The study of human cranial morphology has a long and contentious history. This study is the first large scale analysis of ecoregion specific human cranial modularity and integration. It utilizes an analysis of morphometric craniofacial variation and ecoregion affinity to better understand the environmental contribution to biological shape. This study tested three hypotheses. First, that there was variation in craniofacial shape that was linked to an individual’s ecoregion. Second, that there were ecoregion specific patterns of cranial modularity. And third, that the patterns of cranial integration (or the level of covariation between any two modules) were also associated with an individual’s ecoregion, and that different environments would result in different patterns of modular dependence and independence. Three-dimensional scans of 298 human crania were collected from museums, representing four higher level ecoregions and 11 lower-level ecoregions. Each cranium was mapped and placed within two hierarchical ecoregions. By examining ecoregions, instead of individual climatic variables, this analysis gives a more complete picture of how the environment is influencing cranial variation. Modules, or relatively independent morphological regions of the crania, were identified and their level of integration was assessed for every ecoregion. Modular integration is an analysis of the relative strength of the covariation between any two modules, and previous research theorized that changes in integration reflected changes in modular independence during development (Bastir and Rosas, 2005; Hall, 2005; Raff, 1996). The variation in strength between modules, both intrapopulation and interpopulation, were assessed and various explanations were explored. This analysis found that each ecoregion exhibited significantly different craniofacial shape from one another. Patterns of integration were also variable by ecoregion, suggesting that the ecological shape variation observed was solidified early in development. This study also identified the presence of a nasal module in each ecoregion. Overall, the findings of this study demonstrate that human crania are variable by ecoregion and that environmental conditions have led to ecoregion specific patterns of cranial modular integration. / Anthropology

In forensic anthropology, methods for estimating sex from the skeleton have historically been developed on skeletal collections comprised exclusively U.S. Black and white populations and thus inherently rely on ancestry estimation as a foundational component for the construction of the biological profile. However, these population-specific methods of sex estimation fundamentally limit the applicability, accuracy, and reliability of the method for use on remains of diverse population affiliations (ancestry). A reliable and population-inclusive method for estimating sex in the skeleton can serve as a useful tool for forensic investigators, especially in cases with unidentified remains where the population affiliation is indeterminate and in light of recent discourse involving the removal of ancestry estimation from the biological profile as a whole This study assessed the reliability of population-inclusive nonmetric and metric sex estimation from 3D-volume rendered computer tomography (CT) scans of the skull. The study sample was comprised of 431 individuals (242 males and 189 female) from the New Mexico Decedent Imaging Database (NMDID) and included a relatively equal distribution of African American, Asian American, European American, Latin American, and Native American population affinities. The images were obtained from the CT slices using 3D-reconstructions and volume rendering technique (VRT) in the Digital Imaging and Communications in Medicine (DICOM) viewer, exported to Meshmixer™ and then processed to isolate the skull from the postcranial skeleton and remove identifying objects. In Meshmixer™, nonmetric traits were scored following Buikstra and Ubelaker (1994) and Walker (2008) and included the supraorbital ridge/glabella, supraorbital margin, mastoid process, mental eminence and nuchal crest. The metric traits, following Spradley and Jantz (2011), included 18 points of measurement of the cranium and mandible. Binary logistic regression (BLR) and discriminant function analyses (DFA) were used to produce models and probabilities from the nonmetric a metric data respectively and an additional binary logistic regression was developed that combined both the nonmetric and metric data. Overall, the population-inclusive nonmetric and metric model produced classification accuracies that ranged from 81-87% and 86.7-87% respectively, and performed as well as population-specific models in estimating sex and were not significantly different from population-specific accuracies. When some of the population-specific models were applied across population, particularly the European American model, the classification accuracy was significantly reduced relative to the population-inclusive model. Intraobserver error was assessed for the nonmetric and metric data collection and confirmed that the nonmetric and metric methods of data collection for the volume-rendered images was consistent. The results of this study indicate that a population-inclusive nonmetric and metric models of sex estimation using the skull can be used in place of more traditional population-specific models in cases where ancestry is unknown, indeterminate, or in the event ancestry is removed from the biological profile.

This thesis explores the life history of six isolated skulls interred in Mound 3 of the Elizabeth site, a Middle Woodland site in the lower Illinois valley. This study employs analyses of osteological features, stable and radiogenic isotopes, and biodistance for a cross-section of the Mound 3 population (n=15), including the isolated crania. Isotopic results reveal significant variation in lead isotope ratios in enamel, and interpretively meaningful variation in strontium values. However, bone carbonate oxygen values are not significantly different. Carbon isotope values from bone carbonate revealed only sex-based dietary differences. Biodistance data indicate relatively genetic homogeneity at the site, although significant variation was present in two of the isolated crania. Ultimately, data indicate that two of the six isolated skulls likely originated from elsewhere in the valley, but that the population likely resided in the Elizabeth site vicinity in the decade preceding death, and were not outsiders.

No description available.

No description available.