Matching Items (32)

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Positional behaviors and the neck: a comparative analysis of the cervical vertebrae of living primates and fossil hominoids

Description

Despite the critical role that the vertebral column plays in postural and locomotor behaviors, the functional morphology of the cervical region (i.e., the bony neck) remains poorly understood, particularly in

Despite the critical role that the vertebral column plays in postural and locomotor behaviors, the functional morphology of the cervical region (i.e., the bony neck) remains poorly understood, particularly in comparison to that of the thoracic and lumbar sections. This dissertation tests the hypothesis that morphological variation in cervical vertebrae reflects differences in positional behavior (i.e., suspensory vs. nonsuspensory and orthograde vs. pronograde locomotion and postures). Specifically, this project addresses two broad research questions: (1) how does the morphology of cervical vertebrae vary with positional behavior and cranial morphology among primates and (2) where does fossil hominoid morphology fall within the context of the extant primates. Three biomechanical models were developed for the primate cervical spine and their predictions were tested by conducting a comparative analysis using a taxonomically and behaviorally diverse sample of primates. The results of these analyses were used to evaluate fossil hominoid morphology. The two biomechanical models relating vertebral shape to positional behaviors are not supported. However, a number of features distinguish behavioral groups. For example, the angle of the transverse process in relation to the cranial surface of the vertebral body--a trait hypothesized to reflect the deep spinal muscles' ability to extend and stabilize the neck--tends to be greater in pronograde species; this difference is in the opposite of the direction predicted by the biomechanical models. Other traits distinguish behavioral groups (e.g., spinous process length and cross-sectional area), but only in certain parts of the cervical column. The correlation of several vertebral features, especially transverse process length and pedicle cross-sectional area, with anterior cranial length supports the predictions made by the third model that links cervical morphology with head stabilization (i.e., head balancing). Fossil hominoid cervical remains indicate that the morphological pattern that characterizes modern humans was not present in Homo erectus or earlier hominins. These hominins are generally similar to apes in having larger neural arch cross-sectional areas and longer spinous processes than modern humans, likely indicating the presence of comparatively large nuchal muscles. The functional significance of this morphology remains unclear.

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Date Created
  • 2013

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Where did you come from? Where will you go?: human evolutionary biology education and American students' academic interests and achievements, professional goals, and socioscientific decision-making

Description

In the United States, there is a national agenda to increase the number of qualified science, technology, engineering, and maths (STEM) professionals and a movement to promote science literacy among

In the United States, there is a national agenda to increase the number of qualified science, technology, engineering, and maths (STEM) professionals and a movement to promote science literacy among the general public. This project explores the association between formal human evolutionary biology education (HEB) and high school science class enrollment, academic achievement, interest in a STEM degree program, motivation to pursue a STEM career, and socioscientific decision–making for a sample of students enrolled full–time at Arizona State University. Given a lack of a priori knowledge of these relationships, the Grounded Theory Method was used and was the foundation for a mixed–methods analysis involving qualitative and quantitative data from one–on–one interviews, focus groups, questionnaires, and an online survey. Theory development and hypothesis generation were based on data from 44 students. The survey instrument, developed to test the hypotheses, was completed by 486 undergraduates, age 18–22, who graduated from U.S. public high schools. The results showed that higher exposure to HEB was correlated with greater high school science class enrollment, particularly for advanced biological science classes, and that, for some students, HEB exposure may have influenced their enrollment, because the students found the content interesting and relevant. The results also suggested that students with higher K–12 HEB exposure felt more prepared for undergraduate science coursework. There was a positive correlation between HEB exposure and interest in a STEM degree and an indirect relationship between higher HEB exposure and motivation to pursue a STEM career. Regarding a number of socioscientific issues, including but not limited to climate change, homosexuality, and stem cell research, students' behaviors and decision–making more closely reflected a scientific viewpoint—or less–closely aligned to a religion–based perspective—when students had greater HEB exposure, but this was sometimes contingent on students' lifetime exposure to religious doctrine and acceptance of general evolution or human evolution. This study has implications for K–12 and higher education and justifies a paradigm shift in evolution education research, such that more emphasis is placed on students' interests, perceived preparation for continued learning, professional goals and potential contributions to society rather than just their knowledge and acceptance.

