90 research outputs found

    A Precise Chronology of Middle to Late Holocene Bison Exploitation in the Far Southern Great Plains

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    In regions on the margins of the Great Plains grasslands, documenting the intermittent history of bison exploitation has presented challenges to archeologists. Chronologies based on archeological associations have long been useful in regional research, but can be imprecise and of inadequate resolution for constructing precise sequences of prehistoric events. Here, we present a record of directly dated bison from archeological contexts spanning the last 6000 years on the very southern extent of the Great Plains. This study includes 61 specimens from archeological contexts that were dated by XAD purified AMS radiocarbon, with reported errors of only 15-20 14C years for most dates. The resulting record of bison exploitation for this area defines four main periods (Calf Creek, Late Archaic 1 and 2, and early Toyah) during which bison were exploited. Several dates also indicate an early historic presence of bison; this period may represent a late facet of the Toyah horizon. This study adds significant chronological resolution to the regional record of bison in parts of Texas and begins to help correlate cultural chronologies with important climatic data. It also points to the research value of obtaining additional directly dated bison samples from temporally and geographically diverse archeological contexts in our study area and beyond

    Ancient genomes in South Patagonia reveal population movements associated with technological shifts and geography

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    Archaeological research documents major technological shifts among people who have lived in the southern tip of South America (South Patagonia) during the last thirteen millennia, including the development of marine-based economies and changes in tools and raw materials. It has been proposed that movements of people spreading culture and technology propelled some of these shifts, but these hypotheses have not been tested with ancient DNA. Here we report genome-wide data from 20 ancient individuals, and co-analyze it with previously reported data. We reveal that immigration does not explain the appearance of marine adaptations in South Patagonia. We describe partial genetic continuity since ~6600 BP and two later gene flows correlated with technological changes: one between 4700‚Äď2000 BP that affected primarily marine-based groups, and a later one impacting all <2000 BP groups. From ~2200‚Äď1200 BP, mixture among neighbors resulted in a cline correlated to geographic ordering along the coast.Fil: Nakatsuka, Nathan. Harvard Medical School; Estados UnidosFil: Luisi, Pierre. Universidad Nacional de C√≥rdoba. Facultad de Filosof√≠a y Humanidades; ArgentinaFil: Motti, Josefina Mar√≠a Brenda. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas; ArgentinaFil: Salemme, Monica Cira. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas. Centro Austral de Investigaciones Cient√≠ficas; Argentina. Universidad Nacional de Tierra del Fuego; ArgentinaFil: Santiago, Fernando Carlos. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas. Centro Austral de Investigaciones Cient√≠ficas; ArgentinaFil: D'angelo del Campo, Manuel Domingo. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Sociales. Grupo de Estudios Interdisciplinarios sobre Poblaciones Humanas de Patagonia Austral; Argentina. Universidad Aut√≥noma de Madrid; Espa√ĪaFil: Vecchi, Rodrigo Javier. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas; Argentina. Universidad Nacional del Sur; ArgentinaFil: Espinosa Parrilla, Yolanda. Consejo Superior de Investigaciones Cient√≠ficas; Espa√ĪaFil: Prieto, Alfredo. Universidad de Magallanes; ChileFil: Adamski, Nicole. Harvard Medical School; Estados UnidosFil: Lawson, Ann Marie. Harvard Medical School; Estados UnidosFil: Harper, Thomas K.. University of Pennsylvania; Estados UnidosFil: Culleton, Brendan J.. University of Pennsylvania; Estados UnidosFil: Kennett, Douglas J.. University of California; Estados UnidosFil: Lalueza Fox, Carles. Consejo Superior de Investigaciones Cient√≠ficas; Espa√ĪaFil: Mallick, Swapan. Harvard Medical School; Estados UnidosFil: Rohland, Nadin. Harvard Medical School; Estados UnidosFil: Guich√≥n, Ricardo A.. Universidad Nacional del Centro de la Provincia de Buenos Aires; ArgentinaFil: Cabana, Graciela S.. University of Tennessee; Estados UnidosFil: Nores, Rodrigo. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas. Centro Cient√≠fico Tecnol√≥gico Conicet - C√≥rdoba. Instituto de Antropolog√≠a de C√≥rdoba. Universidad Nacional de C√≥rdoba. Facultad de Filosof√≠a y Humanidades. Instituto de Antropolog√≠a de C√≥rdoba; ArgentinaFil: Reich, David. Harvard Medical School. Department Of Medicine; Estados Unido

