Browsing by Subject "Biological Anthropology"

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    Open Access
    Assessment and improvement of current sex estimation standards for application in Holocene San and Khoekhoe populations
    (2022) Malek, Sadiyah; Gibbon, Victoria; Sealy, Judith
    Skeletal sex estimation is important in biological anthropology. Population-specific sex estimation standards do not exist for southern African Holocene San and Khoekhoe (HS-K) population. Due to their markedly small stature, skeletal gracility, and physically active lifestyle, they exhibit reduced sexual dimorphism. In this study I aimed to assess the accuracy of current sex estimation methods, and to optimise the assessed methods for population-specific application in the HS-K population. Seven morphological traits (cranial and mandibular) and six metrical parameters (mandibular, humeral, and femoral) were analysed in 175 adult HS-K skeletons. Accuracy was determined by comparison with pelvic sex estimates. Results were analysed using chi-squared tests, univariate statistics, and cross-validated discriminant function analysis. Trait/parameter preservation rates were assessed and reported: Of the traits, supra-orbital margin and glabella were best preserved (90% and 88% respectively), and mandibular shape least (71%). Of the metrical parameters assessed, femoral and humeral vertical head diameters (FVHD and HVHD) were best preserved (89% and 80% respectively), and bicondylar breadth (BB) least (44%). The highest sex classification accuracies obtained were for mastoid process (73%) and mandibular shape (72%), whilst the lowest were for mental eminence (53%) and nuchal crest (53%). Following categorisation by pelvic sex, the highest accuracies in females were for nuchal crest (98%) and mental eminence (95%), and in males, mandibular shape (80%) and gonial eversion/flaring (81%), illustrating differential sexual dimorphic expression for certain traits. All six metrical parameters were sexually dimorphic, with dimensions of FVHD and HVHD being the most discriminatory. The highest discriminant function accuracy for a single measurement (univariate) was 75% for FVHD, and for combined measurements (multivariate) were 77% for direct combination of BB, FVHD and HVHD, and 73% for stepwise combination of FVHD and HVHD. Whilst all traits/parameters assessed were sexually dimorphic, they produced lower accuracy rates than in other populations. This confirms that the range of sexual dimorphism exhibited by the HS-K does not conform to existing standards, illustrating the need for methodological adjustments. This study identified the most accurate areas to target for sex estimation in the HS-K and generated the first population-specific discriminant functions for sex estimation with known accuracies.
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    Circulus arteriosus cerebri: Anatomical variations and their correlation to cerebral aneurysms
    (2015) Du Toit, Francesca; Louw, Graham
    The anatomical structure of circulus arteriosus cerebri was first described by Thomas Willis in 1664. Many variations in the circulus arteriosus cerebri have since been reported. The extent to which anatomical variations within the circle influence aneurysm formation in a South African sample has not yet been established. The results of such a study would be of value to clinicians treating patients with vascular diseases. The aim of the study was to determine if there is a correlation between arterial variations in the circulus arteriosus cerebri and cerebral aneurysm formation. The brains of 39 cadavers at the Faculty of Health Sciences were removed and the circulus arteriosus dissected. In addition, 113 patients who underwent a MRI or MRA of the circulus arteriosus cerebri at the Department of Radiology at the Groote Schuur Hospital, Cape Town were included. For both of these samples the anatomical variations and any aneurysms present were documented. The external diameters of the arteries forming the circulus arteriosus cerebri were also measured. No aneurysms were found in the cadaver sample, thus the correlation could not be tested. In the sample of images from the 113 patients, 111 images showed one or more anatomical variation of the circulus arteriosus cerebri. Of these, 59 had one or more cerebral aneurysm and 52 had no aneurysms. Statistical analysis showed no significant correlation between cerebral aneurysms and anatomical variations in the circulus arteriosus cerebri for a South Africans ample. This is contradictory to what is seen in the literature. Further investigation is required to establish the reason why the results from this South African sample differ from the results reported in the international literature.
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    Identification of the deceased: A retrospective review of forensic anthropology Cape Town casework
    (2020) Baliso, Athi; Gibbon, Victoria Elaine; Heathfield, Laura Jane
    A serious issue faced in South Africa is the identification of unknown persons, particularly those who are decomposed, skeletonised or burnt. In this regard, Forensic Anthropology Cape Town (FACT), a service provider at the University of Cape Town (UCT), has assisted with identification. Data pertaining to anthropologically analysed cases in the Western Cape (WC) province is lacking and little is known about the contribution FACT has made to local forensic investigations. Thus, this study sought to identify the profile of FACT cases and evaluate their impact on police case resolution and identification. Cases referred to FACT between 2006 – 2018 from Forensic Pathology Services (FPS) were retrospectively reviewed (n = 208). Univariate, bivariate and multivariate statistical analyses were performed to find patterns in the data. Of these, 172 were of forensic relevance. There was a predominance of men (67%), and adults older than 35 years (54%). Regarding ancestry, 37% of decedents were of Mixed ancestry, 22% were of African ancestry and 3% were of European ancestry. Ante- and perimortem injuries were observed in 41% and 29% of decedents, respectively. Most decedents (51%) were discovered in high crime police precincts; however, a significant number were also found in low crime sparsely populated areas (47%), popular for recreational activities. These findings highlighted common areas for the discovery of decomposed bodies that may guide future forensic taphonomic research to better understand local decomposition rates. Positive identifications were reached for 37% of decedents, and of these, anthropological estimations were correct in 98% cases for sex, 84% for age-at-death, 80% for ancestry and 100% for stature. Communication issues between relevant stakeholders, the discretion of the authorities (when FACT would be consulted) and the availability of FACT members or resources (e.g., transport for the body to FACT laboratory) were among the main factors impacting FACT consultations and analysis; indicating that the legislation of forensic anthropology in South Africa is needed. Nevertheless, where identifications were subsequently made, the demographic estimations showed a high level of accuracy, suggesting that the anthropological techniques employed by FACT perform well in local forensic casework and FACT is assisting with social and criminal justice.