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Implications of dimorphism, population variation, and secular change in estimating population affinity in the Iberian Peninsula
Abstract
Morphometric cranial variation among Spanish samples was compared to a 19th century Portuguese sample using both traditional and three-dimensional approaches. The Spanish samples included the regional 19th century Oloriz collection and the local 16-17th century Villanubla and Vallolid sample from northwestern Spain. Results suggest moderate variation among the samples and suggest that varying patterns of regional variation, sexual dimorphism and secular change represent important factors to be considered in the evaluation of population affinity using craniometric approaches.
... We define "ancestry" as biogeographically patterned, clinal, genetic variation that is often continentally derived and defined (sensu Algee-Hewitt 2016; Hughes et al. 2013;Hughes et al. 2019;Konigsberg et al. 2009;Kranioti et al. 2018;Ross et al. 2011;SWGANTH 2013). In forensic anthropological practice, the term "ancestry" has largely replaced the term "race" to describe a decedent's affinity with a particular population or group, and the terms are often used interchangeably (Albanese & Saunders 2006;Albanese et al. 2016a, b;Ousley et al. 2009). ...
... As defined by Spradley and Stull (2018:17), complex populations are "population groups that have two or more parental population groups, e.g., American Black or Hispanics." Indeed, our sample showed that studies of Hispanic populations were more prone to provide some background on population histories and structures (e.g., Dudzik 2019; Edgar 2013; Hefner et al. 2015;Hughes et al. 2013;Hughes et al. 2019;Hurst 2012;Maier 2018;Ross et al. 2011;Spradley et al. 2008) (see Table 1 Table 1). However, the same was not true for African American or European American samples considered in our review. ...
Forensic anthropologists traditionally estimate “race” or “ancestry” as part of the biological profile. While practitioners may have changed the terms used to describe regionally patterned human skeletal variation, the degree to which they have altered their typological approaches remains unclear. This study analyzed 119 peer-reviewed forensic anthropology articles published in four relevant journals (1966–2020) by matching combination(s) of the key words “race,” “ancestry,” “ethnicity,” and/or “population affinity.” Results indicated that while “ancestry” has supplanted “race,” this change has not brought concurrent modifications in approach, nor deeper scrutiny of underlying concepts. “Race” and “ancestry” were infrequently defined in 13% and 12% of sampled articles, respectively, and a plethora of social, geographic, and pseudoscientific terms persisted. Forensic anthropologists increasingly engaged with questions addressing the forces patterning human biological variation: 65% of studies postdating 1999 discussed population histories/structures and microevolution; 38% between 1966–1999. Fewer studies contextualized or critiqued approaches to analyzing population variation (32% of studies postdating 1999; 4% from 1966–1999), and virtually no studies considered the possibility that skeletal variation reflected embodied social inequity (5% of studies postdating 1999; 0% from 1966–1999). This lack of interrogation and clarity contributes to the faulty notion that all forensic anthropologists share similar definitions and leads to an oversimplification of complex biocultural processes. While the lack of definitions and biocultural engagement may be partly due to editorial and peer-review pressures, it is likely that many forensic anthropologists have not interrogated their own perspectives. This article holds that it is essential for us to do so.
... The combined effects of regional and secular variation call for the iteration of research regarding sex dimorphism to account for disparities at a population and chronological level. 36 This study aims to produce specific metric standards for the assessment of sex through the femur in skeletal Portuguese populations. As such, the key goal is to create models for the prediction of biological sex based on linear dimensions of the femur e including models that combine metric variables from complete and well preserved femora, and also from incomplete and fragmentary femora. ...
... All measurements are significantly dimorphic in both samples, but the degree of sexual dimorphism e evaluated through a measure based on sample means e appears to diminish in the testing sample, CEI/XXI, a chronologically later sample, supporting the view that secular changes modify the pattern and degree of sexual dimorphism. 36,55 The general trend shows an increase in femoral linear dimensions in the most recent sample that reaches statistical significance in the NBF, APSDF, APMDF, MLMDF and EBF, in females; and in the NHF and NBF, in males. Changes are more conspicuous in women, with female linear dimensions generally increasing relatively more in the recent sample. ...
The assessment of sex is of paramount importance in the establishment of the biological profile of a skeletal individual. Femoral relevance for sex estimation is indisputable, particularly when other exceedingly dimorphic skeletal regions are missing. As such, this study intended to generate population-specific osteometric models for the estimation of sex with the femur and to compare the accuracy of the models obtained through classical and machine-learning classifiers. A set of 15 standard femoral measurements was acquired in a training sample (100 females; 100 males) from the Coimbra Identified Skeletal Collection (University of Coimbra, Portugal) and models for sex classification were produced with logistic regression (LR), linear discriminant analysis (LDA), support vector machines (SVM), and reduce error pruning trees (REPTree). Under cross-validation, univariable sectioning points generated with REPTree correctly estimated sex in 60.0-87.5% of cases (systematic error ranging from 0.0 to 37.0%), while multivariable models correctly classified sex in 84.0-92.5% of cases (bias from 0.0 to 7.0%). All models were assessed in a holdout sample (24 females; 34 males) from the 21st Century Identified Skeletal Collection (University of Coimbra, Portugal), with an allocation accuracy ranging from 56.9 to 86.2% (bias from 4.4 to 67.0%) in the univariable models, and from 84.5 to 89.7% (bias from 3.7 to 23.3%) in the multivariable models. This study makes available a detailed description of sexual dimorphism in femoral linear dimensions in two Portuguese identified skeletal samples, emphasizing the relevance of the femur for the estimation of sex in skeletal remains in diverse conditions of completeness and preservation.
... 49 The main purpose of this study is to generate and test models for 50 the prediction of sex based on the total area of the proximal femur, a 51 two-dimensional areal measurement performed with DXA. Also, the 52 performance of classical classifiers, such as logistic regression and 53 Fisher's linear discriminant analysis, which have been extensively 54 used for classification of problems where the dependent variable is 55 dichotomous, is compared with that of classification and regression 56 trees and reduce error pruning trees, which are non-parametric 57 decision tree learning techniques. 58 ...
... Sex specific accuracy is probably related with secular change in257 bone dimensions[53,54], usually inducing a higher proportion of 258 misclassified females when a model fitted in a chronologically 259 older sample is used to estimate sex. The training sample (CISC) is, 260 on average, composed by individuals that were born much earlier 261 than individuals in the testing sample (ISC/XXI)with other status and mortality patternbut the magnitude of sexual 264 dimorphism in the total area of the proximal femur is very similar 265 in both samples. ...
The estimation of sex is a central step to establish the biological profile of an anonymous skeletal individual. Imaging techniques, including bone densitometry, have been used to evaluate sex in remains incompletely skeletonized. In this paper, we present a technique for sex estimation using the total area (TA) of the proximal femur, a two-dimensional areal measurement determined through densitometry. TA was acquired from a training sample (112 females; 112 males) from the Coimbra Identified Skeletal Collection (University of Coimbra, Portugal). Logistic regression (LR), linear discriminant analysis (LDA), reduce error pruning trees (REPTree), and classification and regression trees (CART) were employed in order to obtain models that could predict sex in unidentified skeletal remains. Under cross-validation, the proposed models correctly estimated sex in 90.2 to 92.0% of cases (bias ranging from 1.8% to 4.5%). The models were evaluated in an independent test sample (30 females; 30 males) from the 21st Century Identified Skeletal Collection (University of Coimbra, Portugal), with a sex allocation accuracy ranging from 90.0% to 91.7% (bias from 3.3% to 10.0%). Overall, data mining classifiers, especially the REPTree, performed better than the traditional classifiers (LR and LDA), maximizing overall accuracy and minimizing bias. This study emphasizes the significant value of bone densitometry to estimate sex in cadaveric remains in diverse states of preservation and completeness, even human remains with soft tissues.
... Previous studies have focused on using different human skeleton parts, including the humerus, radius, ulna, femur, tibia, talus, ribs, and metatarsals (4). After development, the morphological changes of the scapula bone are usually insignificant during life (5,6). Also, the processes of fossilization, decomposition, and feeding of carnivores cause damage to bones such as the pelvis and skull, but usually, the scapula is less damaged (7). ...
Background: In forensic medicine, several bones are used to determine gender. The most important and widely used are the skull and pelvis. But in some cases, the mentioned bones may not be available, and other bones, such as the scapula bone, should be used. Objectives: This study aimed to investigate and locate the anthropometric indices of scapula bone in the Iranian population to determine gender. Methods: In this project, a study was performed on a chest scan of 259 Iranians referred to Besat NAHAJA Hospital in 2016. Pack software was used to measure the scapula's indices. The obtained data, including age, gender, and different scapula sizes of max width of glenoid (MWG), max length of glenoid (MLG), max width of scapula (MWS), and max length of scapula (MLS), were analyzed using appropriate statistical tests. Assessment of differential ability, sensitivity, and specificity of scapula anthropometric indices was used in determining gender. Results: Of 259 participants in this study, 133 (51.4%) were female, and 126 (48.6%) were male. Generally, the mean index of MWG, MLG, MWS, and MLS was higher in men than women in the studied population. The results of this study showed there is a significant difference among scapula features in men and women (P < 0.05). The highest accuracy in determining gender was assigned to MLS, with 88.9%, and the lowest was assigned to MLG, with 66.3%. Conclusions: Our study showed that measured anthropometric indices, including length and width of scapula bone and glenoid cavity, will help to predict gender and also can be used as an accurate and practical tool in gender determination.
... Long-term changes can be precipitated by the restraint of factors that inhibit growth [3]. These are attributed to the improvement of living conditions that started in the late 19th and early 20th centuries, especially in the more industrialized Western countries [4], e.g., dietary improvement-with lower or no periods of caloric deficit-better sanitation, reduction of infant mortality rates due to medical advances and public health policies, as well as rising socio-economic status [5][6][7]. ...
Potential secular changes in the human scapula are fundamentally unbeknownst, with most of the preceding anatomical studies focusing on long-term changes in the long bones and the skull. As such, the cardinal purpose of this study pertains to the evaluation of secular trends on the shape and size of the scapula in a time period spanning from the 19th to the early 21st centuries. The study sample included 211 individuals (100 males and 111 females) from the Coimbra Identified Skeletal Collection and the 21st Century Identified Skeletal Collection. The size and shape of the scapula were evaluated using geometric morphometrics. Results show secular changes over a relatively short period of time in both the shape and size of the scapula in Portuguese nationals. Shape changes were observed in both sexes but expressed minimally, while a significant negative trend in the size of the scapula was detected in males. Scapular size decrement in males conceivably echoes general trends of the overall anatomy towards a narrower body associated with higher standards of living that include enhanced nutrition and universal healthcare, among other factors.
