According to the "Out-of-Africa 2" theory of human evolution all living humans today descend from a group of Anatomically Modern Homo sapiens or Anatomically Modem Humans that evolved in Africa 200,000 years ago and subsequently migrated out of Africa and spread into the rest of the World around 100,000 years. As a result an interest has developed in establishing a concrete theory of the factors that compelled and/or motivated our ancestors to venture out of their African origins at this time. Interestingly, the Earth's Last Glacial Cycle also dates from this period--stretching from 115,000 to 10,000 years ago. Current paleoclimate evidence suggests that the climatic repercussions of this glacial cycle in Africa resulted in a shift towards a drier and somewhat cooler climate state and the fragmentation of the formerly extensive forested African landscape. As a result, theories of early human migration have cited African climate change during the late Pleistocene as a determinant; however, the mechanisms responsible for the development of hyper-arid conditions in Africa at this time have remained unresolved. Although, past global climate change has been ascribed to changes in radiative forcing and changes in atmospheric carbon dioxide, recent paleoclimate studies have revealed that African climate is sensitive to changes in SSTs in the Atlantic, as it appears that subtropical Africa was more arid when North Atlantic sea surface temperatures (SSTs) were cold during glacial periods. The forcing mechanism believed to be responsible for the development of these cold SSTs are the so-called Heinrich Events that are documented as massive surges of icebergs (from high-latitude ice sheets) into the North Atlantic Ocean during high-latitude glaciations. These Heinrich events resulted in the release of large quantities of freshwater into the North Atlantic, which in turn led to a weakening on the global ocean thermohaline circulation and widespread cooling throughout the region. In particular, marine sediment records from the Nordic Sea document a widespread cooling and ice-rafting event that occurred around 105 kya, known as Heinrich event 9. In order to investigate the climate processes responsible for promoting cooler and drier conditions in Africa during the migration event of AMH (around 100 kya) I used the University of Victoria Earth System Climate Model (UVic ESCM) to conduct two climate model experiments that compared the global-scale response of climate at 105 kya, in particular the Atlantic Ocean and the African climate system, to: 1) orbitally-controlled solar radiation and atmospheric carbon dioxide forcing appropriate for 105 kya and 2) the combined effect of orbitally-controlled solar radiation and atmospheric carbon dioxide at 105 kya, and North Atlantic freshwater forcing. The ultimate goal of this study is to understand how low-latitude and high-latitude climate processes affect the African climate. Overall the comparative analysis of these two climate model states revealed that the complex interaction between orbitally-controlled solar radiation and atmospheric CO2 forcing at 105 kya produced a significant part of the cooling and drying in Africa at this time interval. However, the model also indicated that the climate perturbations, caused by the freshwater forcing, amplified the cooling and drying that was already taking place in Africa due to orbital and CO2 forcing. Guided by paleoclimate data, archaeological data and the results of this study, I consider it likely that the development of hyper-arid conditions in Africa around 100 kya served as the impetus for the migration event of AMH out of Africa, as these climate changes would have rendered Africa unsuitable for hominid occupation at this time. These climate model results also provide compelling evidence that high-latitude cold events, induced by Heinrich Events, are strongly covariant with African aridity, and thus provide support to previous assertions that North Atlantic climate changes can be effectively propagated throughout the globe to produce seemingly simultaneous climate change.

No description available.

The aim of this thesis is to examine the scale of human migration in three prehistoric settlements in the Upper Mun River Valley (UMRV) Northeast Thailand, from c. 1700BC - AD500. Archaeological data implies migration may have had a central role in the development of agriculture and later metal technology in the region, which is suggested to show increased social complexity over this important stage in the development of states in mainland Southeast Asia. The scale of these migrations, however, are not known and based on archaeological evidence it is unclear whether there were large numbers of individuals migrating into the region in order to bring about the changes seen in the archaeological record. Two potentially complementary-methods are used to identify the extent of migration in the UMRV in this thesis. The first method, the study of dental morphological traits, is used as an indication of genotype of 78 prehistoric individuals. The second method is isotope analysis of the dental enamel of 74 individuals, used as indicators of childhood residence and diet. Strontium (Sr), Carbon (C) and Oxygen (O) isotopes are analysed. The first method reflects an individual�s genetic heritage through inherited traits, while the second method is an indication of an individual�s migration during their lifetime. Together, these methods may provide a powerful means to assess the scale of migration over an extended period of time in this region. As it has been posited that the introduction of agriculture is related to migration of people into the region, the current study hypothesises that while immigrants would be identified from outside the UMRV during all phases of occupation at the sites, this would be particularly so during the earlier phases. It is also hypothesised through analysis of the morphological traits that genetic relationships at each site could be suggested. Finally, it is also hypothesised that individuals with evidence for infectious diseases, which are otherwise rare in the region, would be immigrants. The frequencies of the dental morphological traits at each site are calculated, and a local pattern for each site developed. The results from the morphological traits suggest low levels of migration into the UMRV, and overall group homogeneity. Despite this homogeneity, it is suggested that several individuals may have been from a different genetic pool to others at the sites, reflected in a different combination of dental traits. There is also some evidence for genetic relationships between individuals, and over time, possibly indicating familial relationships at the sites. Stability in the Sr isotopes over time suggest a local signature for the UMRV. Sr isotopes did not support a hypothesis of large-scale immigration into the UMRV, as there were few isotopic outliers identified. Those individuals with clear outlier Sr results, and therefore probable immigrants, were predominately female. All phases of occupation of the UMRV attracted some long-range inward movement of people, although the data suggests long-range migration diminished over time. [delta]��C values show no significant change over time, possibly supporting the Sr data of limited migration into the region. While the interpretation of this isotope is primarily from a perspective of migration it is recognised that this may be limited to understanding variation in diet in the individuals. [delta]�⁸O values show significant change over time (p = 0.00, ANOVA), perhaps consistent with previous research which suggested increased aridity in the UMRV. An alternative explanation of the [delta]�⁸O data is that migration increased with time, with people who were differentiated by their O isotopes but not their Sr, however the increased aridity hypothesis is favoured here. The hypothesis that individuals with evidence for infectious disease would be long-range immigrants into the region is rejected. None of the individuals who had physical evidence for infectious disease had chemical data to support their being immigrants. The putative migrants to the UMRV are presented as case studies, assessing the complementarity of the methods used. It is argued that given the changes in the environment over time in the UMRV the area may have become less attractive to immigrants and as a result the communities may have become more insular. The data yielded from the two methods have demonstrated the value of using inherited dental traits together with isotopic data of individual migration for investigating human mobility in the past. Using these methods, this study shows that there were low levels of migration into the UMRV and that long-range migration was more frequent in the earliest phases of occupation in the region.

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 301-344). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 328-378).

Originally presented as the author's Thesis (Ph. D.)--University of Oxford, 2001. / Includes bibliographical references (p. 181-186).

Thesis (Ph. D.)--University of Nevada, Reno, 2008. / "May 2008." Includes bibliographical references. Online version available on the World Wide Web.

Thesis (M.F.A.)--Rochester Institute of Technology, 2008. / Typescript.

Thesis (M.A.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 58-63). Also available on the World Wide Web.

Zugl.: Hamburg, Univ., Diss., 2006. - Zsfassung in engl. Sprache