Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 6 uppsatser.

Magister Scientiae - MSc / The completion of the Human Genome Project, a remarkable feat by any measure, has provided over three billion bases of reference nucleotides for comparative studies. The next, and perhaps more challenging step is to analyse sequence variation and relate this information to important phenotypes. Most human sequence variations are characterized by structural complexity and, are hence, associated with abnormal functional dynamics. This thesis covers the assembly of a computational platform for verifying these variations, based on accurate, published, experimental data. / South Africa

Superior Ethmoidal Breadth (SEB = the maximum breadth between the left and right frontoethmoidal sutures) has been widely employed by anthropologists as a proxy for internal nasal airway dimensions since it is easily measured without imaging. SEB is also commonly argued to evince climatic adaption in modern humans, as populations living in cold-dry environments predictably exhibit narrower SEB dimensions than those inhabiting tropical environments. However, given uncertaintiy regarding its relationship with internal nasal anatomy, the accuracy of SEB as a proxy for airway dimensions remains questionable. Here, I evaluate the correlation between SEB and internal airway dimensions using linear measurements collected on CT scans from a mixed-sex sample of human crania (n=215) ancestrally derived from sub-Saharan Africa, the Arctic Circle, East Asia, and Europe. My results demonstrate that SEB is often located superior to the anatomcial roof of the nasal passages but is highly correlated (R= 0.8119, p<0.0001) with ethmoidal breadth taken at the functional level of the upper airways (i.e., functional airway breadth [FEB]). ANOVA results indicate, in addition to significant differences in SEB (χ2 = 82.20, p<0.0001), regional differences also exist for FEB (χ2 = 54.21, p<0.0001) and its components: the combined superior and superior common meatal breadths (χ2 = 19.03, p< 0.0001) and ethmoid air cell (EAC) breadth (χ2 = 27.67, p<0.0001). Further, following theoretrical expecations, the African-derived sample generally exhibits the widest internal nasal dimensions and the Arctic-derived sample the narrowest. Specifically, the Arctic sample exhibits significantly narrower airway breadths compared to all other groups. Conversely, the African sample possesses significantly wider EAC breadths comapred to all other groups. Cumulatively, these results empirically support use of SEB as proxy for upper nasal airway breadth and bolster claims that clinal variation in internal airway dimensions across human populations is likely attributable to climatic factors.

Studies in human cranial variation are extensive and widely discussed. While skeletal biologists continue to focus on questions of biological distance and population history, group-specific knowledge is being increasingly used for human identification in medico-legal contexts. The importance of this research has been often overshadowed by both philosophic and methodological concerns. Many analyses have been constrained in their scope by the limited availability of representative samples and readily criticized for adopting statistical techniques that require user-guidance and a priori information. A multi-part project is presented here that implements model-based clustering as an alternative approach for population studies using craniometric traits. This project also introduces the use of forced-directed graphing and mixture-based supervised classification methods as statistically robust and practically useful techniques. This project considers three well-documented craniometric sources, whose samples collectively permit large-scale analyses and tests of population structure at a variety of partitions and for different goals. The craniofacial measurements drawn from the world-wide data sets collected by Howells and Hanihara permit rigorous tests for group differences and cryptic population structure. The inclusion of modern American samples from the Forensic Anthropology Data Bank allows for investigations into the importance of biosocial race and biogeographic ancestry in forensic anthropology. Demographic information from the United States Census Bureau is used to contextualize these samples within the range of the racial diversity represented in the American population-at-large. This project's findings support the presence of population structure, the utility of finite mixture methods to questions of biological classification, and the validity of supervised discrimination methods as reliable tools. They also attest to the importance of context for producing the most useful information on identity and affinity. These results suggest that a meaningful relationship between statistically inferred clusters and predefined groups does exist and that population-informative differences in cranial morphology can be detected with measured degrees of statistical certainty, even when true memberships are unknown. They imply, in turn, that the estimation of biogeographic ancestry and the identification of biosocial race in forensic anthropology can provide useful information for modern American casework that can be evidenced by scientific methods.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

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