... Prior research on the sternum and numerous other skeletal parts has demonstrated that osteometric standards for estimating sex cannot be accurately extended to other dissimilar samples due to differences in body size, robustness, and the degree of sexual dimorphism exhibited by the skeleton between human groups. It is important to use bone collections that are typical throughout time periods for developing anthropological standards, such as those used to determine sexuality (11) . ...
... Many researchers and authors strongly suggest that the development of population specific formulae when metric data are used, is of paramount importance in order to produce accurate and statistically robust results (Steyn & Patriquin 2009;Bigoni et al. 2010;Ross et al. 2011;Franklin et al. 2013;Králík et al. 2014;Peckmann et al. 2015;Guyomarc'h et al. 2016). Osteometric sex estimation studies applied on modern Greek population, demonstrate that dimensions received from Greeks cannot correlate with other populations. ...
Sex determination is one of the first biological attributes to be assessed when unidentified remains surface. In material of forensic interest, being able to use every skeletal element available for identification purposes is of paramount importance. The osteometric method from the sternal rib end has been found to generate accurate sex estimates, but as various studies have proved, all osteometric methods should be population-specific, as one equation does not fit all. The aim of this study is to assess sexual dimorphism in a contemporary Greek population sample of 68 males and 43 females, with the use of discriminant function analysis. The superior-inferior height (SIH) and anterior-posterior breadth (APB) from the third to fifth sternal rib ends of both sides were taken from 3D models created with the use of a hand-held 3D scanner. The results demonstrated that SIH is more sexually dimorphic than APB (alpha value of .05) while the application of İşcan’s (1985) formula on the contemporary Greek sample, provided results of low accuracy, ranging from 48.6–52.4%. The cross-validated discriminant functions equations for the current sample, produced results ranging between 74.0–82.9% indicating that population-specific formulas produce results of higher accuracy, that are vital in cases of forensic interest.
... Many researchers and authors strongly suggest that the development of population specific formulae when metric data are used, is of paramount importance in order to produce accurate and statistically robust results (Steyn & Patriquin 2009;Bigoni et al. 2010;Ross et al. 2011;Franklin et al. 2013;Králík et al. 2014;Peckmann et al. 2015;Guyomarc'h et al. 2016). Osteometric sex estimation studies applied on modern Greek population, demonstrate that dimensions received from Greeks cannot correlate with other populations. ...
... Sexual dimorphism and the methods of morphological assessment on the skull and pelvis are often based on the differences caused by shape and size; they can either be differences between biological sexes based on the fact that females have different pelvic morphology to accommodate parturition, or other differences of robustness that are prominent in males, for example, the skull [16]. The fact that population variation plays an important role in skeletal sexual dimorphism [17], the groups vary in terms of their activity patterns [2], and there is an implication of secular trends on sex estimation [18], this demonstrates that the use of sex estimation accuracies are affected by the superimposition of the use of one sample onto another sample derived from different collections representing two separate population groups or from the same collection with specimens from a different temporal period. ...
Objectives: The focus of this research is to evaluate the sex estimation methods on isolated human materials by applying morphological methods published in various forensic and anthropological literature on different skeletal series. Materials and Methods: 165 individuals from the 19th to 20th century Inden skeletal series, 252 individuals from the 13th to 14th century Lübeck skeletal series of German ancestry housed at the Department of Historical Anthropology and Human Ecology, the University of Göttingen, Germany, and 161 individuals from the 19th and 20th century of South African African ancestry housed within the Raymond A. Dart collection of modern human skeletons at the University of Witwatersrand, South Africa, with crania, mandibles, and pelves, were assessed. The evaluation criteria are burial information on the Inden series, genetic sex on both the Inden and the Lübeck series, and previous demography on cadavers from the South African African series. Results and Discussion: The sex estimation with cranial traits perform better in Inden and South Africa samples and worse in Lübeck sample. The mandible accuracies for pooled sexes are not exemplary, but the individual traits perform better for males in the Inden, Lübeck, and South Africa samples, except for gonion and angle, which performs better in females. The pelvic traits perform better in the Inden and South Africa samples compared to the Lübeck sample. The statistical tests show that there is a huge difference in the accuracy rates and the performance between both population groups from Germany itself, considering that Inden and Lübeck samples share the same ancestry. The accuracy rates improve with the exclusion of ambiguous individuals.
... 36,37 Cranial metrics can achieve high rates of accuracy depending on the method used and the population under study, with factors such as sexual dimorphism and secular change having an impact on the accuracy rates. 38 Allocating an unknown individual to any geographical area in the world challenges the estimation of ancestry https://doi.org/10.2147/RRFMS.S272224 ...
... The term population affinity is an estimation of group membership indicating morphological or genetic similarity to a well-defined group and is based on some measure of statistical distance. Recent publications highlight an increase in the use of this term (Berg & Ta'ala 2014;Pilloud & Hefner 2016;Ross et al. 2004;Ross et al. 2011). Forensic anthropologists are good at estimating population affinity within the U.S. because assortative mating practices shaped by miscegenation laws, racism, and social class have shaped our current population structure (Gross & Edgar 2021). ...
While American forensic anthropologists often state that they estimate ancestry, is that what they are really estimating? Although typological terminology, the oids, was replaced with continental terminology, the change was linguistic rather than substantive. The American population is comprised largely of immigrants. Genetic data suggests a high degree of admixture within American population groups. Further, data from documented skeletal collections suggest that Americans have undergone secular changes. Our paper addresses the uniqueness of the American population as compared to ancestral continental and geographic origin groups to address what it is that forensic anthropologists are really estimating, ancestry or something else? We conclude, based on uniqueness of American population groups, that what forensic anthropologists are estimating is best described as affinity, a term that indicates similarity and is not exclusively attached to definitions of race and ethnicity.
... The non-metric measurements (anomalies in the normal anatomy of the skeleton) of the bone have been used in the past, however, nowadays due to advanced technologies, the metric measurements (osteometric measurements) technique using medical images, is ideal for being repeatable, accurate and less expertise required for professionals (16). The studies on the osteometric measurements of the sternum, as well as other bones have shown that the same principle cannot be applied to the different samples, as human groups vary in terms of body size, and degree of sexual dimorphism of the skeleton (18). Although sternum was not evaluated for its dimorphic characteristics, several other studies have established its osteometric properties unique for a particular gender (19). ...
This study was designed, for the first time, to discuss sexual dimorphism in the sternum bone of a specific Pathan race of District Swat, Khyber Pakhtunkhwa. It is hypothesized that the osteometric traits of the sternum will be sexually dimorphic in the peoples of District Swat. The target population was among the patients who came to Radiology Department Saidu Teaching Hospital, Swat for routine investigations with multi-slice computed tomography for chest problems. The population included in the study were, adults aged ranged from 20 to 60 years old, and had no chest wall pathology. A total of 260 (130 each male and female) patients were selected. The parameters studied were sternal area, manubrium length, sternal length, manubrium width and sternal width at two levels. There was a significant difference in the sternum of males than that of females in the Pashtun population of Swat. All the measurements were significantly lower (p <0.001) in female as compared to the male population. The most important prediction of gender is manubrium length, manubrium width and body length. These were the most useful dimensions of the sternum to discriminate genders. In other words, due to the significant differences in the dimensions of the sternum in various ethnicities, gender differentiation is possible by examining all studied parameters.
... Despite the complications surrounding how we understand "ancestry" and how we choose to afford it statistical meaning and practical value, and the greater suitability of population affinity to forensic casework when the goal is to deliver a categorical estimate, the latter term and approach have not gained the disciplinary traction we might expect [19,25,[60][61][62]. Anecdotally, we have witnessed informal debate within the field surrounding the use of this term (in lieu of ancestry), both in our daily practice and as members of the American ...
Using a sample of anonymized U.S. forensic anthropology cases (n = 251) from the FADAMA database, we assess the degree of concordance between decedents’ social identifiers and anthropologists’ continental‐based classifications. We report high success rates (>90%) that generally support previous findings, yet we acknowledge the limitations of assessing “ancestry” accuracy based on resolved cases and draw attention to situations in which our methods fail. For example, forensic anthropologists achieve just 20% accuracy when classifying individuals as “other” or “mixed”—problematic categories that we argue should be rejected. Leveraging our findings, we ask: what are we really estimating when we perform a skeletal assessment of “ancestry” in the US context? We argue that the “ancestry estimates” historically and routinely produced in forensic anthropology instead give information on population affinity: a measure of how similar a given case is to one among several socially relevant groups of interest. Distancing forensic anthropology from genetics and other disciplines that estimate ancestry, the approach of population affinity assesses similarities to both social and biological groupings, potentially at a fine‐grained level, attempting to account for the complex histories, shared biologies, and wide ranges of diversity that characterize our communities and our casework. Population affinity is a flexible and inclusive approach that more accurately describes current forensic anthropological analyses of human variation. Going forward, we must acknowledge and build on the contributions of previous scholars as we work together toward our shared goal of theoretically grounded analyses of human variation that accurately and equitably serve all casework decedents.
... In contrast with the results of the present study, Etli et al. (2019) found that the most dimorphic parameter was PSL. Populations show frequent variations in biological traits, so to develop standard measurement from collection of bones, these measurements should be repeated at regular intervals (Ross et al., 2011). Franklin et al. (2014 observed a sex accuracy rate of < 70% of sacrum in Australian population. ...
... However, most of the methods that are based on the pubic symphysis have been developed on North American collections, made up of African and European descendants. Due to the variability between distinct populations and the consequent age mimicry phenomenon [9][10][11], it is necessary to test these methods for an evaluation of their functionality before proceeding to use them on a population that is different from the one they were developed on. ...
Age-at-death estimation methods are important in forensic anthropology. However, age assessment is problematic due to inter-individual variation. The subjectivity of visual scoring systems can affect the accuracy and reliability of methods as well. One of the most studied skeletal regions for age assessment is the pubic symphysis. Few studies on Spanish pubic symphysis collections have been conducted, making further research necessary as well as the sampling of more forensic skeletal collections. This study is a preliminary development of an age-at-death estimation method from the pubic symphysis based on a new simple scoring system. A documented late twentieth century skeletal collection (N = 29) and a twenty-first century forensic collection (N = 76) are used. Sixteen traits are evaluated, and a new trait (microgrooves) is described and evaluated for the first time in this study. All traits are scored in a binary manner (present or absent), thus reducing ambiguity and subjectivity. Several data sets are constructed based on different age intervals. Machine learning methods are employed to evaluate the scoring system’s performance. The results show that microgrooves, macroporosity, beveling, lower extremity, ventral and dorsal margin decomposition, and lipping are the best preforming traits. The new microgroove trait proves to be a good age predictor. Reliable classification results are obtained for three age intervals (≤ 29, 30–69, ≥ 70). Older individuals are reliably classified with two age intervals (< 80, ≥ 80). The combination of binary attributes and machine learning algorithms is a promising tool for gaining objectivity in age-at-death assessment.
