61 resultados para Human ecology - History


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A 37-year-old woman was admitted to hospital and over the next 5 days developed a progressive encephalitis. Nuchal skin biopsy, analyzed using a Rabies TaqMan(C) PCR, demonstrated rabies virus RNA. She had a history in keeping with exposure to rabies whilst in South Africa, but had not received pre- or post-exposure prophylaxis. She was treated with a therapeutic coma according to the

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The role of climatic change in determining the shape of human evolution,
a theme that came to prominence during the early years of the twentieth
century, has resurfaced with renewed vigor. The author examines the rise and
resurgence of the modern history of the idea that hominid evolutionary pathways
have been triggered by climatic causes to illustrate the continuing vitality of environmental determinism and to highlight some continuities between early-twentieth century and contemporary archaeoanthropology.

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Cores from slopes east of the Great Barrier Reef (GBR) challenge traditional models for sedimentation on tropical mixed siliciclastic-carbonate margins. However, satisfactory explanations of sediment accumulation on this archetypal margin that include both hemipelagic and turbidite sedimentation remain elusive, as submarine canyons and their role in delivering coarse-grained turbidite deposits, are poorly understood. Towards addressing this problem we investigated the shelf and canyon system bordering the northern Ribbon Reefs and reconstructed the history of turbidite deposition since the Late Pleistocene. High-resolution bathymetric and seismic data show a large paleo-channel system that crosses the shelf before connecting with the canyons via the inter-reef passages between the Ribbon Reefs. High-resolution bathymetry of the canyon axis reveals a complex and active system of channels, sand waves, and local submarine landslides. Multi-proxy examination of three cores from down the axis of the canyon system reveals 18 turbidites and debrites, interlayered with hemipelagic muds, that are derived from a mix of shallow and deep sources. Twenty radiocarbon ages indicate that siliciclastic-dominated and mixed turbidites only occur prior to 31 ka during Marine Isotope Stage (MIS) 3, while carbonate-dominated turbidites are well established by 11 ka in MIS1 until as recently as 1.2 ka. The apparent lack of siliciclastic-dominated turbidites and presence of only a few carbonate-dominated turbidites during the MIS2 lowstand are not consistent with generic models of margin sedimentation but might also reflect a gap in the turbidite record. These data suggest that turbidite sedimentation in the Ribbon Reef canyons, probably reflects the complex relationship between the prolonged period (> 25 ka) of MIS3 millennial sea level changes and local factors such as the shelf, inter-reef passage depth, canyon morphology and different sediment sources. On this basis we predict that the spatial and temporal patterns of turbidite sedimentation could vary considerably along the length of the GBR margin.

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Invasive species pose a major threat to biodiversity but provide an opportunity to describe the processes that lead to changes in a species’ range. The bank vole (Myodes glareolus) is an invasive rodent that was introduced to Ireland in the early twentieth century. Given its continuing range expansion, the substantial empirical data on its spread thus far, and the absence of any eradication program, the bank vole in Ireland represents a unique model system for studying the mechanisms influencing the rate of range expansion in invasive small mammals. We described the invasion using a reaction–diffusion model informed by empirical data on life history traits and demographic parameters. We subsequently modelled the processes involved in its range expansion using a rule-based spatially explicit simulation. Habitat suitability interacted with density-dependent parameters to influence dispersal, most notably the density at which local populations started to donate emigrating individuals, the number of dispersing individuals and the direction of dispersal. Whilst local habitat variability influenced the rate of spread, on a larger scale the invasion resembled a simple reaction–diffusion process. Our results suggest a Type 1 range expansion where the rate of expansion is generally constant over time, but with some evidence for a lag period following introduction. We demonstrate that a two-parameter empirical model and a rule-based spatially explicit simulation are sufficient to accurately describe the invasion history of a species that exhibits a complex, density-dependent pattern of dispersal.

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The integrated stratigraphic, radiocarbon and palynological record from an end-moraine system of the Oglio valley glacier (Italian Alps), propagating a lobe upstream in a lateral reach, provided evidence for a complete cycle of glacial advance, culmination and withdrawal during the Last Glacial Maximum and early Lateglacial. The glacier culminated in the end moraine shortly after 25.8 +/- 0.8 ka cal BP, and cleared the valley floor 18.3-17.2 +/- 0.3 ka cal BP. A primary paraglacial phase is then recorded by fast progradation of the valley floor.

