Browsing by Author "Simpson, Rachel"
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ItemAncestry variation in the accuracy of Rogers's method of sex estimation(2020) Simpson, Rachel; McKenzie, HughRogers’s (1999) method of human skeletal sex estimation evaluates morphological variation in four traits of the distal humerus. Although this method has the potential for widespread application in forensic and biological anthropological contexts, previous tests have been unable to replicate Rogers’s initial accuracy rate of 92%. Additionally, the role of ancestry in the accuracy of the method has not been sufficiently explored. This study expands on previous blind tests of Rogers’s (1999) original method, though it differs methodologically from prior studies (Ammer et al. 2019; Falys et al. 2005; Harrison 2017; Horbaly et al. 2019; Rogers 2009; Tallman & Blanton 2019; Vance et al. 2011; Wanek 2002; Watkinson 2012) by explicitly controlling for ancestry (85 American Black and 114 American White individuals, as defined in the Hamann-Todd Osteological Collection), by seriating humeri according to trait expression, and by using logistic regression in addition to chi-square and Fisher’s exact tests for analyzing the results. The findings determined that the method was 67% accurate overall and that correct classifications were 2.03 more likely for American Whites than American Blacks, posing an important consideration for practitioners of this method. ItemAncestry-specific variation in Rogers' method of sex estimation(2018) Simpson, Rachel; McKenzie, HughRogers’ (1999, 2009) visual method is a technique for estimating skeletal sex based on four traits of the distal humerus, and is valuable in cases of commingled or fragmented remains when use of more dominant cranial and pelvic methods is not possible. However, Rogers’ initial accuracy of 92% has not been replicated by subsequent tests of the method, and the role of biological ancestry in the accuracy of this method has not been sufficiently addressed. I conducted a blind test of the method on a sample of nineteenth-century American black and white individuals from the Hamann-Todd Collection. This test resulted in an overall accuracy of 67%, ranging from 54–73% between the two groups. These results demonstrate that accurate estimation of sex using the method is two times more likely for a white individual than for an black individual. More research is required to understand the cause of this variation. Prior to applying this method in bioarchaeological and forensic contexts, future should consider these results that the method is not consistently accurate across all human populations. ItemHistorical overview and new directions in bioarchaeological trace element analysis: a review(2021) Simpson, Rachel; Cooper, David M. L.; Swanston, Treena; Coulthard, Ian; Varney, Tamara L.Given their strong affinity for the skeleton, trace elements are often stored in bones and teeth long term. Diet, geography, health, disease, social status, activity, and occupation are some factors which may cause differential exposure to, and uptake of, trace elements, theoretically introducing variability in their concentrations and/or ratios in the skeleton. Trace element analysis of bioarchaeological remains has the potential, therefore, to provide rich insights into past human lifeways. This review provides a historical overview of bioarchaeological trace element analysis and comments on the current state of the discipline by highlighting approaches with growing momentum. Popularity for the discipline surged following preliminary studies in the 1960s to 1970s that demonstrated the utility of strontium (Sr) as a dietary indicator. During the 1980s, Sr/Ca ratio and multi-element studies were commonplace in bioarchaeology, linking trace elements with dietary phenomena. Interest in using trace elements for bioarchaeological inferences waned following a period of critiques in the late 1980s to 1990s that argued the discipline failed to account for diagenesis, simplified complex element uptake and regulation processes, and used several unsuitable elements for palaeodietary reconstruction (e.g. those under homeostatic regulation, those without a strong affinity for the skeleton). In the twenty-first century, trace element analyses have been primarily restricted to Sr and lead (Pb) isotope analysis and the study of toxic trace elements, though small pockets of bioarchaeology have continued to analyse multiple elements. Techniques such as micro-sampling, element mapping, and non-traditional stable isotope analysis have provided novel insights which hold the promise of helping to overcome limitations faced by the discipline. ItemInsights into biogenic and diagenetic lead exposure in experimentally altered modern and archaeological bone: synchrotron radiation x-ray fluorescence imaging(2021) Simpson, Rachel; Varney, Tamara L.; Coulthard, Ian; Swanston, Treena; Grimes, Vaughan; Munkittrick, T. Jessica A.; Jankauskas, Rimantas; Cooper, David M. L.Bones represent a valuable biological archive of environmental lead (Pb) exposure for modern and archaeological populations. Synchrotron radiation X-ray fluorescence imaging (SR-XFI) generates maps of Pb in bone on a microstructural