... Also, c. 80% of deaths in the LLC sample occurred after 1930, and 70% after 1936, while in the CISC, c. 74% of deaths happened before 1930, with the remaining deaths occurring until 1936. Secular changes in the metric variation of long bones are known to modify the pattern and degree of sexual dimorphism [64][65][66], and the general tendency observed shows a small increase in most radius dimensions in the LLC femalesthe exceptions are the transverse diameter of the head and the inferior epiphysis width. In males, the trend is not as evident, with some linear dimensions of the radius declining in the most recent sample. ...
The assessment of sex is of immense relevance in the analysis of human skeletal remains, as other parameters of the biological profile are usually sex-specific (e.g., age at death or stature). The radius can be used to estimate sex when more dimorphic bones are not available or in the case of incomplete and fragmentary remains. Ten radius measurements collected in a sample of 364 individuals (166 females and 198 males) from the Coimbra Identified Skeletal Collection (late 19th - early 20th centuries) were employed to generate univariable and multivariable models for sex estimation. All models were evaluated with a 10-fold cross-validation method and an independent holdout sample from the Luís Lopes Collection (late 19th - mid 20th centuries) encompassing 50 individuals (25 females and 25 males). Univariable models show an accuracy ranging from 77.7% to 89.8% (cross-validation), and from 70% to 86% (test sample), while accuracy in the multivariable models varies from 88.7% to 93.4% (cross-validation), and 84.0% to 90.0% (test sample). Results suggest that measurements of the radius are useful to develop standard guidelines for sex estimation of anonymous skeletal remains.
... Both intra-and inter-observer repeats of the same specimen were found to be less than 5% of the mean distances between different specimens (i.e. rTEM < 5%), suggesting that observer error is small relative to the variation detected in the complete sample, and is thus unlikely to have influenced the results (Braga & Treil 2007;Ross et al. 2011;Holliday & Friedl 2013). ...
The fibula is often not used for anthropological estimations, as its morphological variation is expected to be insufficient to allow accurate estimations. However, in forensic or archaeological contexts, there is the possibility that the fibula is the only bone available for analysis. The present study applied geometric morphometrics to evaluate the potential of using fibular morphology for assessment of sex and ancestry. Three-dimensional datasets of 1609 fibulae of adult South Africans (412 females, 507 males) were digitized. Datasets were submitted to Generalized Procrustes Analysis for rotation and scaling to a common centroid. Mean centroid sizes were compared using parametric testing, and morphological variation was assessed using multivariate analyses. Discriminant Function Analysis coupled with leave-one-out cross-validation testing was used to assess classification accuracy of sex and ancestry based on these shape variations. Fibulae were smaller in females than males, but show insufficient shape variation to distinguish the sexes. Fibulae of Coloured individuals were relatively and absolutely smaller than those of the Black and White ancestry groups, likely due to contributions of small-bodied groups to the genetic composition of this group. Based on shape variation, ancestry estimations of 72.4-77.2% were obtained. Evaluation of variation according to sex and ancestry combined still produced insufficient distinction between the sexes and decreased the accuracy of ancestry classification. These results show that morphological variation of the fibula may not be useful for sex estimation, but provides reasonable accuracies for ancestry estimations, making it particularly useful in cases where only the fibula is available for analysis.
... Although the precise causality for secular change remains unknown, it is believed to be largely non-genetic/non-evolutionary, and many studies have attributed such changes to large-scale alterations in nutrition, living conditions, medical advancements, and socioeconomic status (Albanese, 2008;Jantz, 2001;Jantz & Meadows Jantz, 2000Ross, Ubelaker, & Kimmerle, 2011;Schmidt, Jorgensen, & Michaelsen, 1995). ...
Objectives
Secular change in cranial and postcranial morphometrics and morphological traits has been documented in several studies. However, to date, few studies have addressed temporal changes occurring in the expression of cranial morphological traits commonly used in ancestry estimation. This study examines secular change in the expression of 23 cranial and mandibular morphological traits; accounting for age‐at‐death, sex, and year‐of‐birth.
Materials & Methods
Data were collected on 23 morphological cranial and mandibular traits for European American individuals (19–97 years of age) from the Hamann‐Todd Skeletal Collection (n = 518) and the William M. Bass Donated Skeletal Collection (n = 602). Individuals were divided into six birth‐year cohorts: 1824–1849 (Cohort 1), 1850–1874 (Cohort 2), 1875–1899 (Cohort 3), 1900–1924 (Cohort 4), 1925–1949 (Cohort 5), and 1950–1987 (Cohort 6).
Results
Statistical analyses, including Pearson's chi‐square, correspondence analysis, and ordinal regression, demonstrate that secular changes have occurred in 11 traits, including: anterior nasal spine (ANS); malar tubercle (MT); nasal bone contour (NBC); postbregmatic depression (PBD); supranasal suture (SPS); transverse palatine suture (TPS); zygomaticomaxillary suture (ZS); ascending ramus shape (ARS); gonial angle flare (GAF); mandibular tori (MDT); and posterior ramus edge inversion (PREI), with changes occurring in both sexes for ANS, MT, TPS, ZS, GAF, MDT, and PREI. Significant changes in trait expression were found predominately between Cohorts 3 and 4, and Cohorts 4 and 5. While the sex of an individual affected the expression of ANS, MT, NBC, PBD, SPS, ZS, ARS, GAF, and PREI, age‐at‐death only affected MT and PREI.
Discussion
This study demonstrates that secular change in morphological cranial and mandibular traits has occurred over the last two centuries in European Americans, with the most considerable change appearing at the turn of the twentieth century. Changes in morphological trait expression over a relatively short period of time correspond with changes seen in craniometric analyses and correlate with the industrialization of society and environmental and cultural changes, such as medical advancements, nutrition, and population health/stress.
... For both the inter-and intra-observer repeats, distances were less than 5% of the mean distance of the different specimens. This suggests that observer error was small relative to the whole sample variability, and thus unlikely to have influenced the results (Braga & Treil 2007;Ross et al. 2011). ...
Recent developments in geometric morphometrics enabled reassessment of features of the cranium in a more robust, objective and quantitative manner. Previous studies show that morphological variation of not only the cranium as a whole, but also parts thereof are useful in differentiating between sex and population groups. The present study used geometric morphometrics to assess variation of frontal bone morphology and its use in estimation of sex and ancestry. Frontal bones of 777 Black, Coloured and White South African adults were digitized and superimposed through Generalized Procrustes Analysis. Centroid sizes and morphological variation between groups were assessed. Accuracy of distinction between groups was assessed using Discriminant Function Analysis and leave-one-out cross-validation. Male frontal bones were more robust and sloped, compared to more gracile, rounded frontal profiles of females, resulting in classification accuracy of 79.3%. Morphological variation related to ancestry was found in the slope and width of the frontal bones, allowing distinction of the groups with 85.9% accuracy, even when including the heterogeneous Coloured group. When assessed according to sex and ancestry combined, 83.3% accuracy was achieved with the six sex-ancestry groups. These results show that variation in frontal bone morphology is sufficient to allow accurate distinction between these closely related groups, with accuracies compatible or exceeding those obtained when using the entire cranium of the same sample. Future studies may be able to investigate similar use of morphological variation of other cranial bones for estimation of sex and/or ancestry for use when the cranium is damaged or fragmented.
... The femur is the most investigated of all long bones 3 and a variety of femoral measurements have been employed to assess sex in human skeletal remains, including head diameters [15][16][17] , the femoral neck 18,19 , the proximal femur [20][21][22][23][24] , the distal femur 25 , and measurements from different femoral regions 2,[26][27][28][29][30] . Most of these methods are related with size parameters and robustness, that can be affected by secular trends, being commonly population-specific 3,[31][32][33] . It is frequently recovered in both forensic and archaeological contexts, and it is usually better preserved than other long bones 33 . ...
The femur has been commonly employed for sex determination of human skeletal remains, and it is a suitable alternative to the more sexually dimorphic pelvis when this skeletal region is incomplete or fragmented. The purposes of this study include the evaluation of femoral sexual dimorphism and the generation of specific metric standards for the estimation of sex with the femur in skeletal Brazilian populations. Two hundred femora (130 males and 70 females) of known age at death, sex, and ancestry were used to generate the models for sex prediction. The best estimators of sex were univariable models, including the biomechanical neck length (BNLF, accuracy under cross-validation: 82.5%), the vertical head diameter (VHDL, accuracy under cross-validation: 81.5%), the transverse head diameter (THDF, accuracy under cross-validation: 84.5%), and the epicondylar breadth (EBF, accuracy under cross-validation: 84.5%). In conclusion, a comprehensive anatomical study of the femur in a reference skeletal sample from Brazil was provided, and the value of univariable sex estimators (BNLF, VHDL, THDF and EBF) was established.
... The early biodistance research focused on archeological and Native American populations in the United States (Hrdlička, 1924a;Neumann, 1952;Zegura, 1975), but in recent years reflects growing interest in populations outside of the United States (Hanihara, 1996;Hanihara, Yoshida, & Ishida, 2008;Ishida, Hanihara, Kondo, & Fukumine, 2009;Kawakubo, Hanihara, Shigematsu, & Dodo, 2008). Biodistance analysis remains an important component of biological anthropology, providing a more nuanced understanding of population structure and history and informing more forensic models (Dudzik & Jantz, 2016;Humphries, Maxwell, Ross, & Ubelaker, 2015;Jantz & Meadows Jantz, 2000;Martínez-Abadias et al., 2006;Ousley et al., 2009;Ross, Slice, Ubelaker, & Falsetti, 2004;Ross, Ubelaker, & Kimmerle, 2011;Spradley, 2016a). These forensic models focus on an individual rather than a population, creating a unique opportunity to apply biological anthropological theory. ...
Forensic anthropologists assist law enforcement agencies and medical examiner's offices with investigations involving human remains, providing insight into trauma analysis, the establishment of postmortem interval, and the estimation of biological profile data. Ancestry is considered one of the more difficult aspects of the biological profile, due in large part to the complicated relationship between skeletal morphology and social constructs. The methods
used to estimate ancestry rely on the correlation between skeletal morphology, geographic origin, and an individual's social race. While there is a well documented contemptible history associated with the development of ancestry estimation methods in biological
anthropology, many of the more traditional, now antiquated, methods are still used in some laboratories. The push to improve the framework within which ancestry data are analyzed requires validation and reassessment for each method in addition to the development of novel approaches utilizing modern technological advances. An array of software programs designed to aid in ancestry estimation is available. These advances do not signal the end of ancestry-related research. Indeed, several areas seemingly stagnated by tradition and time require further study through more than simply review and rarefaction. The future of ancestry estimation research centers on: (a) abandoning the trait list approach, (b) rejecting the three-group model, (c) establishing larger and more representative reference data, (d) assessing the utility of mixed method models, and (e) developing new statistical approaches and updating current software tools.