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Date Created
  • 2014

The population history of the Caribbean: perspectives from ancient and modern DNA analysis

Description

Although the Caribbean has been continuously inhabited for the last 7,000 years, European contact in the last 500 years dramatically reshaped the cultural and genetic makeup of island populations. Several

Although the Caribbean has been continuously inhabited for the last 7,000 years, European contact in the last 500 years dramatically reshaped the cultural and genetic makeup of island populations. Several recent studies have explored the genetic diversity of Caribbean Latinos and have characterized Native American variation present within their genomes. However, the difficulty of obtaining ancient DNA from pre-contact populations and the underrepresentation of non-Latino Caribbean islanders in current research have prevented a complete understanding of genetic variation over time and space in the Caribbean basin. This dissertation uses two approaches to characterize the role of migration and admixture in the demographic history of Caribbean islanders. First, autosomal variants were genotyped in a sample of 55 Afro-Caribbeans from five islands in the Lesser Antilles: Grenada, St. Kitts, St. Lucia, Trinidad, and St. Vincent. These data were used to characterize genetic structure, ancestry and signatures of selection in these populations. The results demonstrate a complex pattern of admixture since European contact, including a strong signature of sex-biased mating and inputs from at least five continental populations to the autosomal ancestry of Afro-Caribbean peoples. Second, ancient mitochondrial and nuclear DNA were obtained from 60 skeletal remains, dated between A.D. 500–1300, from three archaeological sites in Puerto Rico: Paso del Indio, Punta Candelero and Tibes. The ancient data were used to reassesses existing models for the peopling of Puerto Rico and the Caribbean and to examine the extent of genetic continuity between ancient and modern populations. Project findings support a largely South American origin for Ceramic Age Caribbean populations and identify some genetic continuity between pre and post contact islanders. The above study was aided by development and testing of extraction methods optimized for recovery of ancient DNA from tropical contexts. Overall, project findings characterize how ancient indigenous groups, European colonial regimes, the African Slave Trade and modern labor movements have shaped the genomic diversity of Caribbean islanders. In addition to its anthropological and historical importance, such knowledge is also essential for informing the identification of medically relevant genetic variation in these populations.

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Date Created
  • 2017

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Ritual Violence and the Perception of Social Difference: Migration and Human Sacrifice in the Epiclassic Basin of Mexico

Description

Archaeologists have long contended that large-scale human migrations played an essential role in the cultural development of pre-Hispanic central Mexico. During the Epiclassic period (600-900 CE), migration is implicated in

Archaeologists have long contended that large-scale human migrations played an essential role in the cultural development of pre-Hispanic central Mexico. During the Epiclassic period (600-900 CE), migration is implicated in the appearance of new forms of material culture, sociopolitical disruptions, and the emergence of new regional polities. Sweeping social changes accompanied these developments, including demographic reorganization and increased levels of violence. Research across the social sciences finds that violence directed at individuals perceived as categorically distinct also typically increases during such periods of socio-political upheaval. This dissertation investigates identity-based violence in the Epiclassic Basin of Mexico to consider how diverse social identities contributed to the selection of victims of ritual violence.

This research examines the skeletal remains from a sacrificial deposit at the Epiclassic shrine site of Non-Grid 4 in the Basin of Mexico, where a minimum of 180 human crania were interred as ritual offerings. The project reconstructs patterns of paleomobility and biological relatedness to determine whether individuals with distinct categorical social identities were more likely to become victims of human sacrifice. It answers the questions: (1) Were the sacrificed individuals predominantly locals who lived in the Basin of Mexico throughout their lives?; (2) Were the sacrificed individuals comprised of a single kin-group biologically continuous with pre-extant populations in the Basin of Mexico?; and (3) If victims were migrants biologically discontinuous with antecedent populations, from where in ancient Mesoamerica did they originate?

