Fourier analysis of the forehead shape of skull and sex determination by use of computer

The forehead shape of the skull was quantified with the Fourier analysis method by using 100 male and 100 female radiographic lateral views of the skull, and sex difference in the forehead shape was studied. Furthermore to predict the sex of cranial specimens, an automated sexing computer system based on the quantification was created. The effectiveness of the system was evaluated by checking 56 male and 56 female specimens of skulls. This system was proved to discriminate male and female skulls from forehead shapes with 85% accuracy.     

Determining the sex of human remains through cranial morphology

Sex determination is the keystone of a biological profile, yet few qualitative methods of cranial sex determination have been tested. This analysis examines the accuracy and precision of 17 morphological features of the skull commonly used to determine the sex of unknown skeletal remains. The sample consists of 46 identified skulls from the 19th century St. Thomas' Anglican Church Cemetery in Belleville, Canada. Nasal aperature, zygomatic extension, malar size/rugosity, and supraorbital ridge proved the most useful; of secondary value are chin form and nuchal crest; mastoid size is of tertiary consideration; nasal size and mandibular symphysis/ramus size rank fourth; forehead shape ranks fifth; and palate size/shape are sixth. Skull size/architecture provides an internal standard to assess the relative sizes of other traits. This research is a necessary step in establishing the credibility of morphological sex determination with respect to the Daubert and Mohan criteria for admissibility in a court of law.     

Course of the meatus acusticus internus as criterion for sex differentiation

The importance of features that allow the determination of an individual's gender even with skulls that have been largely destroyed is undisputed in archaeological and anthropological practice. Due to its extreme mechanical strength, the pars petrosa ossis temporalis is usually preserved in skulls and the sex dimorphisms of this skeletal part are therefore of particular significance. In the present study, we aimed at clarifying the controversial question whether the course of the meatus acusticus internus (M.a.i.) beneath the superior surface also reveals sex-specific differences. Using 410 forensically modern petrous portions, the course of the canal was examined and the respective angles determined using a specifically developed casting and cutting technique. The median values certainly reveal sex differences: the lateral angle on the male petrous portions is 10 degrees smaller than that of females; the medial angles on female petrous portions are approximately 5 degrees smaller than those of male skulls. Using discriminant analysis, approximately 66% of the specimens can be determined accurately.     

中国汉族人颅骨数字模型的性别判别方法

目的利用步进Fisher法建立多元性别判别函数,对西安地区成年人颅骨进行性别判别。方法从颅面数据库中选择西安地区133个（73男,60女）三维颅骨模型,利用计算机软件测量并统计颅骨的12项几何测量指标和2项角度测量指标,利用步进Fisher方法建立多元性别判别函数,并对方程进行回代检验。结果男性的12项几何测量指标均值大于女性,女性的2项角度测量指标均值大于男性,除2项指标（X7和X14）外,其他指标均存在显著性差异（P〈0.01）。由4项指标建立的判别方程,判别率男性为87.5%,女性为86.67%。结论利用计算机软件可以实现完整颅骨和无下颌的颅骨的性别判别。     

西南地区成人面颅骨的性别判定

目的建立适合西南地区成人的颅骨性别判定函数。方法性别明确的颅骨67个,测量颅骨最大长、颅骨最大宽、颅高等16项指标,所得数据进行统计学分析,建立单一变量及多变量性别判定方程,并对5个无名颅骨进行回带检验。结果 16项指标中有13项存在显著的性别差异,男性大于女性,单变量函数推断性别以鼻高(男78.4%,女83.3%)、颅骨最大长(男83.8%,女73.3%)准确率较高。多变量性别判定函数以颅周长、鼻高贡献最大,判定准确率男89.2%,女90.0%。结论单变量推断颅骨性别以鼻高或颅骨最大长较为理想,但以颅周长、鼻高联合推断性别准确率更高。     

Photogrammetry vs CT Scan: Evaluation of Accuracy of a Low-Cost Three-Dimensional Acquisition Method for Forensic Facial Approximation

