Identification of group affinity from cross-sectional contours of the human midfacial skeleton using digital morphometrics and 3D laser scanning technology

Identifying group affinity from human crania is a long-standing problem in forensic and physical anthropology. Many craniofacial differences used in forensic skeletal identification are difficult to quantify, although certain measurements of the midfacial skeleton have shown high predictive value for group classifications. This study presents a new method for analyzing midfacial shape variation between different geographic groups. Three-dimensional laser scan models of 90 crania from three populations were used to obtain cross-sectional midfacial contours defined by three standard craniometric landmarks. Elliptic Fourier transforms of the contours were used to extract Fourier coefficients for statistical analysis. After cross-validation, discriminant functions based on the Fourier coefficients provided an average of 86% correct classifications for crania from the three groups. The high rate of accuracy of this method indicates its usefulness for identifying group affinities among human skeletal remains and demonstrates the advantages of digital 3D model-based analysis in forensic research.     

Sexual dimorphism in America: geometric morphometric analysis of the craniofacial region

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.     

Sex Determination Using the Second Cervical Vertebra—A Test of the Method*

Abstract: Sex is one of the critical questions addressed when unidentified skeletal remains are discovered in forensic or archeological contexts. Continuous testing and re‐evaluation of existing techniques is essential to improve accuracy and precision. The Wescott (J Forensic Sci 2000; 45 (2):462–6) method of sex determination from dimensions of the second cervical vertebra was blind‐tested on 153 adult individuals from the Spitalfields documented collection of human skeletal remains held at the Natural History Museum, London. Significant sex differences were determined for all dimensions measured (independent two‐sample t‐test, p < 0.05–0.001). The discriminant functions developed by Wescott were shown to have an overall accuracy of classification of 76.99%. Using stepwise discriminant analysis, a discriminant function based on the Spitalfields data correctly classified sex in 83.3% of individuals and was able to classify males and females with equal accuracy. Additional discriminant functions are presented for use in instances where preservation of the second cervical vertebra is poor.     

White‐tailed Deer as a Taphonomic Agent: Photographic Evidence of White‐tailed Deer Gnawing on Human Bone

Ungulate gnawing on bone has been reported in the taphonomic and zooarchaeological literature, but there are no known reports of ungulates altering human remains. Herein, we report on the first known photographic evidence of deer gnawing human remains. As described in nonhuman scavenging literature, forking of the bone characterizes the taphonomic effect of deer gnawing in this case, which is distinct from the effect caused by other scavengers. This type of osteophagia during the winter season is consistent with previously documented behavior of deer gnawing on nonhuman bone, possibly to obtain minerals absent in their diet. In this study, we briefly discuss the distinguishing features of ungulate gnawing, the reasons for this behavior, and possible confusion with other common types of scavenging and modification. This report contributes to taphonomic literature covering the range of animal interactions with human skeletal remains.     

Analysis of Bone Healing in a Postoperative Patient: Skeletal Evidence of Medical Neglect and Human Rights Violations

This study highlights complexities associated with postsurgical trauma interpretation of a 76‐year‐old female patient from a psychiatric institution in Mexico. The skeletal analysis identified complications from an unsuccessful surgical operation for an intertrochanteric fracture of the femur. An improperly placed surgical plate resulted in nonunion due to limited contact between fracture margins. However, it is unclear whether this resulted from surgical complications, ineffective postoperative care, or from the decedent's limited ability to follow postoperative care instructions. Additionally, failure of the plate resulted in degenerative changes to the acetabulum. These complications, associated with degenerative changes to upper limb joints, suggest significant mobility issues. The pattern of antemortem trauma and contextual information support a conclusion of postoperative medical neglect, a documented problem in psychiatric institutions in Latin America. This study provides insight into the relevance of detailed trauma assessment of skeletal remains in cases where neglect and human rights violations are suspected.     

