Sex Discriminant Functions Research Articles

Sex estimation from skull measurements of a contemporary Japanese population using three-dimensional computed tomography images.

In this study, we assessed the sexual dimorphism of the contemporary Japanese skull and established sex discriminant function equations based on cranial measurements using three-dimensional (3D) computed tomography (CT) images. The CT images of 263 corpses (142 males, 121 females) that underwent postmortem CT scanning and subsequent forensic autopsy were evaluated. Twenty-one cranial measurements were obtained from 3D CT reconstructed images, which extracted only bone data. We performed descriptive statistics and discriminant function analyses for the measurements. Nineteen measurements were significantly larger in males, suggesting sexual dimorphism of the Japanese skulls. Univariate discriminant function analyses using these measurements showed a sex classification accuracy of 57.8-88.2%, and bizygomatic breadth provided the highest correct prediction rate. Multivariate discriminant function analyses offered the most accurate model using seven variables with an estimation rate of 93.9%. Our results suggest that cranial measurements based on 3D CT images may help in the sex estimation of unidentified bodies in a contemporary Japanese population.

Towards accurate and simple morphometric sex differentiation in Bonelli’s Eagle Aquila fasciata nestlings: Interpopulation variations and influence of growth conditions

Morphometric methods of sex differentiation may be cheap, simple, quick, and reliable alternatives to molecular approaches. However, there are still important uncertainties regarding the use of morphometric methods in birds, particularly regarding their applicability to different populations and environmental conditions. Between 2004 and 2019, we sampled 245 Bonelli´s Eagle Aquila fasciata nestlings, 197 from nests in Catalonia (northeastern Spain) and Andalusia (southeastern Spain) and 56 that were partially or totally raised in captivity. Our objective was to develop morphometry-based sexing methods for Bonelli’s Eagle nestlings that can be applied in situ to different subpopulations and growth conditions. We recorded up to nine measures related to nestling body mass, bill, tarsus, and claw length. Tail and wing length were used to control for the age of nestlings, and all individuals were sexed genetically. We found important morphometric differences between the two natural subpopulations. According to our discriminant analyses, body mass and claw length were the most discriminant variables, both in wild and captivity conditions. Differences between sexes were more prominent during the flight feathers’ growing period. Feeding ad libitum in captivity conditions led to larger nestlings and reduced between-sexes differences. We provide different models for sexing Bonelli’s Eagle nestlings that can be applied according to the studied geographic location, growth conditions (wild versus captive), and balance between accuracy and simplicity. Overall, our findings highlight that extrapolating sex discriminant functions to different subpopulations and growth conditions may be risky.

Estimation of Sex from Patella Measurements in Sichuan Han Population Based on CT-Three-Dimensional Volume Reconstruction Technique

Objective To estimate sex based on patella measurements of Sichuan Han population by computed tomography three-dimensional volume reconstruction technique, and to explore the application value of patella in sex estimation. Methods CT three-dimensional volume reconstruction images of patella of 250 individuals were collected, the four measurement indicators including patellar length, patellar width, patellar thickness, and patellar volume were measured. The t-test was used to determine measurement indicators with sex differences. Fisher discriminant analysis was used to establish the sex discriminant function and the prediction accuracy was calculated by leave-one-out cross validation. Results The sex differences of the four measurement indicators had a statistical significance （P<0.05）. The accuracy rate of the univariate discriminant function established by the patellar length was the highest （82.0%）. The accuracy rates of the all indicators discriminant function and the stepwise discriminant function were 80.4% and 81.6%, respectively. Conclusion It is feasible and accurate to estimate sex of Sichuan Han population by patella measurements with CT three-dimensional volume reconstruction technique. The method may be used as an alternative for sex estimation of Sichuan Han population when other bones with higher accuracy are not available.

Forensic sex estimation using the vertebrae: an evaluation on two European populations.

