Crania are a reliable source for sex estimation in Euro-Americans, Europeans, and most other populations. Besides morphological assessments, the application of Fordisc® has become a useful tool within the last two decades, creating discriminant functions from morphometric data. Unfortunately, until now, white populations are mostly represented by measurements of American individuals. Therefore, classification rates are lower for European skulls than for Euro-Americans. The aim of this study was to show differences in sexual dimorphism between German and Euro-American crania. Furthermore, their secular change from the nineteenth to the twentieth century has been investigated. Analyses have been performed on glabella subtense (GLS), mastoid height (MDH), and bizygomatic breadth (ZYB). Fordisc® 3.1 was used to study sexual dimorphism and secular change, whereas SAS® was used to perform a two-level ANOVA to test for variation in sex dimorphism. Euro-Americans show greater dimorphism than Germans in all three measurements tested. This larger difference is even increasing from the late nineteenth through the late twentieth century in terms of GLS and MDH, while it stays almost the same in the present Europeans. These results explain the unsatisfying classification rates of German and other European crania on Fordisc®. Data collection for European Fordisc® samples is in progress and should improve the current situation.
The aim of this study was to figure out a new practically applicable method to distinguish between historical and recent human skeletal remains. Therefore, the optical behavior of bone cross sections was investigated using the combination of two methods: a modification of an already established test (UV-induced fluorescence) and a new method (490 nm-induced fluorescence). We evaluated the areal extent of fluorescence of 30 bone cross sections with known postmortem interval (PMI) using ultraviolet light and 490 nm light. For analysis, the areal extend of fluorescent surface was determined using photos of the samples and an image editing software. The results prove that there is a correlation between PMI and the areal extent of fluorescent surface in both tests. Furthermore, the combination of both methods is a good indicator to distinguish within the forensic relevant post mortem interval between PMI < 30 years and PMI > 30 years.
Estimation of the post-mortem interval (PMI) of unknown skeletal remains is a common forensic task. Boaks and colleagues demonstrated a new method for PMI estimation in showing a reduction of the collagen to non-collagen content (Co/NCo ratio) in porcine bones after a PMI of 12 months using the Sirius Red/Fast Green Collagen Staining Kit from Chondrex in 2014 (Boaks et al. Forensic Sci Int 240: 104-110, 2014). The aim of our study was to reproduce this method and to investigate if the method could be used for forensic issues. Sixteen fresh porcine bones were placed in prepared boxes where they were treated regularly with distilled water or with water from hay infusions. For determining the Co/NCo ratio, we used the Sirius Red/Fast Green Collagen Staining Kit from Chondrex, which stains collagenous (Co) proteins red and non-collagenous (NCo) proteins green Chondrex Inc. (2008). After a PMI of 1-3 months, an analysis of porcine bone thin sections was performed on the one hand with spectrophotometry, on the other hand with stereomicroscopy. Using spectrophotometry, we go low and partially negative Co/NCo ratios which were up to 100-fold lower than the results we expected to get. The data we got by stereomicroscopy and calculating the Co/NCo ratio from extracting the red and green content with the software MATLAB and so calculating the Co/NCo ratio showed a correlation between PMI and the Co/NCo ratio in the porcine bone samples. Regular addition of distilled water or water from a hay infusion did not produce any significant differences so that an increased presence of microorganisms had obviously no influence on collagen degradation.
Studying secular changes on human skulls is a central issue in anthropological research, which is however insufficiently investigated for modern German populations. With our study, we focus on morphological cranial variations within Germans during the nineteenth and twentieth centuries. To study this, we recorded different facial landmarks from a cohort study of about 540 German individuals of different age and sex by calculating their cranial size, shape dimensions, and cranial module and cranial capacity to get information about variations occurring during the decades. According to this, measured variables for Germans and Americans, to which we compared our results, were maximum cranial length (glabello-occipital length), basion-bregma height (BBH), basion-nasion length (BNL), maximum cranial breadth (XCB), and cranial base breadth (AUB). Cranial size was calculated as the geometric mean of GOL, BBH, and XCB. Samples were organized into quarter century birth cohorts, with birth years ranging from 1800 to 1950. One-way ANOVA was used to test for variation among cohorts. Over the past 150 years, Americans and Germans showed significant parallel changes, but the American cranium remained relatively higher, with a longer cranial base, as well as narrower than the German cranium. Our results should also lead to the extension of the range of populations listed and investigated for Fordisc®, a forensic software to identify unknown individuals as from their skeletal remains or just parts of them. Fordisc cannot provide a satisfying identification of European individuals yet because the database is missing enough European reference samples.
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