Sudden Death in Marfan Syndrome

Marfan syndrome is an autosomal dominant genetic disorder of the connective tissue. The most serious complications of this syndrome are defects of the heart valves and aorta. Aneurysms of thoracic aorta are known to develop in Marfan syndrome. Other causes for development of aneurysms of the thoracic aorta are trauma, infections, valve and arch anomalies, genetic disorders, and atherosclerosis. These aneurysms upon rupture may lead to sudden deaths. They are usually detected during routine screening or follow‐up of such persons suffering from Marfan syndrome and upon death will be certified by the treating physician. Thus, an autopsy surgeon rarely comes across such deaths. One such case of sudden death due to cardiac tamponade consequent upon rupture of dissecting aortic aneurysm in a 33‐year‐old male who complained of throbbing pains in the chest, radiating to back, became breathless, cyanotic and died on the way to hospital is being presented here.     

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

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

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

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

Antemortem and Postmortem Nonapposite Data—A Multidisciplinary Identification Strategy

Identification of human remains is often achieved by comparing documented reference data with the same type of evidence obtained from the remains. We present a case of a decomposed unidentified body, whose identity was presumed but because of the low validity range of the available data, the identification process could not be completed. Antemortem radiographs of the teeth found in the house of the reputed victim could not be compared to the edentulous cadaver and the kinship between the victim and the only living relative that could provide DNA for comparison was too tenuous. Isolated teeth found at the scene, were neither a source of DNA reference information nor questioned data to be compared to the antemortem radiographs. The strategy implemented by the investigators to reallocate the status of the isolated teeth from the questioned source to the reference source of DNA to be compared with the cadaver is presented.     

Schmorl's nodes in an American military population: frequency, formation, and etiology

This research investigates the frequency of Schmorl's nodes in differing populations, with new data from a skeletal sample from the Central Identification Laboratory (CIL) at the Joint Prisoner of War/Missing in Action Accounting Command, while also reviewing the etiology of Schmorl's node formation. Processes implicated in Schmorl's node formation include trauma, old age, disease, intrinsic abnormalities, and biomechanical factors, and they correlate with Schmorl's node formation to varying degrees. A survey of research from the anthropology and medical literature revealed Schmorl's node population frequencies ranging from 8 to 80%. The current study consists of two samples, one derived from CIL case reports and one analyzing skeletal remains. The case report sample yielded a Schmorl's node frequency of 19.8%. The examined sample yielded a frequency of 73.7%. The disparate frequencies reported are likely due mainly to differences in completeness and observability. It is likely that trauma was a major factor in the formation of Schmorl's nodes in the CIL study.     

Anthropological and Radiographic Comparison of Antemortem Surgical Records for Identification of Skeletal Remains*

Abstract: This case review illustrates the important contributions of forensic archeological methods and forensic anthropological analysis to the identification of found skeletal remains. After reassociation of skeletal remains found in two locations, anthropological analysis provided the basis for a presumptive identification and a request for antemortem medical records. Partial DNA profiles were supportive but not conclusive and antemortem dental records were not available. Comparison of antemortem traumas, skeletal morphology, and surgical artifacts with antemortem radiographs and surgical records led to positive identification of an individual missing for almost a decade.     

Field Contamination of Skeletonized Human Remains with Exogenous DNA

The Armed Forces DNA Identification Laboratory reports the mitochondrial DNA (mtDNA) sequences of over 800 skeletal samples a year for the Joint POW/MIA Accounting Command–Central Identification Laboratory. These sequences are generated from degraded skeletal remains that are presumed to belong to U.S. service members missing from past military conflicts. In the laboratory, it is possible to control for contamination of remains; however, in the field, it can be difficult to prevent modern DNA from being transferred to skeletal elements and being carried forward through the analysis process. Four such cases are described here along with the controls in place in the laboratory to eliminate the possibility of the exogenous DNA being reported as authentic. In each case, the controls implemented by the laboratories prevented the false reporting of contaminant exogenous DNA from remains that were either faunal or human, but lacked endogenous DNA.     

Weight References for Burned Human Skeletal Remains from Portuguese Samples

Weight is often one of the few recoverable data when analyzing human cremains but references are still rare, especially for European populations. Mean weights for skeletal remains were thus documented for Portuguese modern cremations of both recently deceased individuals and dry skeletons, and the effect of age, sex, and the intensity of combustion was investigated using both multivariate and univariate statistics. The cremains from fresh cadavers were significantly heavier than the ones from dry skeletons regardless of sex and age cohort (p < 0.001 to p = 0.003). As expected, males were heavier than females and age had a powerful effect in female skeletal weight. The effect of the intensity of combustion in cremains weight was unclear. These weight references may, in some cases, help estimating the minimum number of individuals, the completeness of the skeletal assemblage, and the sex of an unknown individual.     