As early as 16.7 +/- 0.3 ka cal BP, early stabilization of alluvial fans and lake filling promoted expansion of cembran pine. This is an unprecedented evidence of direct tree response to depletion of paraglacial activity during the early Lateglacial, and also documents the cembran pine survival in the mountain belt of the Italian Alps during the last glaciation. Between 16.1 and 14.6 +/- 0.5 ka cal BP, debris cones emplacement points to a moisture increase favouring tree Betula and Pinus sylvestris-mugo. A climate perturbation renewed paraglacial activity. According to cosmogenic ages on glacial deposits and AMS radiocarbon ages from lake records in South-Eastern Alps such phase compares favourably with the Gschnitz stadial and with the oscillations recorded at lakes Ragogna. Langsee and Jeserzersee, most probably forced by the latest freshening phases of the Heinrich Event 1.

A further sharp pine rise marks the subsequent onset of Bolling interstadial. The chronology of the Oglio glacier compares closely with major piedmont glaciers on the Central and Eastern Alpine forelands. On the other hand, the results of the present study imply a chronostratigraphic re-assessment of the recent geological mapping of the Central Italian Alps. (C) 2012 Elsevier Ltd. All rights reserved.

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“Understanding Human Dignity” aims to help the reader make sense of current debates about the meaning and implications of the idea of “human dignity.” The concept of human dignity has probably never been so omni-present in everyday speech, or so deeply embedded in political and legal discourse. In debates on torture, abortion, same-sex marriage, and welfare reform, appeals to dignity are seldom hard to find. The concept of dignity is not only a prominent feature of political debate, but also, and increasingly, of legal argument. Indeed, courts tell us that human dignity is the foundation of all human rights. But the more important it is, the more contested it seems to have become. There has, as a result, been an extraordinary explosion of scholarly writing about the concept of human dignity in law, political philosophy, and theology. This book aims to reflect on these intra-disciplinary debates about dignity in law, philosophy, history, politics, and theology, through a series of edited essays from specialists in these fields, explored the contested concept in its full richness and complexity.

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Earlier palynological studies of lake sediments from Easter Island suggest that the island underwent a recent and abrupt replacement of palm-dominated forests by grasslands, interpreted as a deforestation by indigenous people. However, the available evidence is inconclusive due to the existence of extended hiatuses and ambiguous chronological frameworks in most of the sedimentary sequences studied. This has given rise to an ongoing debate about the timing and causes of the assumed ecological degradation and cultural breakdown. Our multiproxy study of a core recovered from Lake Raraku highlights the vegetation dynamics and environmental shifts in the catchment and its surroundings during the late Holocene. The sequence contains shorter hiatuses than in previously recovered cores and provides a more continuous history of environmental changes. The results show a long, gradual and stepped landscape shift from palm-dominated forests to grasslands. This change started c. 450 BC and lasted about two thousand years. The presence of Verbena litoralis, a common weed, which is associated with human activities in the pollen record, the significant correlation between shifts in charcoal influx, and the dominant pollen types suggest human disturbance of the vegetation. Therefore, human settlement on the island occurred c. 450 BC, some 1500 years earlier than is assumed. Climate variability also exerted a major influence on environmental changes. Two sedimentary gaps in the record are interpreted as periods of droughts that could have prevented peat growth and favoured its erosion during the Medieval Climate Anomaly and the Little Ice Age, respectively. At c. AD 1200, the water table rose and the former Raraku mire turned into a shallow lake, suggesting higher precipitation/evaporation rates coeval with a cooler and wetter Pan-Pacific AD 1300 event. Pollen and diatom records show large vegetation changes due to human activities c. AD 1200. Other recent vegetation changes also due to human activities entail the introduction of taxa (e.g. Psidium guajava, Eucalyptus sp.) and the disappearance of indigenous plants such as Sophora toromiro during the two last centuries. Although the evidence is not conclusive, the American origin of V. litoralis re-opens the debate about the possible role of Amerindians in the human colonisation of Easter Island.