Sex estimation is one of the primary steps for constructing the biological profile of skeletal remains leading to their identification in the forensic context. While the pelvis is the most sex diagnostic bone, the cranium and other post-cranial elements have been extensively studied. Earlier research has also focused on the vertebral column with varying results regarding its sex classification accuracy as well as the underlying population specificity. The present study focuses on three easily identifiable vertebrae, namely T1, T12, and L1, and utilizes two modern European populations, a Greek and a Danish, to evaluate their forensic utility in sex identification. To this end, 865 vertebrae from 339 individuals have been analyzed for sexual dimorphism by further evaluating the effects of age-at-death and population affinity on its expression. Our results show that T1 is the best sex diagnostic vertebra for both populations reaching cross-validated accuracy of almost 90%, while age-at-death has limited effect on its sexual dimorphism. On the contrary, T12 and L1 produced varying results ranging from 75 to 83% accuracy with the Greek population exhibiting distinctively more pronounced sexual dimorphism. Additionally, age-at-death had significant effect on sexual dimorphism of T12 and L1 and especially in the Greek female and Danish male groups. Our results on inter-population comparison suggest that vertebral sex discriminant functions, and especially those utilizing multiple measurements, are highly population specific and optimally suitable only for their targeted population. An open-source software tool to facilitate classifying new cases based on our results is made freely available to forensic researchers.

The discriminant power of biometrics for sex determination in European Bee-eaters Merops apiaster

ABSTRACT Capsule A combination of several biometric measures enables the reliable sexing of the European Bee-eater Merops apiaster, a species with subtle sex differences in plumage and morphometry. Aims To explore variation in biometrics and their suitability to discriminate sex in adult European Bee-eaters Merops apiaster. Methods We sampled populations of a long-distance migratory species with low sexual size dimorphism, the European Bee-eater Merops apiaster, from colonies in western Iberia (Portugal) and Central Europe (Germany) to investigate body size variation and derive population-specific and general sex discriminant functions. Results Overall, male Bee-eaters were larger than females while Bee-eaters from Germany and Portugal did not differ in size, except for primary length and tail length. The best single measurement to discriminate sex was wing length for Portuguese birds and tail tip length for German birds, as in the combined dataset. Multivariate discriminant functions of head-bill, wing and tail tip lengths provided the highest discriminant accuracy, discriminating sex for 91% of the birds from Portugal, 96% from Germany and 94% when using the combined dataset. Nonetheless, the discriminant accuracy remained high in the functions using only two variables for Portugal (head-bill and tail tip 91%, head-bill and wing 88%, wing and tail tip 88%), Germany (head-bill and tail tip 95%, wing and tail tip 97%) and in the combined dataset (head-bill and tail tip 92%, wing and tail tip 93%). Conclusions Population specific discriminant functions allow sexing of European Bee-eaters by morphometry with high degree of accuracy at least for Iberia and Central European populations. Such discriminant functions can be used to assign the sex of adult Bee-eaters reliably and swiftly while the bird is still in the hand, highlighting the potential of these functions for rapidly sexing species with low degrees of sexual size and plumage dimorphism.

Estimating sex using discriminant analysis of mandibular measurements from a modern Greek sample

BackgroundSex determination is an integral and fundamental step in biological profile construction. The mandible, which holds many dimorphic traits, can be useful for sex estimation in the forensic context. However, reliable sex estimation usually relies on population-specific mandibular morphometric criteria. To date, no such criteria are available for the modern Greek population, and the present study aims to fill this lack of data by identifying the most sexually dimorphic mandibular traits on a modern Greek population sample and reporting the discriminant functions that can most effectively be used for estimating sex.Materials and methodsFor the purposes of this research, the 3D models of 194 adult mandibles (105 males and 89 females) from the Athens skeletal reference collection were used. A battery of 20 linear and 3 angular measurements was calculated from the 3D coordinates of anatomical landmarks positioned on the respective models and was analyzed by means of ANOVA and discriminant function analysis to investigate the expression of sexual dimorphism.ResultsThe coronoid height, the ramus height, and the maximum mandibular length are the most sexually dimorphic metric traits of the mandible, while the produced sex discriminant functions yielded cross-validated classification accuracy up to 85.7% for the Greek sample. Furthermore, most of the examined combinations of measurements exhibited the same sex discriminant capacity between different reference samples, despite their respective discriminant functions being population specific.ConclusionsOur findings indicate that the produced sex discriminant functions can be effectively used for sex determination in forensic casework and to verify the population specificity of these functions but also suggest that the expression of sexual dimorphism in the mandible shares certain features across different populations.

Sex Recognition of Skulls in Chinese Uygur.