Results indicate that a majority of sacrificial victims were immigrants originating north and south of the Basin of Mexico. Biogeochemical analyses of sacrificed individuals find that 80% are non-local migrants into the Basin, suggesting that they were likely targeted for violence based on their divergent residential histories. Multi-scalar biodistance analyses of Non-Grid 4 sacrificial victims demonstrate that they represent two biologically distinct groups. There was evidence, however, for both biological continuity among victims and pre-extant central Mexican populations, as well as for migration from northern and southern Mexico. This project therefore not only improves knowledge of migration during the central Mexican Epiclassic, but also contributes to broader anthropological understandings of the social context of violence.

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Date Created
  • 2020

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Andean Social Identities: Analyses of Community, Gender, and Age Identities at Chiribaya Alta, Peru

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Social identities are fundamental to the way individuals and groups define themselves. Archaeological approaches to social identities in the Andes emphasize the importance of group identities such as ethnicity and

Social identities are fundamental to the way individuals and groups define themselves. Archaeological approaches to social identities in the Andes emphasize the importance of group identities such as ethnicity and community identity, but studies of gender and age identities are still uncommon. In this dissertation, I build on these earlier approaches to Andean social identities and consider community, gender, and age identities at the site of Chiribaya Alta using case studies.

The coastal Ilo Chiribaya polity is associated with the Andean Late Intermediate Period in the lower Osmore drainage of southern Peru. Previous analyses indicate that Chiribaya sites in this area formed a señorío, an Andean chiefdom with separate occupational groups of fishers and farmers. The most complex excavated Chiribaya site in this region is Chiribaya Alta. At this time, excavations have sampled nine of the cemeteries present at the site. Two of these cemeteries, four and seven, have the most elaborate burials at the site and are each associated with different occupational communities.

This dissertation examines community, gender, and age identities at Chiribaya Alta through the use of three case studies. The first case study argues that the iconographic designs on coca bags interred with the dead signified occupational community identities. Coca bags buried in cemetery four have designs relating to mountains and farming, whereas those from cemetery seven have symbols associated with water. These designs correspond to the occupational community groups associated with each of these cemeteries. The second case study uses grave good presence and absence to examine the nature of gender roles and identity at Chiribaya Alta. Multiple correspondence analysis indicates that normative gender roles are reflected in grave good assemblages, but that gender identity was flexible at the individual level. The final case study presents newly generated age-at-death estimations using transition analysis combined with mortuary analyses to explore the manner in which gender and age intersect for older individuals at Chiribaya Alta. This final paper argues that there is an elderly identity present amongst individuals at Chiribaya Alta and that gender and age intersect to impact the lives of older men and women differently.

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Date Created
  • 2019

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Comparative and experimental investigations of cranial robusticity in mid-Pleistocene hominins

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Extremely thick cranial vaults have been noted as a diagnostic characteristic of Homo erectus since the first fossil of the species was identified, but potential mechanisms underlying this seemingly unique

Extremely thick cranial vaults have been noted as a diagnostic characteristic of Homo erectus since the first fossil of the species was identified, but potential mechanisms underlying this seemingly unique trait have not been rigorously investigated. Cranial vault thickness (CVT) is not a monolithic trait, and the responsiveness of its layers to environmental stimuli is unknown. Identifying factors that affect CVT would be exceedingly valuable in teasing apart potential contributors to thick vaults in the Pleistocene. Four hypotheses were tested using CT scans of skulls of more than 1100 human and non-human primates. Data on total frontal, parietal, and occipital bone thickness and bone composition were collected to test the hypotheses: H1. CVT is an allometric consequence of brain or body size. H2. Thick cranial vaults are a response to long, low cranial vault shape. H3. High masticatory stress causes localized thickening of cranial vaults. H4. Activity-mediated systemic hormone levels affect CVT. Traditional comparative methods were used to identify features that covary with CVT across primates to establish behavior patterns that might correlate with thick cranial vaults. Secondly, novel experimental manipulation of a model organism, Mus musculus, was used to evaluate the relative plasticity of CVT. Finally, measures of CVT in fossil hominins were described and discussed in light of the extant comparative and experimental results. This dissertation reveals previously unknown variation among extant primates and humans and illustrates that Homo erectus is not entirely unique among primates in its CVT. The research suggests that it is very difficult to make a mouse grow a thick head, although it can be genetically programmed to have one. The project also identifies a possible hominin synapomorphy: high diploë ratios compared to non-human primates. It also found that extant humans differ from non-human primates in overall pattern of which cranial vault bones are thickest. What this project was unable to do was definitively provide an explanation for why and how Homo erectus grew thick skulls. Caution is required when using CVT as a diagnostic trait for Homo erectus, as the results presented here underscore the complexity inherent in its evolution and development.