... Different standards and methods developed are generally populationspecific and cannot be applied for sex determination of individuals of other population groups. Humans differ with respect to their physical features, bodily size andproportions, skeletal maturity/development and degree of sexual dimorphism16,17 . ...
Biological profiling of unknown human remains is the foremost task required in forensic/medico-legal death investigations and sex determination of such remains is an important element of biological identity of an individual. In present study, 12 anthropometric measurements were recorded on 298 Uttarkashi individuals (150 males and 148 females) between age group of 18-25 years. Majority of measurements were found to have a significant degree of sexual dimorphism among them; being highest for cubit and thumb lengths and lowest for left palm and right foot lengths (p >0.001). From Univariate discriminant function analysis, cubit length and left foot length were selected as the best variables to discriminate sex of about 80% (84% males and 76% females) 79% (84.7% males and 73.6% females) individuals, respectively. Similarly, 86% subjects could be classified to their correct sex category from all the lineal measurements (88.5% males and 87.2% females) or the hand measurements only (83.1% males and 84.6% females) from the multivariate discriminant function analysis. The results of present study can be considered an addendum to the existing population data for forensic anthropological literature.
... Since the publication of comparative studies on the craniometrics and genetic variation of different human populations of the world, it is believed that cranial measurements reflect genetic variation and neutral evolution [103,104]. Craniometric variation is thus geographically structured [105] and it is widely used for population history [106] or population affinity analyses [107], even in palaeoanthropological studies [108,109]. Morphological similarity means closer relatedness, which may be caused by common ancestry, gene flow or a combination of factors [110]. ...
The incomplete cranium discovered at the Zlatý kůň site in the Bohemian Karst is a rare piece of skeletal evidence of human presence in Central Europe during the Late Glacial period. The relative position of cranial fragments was restored and missing parts of the cranium were virtually reconstructed using mirroring and the Thin-plate splines algorithm. The reconstruction allowed us to collect principal cranial measurements, revise a previous unfounded sex assignment and explore the specimen’s morphological affinity. Visual assessment could not reliably provide a sexual diagnosis, as such methods have been developed on modern populations. Using a population-specific approach developed on cranial measurements collected from the literature on reliably sexed European Upper Palaeolithic specimens, linear discriminant analysis confirmed previous assignment to the female sex. However, caution is necessary with regard to the fact that it was assessed from the skull. The Zlatý kůň specimen clearly falls within the range of Upper Palaeolithic craniometric variation. Despite the shift in cranial variation that accompanied the Last Glacial Maximum (LGM), the Zlatý kůň skull exhibits a morphological affinity with the pre-LGM population. Several interpretations are proposed with regard to the complex population processes that occurred after the LGM in Europe.
... Distances for both the inter-and intra-observer repeats of the same humerus were less than 5% of the mean distance between different humeri. Thus, the observer error was small relative to variability of the whole sample and unlikely to have influenced the results [20,59,60]. ...
Recent studies using geometric morphometrics have shown that estimations of demographic parameters can be made using skeletal elements previously not thought useful for such purposes.
This study used geometric morphometrics to assess humeral morphological variation in an adult South African sample, and evaluated the accuracy of sex and ancestry estimations based on this variation.
Humeri of 1046 adult South African individuals (464 females, 582 males) were digitized. Data sets were rotated and scaled to a common centroid using Generalized Procrustes Analysis. Mean centroid sizes between groups were compared using parametric tests, while morphological variation was evaluated using multivariate analyses. Discriminant Function Analysis coupled with leave-one-out cross-validation tests were used to assess the reliability of sex and ancestry classifications based on this variation.
Male humeri were relatively larger and presented with morphological features indicative of larger muscle mass and smaller carrying angles than females. White individuals had relatively larger but morphologically less robust humeri than Black or Coloured individuals, likely a reflection of both genetic and socio-economic differences between the groups as enforced under Apartheid law. When sex and ancestry were assessed together, similar variations were detected than when either parameter was individually assessed. Classification accuracy was relatively low when sex was independently assessed (73.3%), but increased when considered in conjunction with ancestry, indicating greater variation between-groups (ancestry) than within-groups. Ancestry estimation accuracies exceeded 80%, even for the highly diverse Coloured group. Classification accuracies of sex-ancestry groups all exceeded 76%.
These results show that humerus morphological variation is present and may be used to estimate parameters, such as sex and ancestry, even in complex groups such as the Coloured sample of this study.
... Considering populational variability of skeletal morphology as the result of multiple factors, both internal (genetics) and external (environment, social and cultural factors, eating habits, etc.) and the increased migration (globalization), as well as the discrete changes over time (secular trends) due to environmental, lifestyle, nutritional factors, researchers recommend periodic updates of statistical functions and formulas -having also in mind Forensic anthropology from skeletal remains to CT scans that many of the reference studies were conducted on skeletal collections from the 18 th -19 th century [7][8][9]. ...
Sex estimation remains one of the most important steps in a forensic anthropology context, especially when dealing with deteriorated or fragmented skeletal remains. In this respect, the need for the permanent actualisation of study database, as well of the skeletal remains is obvious. Therefore, besides classical skeletal collections an important amount of data can be obtained from computed imaging of the skeletal system, namely CT scans. The CT scans have the advantage of being virtually unlimited in number, not having any interference with secular trends, individuals being of known age and sex as well as increase in accessibility and applicability of data, for subsequent statistical and complex analysis (for instance, geometric morphometric). In the following review, we have gathered and compared some of the most significant studies in the field of physical and forensic anthropology focusing on sexual dimorphism on the skull, both on skeletal collections and CT scans. The results of the studies were similar in terms of sexing accuracy, thus allowing us to conclude that using CT scans in forensic anthropology is a viable and sometimes better option than skeletal collections, in term of data acquisition.
... These data can significantly contribute to studies on population movement, too. These data should be standardized for the study population, so that classification accuracy is assured [17,18]. Pelvis has specific shape for its obstetrics functions and formation of the birth canal, therefore, it is very valuable in sex determination [19]. ...
Background: Pelvic bone has important sex determining features. However, anthropometric reference values vary by study population. This study aimed to determine the accuracy of subpubic angle for sex determination and height estimation in Iranian adults. Methods: In this study, the subpubic angle in the digital pelvic radiographs of 325 Iranian adults (199 males and 126 females) and their standing heights were measured. Then, the relation of subpubic angle with sex and stature was evaluated. Results: The mean(SD) subpubic angle of the studied population was 116.3 (23.7) degrees. Subpubic angle was significantly wider (P<0.001) in females [140.5(14.3) degrees] compared to males [101.0(13.3) degrees]. Moreover, we observed a significant decrease (P<0.001) in females' subpubic angle with an increase in age. A significant reverse correlation (P<0.01) was also observed between the subpubic angle and height (r=0.416). Conclusion: This study showed that the mean subpubic angle in Iranian adults is different from the average in other populations. Our reference values can be used in forensic identification.
... However, the scapula which is a flat short bone; has not been given the same importance as other long bones [4]. Throughout life the scapular changes are not significant after development is finished [5,6], depending on these assumptions, researches already inspected the sexual diversity of the scapula in different populations [7]. With expanding interest for accurate sex determination; it is important to enhance variable estimation methods [8]. ...
... This aspect of the biological profile is one of the most arduous to assess due extreme human variability. Several factors influence the ability to assign a geographic location to a particular skeletal part such as population intermixing, and temporal changes [23], though sex resoluteness is withal affected by these factors, but to a lesser extent. Observing anatomical or morphological traits of craniofacial region (where morphological variation is greatest) is the most reliable and popular way of attributing 'ancestry' because they are known to be more genetically driven and less affected by environmental factors. ...
Objectives: Ancestry and sex estimation using craniometric indices is an important aspect of skeletal identification process, as it limits the number of antemortem records used to compare with a postmortem profile and establish a positive identification. These indices are also affected by secular or temporal changes. So the aim of the study to explore the usefulness of indices for sex and ancestry estimation in North Indian population and effect of secular changes on these indices. Materials and methods: In present study two temporally different skull samples of the North Indian population have been taken and eighteen craniometric indices were calculated on the basis of 17 craniofacial measurements for both sexes to examine the temporal changes and their use in ancestry and sexual differenciation. Contemporary sample comprised of 158 skulls (110 male; 48 females) and subrecent 325 skulls (206 males and 119 females) with an age range of 20-68 years. Results: Craniofacial measurements showed significantly higher values in contemporary males and females. In males highly significant secular/temporal changes were observed in orbital index and transverse frontal index and to a lesser extent in foraman magnum and gnathic index. In females, highly significant differences were observed in cranial, vertical, auriculo vertical and longitudinal craniofacial index. Discussion: There is a lot of variability in Indian and non Indian populations so these indices can be used for ancestry estimation but not for sex discrimination due to poor classification rate. Moreover, the causes of these temporal variations with other issues have also been discussed.
... The three-dimensional nature of GM data in its original state allows for the study of shape without size influences, which can incorporate sophisticated statistics into the formation of biological profiles. While GM can be used to test a variety of hypotheses (46,47), several methods have been developed in recent years to estimate sex and ancestry from cranial, dental, and postcranial information with varying degrees of success (38,(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59). The most holistic of these methods is 3D-ID, a computer program that acts in much the same way as Fordisc to produce sex and ancestry estimates of an unknown cranium (54). ...
Estimation of the biological profile of unidentified human remains is a critical component of an anthropologic evaluation of unidentified human remains. The profile is used to search for missing persons that may match the decedent. The individual components of sex, ancestry, stature, and age at death require reliable methods to ensure accurate recording of these biological markers. This article showcases an unidentified skeleton that was misclassified as a female when the original evaluation was done in 1963. The revaluation in 2004 quickly led to resolution of the identity. Methods used today to evaluate the components of the biological profile are reviewed along with a limited review of the historic literature.
... In combination, the Contemporary, Howells, and Forensic Data Bank databases represent a loose temporal sequence with some overlap of specimens deriving from the inclusion of data in the Angel archives. This sequence allows us to evaluate how craniometric allocation for each specimen changes through time, where time represents both emergent processes of contested biohistory and hybridity as well as secular changes of a strictly biological nature (see Albanese, Osley, & Tuck, 2012;Angel, 1976;Ousley & Jantz, 1998;Jantz, 2001;Jantz & Meadows Jantz, 2000;Ross, Ubelaker, & Kimmerle, 2011;Wescott & Jantz, 2005). ...
