Browsing by Author "Gibbon, Victoria"

Now showing 1 - 7 of 7
  • No Thumbnail Available
    Item
    Open Access
    A mixed methods scoping review of gender and life stage as risk factors of injury-related mortality in the Western Cape, South Africa
    (2024) Voegt, Chelsey; Gibbon, Victoria; Dinkele Elizabeth
    Injury-related mortality is a growing public safety concern in South Africa, especially in the Western Cape Province. Several studies have identified gender and age as risk factors of injury related mortality, although there remains a scarcity of interstudy comparisons of these factors, and the underlying perceptions of causes linked to these. In this study, a scoping review of injury-related mortality from medicolegal death investigations in the Western Cape was conducted by screening online databases for research articles published between 2007 and 2021. Of the 11 articles, six were included in a quantitative analysis to quantify risk by gender and life stage. To assess conceptualisations of these risk factors in research, each article was evaluated using a thematic content analysis. Men were associated with a higher mortality risk for homicide (inclusive of sharp force and firearm causes), suicide, road traffic (and transport-related) deaths, and drowning. The likelihood of homicidal deaths in males (OR = 3.95; 95% CI [3.48 – 4.49]; p ≤ 0.001) was higher than all other causes of injury-related mortality (OR = 0.25; 95% CI [0.22 – 0.29]; p ≤ 0.001). For all causes of injury-related mortality, early adults (20 – 34 years) and middle-aged adults (35 – 49 years) accounted for the most deaths. Homicide was the most significant cause of mortality in early adults, adolescents and middle-aged adults, while road traffic deaths were the leading cause of mortality for infants and children and adults above 49 years of age. Qualitative results from the thematic content analysis suggest that the discourse of violence and injury in the literature differed by gender. Women were more commonly discussed with reference to vulnerability and victimhood. Contrastingly, men were portrayed with reference to culpability – regardless of whether they were victims or perpetrators of violence. Masculinity as a cause of violence, in the literature, was discussed relative to socio-economic conditions and cultural norms leading to risk-taking behaviours. Limited agency and lifestyle behaviours were described as primary causes of violence linked to life stage. Risk of injury in minors was attributed primarily to structural causes of violence, and cognitive reasoning and development linked to life stage. Overall, these results highlight gender-linked biases in forensic death reporting. Injury related deaths and homicides affected more males, yet males were primarily represented as perpetrators of violence. Given the drive to eradicate gender based-violence, this study emphasises the need to address structural causes of violence targeted at expressions of masculinity, social cohesion and identity in different life stages, and genders and the need for an intersectional approach to understanding medicolegal death investigations and injury-related mortality in the Western Cape and South Africa.
  • No Thumbnail Available
    Item
    Open Access
    Adult age-at-death estimation using the pulp/tooth area ratio (PAR) method: a South African validation study using periapical radiography and stereomicroscopy
    (2024) Kotze, Daniël; Gibbon, Victoria; Mole, Calvin
    Conventional skeletal age-at-death estimation methods employed for South African adults are deficient, facing several limitations. Dental ageing techniques remain under-researched for the population. In this study, I aimed to evaluate the applicability of the pulp/tooth area ratio (PAR) ageing method when applied to maxillary canines from a South African cadaveric sample. I explored the utility of under-researched methodological approaches for the method: mesiodistal radiographs, stereomicroscopic tooth section images and PARs excluding the enamel area. To maximise sample size, only maxillary canines were considered, which demonstrate several research advantages (e.g. relatively long functional survival and high accuracy rates). Following extraction, 52 adult teeth were radiographed, sectioned and analysed using stereomicroscopy. Labiolingual and mesiodistal radiographs and labiolingual stereomicroscopic tooth section images were captured and analysed using ImageJ to obtain PARs. Age estimation linear regression models were developed for ratios obtained from each image type, including and excluding the enamel area. Models were compared for performance and accuracy using best subsets regression and cross-validation analyses. The accuracy of international standards was also assessed using the study sample. The PAR method showed promising results. It demonstrated excellent observer reproducibility and sex-independence. Sample-specific models derived from tooth section images had the best performance and accuracy, obtaining cross-validation mean absolute errors (MAEs) and standard error of the estimates (SEEs) of approximately 7 - 8 years and 10 - 11 years, respectively. Labiolingual radiographic models (MAEs = 10 years; SEEs = 12 years) showed better performance and accuracy than mesiodistal radiographic models (MAEs = 12 years; SEEs = 16 2 years). Models excluding the enamel area performed better, producing slightly better cross validation error values. Standard PAR models performed relatively poorly and were inappropriate for the study sample. This research suggests that the PAR method is a suitable technique to complement and inform standard adult skeletal age analyses in South Africa. The labiolingual radiographic approach is most practical as it is relatively accurate, minimally invasive and efficient. This study contributes knowledge to the limited pool of data on dental ageing techniques for South African adults. It informs practitioners of ideal/optimal methodological approaches for the PAR method using maxillary canines.