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Date Created
  • 2012

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Foodborne illness: Yersinia enterocolitica : its relationship to arthritis in populations associated with the domesticated pig

Description

Yersinia enterocolitica is a major foodborne pathogen found worldwide that causes approximately 87,000 human cases and approximately 1,100 hospitalizations per year in the United States. Y. enterocolitica is a very

Yersinia enterocolitica is a major foodborne pathogen found worldwide that causes approximately 87,000 human cases and approximately 1,100 hospitalizations per year in the United States. Y. enterocolitica is a very unique pathogen with the domesticated pig acting as the main animal reservoir for pathogenic bio/serotypes, and as the primary source of human infection. Similar to other gastrointestinal infections, Yersinia enterocolitica is known to trigger autoimmune responses in humans. The most frequent complication associated with Y. enterocolitica is reactive arthritis - an aseptic, asymmetrical inflammation in the peripheral and axial joints, most frequently occurring as an autoimmune response in patients with the HLA-B27 histocompatability antigen. As a foodborne illness it may prove to be a reasonable explanation for some of the cases of arthritis observed in past populations that are considered to be of unknown etiology. The goal of this dissertation project was to study the relationship between the foodborne illness -Y. enterocolitica, and the incidence of arthritis in individuals with and without contact with the domesticated pig.

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Date Created
  • 2015

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Conquest and conversion in Islamic Period Iberia (A.D. 711-1490): a bioarchaeological approach

Description

This dissertation research employs biological distance and mortuary analyses in tandem with historical sources to investigate the degree to which conversion, as opposed to migration, contributed to the spread of

This dissertation research employs biological distance and mortuary analyses in tandem with historical sources to investigate the degree to which conversion, as opposed to migration, contributed to the spread of Islam in southern Iberia. The dynamics of the 8th century conquest of Iberia by Muslim Arab and Berber forces from North Africa, and the subsequent 800-year period of religious, political, and social change, remain contested and poorly understood. Migration of Islamic peoples to the peninsula once was invoked as the primary vehicle of Islamic influence, but religious conversion, whether true or nominal, increasingly is regarded as a key component of those changes. This dissertation proposes that conversion, whether a prelude to or a component of Islamization, altered social group affiliations and interactions among those living in southern Iberia. Such changes in social relations and the resultant patterns of mate exchange will be recognizable by means of altered biological patterns of phenotypic variation. Through the examination of ~900 individuals from both Iberian and North African skeletal collections, this study concludes that conquest resulted in a great increase in phenotypic variability in the peninsula from the 8th-11th centuries. The data further indicate that males contributed this phenotypic variability to the samples in the Early Conquest period. Females, most frequently from Hispano-Roman Christian groups, appear to have ‘intermarried’ with these early conquerors and with the Muwallads, male Islamic converts, and are included in the early Muslim burial programs. From the 11th to the 14th centuries, the data presented here demonstrate a stasis and even a slight decrease in phenotypic variability in southern Iberia, which may be explained by endogamy among religious groups in this region.

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Date Created
  • 2017

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The role of kin relations and residential mobility during the transition from final Neolithic to Early Bronze Age in Attica, Greece

Description

This dissertation addresses the role of kinship and residential mobility during the transition from Final Neolithic to Early Bronze Age (ca. 3500 – 2500 BC) in Attica, Greece. It examines

This dissertation addresses the role of kinship and residential mobility during the transition from Final Neolithic to Early Bronze Age (ca. 3500 – 2500 BC) in Attica, Greece. It examines descent systems, ancestor formation, and the interplay between biological, social, and spatial structure in mortuary practices. It also evaluates the nature and degree of residential mobility and its potential role in the formation and maintenance of social networks. Archaeological hypotheses on the kin-based structure of formal cemeteries, the familial use of collective tombs, marriage practices and mate exchange, and relocation were tested focusing on the Early Helladic cemetery of Tsepi at Marathon. Tsepi constitutes the earliest formally organized cemetery on the Greek mainland and it has also contributed to enduring debates over the nature of the interaction between the eastern Attic coast and the central Aegean islands.