Objectives:
This article uses craniometric allocation as a platform for discussing the legacy of Samuel G. Morton's collection of crania, the process of racialization, and the value of contextualized biohistoric research perspectives in biological anthropology.
Materials and methods:
Standard craniometric measurements were recorded for seven Seminoles in the Samuel G. Morton Crania Collection and 10 European soldiers from the Fort St. Marks Military Cemetery; all individuals were men and died in Florida during the 19th century. Fordisc 3.1 was used to assess craniometric affinity with respect to three samples: the Forensic Data Bank, Howells data set, and an archival sample that best fits the target populations collected from 19th century Florida. Discriminant function analyses were used to evaluate how allocations change across the three comparative databases, which roughly reflect a temporal sequence.
Results:
Most Seminoles allocated as Native American, while most soldiers allocated as Euro-American. Allocation of Seminole crania, however, was unstable across analysis runs with more individuals identifying as African Americans when compared to the Howells and Forensic Data Bank. To the contrary, most of the soldiers produced consistent allocations across analyses. Repeatability for the St. Marks sample was lower when using the archival sample database, contrary to expectations. For the Seminole crania, Cohen's κ indicates significantly lower repeatability. A possible Black Seminole individual was identified in the Morton Collection.
Discussion:
Recent articles discussing the merits and weaknesses of comparative craniometry focus on methodological issues. In our biohistoric approach, we use the patterning of craniometric allocations across databases as a platform for discussing social race and its development during the 19th century, a process known as racialization. Here we propose that differences in repeatability for the Seminoles and Euro-American soldiers reflect this process and transformation of racialized identities during 19th century U.S. nation-building. In particular, notions of whiteness were and remain tightly controlled, while other racial categorizations were affected by legal, social, and political contexts that resulted in hybridity in lieu of boundedness.
... The impact of such differences in DFA classification using the skull is significant (Table 1); the population specificity is confirmed (e.g. Ross et al. 2011, Spradley et al. 2008, Guyomarc'h and Brůžek 2011, and the reliability often falls below an acceptable level. The major variation is the ratio of correctly classified males and females. ...
A contribution to the variability of supracondylar process of humerus. Supracondylar
process of humerus is a bony spur, which occurs on the shaft of humerus approximately 5 – 7 cm
above its medial epicondyle. It occurs in about 1% and its size and shape are highly variable. The
research has evaluated five collections of skeletal remains. The occurrence of the process was
related to the number of individuals and to the number of bones. The highest occurrence of the
supracondylar process was in the prehistoric skeletal collection Brno-Maloměřice, where the
process occurred in 5.1% of individuals and in 2.6% of bones. In the prehistoric skeletal collections
Vedrovice and Hoštice I za Hanou, the occurrence of the process was the same, i.e. in 2.1% of
individuals and 1.1% of bones. As to the medieval and modern skeletal remains from the collection
of Department of Anatomy, the supracondylar process occurred in 2.1% of bones. The lowest
occurrence of the supracondylar process was in the Slavic skeletal collection from Pohansko u
Břeclavi, there it occurred in 1.8% of individuals and in 0.9% of bones.
... In recent publications, we found such studies only for crania from Western Australian and Indian populations [25,30] and in European populations for the clavicle [41], the calcaneus [37], and for the femur [36]. Recently, many authors have argued for the development and use of population-specific formulae for diverse parts of skeleton when metric data are used [25,30,35,[41][42][43][44][45]. ...
Forensic anthropology has developed classification techniques for sex estimation of unknown skeletal remains, for example population-specific discriminant function analyses. These methods were designed for populations that lived mostly in the late nineteenth and twentieth centuries. Their level of reliability or misclassification is important for practical use in today's forensic practice; it is, however, unknown. We addressed the question of what the likelihood of errors would be if population specificity of discriminant functions of the tibia were disregarded. Moreover, five classification functions in a Czech sample were proposed (accuracies 82.1-87.5 %, sex bias ranged from -1.3 to -5.4 %). We measured ten variables traditionally used for sex assessment of the tibia on a sample of 30 male and 26 female models from recent Czech population. To estimate the classification accuracy and error (misclassification) rates ignoring population specificity, we selected published classification functions of tibia for the Portuguese, south European, and the North American populations. These functions were applied on the dimensions of the Czech population. Comparing the classification success of the reference and the tested Czech sample showed that females from Czech population were significantly overestimated and mostly misclassified as males. Overall accuracy of sex assessment significantly decreased (53.6-69.7 %), sex bias -29.4-100 %, which is most probably caused by secular trend and the generally high variability of body size. Results indicate that the discriminant functions, developed for skeletal series representing geographically and chronologically diverse populations, are not applicable in current forensic investigations. Finally, implications and recommendations for future research are discussed.
... Another advantage of the morphometric technique is that it can provide data for contemporary populations where there is a lack osteological collections. Furthermore, it overcomes the endogenous limitations of collections, e.g., poor recording, lack of representation of dynamic changes in skeletal morphology over time, secular changes, or effect of genetic mixtures [11,14,15]. ...
Purpose:
Identification of a deceased individual is an essential component of medicolegal practice. However, personal identification based on commingled limbs or parts of limbs, necessary in investigations of mass disasters or some crimes, is a difficult task. Limb measurements have been utilized in the development of biological parameters for personal identification, but the possibility to estimate the dimensions of parts of limbs other than hands and feet has not been assessed. The present study proposes an approach to estimate the dimensions of various parts of limbs based on other limb measurements.
Methods:
The study included 320 Sudanese adults, with equal representation of men and women. Nine limb dimensions were measured (five based on the upper limb, four based on the lower limb), and extensive statistical analysis of the distribution of values was performed.
Results:
The results showed that all of the measured dimensions were sexually dimorphic and that there was a significant positive correlation between the dimensions of various parts of limbs. Regression models (direct and stepwise) were developed to estimate the dimensions of parts of limbs based on measurements pertaining to one or more other parts of limbs.
Conclusions:
The study revealed that the dimensions of parts of the upper and lower limb can be estimated from one another. These findings can be used in medicolegal practice and extended to constructive surgery, orthopedics, and prosthesis design for lost limbs.
... Humans differ with respect to their physical features, bodily size and proportions, skeletal maturity/development and degree of sexual dimorphism 56,57 . Skeletal growth and maturity is a complex process influenced by various genetic, endocrinal and nutritional factors 1,58 . ...
The clavicle and the sternum are important bones of the anterior thoracic skeleton that are commonly found well preserved in forensic contexts. To assess the concurrent suitability of two bones of the same individual in forensic sex estimations, both clavicles and sternums were collected from 252 male and 91 female autopsy cadavers. This study’s bone dimensions were found to be significantly smaller than of subjects of other nationalities and also higher than previous Indian studies. Statistically significant sex differences were noticed in different dimensions of the two bones (p < 0.001). The univariate DFA found that the product index of the clavicle and combined sternal length were the best sex discriminating variables to identify the sex of about 85% of the cadavers. From the multivariate discriminant function analysis of all linear variables (DF: –18.664 + 0.107 (MCI–L) + 0.180 (MCC–R) +.045(MBL) – 0.071(MDL–L), the sex of 90.7% of the cadavers could be estimated correctly and this percentage was highest when either clavicular or sternal measurements were used in the analyses. The concurrent use of the two bones provided higher accuracy levels with lower sex biases than the individual use of either bone in univariate or multivariate analysis. The clavicle was found to be better and more reliable than the sternum for sex estimations in the current autopsy samples. Further studies are needed to corroborate or negate the findings of these investigations.
... It has been recognized that the magnitudes of sexually dimorphic characteristics vary among populations [18]. Nonpopulation-specific standards for sex estimation usually provide a low classification rate [19]. Thus, different populations should have specific standards to optimize the accuracy of identification. ...
Accurate sex estimation is important in forensic investigation to determine the identity of unknown individuals. The aim of this study was to investigate the accuracy of sex assessment based on measurements of the second cervical vertebra (C2) using computed tomographic (CT) images in a Japanese population and to develop discriminant function formulae. The data were collected from 224 Japanese cadavers (112 male subjects, 112 female subjects) on which postmortem CT scanning and subsequent forensic autopsy were performed. Nine CT measurements of the C2 were performed for CT images of each subject. The measurements were assessed using descriptive statistics and discriminant function analyses (DFA). All of the measurements demonstrated significant sexual dimorphism. Multiple DFA with stepwise variable selection resulted in multivariable models; a five-variable model reached an accuracy rate of 92.9%. Our results suggest that metric analysis based on CT images of the C2 can accurately determine the sex from the human skeletal remains in a contemporary Japanese population and may be useful for sex estimation in forensic anthropology.
El reconocimiento y la determinación del sexo a partir de fragmentos y restos de esqueletos humanos ha sido, hasta ahora, una tarea compleja para expertos forenses y antropólogos. Para los primeros, se vuelve crucial en casos de desastres masivos, catástrofes, como actos terroristas y guerras. El estudio con huesos de pelvis, cráneo, fémur y otros huesos largos ha contribuido significativamente a analizar la determinación del sexo en estas situaciones. El estudio del dimorfismo del esternón puede convertirse en un elemento más que puede colaborar con este tipo de conocimiento. El presente estudio buscó investigar, en fetos humanos, el dimorfismo sexual del esternón, a partir de sus mediciones perimetrales, que fueron tratadas por métodos estadísticos. Para ello, tres observadores diferentes utilizaron un paquimetro digital con una precisión de 0,01mm y se calculó la media de las mediciones obtenidas. Las diferencias en el promedio se evaluaron mediante la prueba t y la prueba de Mann-Whitney, así como el análisis discriminante. Los hallazgos de las mediciones del esternón en fetos humanos no nos parecieron un indicador confiable de la determinación del sexo. Esperamos que otros estudios con un mayor número de muestras y el uso de otras técnicas posibles también colaboren con el sujeto.