scale, potentially providing insights into an individual's history of Pb exposure and, in the context of archaeological bone, the biogenic or diagenetic nature of its uptake. The aims of this study were to (1) examine biogenic spatial patterns for Pb from bone samples of modern cadavers compared with patterns observed archaeologically, and (2) test the hypothesis that there are spatial differences in the distribution of Pb for diagenetic and biogenic modes of uptake in bone. To address these aims, this study used inductively coupled plasma-mass spectrometry (ICP-MS) and SR-XFI on unaltered and experimentally altered cadaveric bone samples (University of Saskatchewan, Saskatoon, SK) and archaeological bone samples from 18th to 19th century archaeological sites from Antigua and Lithuania. Bone concentrations of modern individuals are relatively low compared to those of archaeological individuals. SR-XFI results provide insights into modern Saskatchewan Pb exposure with some samples demonstrating a pattern of relatively low Pb exposure with higher levels of Pb exposure occurring in bone structures of a relatively older age that formed earlier in life, likely during the era of leaded gasoline (pre1980s), and other samples demonstrating a pattern of fairly consistent, low-level exposure. Results support hypotheses for the spatial distribution of Pb corresponding to biogenic vs. diagenetic uptake. Diagenetic Pb is mainly confined to the periosteal surface of each sample with some enrichment of cracks and sub-periosteal canals. This may be useful in the future for differentiating diagenetic from biogenic Pb accumulation, analyzing environmental contamination, and informing sampling strategies in archaeological or fossil bone. ItemInvestigating past lead exposure in bioarchaeological remains with synchrotron X-ray fluorescence and absorption spectroscopy(2019) Simpson, Rachel; Varney, Tamara L.; Swanston, Treena; Coulthard, Ian; Cooper, David M. L.Bioarchaeology, the sub-discipline of archaeology concentrating on human remains, involves the study of skeletal tissues to make inferences about lifeways in the past. Trace metals such as lead (Pb), strontium (Sr), mercury (Hg), and barium (Ba) have a strong affinity for bones and teeth and consequently accumulate in these tissues during different timeframes of an individual's life. Bones, which constantly undergo the process of remodeling, reflect an individual's relatively recent exposure (years to decades) to trace elements , whereas dental tissues, which do not remodel, reflect trace element exposure during their formation during childhood. Trace element analysis of archaeological bones and teeth has the potential to provide the bioarchaeologist with insights into past human diet, health, environment, mobility, occupation, social activities, and burial conditions . Lead is historically significant, given the breadth of its use throughout the human past, as well as its toxic health impacts on populations. First exploited by humans as early as the sixth millennium BCE , lead has been widely used by humans in paint, ammunition, cosmetics, plumbing, and as a food additive  with prominent peaks in lead use occurring in antiquity, the Middle Ages, and following the European Industrial Revolution [4, 5]. As such, lead has been the focus of several previous bioarchaeological studies [6–9]. Methods conventionally used to assess lead in skeletal remains are limited in their ability to discern the nature and timing of lead uptake into bone. This article will review the strides that synchrotron X-ray microbeam techniques have made regarding the analysis of lead in bioarchaeological remains by summarizing key studies and methodological advancements, such as the addition of confocal optics. ItemPopulation-specific variation in the accuracy of Rogers’ method of sex estimation(2018) Simpson, Rachel; McKenzie, HughRogers’ (1) method of sex estimation is a visual technique that evaluates morphological variation in four traits of the distal posterior humerus. This method has the potential for widespread application in biological anthropology, but previous tests have been unable to replicate Rogers’ initial accuracy rate of 92%. Additionally, the role of populations in the accuracy of the method has not been sufficiently explored, as only one study (2) has controlled for it. Wanek (2) found differences in the accuracy of Rogers’ method correlated with different populations but concluded the method could be used on all human populations, regardless. This study tests Wanek’s (2) conclusion through a blind test of Rogers’ (1) original method, though it differs methodologically from previous studies (1–7) by seriating humeri according to trait expression, and by using logistic regression for analysis of results. In conducting a blind test on a sample of American black and white individuals from The Hamann-Todd Osteological Collection, I found that the method was 67% accurate overall, and that odds for a correct classification were 2.03 more likely for a white individual than for a black individual. Prior to applying this method in the future, bioarchaeologists and forensic anthropologists should consider these results within the context of their study.