This study integrates osteological, biogeochemical, and archaeological data. Inherited dental and cranial features were used to examine biological relatedness and postmarital residence (biodistance analysis). Biochemical analysis of archaeological and modern samples was conducted to examine the geographic origins of the individuals buried in the cemetery and reconstruct mobility patterns. Osteological and biogeochemical data were interpreted in conjunction with archaeological and ethnographic/ethnohistoric data.

The results generally supported a relationship between spatial organization and biological relatedness based on phenotypic similarity at Tsepi. Postmarital residence analysis showed exogamous practices and tentatively supported higher male than female mobility. This practice, along with dietary inferences, could also be suggestive of maritime activities. Biogeochemical analysis showed a local character for the cemetery sample (96%). The common provenance of the three non-local individuals might reflect a link between Tsepi and a single locale. Burial location was not determined by provenance or solely by biological relatedness. Overall, the results point towards more nuanced reconstructions of mobility in prehistoric Aegean and suggest that burial location depended on a complex set of inter-individual relationships and collective identities. The contextualized bioarchaeological approach applied in this study added to the anthropological investigations of social practices such as kin relations (e.g., biological, marital, social kinship) and residential relocation as diachronic mechanisms of integration, adaptation, or differentiation.

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Date Created
  • 2015

Primate skeletal epigenetics: evolutionary implications of DNA methylation patterns in the skeletal tissues of human and nonhuman primates

Description

Within the primate lineage, skeletal traits that contribute to inter-specific anatomical variation and enable varied niche occupations and forms of locomotion are often described as the result of environmental adaptations.

Within the primate lineage, skeletal traits that contribute to inter-specific anatomical variation and enable varied niche occupations and forms of locomotion are often described as the result of environmental adaptations. However, skeletal phenotypes are more accurately defined as complex traits, and environmental, genetic, and epigenetic mechanisms, such as DNA methylation which regulates gene expression, all contribute to these phenotypes. Nevertheless, skeletal complexity in relation to epigenetic variation has not been assessed across the primate order. In order to gain a complete understanding of the evolution of skeletal phenotypes across primates, it is necessary to study skeletal epigenetics in primates. This study attempts to fill this gap by identifying intra- and inter-specific variation in primate skeletal tissue methylation in order to test whether specific features of skeletal form are related to specific variations in methylation. Specifically, methylation arrays and gene-specific methylation sequencing are used to identify DNA methylation patterns in femoral trabecular bone and cartilage of several nonhuman primate species. Samples include baboons (Papio spp.), macaques (Macaca mulatta), vervets (Chlorocebus aethiops), chimpanzees (Pan troglodytes), and marmosets (Callithrix jacchus), and the efficiencies of these methods are validated in each taxon. Within one nonhuman primate species (baboons), intra-specific variations in methylation patterns are identified across a range of comparative levels, including skeletal tissue differences (bone vs. cartilage), age cohort differences (adults vs. juveniles), and skeletal disease state differences (osteoarthritic vs. healthy), and some of the identified patterns are evolutionarily conserved with those known in humans. Additionally, in all nonhuman primate species, intra-specific methylation variation in association with nonpathological femur morphologies is assessed. Lastly, inter-specific changes in methylation are evaluated among all nonhuman primate taxa and used to provide a phylogenetic framework for methylation changes previously identified in the hominin lineage. Overall, findings from this work reveal how skeletal DNA methylation patterns vary within and among primate species and relate to skeletal phenotypes, and together they inform our understanding of epigenetic regulation and complex skeletal trait evolution in primates.

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Date Created
  • 2017