Das Erkennen und Bestimmen des Geschlechts aus Fragmenten und Überresten menschlicher Skelette war bisher eine komplexe Aufgabe für Forensiker und Anthropologen. Für erstere wird es bei Massenkatastrophen, Katastrophen wie Terroranschlägen und Kriegen von entscheidender Bedeutung. Die Studie mit Knochen des Beckens, des Schädels, des Oberschenkelknochens und anderer langer Knochen hat wesentlich dazu beigetragen, die Bestimmung des Geschlechts in diesen Situationen zu analysieren. Das Studium des Brustbeindimorphismus kann ein weiteres Element sein, das mit dieser Art von Wissen zusammenarbeiten kann. Ziel der vorliegenden Studie war es, bei menschlichen Föten den Geschlechtsdimorphismus des Brustbeins auf der Grundlage seiner Umfangsmessungen zu untersuchen, die mit statistischen Methoden behandelt wurden. Zu diesem Zweck verwendeten drei verschiedene Beobachter ein digitales Pachymeter mit einer Genauigkeit von 0,01 mm und berechneten den Durchschnitt der erhaltenen Messungen. Unterschiede im Durchschnitt wurden mit dem t-Test und dem Mann-Whitney-Test sowie der Diskriminanzanalyse bewertet. Befunde aus Messungen des Brustbeins bei menschlichen Föten schienen uns kein verlässlicher Indikator für die Geschlechtsbestimmung zu sein. Wir hoffen, dass weitere Studien mit einer größeren Anzahl von Proben und der Verwendung anderer möglicher Techniken ebenfalls mit dem Thema zusammenarbeiten werden.
The recognition and determination of sex from fragments and remnants of human skeletons has been, until now, a complex task for forensic experts and anthropologists. For the former, it becomes crucial in cases of mass disasters, catastrophes, such as terrorist acts and wars. The study with bones of the pelvis, skull, femur and other long bones has significantly contributed to analyze the determination of sex in these situations. The study of sternum dimorphism can become one more element that may collaborate with this type of knowledge. The present study sought to investigate, in human fetuses, the sexual dimorphism of the sternum, based on its perimeter measurements, which were treated using statistical methods. For this purpose, three different observers used a digital pachymeter with a precision of 0.01mm and the average of the measurements obtained was calculated. Differences in average were evaluated using the t-test and Mann-Whitney test, as well as discriminant analysis. Findings from measurements of the sternum in human fetuses did not seem to us to be a reliable indicator of sex determination. We hope that further studies with a larger number of samples and the use of other possible techniques will also collaborate with the subject.
Population affinity estimation is an important step in the identification of unknown individuals. To ensure accurate results, validation studies of newly developed methods must be performed using different target populations and skeletal elements. This research aims to determine the accuracy and reliability of population affinity estimation on a modern Spanish sample using two online software applications.
The sample consists of 114 adult individuals (51 males, 63 females) using 38 measurements and one angle from the skull and mandible. AncesTrees was used for craniometric measurements and (hu)MANid for mandibular variables with different classification models and probability thresholds being evaluated. The required parameters were inputted for each individual and statistics were generated to assess the accuracy of the estimation.
AncesTrees performed with the greatest accuracy as the program correctly classified the sample as Southwestern European or European, with highest accuracies being 54.56% (trial 1), 86.05% (trial 2), 82.61% (trial 3), 34.55% (trial 4) and 100.00% (trial 5). (hu)MANid correctly classified the sample as being from white origin with accuracies ranging from 70.59 to 80.00% without considering correct sex estimation, while accuracy ranged between 62.75 and 80.00% accounting for estimated sex.
Population affinity estimation may determine subsequent methods used in the construction of the biological profile. Our results demonstrate varying accuracy rates depending on the element and method, offering a critical view in relation to software applicability and validity. Reference populations and intrinsic and extrinsic factors can potentially influence the method accuracy and reliability. Future research should focus on the inclusion of underrepresented groups.
Forensic anthropologists have expertize in the analysis of the human skeleton and are routinely involved in cases involving deceased persons but may also be consulted in cases concerning living persons. Forensic anthropologists are typically requested to examine complete and /or fragmentary human remains in different states of preservation including, but not limited to, fresh, decomposed, traumatized, and/or burnt. This article describes the range of possible analyzes the forensic anthropologist may undertake. The type of contexts where a forensic anthropologist may work are discussed; highlighting that the contribution made by the forensic anthropologist will differ depending not only on preservation, but also on the type of case, and therefore the associated questions being asked. Developments in research and teaching in forensic anthropology are then discussed and professional issues posed by such developments are considered.
Background
Sex determination of unidentified remains found in archaeological or forensic situations has been one of the primary tasks for specialists such as forensic anthropologists or bioarchaeologists. In cases of mass disasters such as armed conflicts, terrorist attacks, plane crashes, war-related crimes, etc., when decomposed, mutilated or damaged mortal remains consisting of only a few bones or their fragments are recovered from the scene, it becomes crucial to establish the biological identity, especially the sex of a missing individual. Although several bones, such as the pelvis, skull and femur, have contributed significantly as an indicator in the determination of sex, we often make use of less dimorphic elements of the skeleton, as is the case of the sternum. The objective of this study was to investigate the sexual dimorphism of the sternum of human fetuses from northeastern Brazil and to verify through statistical methods the accuracy of the sternum measurements to estimate the sex. All measurements of the sternum bones in human fetuses were made with the aid of a digital caliper with a precision of 0.01 mm by 3 different observers and the average was calculated. The means differences were evaluated using the T test and Mann-Whitney test and discriminant analysis.
Result
It was observed that all measurements (length and width of the sternum) in males showed slightly higher means. We can also infer for the model with all variables that the length and widths 2 and 3 of the sternum had an accuracy of 73.3%, whereas in the individual models, width 3 of the sternum had better accuracy (60%).
Conclusion
We can conclude that the sternum measurements of fetuses have not been shown to be reliable as an indicator in the determination of sex. Further development of these methods, as well as the expansion of the database, may help us to develop further sternum-based sex estimation functions and standard measurements for other potentially useful bones.
The aim of this study is to contribute to sex determination studies from the scapula in the Turkish population and compare with previous studies. This study was performed with 200 scapulae (100 males and 100 females). The age range of the patients was between 18-93 years old. Computed tomography scans were used and length of glenoid cavity (LGC), breadth of glenoid cavity (BGC), depth of glenoid cavity (DGC), perimeter (PM) and volume (VL) were measured. Randomly selected 20 scapulae were measured three times for examine the intra-rater reliability from those measurements. Gender logistic regression analysis was conducted to find the significant variables at sex determination from the scapula. The most effective parameter in determining sex from scapula was found to be VL (88.5%). The effects of LGC, PM, BGC and DGC at sex determination from scapula were found to be 83%, 82.5%, 79.5%, 66%, respectively. The combination of VL and PM (89.5%) was found to be the most effective combination at sex determination from the scapula. The intraclass correlation values of all measurements were found to be at high reliability. According to the literature, PM and DGC along with the VL in Turkish population, were not used previously for sex determination from the scapula. A combination of the VL and PM was found to be the most effective parameters at sex determination from scapula in the Turkish population. There are few studies on the sex determination from scapula in the Turkish population. This study will guide anthropologists, forensic scientists and anatomists at sex determination studies from scapula and surgeons by morphometrically in clinical situations related to the scapula.
Objectives:
Thousands of migrants have died along the United States/Mexico border and many remain unidentified. The purpose of this research is to test whether estimations of population affinity, derived from craniometric data, can facilitate identification of migrant remains and provide a geographic region of origin rather than the broad label Hispanic. The appropriateness of current forensic reference data will also be assessed.
Methods:
A case study combined with craniometric data from positively identified and unidentified migrants from the Pima County Office of the Medical Examiner (n = 489) in Arizona and operation identification (n = 201) in Texas were compared to skeletal data representing Guatemalan (n = 87) and Mexican (n = 65) Mayans. Biological distance and discriminant function analyses were used to assess overall population relationships and classificatory models for forensic anthropological application.
Results:
The majority of evidence indicates that estimations of population affinity can assist in the facilitation identification of migrant remains, even when a broad classification is used. Biological distances among the groups suggest that positively identified Guatemalan and Mexican migrants are similar to one another but differ from Guatemalan and Mexican Mayans.
Conclusions:
Population affinity estimations can aid migrant identification, and current reference data used in forensic anthropological practice should be replaced with data from positive identifications. Estimates of geographic origin may be more useful than the broad generic term Hispanic for narrowing down the search for a missing person, but more data and research is needed to achieve this goal. Although, the utility of geographic origin estimates relies on transnational data centralization and sharing, which is not always the case.
The present study is an attempt to estimation of stature and sex from skull measurements by multidetector computed tomography (MDCT) in contemporary Chinese. In the present study, fifteen measurements for every skull were taken from CT image of 382 Chinese. The sample was composed of 200 males and 182 females with an average age of 47 and 46 years, respectively. Discriminant function was used in sex determination and regression analysis was used in stature estimation from skull measurements. The stepwise analysis of all measurements yielded a sex classification accuracy rate of 89.3%. The classification accuracy rates of the univariate discriminant function analyses were from 50.5% to 84.8%. For stature estimation, the standard error of estimate (SEE) ranged from 5.072 to 6.355 cm for male, from 5.090 to 5.829 cm for female, respectively. This study is the first to provide a metric and statistical characterization of the skull in contemporary Chinese, and indicates that it is feasible to sex estimation by skull measurement. Furthermore, the equations presented for stature estimation in this study may be used as alternatives in forensic cases, particularly in cases where better predictors such as the long bones are not available.
Objectives
The evaluation of developmental stability (DS) by measuring fluctuating asymmetry (FA), a bioindicator of general cumulative stress, is an approach that has often been used to characterize health status in past populations. New techniques of geometric morphometrics now enable a better appreciation of FA than before, with a more refined quantification of variation. The aim of our study is to determine the effectiveness of geometric morphometrics analyses of asymmetry in the human femur for the study of individual DS and inferring health status of human populations.
Materials and methods
We conducted a comparative analysis between two diachronic populations of distinct and known health status. Two samples of 70 pairs of adult femurs from individuals of comparable age range and sex were selected and CT‐scanned. For each 3D reconstruction, two sets of 27 landmarks were digitized to quantify and minimize the effect of measurement error on the evaluation of FA.
Results
While the measurement of FA in femoral centroid size seemed comparable between the samples, the amount of FA in femoral shape differed. Individuals who experienced high levels of environmental stress presented higher intra‐individual variation. In parallel, results did not reveal any significant differences in DS between sexes or age groups.
Discussion
The geometric morphometrics analysis of femoral asymmetry was effective for distinguishing two populations. After considering various factors of influence, genetics and biomechanics seem to have a limited impact on the results. Expressing FA appears to be normal but dependent on the disturbances of DS produced by environmental stress.
Craniometric studies of South Africans yield high accuracies of sex and ancestry classification, but most assess only intergroup
variation of Black and White individuals, excluding the highly heterogeneous Colored group, which constitute a significant proportion of
the population. This study applied a geometric morphometric approach to the neurocrania of 774 Black, Colored, and White individuals to
assess sex and ancestry estimation accuracy based on the detected morphological variation. Accuracies of 70% and 83% were achieved for sex
and ancestry, respectively, with ancestry-related variation contributing the largest proportion of overall observed variation. Even when comparing
the closely related Black and Colored groups, relatively high accuracies were obtained. It is thus recommended that a similar approach be
used to develop a contemporary three-dimensional database, which can be used to objectively, reliably, and accurately classify unknown
remains in the South African forensic context.