    Findings from an in-depth annual tree-ring radiocarbon inter-comparison

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    The radiocarbon calibration curve so far contains annually resolved data only for a short period of time. With accelerator mass spectrometry (AMS) matching the precision of decay counting, it is now possible to efficiently produce large datasets of annual resolution for calibration purposes using small amounts of wood. The radiocarbon inter-comparison on single-year tree-ring samples presented here is the first to investigate specifically possible offsets between AMS laboratories at high precision. The results show that AMS laboratories are capable of measuring samples of Holocene age with an accuracy and precision that is comparable or even goes beyond what is possible with decay counting, even though they require a thousand times less wood. It also shows that not all AMS laboratories always produce results that are consistent with their stated uncertainties. The long-term benefits of studies of this kind are more accurate radiocarbon measurements with, in the future, better quantified uncertainties.Additional co-authors: Douglas J Kennett, Timothy D J Knowles, Margot Kuitems, Todd E Lange, Fusa Miyake, Marie-Josée Nadeau, Toshio Nakamura, J Philip Naysmith, Jesper Olsen, Takayuki Omori, Fiona Petchey, Bente Philippsen, Christopher Bronk Ramsey, G V Ravi Prasad, Martin Seiler, John Southon, Richard Staff, Thibault Tun

    The genomic history of the Iberian Peninsula over the past 8000 years

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    We assembled genome-wide data from 271 ancient Iberians, of whom 176 are from the largely unsampled period after 2000 BCE, thereby providing a high-resolution time transect of the Iberian Peninsula.We document high genetic substructure between northwestern and southeastern hunter-gatherers before the spread of farming.We reveal sporadic contacts between Iberia and North Africa by ~2500 BCE and, by ~2000 BCE, the replacement of 40% of Iberia's ancestry and nearly 100% of its Y-chromosomes by people with Steppe ancestry.We show that, in the Iron Age, Steppe ancestry had spread not only into Indo-European-speaking regions but also into non-Indo-European-speaking ones, and we reveal that present-day Basques are best described as a typical Iron Age population without the admixture events that later affected the rest of Iberia. Additionally, we document how, beginning at least in the Roman period, the ancestry of the peninsula was transformed by gene flow from North Africa and the eastern Mediterranean

    Aerosol forcing of the position of the intertropical convergence zone since AD1550

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    The position of the intertropical convergence zone is an important control on the distribution of low-latitude precipitation. Its position is largely controlled by hemisphere temperature contrasts1, 2. The release of aerosols by human activities may have resulted in a southward shift of the intertropical convergence zone since the early 1900s (refs 1, 3, 4, 5, 6) by muting the warming of the Northern Hemisphere relative to the Southern Hemisphere over this interval1, 7, 8, but this proposed shift remains equivocal. Here we reconstruct monthly rainfall over Belize for the past 456 years from variations in the carbon isotope composition of a well-dated, monthly resolved speleothem. We identify an unprecedented drying trend since ad 1850 that indicates a southward displacement of the intertropical convergence zone. This drying coincides with increasing aerosol emissions in the Northern Hemisphere and also marks a breakdown in the relationship between Northern Hemisphere temperatures and the position of the intertropical convergence zone observed earlier in the record. We also identify nine short-lived drying events since ad 1550 each following a large volcanic eruption in the Northern Hemisphere. We conclude that anthropogenic aerosol emissions have led to a reduction of rainfall in the northern tropics during the twentieth century, and suggest that geographic changes in aerosol emissions should be considered when assessing potential future rainfall shifts in the tropics

    Dynamic changes in genomic and social structures in third millennium BCE central Europe