Photogrammetry is a three-dimensional acquisition method potentially applicable to the forensic field. This possibility requires the verification of its accuracy. In this study, 3D volumes of skulls are generated to compare the photogrammetry versus the CT scan. In order to provide eligible material to the photogrammetric software, photographs were captured at a distance of 30 cm from the skull placed on a support 1 m in height and illuminated with diffused laboratory ceiling artificial light. A Nikon Coolpix P7100 camera was used. Photographs capture common elements with the previous and the next photograph so as to allow the photogrammetric software to recognize these common points between photographs and create a 3D puzzle. The Zephyr Lite (3DFlow©) software was employed to register the 3D volume. CT-based skulls are taken as a metric reference. The photogrammetry-based skulls are then enlarged according to the measurements of some landmarks or Zygion and Zygion, the distance between end of nasal and base of nasal pyramid for frontal projection, and minimum breadth of the mandibular ramus for the right lateral projection. The accuracy of the photogrammetry is compared to that of the CT scan by measuring the 3D volumes of the skulls studied. Specific landmarks are used as reference points for the measures in both frontal and lateral views. Bland–Altman graph shows homogeneity. The mean difference (1.28 mm) indicates that the measurements taken on the photogrammetry-based skull tend to slightly overestimate compared with the measurements taken on the CT-based skull.     

The roughness of the supranasal region--a morphological sex trait

The supranasal region often attracts attention by a remarkable rough and jagged quality of the bony surface caused by an irregular supranasal suture and additional holes and pores. Some authors point out that there is a positive relation between the supranasal suture, the superciliar arches, and the forehead contour. For this a relation to sex is conceivable. This present study was done to prove the value of this morphological trait for sexing skulls.A total of 80 human skulls of known sex (40 females, 40 males) were collected from autopsy material used in anatomy teaching classes and from forensic cases. The mean age of the female sample was 70.98 years (minimum 38, maximum 93), that of the male sample was 74.10 years (minimum 57, maximum 99). To quantify the roughness of the supranasal region the calculation of the box-counting dimension was used. The results were normally distributed in both, the male and female group. The male dimension values were well grouped (maximum 1.51111, minimum 0.98765, mean 1.26159, S.D. 0.12268, 95% CI 1.22236-1.26604) whereas the female showed a wide range (maximum 1.46744, minimum 0.44755, mean 1.15052, S.D. 0.21388, 95% CI 1.08212-1.21892), widely overlapping the male range. Statistical analysis showed that there was a less than 1% probability that the female box-counting dimension was lower than the male by chance (P-value 0.00593). For this results the admission of the trait 'quality of the supranasal region' into a catalogue of features regarding morphognostic sex determination following the scheme: hyperfemininity: very smooth and regular--femininity: more smooth and regular--indifferent--masculinity: more rough and irregular--hypermasculinity: very rough and irregular, seems to be justified.     

现代人面颅角度测量的种族差异性

目的探索面颅角度指标在种族鉴定方面的差异性。方法选取现代人头骨57例,其中中国黄种人头骨30例（女性9例,男性21例）,包括吉林1例,河北5例,山东4例,青海4例,安徽4例,江西3例,云南3例,贵州3例,广西3例。欧洲自种人头骨27例,性别不详,取自欧洲Zellemdorf、Vresovice、Kysperka3地。按体质人类学测量方法,通过参考相关文献和对颅骨形态特点的观察,设计面颅左侧眶角、右侧眶角、鼻颌角3个角度指标进行测量。对测量数据进行描述性统计分析和两独立样本之间的t检验。结果3个角度指标在种族差异性方面,眶角的种族差异性具有显著统计学意义（P〈0．01）,而鼻颌角之间的种族差异性无统计学意义（P〉0．05）。结论有些角度指标显示出明显的种族差异性,今后需要加强此方面的研究。     

Sex diagnosis of Chinese skulls using multiple stepwise discriminant function analysis.