  • Thumbnail Image
    Item
    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.
  • No Thumbnail Available
    Item
    Open Access
    Dental pathology and macrowear: a biocultural analysis of southern African holocene hunter-gatherers and hunter-herders
    (2023) Olszewski, Judyta; Gibbon, Victoria
    Dental macrowear quantity, direction, and oral pathology were assessed against demographic factors in southern African Holocene hunter-gatherers and -herders (sAHGH). This is the first study to investigate inter-related implications of diet, health, and behaviour across time and space using only teeth on a large sAHGH sample. This aim was accomplished through a systematic assessment of macroscopic dental examinations, particularly including direction, a method not yet addressed for sAHGH teeth. Data were obtained using a multimethod approach on 369 individuals and 6271 teeth and statistically analysed using R (version 4.1.3) and IBM© SPSS. The results showed a need for an adaptation of the Brabant index; therefore, I created a novel adaption to the method inclusive of a visual guide. Individuals were better preserved from coastal regions (n = 313) and young/middle-ages (n = 71), and sex and temporal divisions were similarly distributed, with fewer individuals dating to the earlier Holocene (n = 50). Wear quantity advanced rapidly, with increased odds in anterior teeth (OR=18, p≤0.01) and first molars (OR=4.6, p≤0.01). Horizontal and plane wear directions frequently occurred (n = 8321 teeth), and combined wear results reflected a plant-based diet and using teeth as tools. Tool use was further demonstrated by non-masticatory wear (n = 22) and microchipping (n = 55), elucidating behaviours such as occupational tasks and dental hygiene. Generally, the teeth demonstrated good health; however, the first molar was affected most frequently with antemortem tooth loss (OR=13.6, p≤0.01), infections (OR=4.4, p≤0.01), and caries (OR=28.7, p≤0.01). Overall, pathological lesions post-2000 BP reduced, suggesting health improvements. Notably, incidence rates for enamel hypoplasia on the first molars (n = 26) alluded to increased infant stress possibly related to herding. Interestingly, amelogenesis imperfecta was found, demonstrating a hereditary condition associated with comorbidities. Despite increasing oral pathology and wear into old age, good survival rates suggest biological resilience. The results of this study support resource-sharing practices regardless of developmental stage between sexes, as sAHGH retained homogeneous diets and labour-based contributions from childhood. This research contributes to holistic inferences on health and behaviour through the direct analyses of sAHGH, integrating biology with the environment, and elaborates on the discussion of the role of dental wear and behaviours contributing to pathology susceptibility. A macroscopic, multimethod approach proved effective in analysing the interplay of masticatory mechanisms and systematic assessments using non-destructive methods. These results demonstrated how hunter-gatherer groups thrived over millennia, and that sAHGH are a good adaptive representation of dental analyses for precontact populations
  • No Thumbnail Available
    Item
    Open Access
    Sex estimation of unidentified human remains: Concordance between morphological anthropological assessment and DNA analysis
    (2025) Leggett, Celeste Esther; Heathfield, Laura; Gibbon, Victoria
    Identifying skeletonised human remains is a challenge worldwide, and sex determination is an important part of the process. Recently in Cape Town, there have been two medico-legal death investigations involving unidentified skeletonised remains who were estimated to be female anthropologically but were biologically sexed male based on DNA analyses. This study aimed to assess the agreement of sexing methods in a Western Cape South African forensic sample of skeletonised individuals (n=126), who were morphologically estimated to have biological sex as female (n=41). Of the 41 anthropologically estimated to be female cases, 19 were excluded for being probable or likely 'archaeological'. DNA was extracted from hard tissue samples from the remaining 22 individuals and biological sex was assessed by quantitative real-time PCR. DNA from thirteen cases (13/22; 59%) were amplified, with six showing evidence of Y-chromosomal DNA and inferred male sex. However, since the DNA concentrations were below the validated dynamic range, these results were suggestive only. DNA profiling confirmed that one case was male but did not provide further clarity on the biological sex of the remainder of cases due to low copy number (LCN) DNA. This study presents another confirmed case report of sex discordance between anthropological and DNA analysis for a sample of decedents from the Western Cape, South Africa. While qPCR suggested 54% (7/13) agreement and 46% (6/13) disagreement, confirmation in most cases was hindered by LCN DNA. The Western Cape population, influenced by San and Khoe ancestry, tends to have smaller body size and gracility, which may impact the accuracy of morphology-based assessments of male robusticity as they may appear more female or ambiguous. These results highlight the need to update anthropological data for the diverse South African population and implement improved molecular techniques for reliable DNA profiling. This study underscores the limitations of both anthropological and molecular sex methods and stresses the importance of interdisciplinary collaboration for accurate forensic identification.