Objective Logistic regression method was used to establish a multiple regression sex discriminant function to discriminate the complete skull model and the incomplete skull model without frontal bone, occipital bone and mandible of Uygur adults in Turpan, Xinjiang. Methods A total of 117 （60 male and 57 female） three-dimensional skull models were collected by CT. Sixteen cranial measurement indexes were measured and calculated by computer software. The multivariate regression sex discriminant function was established with Logistic regression method and retrospectively tested. Results Among the 16 measurement indexes, except for nose width （x7） and maximum frontal breadth （x13）, the remaining 14 indexes had statistical significance of differences between male and female （P<0.05）. For the discriminant function of complete skull established by eyebrow arch convexity （x4）, mastoid width （x6）, maximum cranial length （x12）, cranial base length （x15）, cranial circumference （x16）, the male and female discrimination accuracy was 90.0% and 94.7%, respectively. For the sex discriminant function of incomplete skull without frontal bone established by mandibular angle width （x10）, mandibular height （x11） and cranial circumference （x16）, the discrimination accuracy of male and female was 85.0% and 84.2%, respectively. For the sex discriminant function of incomplete skull without occipital bone established by the index of eyebrow arch convexity （x4）, the discrimination accuracy of male and female was 80.0% and 73.7%, respectively. For the sex discriminant function of incomplete skull without mandible established by frontal chord （x5） and occipital protrusion angle （x9）, the discrimination accuracy of male and female was 85.0% and 78.9%, respectively. Conclusion The computer software and system developed in our study can achieve sex discrimination of complete skulls and incomplete skulls without frontal bone, occipital bone or mandible.

Is “Latin American” population-specific? Testing sex discriminant functions from the Mexican tibia on a Chilean sample

Latin American populations are traditionally reported as one ancestral group in the forensic anthropology literature. However, this study illustrates the need for population-specific methodologies for ancestral groups that are considered Latin American. This project evaluated the accuracy of the sex estimation discriminant function created from the tibia of a Mexican population, when applied to a Chilean population. The maximum distal epiphyseal breadth (MDEB) and the anterior-posterior diameter at the nutrient foramen (APDNF) were measured on 203 tibiae (108 males and 95 females) from the Subactual Skeletal Collection at the University of Chile. The individuals ranged in age from 20 to 96 years old. When the Mexican discriminant function was applied to the Chilean population, accuracy rates ranged from 76.0% (males) to 85.0% (females). Mean tibial size comparisons were made to a Mexican, Croatian, White South African, archaeological Hispanic, and North Indian population and showed some significant differences between the variables measured. Population-specific discriminant functions were created for the Chilean population with overall sex classification accuracy rates of 71.4% (MDEB only) to 89.2% (MDEB and APDNF). This study illustrates the need for population-specific and temporally-specific discriminant functions for estimation of sex from the tibia.

Sex determination from calcaneus in Gujarati population by discriminant function analysis

IntroductionSex, age and racial affinity are the three most vital determinations that must be made when dealing with skeletal remains. Success in sex determination from skeletal remains is limited as most of the bones are available in fragments. The calcaneus, the largest tarsal bone, is apt for studying sexual dimorphism as it is relatively well preserved due to its density. MethodsEleven measurements of 51 adult human calcanei (31 male and 20 female) have been taken to determine accuracy of calcaneus in sex determination and to derive sex discriminant function equations specific for Gujarati population. ResultsThe correct sex classification rate after the direct discriminant function analysis of all parameters is 94.25%. Subsequent to stepwise analysis, two parameters (dorsal articular facet length and middle breadth) have been selected as the best sex determinants with an accuracy of 94.3%. Among the dimensional groups, the breadth dimensional group has the highest accuracy. The sex discriminant function equations specific for Gujarati population have been derived. DiscussionThe accuracy rate in sex determination obtained in the present study is comparable to the accuracy rates reported by previous researchers.