Sixty Chinese skulls (30 males and 30 females) from Liaoning Province of the People's Republic of China were used in this study. Forty-one variables on each skull were measured and one group of 14 and a second group of 5 variables were selected from all the variables by applying multiple stepwise regression on a computer. Discriminant equations for the 14 and 5 variables for sex diagnosis have been obtained and these variables are highly significant. The discriminant rate for the group of 5 variables resulted in accurate sex determination in 96.7% of cases. For the group of 14 variables there was 100% success rate.     

Evaluating the accuracy and precision of cranial morphological traits for sex determination

Sex determination is a key analysis that forensic anthropologists perform in order to construct a biological profile of human remains. The techniques used in forensic investigations must meet the Mohan or Daubert criteria, for admissibility in a court of law. In this study, the precision and accuracy of 21 morphological characteristics of the skull were tested on a modern sample of 50 adult crania of European White ancestry. The following craniofacial features are identified as high-quality traits, defined by intraobserver error or=80%: mastoid size, supraorbital ridge size, general size and architecture, rugosity of the zygomatic extension, size and shape of the nasal aperture, and gonial angle. Ninety-six percent accuracy and 92% precision were achieved using 20 traits in combination. Fisher's exact probability tests revealed no significant differences (p=0.05) in the levels of precision or accuracy between age categories. Sex-related bias in accuracy was found for the following cranial features: ramus symphysis (p=0.009), zygomatic extension (p=0.0016), and occipital markings (p=0.0013). These traits demonstrated a greater tendency to be scored male than female.     

Recent human sexual dimorphism study using cephalometric plots on lateral teleradiography and discriminant function analysis

Abstract:  The examination of skull sexual dimorphism has been the subject of numerous morphologic and craniometric studies, but the disadvantage of these studies is that they are dependent on the experience of the operator and involve subjectivity. In 1996, a team from Taiwan refined the methods enabling the sex of an individual to be determined using cephalometric plots made from lateral teleradiography. To validate their work using a European population, 114 dry skulls (59 men and 55 women) were examined. Cephalometric plots were made on lateral teleradiography with an orthodontic software and 18 cephalometric variables were analyzed. Sex was determined with 95.6% accuracy using the 18 variables discriminant function. A subset of eight variables was selected and could predict sex with the same accuracy. In conclusion, it can be said that skull-sexing methods using lateral teleradiography seem always suitable but the most indicative variables could differ relative to the ethnic population concerned.     

Methodology for estimating endocranial capacity in a modern European population

Various methods have been published in the literature to estimate endocranial capacity. These are based on mathematical equations using measurements made directly on the skull or indirectly from X-rays, by filling the skull with various materials, by endocasts both physical and virtual (using 3D CT-scan reconstructions). Each method has its advantages, limits and drawbacks. A useful method is one that is simple, time-efficient, cheap, and reproducible. For this study we estimated endocranial capacity by filling the skull with calibrated glass beads. We used a thorough protocol of tamping to ensure results reproducibility. Intra- and inter-observer trials showed no significant differences. The method was applied to 130 recent French (West European) skulls (65 males and 65 females). Sexual dimorphism was studied using logistic regression functions, discriminant analysis, and neural network. The best results were obtained using the neural network, built with two hidden nodes in the hidden layer and one output node, and trained with a steepest descent algorithm. Our tests show that there is obvious sexual dimorphism (p < 10(-5)) of the weight of the skulls (623.44 ± 106.83 g in males; 548.07 ± 94.57 in females), the weight of the glass beads used to fill the skulls (2379.83 ± 228.92 g in males; 2095.95 ± 145.49 in females), and endocranial capacity (1676.47 cm(3) ± 161.26 in males; 1476.48 ± 102.49 in females), but overlapping between sexes is quite significant. The average ECC in male (1676.5 cm(3)) and in female (1476.5 cm(3)) subjects is higher than those previously published, which deserves some discussion.     

