Americans (Sex, F = 17.50, d.f. = 36, 63, p > F = 0.0001; Size, F = 2.56, d.f. = 36, 63, p > F = 0.0022) and African Americans (Sex, F = 21.18, d.f. = 36, 63, p > F = 0.0001; Size, F = 2.59, d.f. = 36, 63, p > F = 0.0005). The discriminant analysis shows that sexing accuracy for European Americans is 98% for both males and females, 98% for African American females, and 100% for African American males.     

中国汉族人耻骨性别判定的研究

目的为了探讨耻骨性别判定的更为简便可靠的方法。方法对96副已知生前确切性别的耻骨进行了性别差异的研究,其中男性耻骨73副,女性耻骨23副。测量项目有:缘枝角,耻骨宽,耻骨联合面的高及厚。结果将耻骨的测量数据输入电脑,用SPSS软件,对耻骨的测量数据进行了统计分析,建立了耻骨性别判定的判别方程。结论其性别判别率最高可达95.5%,该方法可以用于法医学实践。     

Estimating sex of the human skeleton based on metrics of the sternum

Estimating the sex of skeletal remains is critical in creating the biological profile of an adult individual. Previous research has shown that analyzing the sternum may lead to an accurate estimation of sex based on studies performed on various populations around the globe, such as Indian, European, African, Canadian and North American. The motivation of the current study is to develop classification functions and sectioning points for use in forensic investigations in the United States. The majority of previously published methods are population specific, meaning the data would not prove useful in the United States. For this study, sternal measurements were collected from the William M. Bass Donated Skeletal Collection located at The University of Tennessee, Knoxville following the metric definitions provided by Schwartz and Bass. This collection consists of recent skeletal remains with known age at death, ancestry and sex. Material for the present study consisted of 410 human sterna: 285 male (256 American White/29 American Black) and 125 female (120 American White/5 American Black). Previous studies analyze the applicability of Hyrtl's law in the estimation of sex. This law follows that the mesosternum is greater than twice the length of the manubrium in males and in females the length of the manubrium is greater than half the length of the mesosternum. In this study, comparisons of the proportion of the length of the manubrium to the length of the mesosternum were performed to determine if Hrytl's law is applicable in an American population. Comparisons of these measurements between individuals identified as American Black and American White were analyzed to determine whether this method could be used on both population groups. Further, discriminant function analysis was used to estimate sex and provide a population specific classification function for use in the United States. The discriminate function analysis produced an overall cross-validation classification rate of 84.12% for sex estimation. The cross-validation classification rate for males and females was 80.00% and 88.24%, respectively.