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    Europe‚Äôs prehistory oversaw dynamic and complex interactions of diverse societies, hitherto unexplored at detailed regional scales. Studying 271 human genomes dated ~4900 to 1600 BCE from the European heartland, Bohemia, we reveal unprecedented genetic changes and social processes. Major migrations preceded the arrival of ‚Äústeppe‚ÄĚ ancestry, and at ~2800 BCE, three genetically and culturally differentiated groups coexisted. Corded Ware appeared by 2900 BCE, were initially genetically diverse, did not derive all steppe ancestry from known Yamnaya, and assimilated females of diverse backgrounds. Both Corded Ware and Bell Beaker groups underwent dynamic changes, involving sharp reductions and complete replacements of Y-chromosomal diversity at ~2600 and ~2400 BCE, respectively, the latter accompanied by increased Neolithic-like ancestry. The Bronze Age saw new social organization emerge amid a ‚Č•40% population turnover.Peer reviewe

    Ancient DNA and deep population structure in sub-Saharan African foragers

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    Multiple lines of genetic and archaeological evidence suggest that there were major demographic changes in the terminal Late Pleistocene epoch and early Holocene epoch of sub-Saharan Africa(1-4). Inferences about this period are challenging to make because demographic shifts in the past 5,000 years have obscured the structures of more ancient populations(3,5). Here we present genome-wide ancient DNA data for six individuals from eastern and south-central Africa spanning the past approximately 18,000 years (doubling the time depth of sub-Saharan African ancient DNA), increase the data quality for 15 previously published ancient individuals and analyse these alongside data from 13 other published ancient individuals. The ancestry of the individuals in our study area can be modelled as a geographically structured mixture of three highly divergent source populations, probably reflecting Pleistocene interactions around 80-20 thousand years ago, including deeply diverged eastern and southern African lineages, plus a previously unappreciated ubiquitous distribution of ancestry that occurs in highest proportion today in central African rainforest hunter-gatherers. Once established, this structure remained highly stable, with limited long-range gene flow. These results provide a new line of genetic evidence in support of hypotheses that have emerged from archaeological analyses but remain contested, suggesting increasing regionalization at the end of the Pleistocene epoch. DNA analysis of 6 individuals from eastern and south-central Africa spanning the past approximately 18,000 years, and of 28 previously published ancient individuals, provides genetic evidence supporting hypotheses of increasing regionalization at the end of the Pleistocene.info:eu-repo/semantics/publishedVersio

    CD8+ T cells from a novel T cell receptor transgenic mouse induce liver-stage immunity that can be boosted by blood-stage infection in rodent malaria

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    To follow the fate of CD8+ T cells responsive to Plasmodium berghei ANKA (PbA) infection, we generated an MHC I-restricted TCR transgenic mouse line against this pathogen. T cells from this line, termed PbT-I T cells, were able to respond to blood-stage infection by PbA and two other rodent malaria species, P. yoelii XNL and P. chabaudi AS. These PbT-I T cells were also able to respond to sporozoites and to protect mice from liver-stage infection. Examination of the requirements for priming after intravenous administration of irradiated sporozoites, an effective vaccination approach, showed that the spleen rather than the liver was the main site of priming and that responses depended on CD8&alpha;+ dendritic cells. Importantly, sequential exposure to irradiated sporozoites followed two days later by blood-stage infection led to augmented PbT-I T cell expansion. These findings indicate that PbT-I T cells are a highly versatile tool for studying multiple stages and species of rodent malaria and suggest that cross-stage reactive CD8+ T cells may be utilized in liver-stage vaccine design to enable boosting by blood-stage infections

    Reconstructing the Deep Population History of Central and South America

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    We report genome-wide ancient DNA from 49 individuals forming four parallel time transects in Belize, Brazil, the Central Andes, and the Southern Cone, each dating to at least 9,000 years ago. The common ancestral population radiated rapidly from just one of the two early branches that contributed to Native Americans today. We document two previously unappreciated streams of gene flow between North and South America. One affected the Central Andes by 4,200 years ago, while the other explains an affinity between the oldest North American genome associated with the Clovis culture and the oldest Central and South Americans from Chile, Brazil, and Belize. However, this was not the primary source for later South Americans, as the other ancient individuals derive from lineages without specific affinity to the Clovis-associated genome, suggesting a population replacement that began at least 9,000 years ago and was followed by substantial population continuity in multiple regions
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