Independent instances of "souvenir" Asian skulls from the Tampa Bay area

In the summer of 1984, police in Pinellas County, Florida, confiscated six identically colored imported Asian skulls (in a shipping case) from a private citizen. In May 1988, in nearby Hillsborough County, police confiscated a very similar skull from another private citizen, who allegedly had found it in an abandoned house. Aside from slight color differences between the six found in Pinellas County and the one found in Hillsborough County, the skulls are virtually identical in their osteological characteristics and condition and in the vital statistics derived from each. Each skull is as clean and dry as those typically sold by commercial scientific supply outlets in the United States. Each is edentulous (primarily premortem), between approximately 20 and 60 years of age at death, and morphologically Asian. Five of the seven are morphologically male, one is morphologically female, and one is a mosaic with respect to gender-related features. Police, medical examiners, coroners, and forensic anthropologists should be aware of such "souvenir" specimens, in the event that they encounter similar skulls. Discriminant function analyses for race and sex yield considerably conflicting results, which underscores the need for using extreme caution when interpreting forensic science estimates based on such techniques.     

The reliability of sex determination of skeletons from forensic context in the Balkans

In this study we have tested the applicability of morphological methods for sex assessment, based on seven pelvic and nine cranial traits, using contemporary Balkans population. The material involved in the study comprises 262 pelvic bones and 180 skulls of male individuals from two mass graves in Serbia. The material was examined separately by an experienced and an inexperienced physical anthropologists. Sex was correctly estimated by the experienced anthropologist in 100% of individuals using all of the 16 pelvic and cranial criteria. In fact, sex differences in pelvic morphology were large enough to allow sexing the individuals with 100% accuracy. Among seven features observed on the pelvic bones, the least reliable single sex indicator was the width of the great sciatic notch (with accuracy of 79.15%). Looking at the skull alone, sex was correctly determined in 70.56% cases. It was shown that the most accurate single indicators among cranial methods was the robustness of the mandible (with accuracy of 70.93%), while the sharpness of the supraorbital margins was the least reliable indicator demonstrating accuracy in only 28.75% of crania. Examination of the sample by an individual with training in physical anthropology, but no case experience, suggests that experience is likely to contribute moderately to the accuracy of the sex determination. Namely, the inexperienced anthropologist accurately assessed the sex of the sample 95.04% of the time; 4.06% less accurate than the experienced anthropologist. The two anthropologists showed the least agreement in scoring the ventral arc and composite arc on the pelvic bones.     

西南地区成人男性颅骨的相关回归分析

目的研究颅骨部分测量指标间的相关性,以期建立在对破损颅骨进行颅骨面貌复原时,利用尚存指标推断缺失指标的方法。方法用人体骨骼测量仪对41个男性颅骨的颅长、颅宽、颅高等14个指标进行测量,将测量值输入SPSS统计软件,找出相关性好的指标,建立各指标间相互推断的回归方程。结果部分测量指标间呈中度以上相关,应用逐步回归的方法得出回归方程24个,方差检验均具统计学意义(P<0.01)。结论本研究所建立的回归方程可为法医人类学和考古人类学的颅骨修复提供备选方法。     

Reliability of Craniofacial Superimposition Using Three‐Dimension Skull Model

Craniofacial superimposition is a technique potentially useful for the identification of unidentified human remains if a photo of the missing person is available. We have tested the reliability of the 2D‐3D computer‐aided nonautomatic superimposition techniques. Three‐dimension laser scans of five skulls and ten photographs were overlaid with an imaging software. The resulting superimpositions were evaluated using three methods: craniofacial landmarks, morphological features, and a combination of the two. A 3D model of each skull without its mandible was tested for superimposition; we also evaluated whether separating skulls by sex would increase correct identifications. Results show that the landmark method employing the entire skull is the more reliable one (5/5 correct identifications, 40% false positives [FP]), regardless of sex. However, the persistence of a high percentage of FP in all the methods evaluated indicates that these methods are unreliable for positive identification although the landmark‐only method could be useful for exclusion.     