Bones can reflect the basic framework of human body and may provide valuable information about the biological identity of the deceased. They, often, survive the morphological alterations, taphonomic destructions, decay/mutilation and decomposition insults. In-depth knowledge of variations in clavicular shape, size and its dimensions is very important from both clinical (fixation of clavicular fractures using external or inter-medullary devices, designing orthopedic fixation devices) as well as forensic anthropological perspectives. Human clavicle is the most frequently fractured bone of human skeleton, possessing high degree of variability in its anatomical, biomechanical and morphological features. Extended period of skeletal growth (up to third decade) in clavicle imparts it an additional advantage for forensic identification purposes. In present study, five categories of clavicular features like lengths, diameters, angles, indices and robustness were examined to explore the suitability of collarbone for forensic and clinical purposes. For this purpose, 263 pairs of adult clavicles (195 Males and 68 Females) were collected from autopsied cadavers and were studied for 13 anatomical features. Gender and occupational affiliations of cadavers were found to have significant influences on anatomical dimensions of their clavicles. Product index, weight and circumference of collarbone were found the best univariate variables, discriminating sex of more than 80% individuals. The best multivariate Function-I (DF: -17.315 + 0.054 CL-L+0.196 CC-R+0.184 DM-L) could identify sex and occupation of 89.4% (89.2% Male and 89.7% Female) and 65.4% individuals, respectively. All clavicular variables were found bilaterally asymmetric; left clavicles being significantly longer in length, lighter in weight, smooth in texture and less curved than the right side bones. Among non-metric traits, sub-clavian groove, nutrient foramina and ‘type’ of clavicle exhibited significant sexual dimorphism. Thus, both metric and non-metric features of clavicle can have decisive role in forensic identifications and clinical interventions. Present results would be of great significance for anatomists, orthopedicians, surgeons and the forensic anthropologists in their professional endeavors.
In this study, we present ongoing research documenting the diversity of European and Hispanic populations. A sample of 1199 crania representing two large geographically and demographically heterogeneous regions (Central and Southern Europe and Brazil) was tested against a sizable database incorporated in the previous version of 3D-ID software. Craniofacial morphology was described by 3-D spatial data processed by methods of geometric morphometrics. The results illustrate morphological complexity and specificity of the examined geographic regions. They also support the need to reevaluate traditional classification systems used in the assessment of ancestry.
In order to develop population - specific discriminant function equations and stature prediction equations for predicting sex and stature from measurements of the scapula in a contemporary Chinese, 414 individual 3D CT images were collected from participants undergoing routine examination. Sex differences for the variables were tested by Student’s T-test. Fisher’s method has been followed for discriminant analysis. Regression analysis were applied to match the six linear parameters against stature. The stepwise analysis of all measurements yielded a sex classification accuracy rate of 86.7 % and a sex bias of 3.1 %. All the classification accuracy rates of the univariate discriminant function analyses are of more than 80%. For stature estimation, the accuracy of stature prediction ranged from 5.252 to 7.210 cm for male, from 4.630 to 6.484 cm for female, respectively. This paper provides indications that the scapula is an important bone for sex diagnosis and it could be effectively used as alternatives in forensic cases. Furthermore, the equations presented for stature estimation in this study should be used as alternatives in forensic cases when long bones were unavailable for stature estimation.
The human skull offers a rigid unit for the study of past populations and for personal identification. Consisting of at least 21 individual bones, united according to anatomical principles peculiar to man, the skull develops during childhood and youth to reach a size and expression which in general, but not completely in detail, may be regarded as final. Because of genetical differences between the major races of the world (Caucasian, Mongoloid, Negroid), principal differences in the appearance between typical skulls from these groups may easily be pointed out in terms of morphology. These differences are the result of different kinds of skull growth in the different groups, and may be expressed in terms of facial flatness, cranial indices, or degrees of prognatism. By tradition in craniometry, and more or less supported by direct or indirect evidence such as historical records, differences in mean skull measurements between subpopulations from neighbouring geographical regions are similarly regarded as expressions of population differences related to differences in the genetic composition of the populations.
Craniometric variation in humans reflects different genetic and environmental influences. Long-term climatic adaptation is less likely to show an impact on size and shape variation in a small local area than at the global level. Aim: The aim of this work was to assess the contribution of the particular environmental factors to body height and craniofacial variability in a small geographic area of Croatia.
A total of 632 subjects, aged 18-21, participated in the survey. Body height, head length, head breadth, head height, head circumference, cephalic index, morphological face height, face breadth, and facial index were analysed regarding geographic, climatic and dietary conditions in different regions of the country, and correlated with the specific climatic variables (cumulative multiyear sunshine duration, cumulative multiyear average precipitation, multiyear average air temperatures) and calcium concentrations in drinking water. Significant differences between groups classified according to geographic, climatic or dietary affiliation, and the impact of the environmental predictors on the variation in the investigated traits were assessed using multiple forward stepwise regression analyses.
Higher body height measures in both sexes were significantly correlated with Mediterranean diet type. Mediterranean diet type also contributed to higher head length and head circumference measures in females. Cephalic index values correlated to geographic regions in both sexes, showing an increase from southern to eastern Croatia. In the same direction, head length significantly decreased in males and head breadth increased in females. Mediterranean climate was associated with higher and narrower faces in females. The analysis of the particular climatic variables did not reveal a significant influence on body height in either sex. Concurrently, climatic features influenced all craniofacial traits in females and only head length and facial index in males. Mediterranean climate, characterized by higher average sunshine duration, higher average precipitation and higher average air temperatures, was associated with longer, higher and narrower skulls, higher head circumference, lower cephalic index, and higher and narrower faces (lower facial index). Calcium concentrations in drinking water did not correlate significantly with any dependent variable.
A significant effect of environmental factors on body height and craniofacial variability was found in Croatian young adult population. This effect was more pronounced in females, revealing sex-specific craniofacial differentiation. However, the impact of environment was low and may explain only 1.0-7.32% variation of the investigated traits.
An evolutionary, diachronic approach to the phenotypic craniofacial pattern arisen in a human population after high levels of admixture and gene flow was achieved by means of geometric morphometrics. Ad-mixture has long been studied after molecular data. Nevertheless, few efforts have been made to explain the morphological outcome in human craniofacial samples. The Spanish-Amerindian contact can be considered a good scenario for such an analysis. Here we present a comparative analysis of craniofacial shape changes observed between two putative ancestor groups, Spanish and precontact Aztecs, and two diachronic admixed groups, corresponding to early and late colonial periods from the Mexico's Central Valley. Quantitative shape comparisons of Amerindian, Spanish, and admixed groups were used to test the expectations of quantitative genetics for admixture events. In its simplest form, this prediction states that an admixed group will present phenotypic values falling between those of both parental groups. Results show that, in general terms, although the human skull is a complex, integrated structure, the craniofacial morphology observed fits the theoretical ex-pectations of quantitative genetics. Thus, it is predictive of population structure and history. In fact, results obtained after the craniofacial analysis are in accordance with previous molecular and historical interpretations, providing evidence that admixture is a main microevolu-tionary agent influencing modern Mexican gene pool. However, expectations are not straightforward when moderate shape changes are considered. Deviations de-tected at localized structures, such as the upper and lower face, highlight the evolution of a craniofacial pat-tern exclusively inherent to the admixed groups, indicat-ing that quantitative characters might respond to admix-ture in a complicated, nondirectional way. Am J Phys Anthropol 000:000–000, 2006. V
Morphometrics is the statistical study of biological shape and shape change. Its richest data are landmarks, points such as 'the bridge of the nose' that have biological names as well as geometric locations. This book is the first systematic survey of morphometric methods for landmark data. The methods presented here combine conventional multivariate statistical analysis with themes from plane and solid geometry and from biomathematics to support biological insights into the features of many different organs and organisms. This book will be of value to applied statisticians and geometers, as well as to all biological and biomedical researchers who need quantitative analyses of information from biomedical images.
This study evaluates issues of precision, repeatability, and validation in three-dimensional (3D) landmark coordinates. Two observers collected 19 homologous cranial landmarks from three skulls during three separate digitizing sessions. Statistical analysis was conducted on the 171 interlandmark distances (ILDs) derived from the original coordinate data. A mixed model ANOVA detected significant within-subject error in 54 of the 171 ILDs (i.e., 32%). A GLM procedure revealed significant between-observer variation in 14 ILDs and significant observer-by-session differences in 13 ILDs. The majority of these differences involved ILDs with type 3 landmarks as endpoints, such as euryon and alare. Unlike type 1 and 2 landmarks which are biologically informative in all directions, type 3 landmarks contain a substantial arbitrary component. Thus, it is not surprising type 3 landmarks displayed significant digitizing error. Given these results, we caution researchers to be mindful of type 3 landmarks measurement discrepancies when selecting landmarks for coordinate data evaluation.
One of the four pillars of the anthropological protocol is the estimation of sex. The protocol generally consists of linear metric analysis or visually assessing individual skeletal traits on the skull and pelvis based on an ordinal scale of 1–5, ranging from very masculine to very feminine. The morphologic traits are then some how averaged by the investigator to estimate sex. Some skulls may be misclassified because of apparent morphologic features that appear more or less robust due to size differences among individuals. The question of misclassification may be further exemplified in light of comparisons across populations that may differ not only in cranial robusticity but also in stature and general physique. The purpose of this study is to further examine the effect of size and sex on craniofacial shape among American populations to better understand the allometric foundation of skeletal traits currently used for sex estimation. Three-dimensional coordinates of 16 standard craniofacial landmarks were collected using a Microscribe-3DX digitizer. Data were collected for 118 American White and Black males and females from the W.M. Bass Donated Collection and the Forensic Data Bank. The MANCOVA procedure tested shape differences as a function of sex and size. Sex had a significant influence on shape for both American Whites (F = 2.90; d.f. = 19, 39; p > F = 0.0024) and Blacks (F = 2.81; d.f. = 19, 37; p > F = 0.0035), whereas size did not have a significant influence on shape in either Whites (F = 1.69; d.f. = 19, 39; p > F = 0.08) or Blacks (F = 1.09; d.f. = 19, 37; p > F = 0.40). Therefore, for each sex, individuals of various sizes were statistically the same shape. In other words, while significant differences were present between the size of males and females (males on average were larger), there was no size effect beyond that accounted for by sex differences in size. Moreover, the consistency between American groups is interesting as it suggests that population differences in sexual dimorphism may result more from human variation in size than allometric variation in craniofacial morphology.
