Sebastian K.T.S. Wärmländer

Sexual dimorphism in human browridge volume measured from 3D models of dry crania: A new digital morphometrics approach

Sex estimation from the human skull is often a necessary step when constructing a biological profile from unidentified human remains. Traditional methods for determining the sex of a skull require observers to rank the expression of sexually dimorphic skeletal traits by subjectively assessing their qualitative differences. One of these traits is the prominence of the glabellar region above the browridge. In this paper, the volume of the browridge region was measured from digital 3D models of 128 dry crania (65 female, 63 male). The 3D models were created with a desktop laser scanner, and the browridge region of each 3D model was isolated using geometric planes defined by cranial landmarks. Statistical analysis of browridge-to-cranium volume ratios revealed significant differences between male and female crania. Differences were also observed between geographically distinct populations, and between temporally distinct populations from the same locale. The results suggest that in the future, sex determination of human crania may be assisted by quantitative computer-based volume calculations from 3D models, which can provide increased objectivity and repeatability when compared to traditional forensic techniques. The method presented in this paper can easily be extended to other volumetric regions of the human cranium.

Identification of Group Affinity from Cross-sectional Contours of the Human Midfacial Skeleton Using Digital Morphometrics and 3D Laser Scanning Technology

Abstract:u2002 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.

Characterization of 17Th-19Th Century Metal Threads from the Colonial Andes

Abstract In a detailed study of South American metal threads, samples of metal embroidery and decorative metal leaves found on colonial Andean ecclesiastic objects have been investigated in order to characterize their composition, manufacture, and deterioration. The samples were examined with a range of methods, including optical microscopy, x-ray fluorescence spectroscopy, x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectroscopy, and Fourier transform infrared spectroscopy. The results show that the studied metal threads are made from gilt silver, or brass- or silver-coated copper, with elemental compositions and manufacturing techniques similar to metal threads found in Europe and Asia. Since all metal threads so far encountered in South America date to after the arrival of Europeans, it has been suggested that they were first introduced to the continent by the Spaniards. Although it cannot be determined whether the analyzed metal threads were imported or locally manufactured, the similarity to European metal threads suggests that the examined samples were produced according to the European tradition, without any local Andean modifications to the design patterns or manufacture processes. This strengthens the hypothesis that no tradition of metal-thread-making existed in South America in precolonial times.

Sampling and statistical considerations for the Suchey–Brooks method for pubic bone age estimation: Implications for regional comparisons

Although the Suchey-Brooks (SB) system is currently the most widely used method for age-at-death estimation from the pubic bone, the system continues to evolve through stepwise improvements. Since the system was developed from a pubic bone sample derived mainly from North Americans, it is unclear how well it performs on populations from other continents. During the last decade, studies of the SB system on pubic bone samples from local populations in Europe and Asia have indicated regional differences in the relationship between age and pubic bone development. However, these studies have for the most part followed different research protocols, which make comparisons between their results less meaningful. It would be most useful if future regional analysis of the SB system were done in a rigorous and uniform fashion, following standard procedures. In this paper, sampling and statistical considerations are outlined that hopefully will help to standardize research on the SB system.

Brief communication: Additional cases of maxillary canine-first premolar transposition in several prehistoric skeletal assemblages from the Santa Barbara Channel Islands of California.

This article identifies and discusses seven new cases of complete maxillary canine-premolar transposition in ancient populations from the Santa Barbara Channel region of California. A high frequency of this tooth transposition has been previously documented within a single prehistoric cemetery on one of the Channel Islands. A total of 966 crania representing 30 local sites and about 7,000 years of human occupation were examined, revealing an abnormally high prevalence of this transposition trait among islanders during the Early period of southern California prehistory ( approximately 5500-600 B.C.). One of the affected crania is from a cemetery more than 7,000-years-old and constitutes the earliest case of tooth transposition in humans so far reported. The results are consistent with findings by other studies that have indicated inbreeding among the early Channel Islands groups. Together with the normal transposition rates among mainland populations, the decreasing prevalence of maxillary canine-first premolar transposition among island populations across the Holocene suggests that inbreeding on the northern Channel Islands had all but ceased by the end of the first millennium B.C., most likely as a result of increased cross-channel migration and interaction.