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Assessing the accuracy of the zygoma for estimating ancestry using geometric morphometrics in a South African sample
The large number of unidentified, decomposed and skeletonised remains found in South Africa (SA) necessitates relevant and reliable methods to assist in victim identification. Ancestry estimation from unknown skeletal remains is essential when reconstructing a demographic profile of a missing person...
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| Format: | Thesis |
| Language: | English |
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Department of Pathology
2020
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| _version_ | 1867613255014285312 |
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| access_status_str | Open Access |
| author | Tawha, Tafadzwa Primrose Rudo |
| author2 | Gibbon, Victoria E |
| author_browse | Gibbon, Victoria E Tawha, Tafadzwa Primrose Rudo |
| author_facet | Gibbon, Victoria E Tawha, Tafadzwa Primrose Rudo |
| author_sort | Tawha, Tafadzwa Primrose Rudo |
| collection | Thesis |
| description | The large number of unidentified, decomposed and skeletonised remains found in South Africa (SA) necessitates relevant and reliable methods to assist in victim identification. Ancestry estimation from unknown skeletal remains is essential when reconstructing a demographic profile of a missing person. In the SA population, estimating ancestry is problematic as standards developed internationally rarely apply to the local, biologically heterogenous population. Craniofacial morphology is known to be ancestrally distinct and studies are yet to explore shape and size variation in the zygomatic bone of the SA population. The aim of this study was to assess ancestral variation in zygomatic shape and size in a SA population using three-dimensional geometric morphometric analyses. A sample of 158 individuals were analysed from Bantu-speaking (BA), European (EA) and Mixed Ancestral (MA) South African groups. Males were larger in size than females, but no size differences were observed between ancestral groups. Significant shape differences were observed between ancestral groups, while none were observed between males and females. BA and MA individuals had narrower, shorter and more anteriorly projecting zygomas than EA individuals. The zygoma was shown to accurately distinguish EA (84%) from BA (81%), and MA (80%) from EA (68%) individuals, but unreliably distinguished BA (60%) from MA (66%) individuals. This is likely correlated to the historical peopling of SA and historical forced racial classification. Age-related changes and antemortem tooth loss did not confound the ancestral variation in size, despite minor changes in zygomatic shape being associated with these two factors. These confounders did not impact ancestry estimation accuracies, further suggesting a minor impact on overall zygomatic shape. Furthermore, the patterning of ancestral variation in the zygoma revealed the need for further research to distinguish between the biologically heterogenous ancestral groups in SA. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/31282 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:13.838Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2020 |
| publishDateRange | 2020 |
| publishDateSort | 2020 |
| publisher | Department of Pathology |
| publisherStr | Department of Pathology |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/31282 Assessing the accuracy of the zygoma for estimating ancestry using geometric morphometrics in a South African sample Tawha, Tafadzwa Primrose Rudo Gibbon, Victoria E Dinkele, Elizabeth Mole, Calvin Biomedical Forensic Science The large number of unidentified, decomposed and skeletonised remains found in South Africa (SA) necessitates relevant and reliable methods to assist in victim identification. Ancestry estimation from unknown skeletal remains is essential when reconstructing a demographic profile of a missing person. In the SA population, estimating ancestry is problematic as standards developed internationally rarely apply to the local, biologically heterogenous population. Craniofacial morphology is known to be ancestrally distinct and studies are yet to explore shape and size variation in the zygomatic bone of the SA population. The aim of this study was to assess ancestral variation in zygomatic shape and size in a SA population using three-dimensional geometric morphometric analyses. A sample of 158 individuals were analysed from Bantu-speaking (BA), European (EA) and Mixed Ancestral (MA) South African groups. Males were larger in size than females, but no size differences were observed between ancestral groups. Significant shape differences were observed between ancestral groups, while none were observed between males and females. BA and MA individuals had narrower, shorter and more anteriorly projecting zygomas than EA individuals. The zygoma was shown to accurately distinguish EA (84%) from BA (81%), and MA (80%) from EA (68%) individuals, but unreliably distinguished BA (60%) from MA (66%) individuals. This is likely correlated to the historical peopling of SA and historical forced racial classification. Age-related changes and antemortem tooth loss did not confound the ancestral variation in size, despite minor changes in zygomatic shape being associated with these two factors. These confounders did not impact ancestry estimation accuracies, further suggesting a minor impact on overall zygomatic shape. Furthermore, the patterning of ancestral variation in the zygoma revealed the need for further research to distinguish between the biologically heterogenous ancestral groups in SA. 2020-02-24T13:09:00Z 2020-02-24T13:09:00Z 2019 2020-02-24T10:47:37Z Master Thesis Masters MPhil http://hdl.handle.net/11427/31282 eng application/pdf Department of Pathology Faculty of Health Sciences |
| spellingShingle | Biomedical Forensic Science Tawha, Tafadzwa Primrose Rudo Assessing the accuracy of the zygoma for estimating ancestry using geometric morphometrics in a South African sample |
| thesis_degree_str | Master's |
| title | Assessing the accuracy of the zygoma for estimating ancestry using geometric morphometrics in a South African sample |
| title_full | Assessing the accuracy of the zygoma for estimating ancestry using geometric morphometrics in a South African sample |
| title_fullStr | Assessing the accuracy of the zygoma for estimating ancestry using geometric morphometrics in a South African sample |
| title_full_unstemmed | Assessing the accuracy of the zygoma for estimating ancestry using geometric morphometrics in a South African sample |
| title_short | Assessing the accuracy of the zygoma for estimating ancestry using geometric morphometrics in a South African sample |
| title_sort | assessing the accuracy of the zygoma for estimating ancestry using geometric morphometrics in a south african sample |
| topic | Biomedical Forensic Science |
| url | http://hdl.handle.net/11427/31282 |
| work_keys_str_mv | AT tawhatafadzwaprimroserudo assessingtheaccuracyofthezygomaforestimatingancestryusinggeometricmorphometricsinasouthafricansample |