This work deals with the assessment of cranial sexual dimorphism in human skeletal samples applying geometric morphometric techniques. The purpose of this research is to apply such techniques to quantitatively describe in craniofacial traits the degree and pattern of shape and size sexual dimorphism. Likewise, we evaluate the precision and accuracy of semilandmark-based techniques for sex estimation. We employ a sample of 125 adult skulls of known sex from the Coimbra collection. A set of coordinate points was selected to describe glabella, mastoid, frontal and zygomatic processes. The results of intra-class correlation coefficient (ICC) show excellent intra- and inter-observer agreement (ICC > 0.96) in the location of the coordinates of points employed. The principal component analysis (PCA) performed on shape variables shows a large superposition of both sexes, suggesting a relatively low degree of dimorphism in shape. As a consequence, the average percentages of correct sex estimations based on these variables were of 60.12 and 68.90%, obtained by discriminant analysis with leave-one-out cross validation and k-means clustering respectively. Conversely, when centroid size is included in PCA, females and males exhibit large separation along the first component. The highest values of correct assignment (77.86 and 72.15%) were found using shape–size variables with discriminant and k-means clustering analysis, indicating that the traits analysed display marked sex differences related to the larger size and more robust features of males. Finally, the advantages of geometric morphometric techniques are discussed. Copyright © 2009 John Wiley & Sons, Ltd.
A multivariate analysis of four prehistoric and nine historic populations from the Iberian Peninsula and Balearic Islands with large sample sizes (n > 30 individuals for the neurocranium and n > 15 for the facial skeleton) is presented, considering 874 male and 557 female skulls and using 20 craniometric measurements. Cluster analyses have been undertaken using the squared Euclidean distance as a measure of proximity and the average linkage between groups (UPGMA), and neighbor-joining algorithms as a branching method, and a bootstrap analysis was used to assess the robustness of the clustering topology. The study was complemented with a principal coordinate analysis and with the application of the Mantel test to measure the degree of correspondence between the information furnished by the female and the male samples. The analyses show that the main source of morphometric variability in the Iberian Peninsula is the Basque population. The second source of variation is provided by two populations (Muslims and Jews), different from the rest from an archaeological and cultural point of view, and can probably be attributed to influences from sub-Saharan Africa. The massive deportations of the Jews in 1492 and of the Moors between the 15th and 17th centuries may have erased this source of variability from the present population of the Iberian Peninsula. The remaining studied populations, including samples from Castile, Cantabria, Andalusia, Catalonia and Balearic Islands, are grouped together, showing a notable morphological homogeneity, despite their temporal and geographic heterogeneity. These results are in general agreement with those obtained in synthetic maps, by analyzing multiple genetic markers. In such studies, the Basque population is described as the main source of genetic variability, not only in the Iberian Peninsula, but also in Western Europe.
Recently discovered crania of Australopithecus africanus from Sterkfontein Member 4 and Makapansgat enlarge the size range of the species and encourage a reappraisal of both the degree and pattern of sexual dimorphism. Resampling methodology (bootstrapping) is used here to establish that A. africanus has a greater craniofacial size range than chimpanzees or modern humans, a range which is best attributed to a moderately high degree of sexual dimorphism. Compared to other fossil hominins, this variation is similar to that of Homo habilis (sensu lato) but less than that of A. boisei. The finding of moderately high dimorphism is corroborated by a CV-based estimate and ratios between those specimens considered to be male and those considered to be female. Inferences about the pattern of craniofacial dimorphism in the A. africanus face currently rely on the relationship of morphology and size. Larger specimens, particularly Stw 505, show prominent superciliary eminences and glabellar regions, but in features related in part to canine size, such as the curvature of the infraorbital surface, large and small specimens of A. africanus are similar. In this respect, the pattern resembles that of modern humans more so than chimpanzees or lowland gorillas. A. africanus may also show novel patterns of sexual dimorphism when compared to extant hominines, such as in the form of the anterior pillar. However, males of the species do not exhibit characteristics of more derived hominins, such as A. robustus.
Five craniofacial variables (glabella-occipital length, basion-bregma height, maximum cranial breadth, nasion-prosthion height, and bizygomatic breadth) were used to examine secular change in morphology from the mid-19(th) century to the 1970s. The 19(th) century data were obtained from the Terry and Hamann-Todd anatomical collections, and the 20(th) century data were obtained from the forensic anthropology databank. Data were available for Blacks and Whites of both sexes. Secular change was evaluated by regressing cranial variables on year of birth. Two analyses were conducted, one using the original variables and one using size and shape. Size is defined as the geometric mean of the cranial variables, and shape is the ratio of each variable to size. The results show remarkable changes in the size and shape of the cranial vault. Vault height increases in all groups in both absolute and relative terms. The vault also becomes longer and narrower, but these changes are less pronounced. Face changes are less than the vault changes, but to the extent that they occur, the face becomes narrower and higher. Overall cranial vault size has increased, but shape changes are greater than size changes. The magnitude of secular change in vault height exceeds that for long bones over a comparable time period, but follows a similar course, which suggests that vault height and bone length respond to the same forces. Changes in vault dimensions must occur by early childhood because of the early development of the vault. Am. J. Hum. Biol. 12:327-338, 2000. Copyright 2000 Wiley-Liss, Inc.
Identification criteria, specifically discriminant function formulae derived from traditional craniometrics, currently used in South Florida for Cuban Americans and other “Hispanic” groups, are unsuitable to provide adequate biological profiles due to complex biological histories as well as widely diverse geographic origins. Florida's total population is approximately 16 million (15,982,378) individuals. Of the total population 2,682,715, or 16.8%, are self-identified as “Hispanic”. South Florida (herein defined as Miami-Dade, Broward and Collier Counties) is home to 60% of the total Hispanic population of Florida with 1,291,737 (48.15%) residing in Miami-Dade County.
The Hispanic population of Miami-Dade County makes up 57.0% of the total population of 2,253,362. Each recognized sub-group of Hispanics (Mexican, Puerto Rican, and Cuban) includes its own geographic point-of-origin and population history. Cuban-Americans (arriving in the late 1950's and early 1960's) make up the largest sub-population of Florida's Hispanics in any county and in Miami-Dade number 650,601 or 51% of the total Latin population. Additionally, as in other agricultural states, Florida has a very large population of undocumented workers who primarily arrive from Texas and points south of the Straits of Florida.
Thus the application of the available traditional craniometric and non-metric methods are not appropriate for South Florida's Latin population. To begin to address this issue in relation to South Florida's Cuban population, we present an analysis of cranio-facial shape variation in a 19th Century Cuban sample, 17th Century Spanish sample, a Precontact Cuban sample, and Terry Blacks using geometric morphometric methods. Significant biological shape differences and patterns of variation are observed among the groups. These results provide us with a context in which to begin to understand the biological variation of Cuban Americans, which will enable the development of identification criteria specific for this U.S. hybrid Hispanic community.
An evolutionary, diachronic approach to the phenotypic craniofacial pattern arisen in a human population after high levels of admixture and gene flow was achieved by means of geometric morphometrics. Admixture has long been studied after molecular data. Nevertheless, few efforts have been made to explain the morphological outcome in human craniofacial samples. The Spanish-Amerindian contact can be considered a good scenario for such an analysis. Here we present a comparative analysis of craniofacial shape changes observed between two putative ancestor groups, Spanish and precontact Aztecs, and two diachronic admixed groups, corresponding to early and late colonial periods from the Mexico's Central Valley. Quantitative shape comparisons of Amerindian, Spanish, and admixed groups were used to test the expectations of quantitative genetics for admixture events. In its simplest form, this prediction states that an admixed group will present phenotypic values falling between those of both parental groups. Results show that, in general terms, although the human skull is a complex, integrated structure, the craniofacial morphology observed fits the theoretical expectations of quantitative genetics. Thus, it is predictive of population structure and history. In fact, results obtained after the craniofacial analysis are in accordance with previous molecular and historical interpretations, providing evidence that admixture is a main microevolutionary agent influencing modern Mexican gene pool. However, expectations are not straightforward when moderate shape changes are considered. Deviations detected at localized structures, such as the upper and lower face, highlight the evolution of a craniofacial pattern exclusively inherent to the admixed groups, indicating that quantitative characters might respond to admixture in a complicated, nondirectional way.
A large collection of identified human skeletons curated at the Bocage Museum (National Museum of Natural History, Lisbon, Portugal) has remained in relative anonymity since its collecting protocol was initiated in the 1980s. This collection originates from modern cemetery sources and is comprised of 1,692 skeletons with basic documentary data (age at death, place of birth, occupation, place of residence, and date and cause of death). At present, this information is more readily available for 699 individuals. The remaining 993 are in the process of being fully documented. The skeletons consist largely of Portuguese nationals who lived in the 19th and 20th centuries (1805-1975) in Lisbon. Both sexes are equally represented, and ages at death range from birth to 98 years, including 92 subadults (<20 years old).
A secular change of body height and neurocranial variables was registered in the Croatian population during the last century. We investigated the continuity of this process, and introduced facial measurements into the study. The results cover a 13-year period, from the birth of the subjects in 1974-1986, with a gap in the period from 1977-1981. The subjects were first-year students of the University of Rijeka School of Medicine, aged 19-21 years. Secular changes were evaluated by analysis of variance and multivariate regression analysis. A statistically significant decrease was found in head breadth, and an increase in morphological face height values, in both sexes. A significant increase of head circumference was observed in female students. The height and length of the head in both sexes displayed a slight but insignificant increase, while face breadth revealed no notable change during the investigated period. The results allow an assumption of a trend of cranial vault and face shape remodeling in our younger adult population toward a narrower vault and more elongated face, consistent with ongoing dolichocephalization. The correlation analysis revealed a low to moderate relationship of vertical and longitudinal craniofacial measures and body height, while partial correlation analysis showed facial height changes in our sample to be independent of cranial breadth changes.
The United States (U.S.) population structure is currently in a state of flux with one of the most profound changes being the increasing number of people referred to as Hispanic. In the U.S., much of the identification criteria for a biological profile are based on American Black and White individuals from anatomical collections. Using metric data from the Forensic Anthropology Data Bank (FDB), this paper will attempt to explore several issues that forensic anthropologists face when confronted with Hispanic remains. These will involve estimation of sex, height, and ancestry, the initial components of a biological profile. Discriminant function analyses indicate that American White criteria provide poor estimations of sex when applied to Hispanics and that ancestry estimation of Hispanic crania is difficult. Additionally, a new linear regression equation is presented that estimates stature for Hispanic individuals, although population specific criteria are still needed for Hispanic individuals from diverse geographical origins.
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