Computer-assisted skull identification system using video superimposition

This system consists of two main units, namely a video superimposition system and a computer-assisted skull identification system. The video superimposition system is comprised of the following five parts: a skull-positioning box having a monochrome CCD camera, a photo-stand having a color CCD camera, a video image mixing device, a TV monitor and a videotape recorder. The computer-assisted skull identification system is composed of a host computer including our original application software, a film recorder and a color printer. After the determination of the orientation and size of the skull to those of the facial photograph using the video superimposition system, the skull and facial photograph images are digitized and stored within the computer, and then both digitized images are superimposed on the monitor. For the assessment of anatomical consistency between the digitized skull and face, the distance between the landmarks and the thickness of soft tissue of the anthropometrical points are semi-automatically measured on the monitor. The wipe images facilitates the comparison of positional relationships between the digitized skull and face. The software includes the polynomial functions and Fourier harmonic analysis for evaluating the match of the outline such as the forehead and mandibular line in both the digitized images.     

Descriptive morphological features of the nose--an assessment of their importance for plastic reconstruction

On a series of lateral radiographs of 154 males and 199 females from Vienna, Austria, 3 qualitative morphological features of the external nose were recorded. Their relationship to craniometric dimensions, age, and the contour of the nasal bones was tested using Wilks' stepwise discriminant analyses. All tests gave significant results at the 1% probability level, but, overall, correct assignment of the features to their categories did not exceed 61%. Although height dimensions were used for discrimination in females, the prominence of the nasal bones and age appeared to be the most important discriminating variables in both sexes. Analyses further revealed that the nasal bridge and the direction of the nasal septum are highly correlated, whereas the tip of the nose seemed to be independent; this may reflect the dependence of the latter on exogenous influences, especially nutrition. It was demonstrated that the profile line of the external nose does not follow its underlying bony structures, that is, the profile line of the nasal bones. Thus, the present study showed that obtaining soft tissue thicknesses alone is not sufficient for successful facial reconstruction, but that a more holistic approach should be used to elucidate the relationships between soft tissue cover and the underlying hyaline and bony structures.     

Photo‐Realistic Statistical Skull Morphotypes: New Exemplars for Ancestry and Sex Estimation in Forensic Anthropology

Graphic exemplars of cranial sex and ancestry are essential to forensic anthropology for standardizing casework, training analysts, and communicating group trends. To date, graphic exemplars have comprised hand‐drawn sketches, or photographs of individual specimens, which risks bias/subjectivity. Here, we performed quantitative analysis of photographic data to generate new photo‐realistic and objective exemplars of skull form. Standardized anterior and left lateral photographs of skulls for each sex were analyzed in the computer graphics program Psychomorph for the following groups: South African Blacks, South African Whites, American Blacks, American Whites, and Japanese. The average cranial form was calculated for each photographic view, before the color information for every individual was warped to the average form and combined to produce statistical averages. These mathematically derived exemplars—and their statistical exaggerations or extremes—retain the high‐resolution detail of the original photographic dataset, making them the ideal casework and training reference standards.     

活体跟骨数字X线片性别判定

目的应用数字X线摄影方法测量跟骨,评估5项测量指标在法医学性别判定中的价值。方法393例受试对象随机分组,实验组334例(男性148例,女性186例),验证组59例(男性26例,女性33例)。每一受试对象按照规定投照方法摄跟骨侧位DR片,分别测量5项跟骨长度指标。方差分析检验实验组各项指标性别间差异,Fisher判别分析及多元逐步判别分析建立性别判别函数。验证组样本数据回代,前瞻性评估判别效能。结果5项指标性别差异有统计学意义(P<0.001)。共建立了6组性别判别函数,性别判断正确率在78.4%～88.9%之间;回代检验,判断正确率在79.7%～86.4%之间。结论跟骨侧位数字X线片5项长度测量指标代入判别函数进行性别判定的方法可为法医学个人识别中的性别判定提供帮助。