Evaluation of discriminant functions for sexing skulls from visually assessed traits applied in the Rainer Osteological Collection (Bucharest, Romania)

The sexing of human skeletal remains based on visual scoring of descriptive traits on the skull is useful for both forensic and bioarchaeological studies, given that many such features preserve well in the field and can be assessed quickly. The goal of our work is to evaluate the accuracy of this method on an age-balanced, known sex, random sample of 360 modern adult crania in the Rainer Osteological Collection. Consistent with Walker (2008), we scored glabella area (G), the mastoid process (Ma), the mental eminence (M), the orbital edge (O) and the nuchal crest (N), on a five-point scale. We generated sex discriminant functions (logistic), selected the most accurate of them, and subsequently applied them to archaeological samples from Romania. Each skull feature showed significant score differences by sex. Eight out of 31 discriminant functions passed criteria of high accuracy (∼90%), sex bias (±2%), and ease of use (direct calculation of sex). The best estimates were obtained for the 30–60 age groups. Further testing these functions on six archaeological samples showed high percentages of agreement with the sex assessed on the coxal bone. The study also indicated that, although easy to learn by novices, the method of visually scoring the skull traits depends on prior experience with human osteology. The accuracy of the method may be influenced by geographical and historical differences which are bound to exist between populations.

Discriminant function analysis for sex determination using landmark coordinate data from three-dimensional mandible models

In this study, we aimed to investigate the sex-discriminating potential of mandible dimensions, which we hypothesise can be measured easily and can indicate various sex discriminant functions in a simple manner. Statistical analysis was performed using data from five linear measurements and 10 indexes acquired from 14 landmark coordinates on 240 three-dimensional Korean mandible models (120 male and 120 female). The Korean mandible showed sex dimorphism in all the measurements and in four indexes (p < 0.01). Discriminant functions were generated by univariate, bivariate, and multivariate analyses using direct and stepwise methods, with accuracy ranging from 51.3% to 89.6%. Moreover, when comparing the dimensions of Korean mandibles with other populations, morphological differences were observed, thus implying that the sex discriminant functions can be generated according to each population. Therefore, in the present study, we noted that the various discriminant functions assessed using three-dimensional models of the mandible in this study indicated that the mandible dimensions alone had sex-discriminant potential, and our findings thus provided useful information for forensic examiners to accurately predict sex in a Korean population.

Sex identification in Gentoo (Pygoscelis papua) and Chinstrap (Pygoscelis antarctica) penguins: Can flow cytometry be used as a reliable identification method?

An important scientific question in ecology is how to differentiate males from females that have similar morphology. In penguins, due to their monomorphic plumage, it is difficult to determine gender. So far, most approaches to address this problem have focused on using sex based discriminant functions combined with DNA based tools as a validation method. As discriminant functions can be species and locality specific, in this study we explored the feasibility of using flow cytometry to determine the sex of two species of penguins, Pygoscelis antarctica and Pygoscelis papua. Our results for sex assessment determined by flow cytometry were compared with those obtained using morphological characters (bill length and depth), and DNA based methods (using the PL/PR primer pair) were used to validate both approaches. For both species, statistically significant differences were observed between males and females, with males presenting on average 2.1% more nuclear DNA than females. Flow cytometry enabled similar or better rates of correct sex assignment (86.4% and 80.0%) than sex discriminant functions (31.8% and 90.0%) for P. antarctica and P. papua, respectively, and thus may be considered as a promising alternative to the use of morphological data for sex identification. Nevertheless, some individuals with intermediate genome size values were observed, which increased the difficulty of categorically assigning their sex. Therefore, flow cytometry alone cannot be considered in all cases, but if used together with DNA-based methods in targeted samples, it can be used to efficiently estimate the gender of, at least, these two penguin species, with the potential to be used in other species.

Sexual Dimorphism in Perissodactyl RhinocerotidChilotherium wimanifrom the Late Miocene of the Linxia Basin (Gansu, China)

Sexual dimorphism is reviewed and described in adult skulls of Chilotherium wimani from the Linxia Basin. Via the analysis and comparison, several very significant sexually dimorphic features are recognized. Tusks (i2), symphysis and occipital surface are larger in males. Sexual dimorphism in the mandible is significant. The anterior mandibular morphology is more sexually dimorphic than the posterior part. The most clearly dimorphic character is i2 length, and this is consistent with intrasexual competition where males invest large amounts of energy jousting with each other. The molar length, the height and the area of the occipital surface are correlated with body mass, and body mass sexual dimorphism is compared. Society behavior and paleoecology of C. wimani are different from most extinct or extant rhinos. M/F ratio indicates that the mortality of young males is higher than females. According to the suite of dimorphic features of the skull of C. wimani, the tentative sex discriminant functions are set up in order to identify the gender of the skulls.