  • Thumbnail Image
    Item
    Open Access
    The effect of clothing and carrion biomass load on decomposition and scavenging in a forensically significant thicketed habitat in Cape Town, South Africa
    (2022) Jan Spies, Maximilian; Gibbon, Victoria; Finaughty, Devin; Friedling, Jacqui
    Estimating the post-mortem interval is important to help identify the deceased in forensic death investigations and requires biogeographically specific knowledge of the rate of decay. Decomposition is influenced by numerous variables, including clothing, climate, and vertebrate scavenging guilds, requiring local studies. Conflicting results have been reported for clothing's effect on decomposition from various international habitats, with no data for Cape Town, South Africa, despite most local forensic cases involving single clothed decedents. Most taphonomic research uses large samples of unclothed human/animal remains to increase statistical reliability, despite this design not simulating common forensic scenarios. This study examined the effect of seasonally appropriate clothing and carrion biomass load on decomposition and scavenging in the thicketed Cape Flats Dune Strandveld, a forensically significant local habitat. Clothing was identified from forensic case files and tailored to ensure an appropriate fit, preventing unrealistic scavenger access. The decay of ten ~60 kg porcine carcasses, as proxies for human decomposition, was quantitatively examined using daily weight loss. This occurred over two consecutive summers and winters between 2018 and 2020, initially comparing clothed versus unclothed carcasses, then examining single clothed carcasses to ascertain the effect of carrion biomass load. On average, double-layer coolweather clothing notably delayed decomposition in winter, but single-layer warm-weather clothing had a comparatively negligible impact in summer. Weight loss correlated with scavenging activity by the Cape grey mongoose (Galerella pulverulenta), which displaced clothing to feed on the abdomen, more so during winter. Scavenging was hindered by the denim trousers, altering feeding patterns and causing preferential scavenging on unclothed carcasses. Single carcasses received more, longer mongoose visits and decomposed quicker than multi-carcass deployments. These results suggest that clothing delays decomposition locally by modulating the effect of seasonal weather and scavenging behaviour. Additionally, research forgoing forensic realism, with large unclothed samples deployed simultaneously, will inadvertently alter the decay rate, creating inaccurate decomposition models for postmortem interval estimation. Future studies should balance statistical robusticity and forensic realism, especially in environments where scavenging is prevalent. Single carcasses clothed in forensically realistic season-specific appropriately tailored clothing should be considered with statistical replication obtained via temporally separated repeat deployments.
  • No Thumbnail Available
    Item
    Open Access
    The effect of clothing on decomposition and scavenging in two forensically significant habitats in Cape Town, South Africa
    (2024) Adams, Kara Sierra; Gibbon, Victoria
    In South Africa, identifying unknown human remains presents an ongoing challenge given the high murder rate in the country. A crucial aspect of the forensic death investigation involves estimating the postmortem interval, which is influenced by biogeographic factors specific to the region. To ensure the collection of forensically relevant data, the experimental design incorporated single, clothed individuals, as they constitute the majority of unidentified human remains in the Western Cape province. The effect of clothing on scavenging and decomposition were examined in two forensically significant habitats in Cape Town, South Africa. To explore the impact of clothing on scavenging and decomposition, research was conducted in two open habitats, one periurban habitat and one suburban habitat. Six clothed and uncaged porcine carcasses weighing 60kg each were deployed between July 2021 and January 2023 (FHS SEC REF 018_023 & 022_001). Data were collected on carcass mass loss over time, vertebrate scavenger activity, prevailing weather, and carcass tissue desiccation. A comparative sample of 16 unclothed carcasses deployed between 2014 and 2016 was analysed to assess the impact of clothing and biomass load on the decomposition rate. Overall, winter-season clothing delayed decomposition, but summer-season clothing accelerated the process. Carcass weight loss was directly affected by the scavenging of the Cape grey mongoose (Galerella pulverulenta), which accelerated the decomposition rate. Additionally, single carcasses within the same habitat decomposed quicker than the multi-carcass deployments. Natural precocious mummification is a unique phenomenon documented in the Western Cape province, and a novel component of this research was that it formed the first quantitative assessment of desiccation leading to precocious mummification. Printed computing boards inserted into the carcass tissue recorded full-thickness tissue moisture content from three sites on each carcass in 15-minute intervals. The data were analysed through generalised additive modelling with environmental temperature, humidity, solar radiation, and precipitation as covariates. Desiccation in summer appeared to follow an exponential decline, and temperature was the most influential environmental factor. These novel data demonstrate the potential of utilising accumulated degree days and moisture content to estimate the postmortem interval. The combined results advocate using single-clothed carcasses deployed across multiple seasonal trials in forensically significant locations to produce data that can be considered forensically realistic.