The Effect of Time on Bone Fluorescence: Implications for Using Alternate Light Sources to Search for Skeletal Remains

Bones fluoresce when exposed to certain wavelengths of shortwave light, and this property can be useful in locating and sorting skeletal remains in forensic contexts. The proteins in bone collagen are largely responsible for its fluorescent properties, but these proteins degrade and denature over time. This study examined the fluorescence of bones from four temporal groups (recent, semi‐recent, ancient, and historic) ranging from 0 to 1064 years before present. Specimens were photographed under 490 nm wavelength light, and fluorescence was quantified by converting intensity to a gray scale value based on the RGB color model using ImageJ^® software. Significant (p < 0.05) differences were found in mean fluorescence between all four temporal groups, and a 0.324 coefficient of correlation indicates a significant (inverse) relationship between fluorescence and time. Bone fluorescence decreases with time, but some fluorescence is retained even in older samples. Fluorescence can therefore be reliably used in many modern skeletal remains searches.     

Discriminant function analysis for sex assessment in pelvic girdle bones: sample from the contemporary Mexican population

Sex assessment of skeletal remains plays an important role in forensic anthropology. The pelvic bones are the most studied part of the postcranial skeleton for the assessment of sex. It is evident that a population-specific approach improves rates of accuracy within the group. The present study proposes a discriminant function method for the sex assessment of skeletal remains from a contemporary Mexican population. A total of 146 adult human pelvic bones (61 females and 85 males) from the skeletal series pertaining to the National Autonomous University of Mexico were evaluated. Twenty-four direct metrical parameters of coxal and sacral bones were measured and subsequently, sides and sex differences were evaluated, applying a stepwise discriminant function analysis. Coxal and sacra functions achieved accuracies of 99% and 87%, respectively. These analyses follow a population-specific approach; nevertheless, we consider that our results are applicable to any other Hispanic samples for purposes of forensic human identification.     

Determination of sex from juvenile crania by means of discriminant function analysis

This study provides evidence of craniofacial growth variation between the sexes in juveniles of European descent. Data were collected from lateral cephalometric radiographs belonging to the Michigan Craniofacial Growth Study. The collection consists of longitudinal lateral radiographs that represent individuals 5-16 years of age. Each radiograph was manually traced on hyprint vellum from which eight craniometric points were identified. From these points, 20 craniofacial measurements were recorded and then analyzed by means of a canonical discriminant function analysis. Sex classification equations were then created by applying a backward stepwise procedure to the discriminant functions. The analysis demonstrates the presence of sexually dimorphic differences in craniofacial growth. The neurocranium is the most sexually dimorphic region of the juvenile craniofacial skeleton, until the onset of puberty. Size is the main source of variation with males having taller and longer heads than females. Overall, sex classification in the sample ranges from 78 to 89% accuracy.     

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

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

Skeletal Indicators of Shark Feeding on Human Remains: Evidence from Florida Forensic Anthropology Cases

This research examines a series of six Florida forensic anthropology cases that exhibit taphonomic evidence of marine deposition and shark‐feeding activities. In each case, we analyzed patterns of trauma/damage on the skeletal remains (e.g., sharp‐force bone gouges and punctures) and possible mechanisms by which they were inflicted during shark predation/scavenging. In some cases, shark teeth were embedded in the remains; in the absence of this evidence, we measured interdental distance from defects in the bone to estimate shark body length, as well as to draw inferences about the potential species responsible. We discuss similarities and differences among the cases and make comparisons to literature documenting diagnostic shark‐inflicted damage to human remains from nearby regions. We find that the majority of cases potentially involve bull or tiger sharks scavenging the remains of previously deceased, adult male individuals. This scavenging results in a distinctive taphonomic signature including incised gouges in cortical bone.     

清代遗骸Y-STR检验1例

法医学实践中经常遇到对骨骼DNA检验的案例,但对保存超过100年的骨骼样本的检验报道较少。本文成功提取到150年前土埋遗骸的骨骼DNA,采用Y—filer试剂盒在9700型扩增仪上进行扩增,3130XL型遗传分析仪进行检测,得到遗骸Y—STR分型,并与对照样本比对,确认了遗骸身份。