A Sex Discriminant Function Analysis by the Dental Measurements of Koreans

A Sex Discriminant Function Analysis by the Dental Measurements of Koreans

Sex Assessment from Metacarpals of the Human Hand

Discriminant functions designed for the determination of sex from metacarpal measurements are presented. Three samples of metacarpal specimens were employed in the analysis; one consisting of 212 individuals from the Terry Collection, one of 33 individuals from the Royal Free Medical School in London, and finally, 40 individuals from the Forensic/Donated Collection, Maxwell Museum of Anthropology, University of New Mexico, all of whom had documented sex. Five measurements designed to characterize the size and shape of the human metacarpal were taken on all five digits. Based on the Terry Collection, significant metric differences attributed to race were found for digits I and III, and thus functions could only be derived for the three remaining metacarpals. Sex discriminant functions derived from the Terry Collection for digits II, IV, and V provide correct classification of 92.0, 86.26, and 84.37 percent. The resulting three linear equations were then independently applied to the Royal Free Medical School and Forensic/Donated samples to validate the accuracy of the original functions. Percentage of correct classification for each of the test samples varies.

The construction of sex discriminant functions from a large collection of skulls of known sex

The suitability of the large collection of skulls of known sex (n♂=357, n⧫=213), housed in the Department of Anthropology of the University of Coimbra, as a reference series for sex diagnosis from skulls, was investigated. This was done by calculating estimates for the maximum «actual discriminatory value for samples being diagnosed». here called Dt max. The estimates for this statistic were found to be relatively low. Depending on the estimation procedure used, values of 1.68 and 1.64, were obtained, which correspond with theoretical percentages of correct classification of 79.8 and 79.3, respectively. An attempt was then made to investigate whether the low level of sexual dimorphism was due to heterogeneity in the series, which was therefore partitioned into Northern, Central and Southern groups according to place of birth. Only in the Southern group was the level of sexual dimorphism found to be slightly higher than in the whole series.The need for large well documented reference series for deriving techniques for sex determination from the skull and other skeletal elements is discussed and an extensive description of the methods emploved in this study is given.

Development of a Generalized Discriminant Function for Cross-Population Determination of Sex from Long Bones of the Arm and Leg

ABSTRACTExplanations are provided for the multivariate statistical techniques which utilize ordinarily reported basic statistics for examining interpopulation variation of sexual dimorphism and for constructing a common discriminant function for sex determination. These techniques are used to analyze extremity long bone measurement data in 11 populations. Interpopulation variation of sexual dimorphism has often been employed to interpret both the interpopulation variation of coefficients of sex discriminant function and the decrease of correct diagnosis rate in cross-population application. Statistical examination shows, however, that many such phenomena are attributable to sampling errors. Although significant variation of sexual dimorphism certainly exists even among subpopulations within the modern Japanese, this does not prohibit use of the formally derived common discriminant function. Its discriminant efficiency varies among populations, but compares well with that of each population-specific functi...

Sexual dimorphism in human skulls. A comparison of sexual dimorphism in different populations

Application and comparison of sex discriminant functions in different populations led to the conclusion that a certain combination and weighting of a few sex dimorphism variables (in this study we only used craniometric variables) can give a good discrimination between male and female individuals, independent of the racial group to which this function is applied.

Possibilities of metric sex determination from the pars petrosa ossis temporalis

Based on a sample of petrous bones of known sex (47 males and 47 females) discriminant functions were worked out for sexing both uncremated and cremated petrous bones. Classification values were certain to range from 70.2% to 76.6% for uncremated petrosals and from 67.0% to 73.4% for cremated ones. The results do not support the more promising values suggested by Wahl (1981).

Sex determination of finnish crania by discriminant function analysis

AbstractUsing multivariant discriminant function analysis, the sex of 232 Finnish crania of known sex was determined. Eight measurements were used to form two discriminant functions. In 80% of cases the sex determination by means of the discriminant functions was identical with the original information. The applicability of the sex discriminant function of Giles and Elliot ('63) for American white and Negro crania was also tested on the Finnish crania. An accuracy of only 65% was attained.