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The effect of glycosylation on susceptibility of skin collagen to collagenase digestion was studied in a skin sample obtained at autopsy from the interscapular region of a 24 year old white male who had died of an acute illness and who had no history of diabetes. Homogeneous suspensions of insoluble collagen were prepared, and were incubated in 50 mmol l-1 dextrose at pH 7.35 and 37 degrees C for 7 days. Non-enzymatic glycosylation measured by the weak acid hydrolysis/thiobarbituric acid method increased from 13.1 +/- 1.0 (n = 5) to 45.2 +/- 5.5 (n = 8) nmol fructose per 10 mg collagen (P less than 0.001). Digestion of collagen using clostridial collagenase was monitored by measuring (a) hydroxyproline content and (b) absorption at 206 nm of the supernatant after centrifugation to remove substrate. The rate of digestion was similar in glycosylated and control collagen. We conclude that the ketoamine link formed in non-enzymatic glycosylation does not increase the resistance of collagen to enzymatic digestion. The possibility remains that subsequent rearrangement of this link could be important in this respect.

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There is extensive debate concerning the cognitive and behavioral adaptation of Neanderthals, especially in the period when the earliest anatomically modern humans dispersed into Western Europe, around 35,000–40,000 B.P. The site of the Grotte du Renne (at Arcy-sur-Cure) is of great importance because it provides the most persuasive evidence for behavioral complexity among Neanderthals. A range of ornaments and tools usually associated with modern human industries, such as the Aurignacian, were excavated from three of the Châtelperronian levels at the site, along with Neanderthal fossil remains (mainly teeth). This extremely rare occurrence has been taken to suggest that Neanderthals were the creators of these items. Whether Neanderthals independently achieved this level of behavioral complexity and whether this was culturally transmitted or mimicked via incoming modern humans has been contentious. At the heart of this discussion lies an assumption regarding the integrity of the excavated remains. One means of testing this is by radiocarbon dating; however, until recently, our ability to generate both accurate and precise results for this period has been compromised. A series of 31 accelerator mass spectrometry ultra?ltered dates on bones, antlers, artifacts, and teeth from six key archaeological levels shows an unexpected degree of variation. This suggests that some mixing of material may have occurred, which implies a more complex depositional history at the site and makes it dif?cult to be con?dent about the association of artifacts with human remains in the Châtelperronian levels.

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Invasion ecology urgently requires predictive methodologies that can forecast the ecological impacts of existing, emerging and potential invasive species. We argue that many ecologically damaging invaders are characterised by their more efficient use of resources. Consequently, comparison of the classical ‘functional response’ (relationship between resource use and availability) between invasive and trophically analogous native species may allow prediction of invader ecological impact. We review the utility of species trait comparisons and the history and context of the use of functional responses in invasion ecology, then present our framework for the use of comparative functional responses. We show that functional response analyses, by describing the resource use of species over a range of resource availabilities, avoids many pitfalls of ‘snapshot’ assessments of resource use. Our framework demonstrates how comparisons of invader and native functional responses, within and between Type II and III functional responses, allow testing of the likely population-level outcomes of invasions for affected species. Furthermore, we describe how recent studies support the predictive capacity of this method; for example, the invasive ‘bloody red shrimp’ Hemimysis anomala shows higher Type II functional responses than native mysids and this corroborates, and could have predicted, actual invader impacts in the field. The comparative functional response method can also be used to examine differences in the impact of two or more invaders, two or more populations of the same invader, and the abiotic (e.g. temperature) and biotic (e.g. parasitism) context-dependencies of invader impacts. Our framework may also address the previous lack of rigour in testing major hypotheses in invasion ecology, such as the ‘enemy release’ and ‘biotic resistance’ hypotheses, as our approach explicitly considers demographic consequences for impacted resources, such as native and invasive prey species. We also identify potential challenges in the application of comparative functional responses in invasion ecology. These include incorporation of numerical responses, multiple predator effects and trait-mediated indirect interactions, replacement versus non-replacement study designs and the inclusion of functional responses in risk assessment frameworks. In future, the generation of sufficient case studies for a meta-analysis could test the overall hypothesis that comparative functional responses can indeed predict invasive species impacts.

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Fundamental ecological research is both intrinsically interesting and provides the basic knowledge required to answer applied questions of importance to the management of the natural world. The 100th anniversary of the British Ecological Society in 2013 is an opportune moment to reflect on the current status of ecology as a science and look forward to high-light priorities for future work. To do this, we identified 100 important questions of fundamental importance in pure ecology. We elicited questions from ecologists working across a wide range of systems and disciplines. The 754 questions submitted (listed in the online appendix) from 388 participants were narrowed down to the final 100 through a process of discussion, rewording and repeated rounds of voting. This was done during a two-day workshop and thereafter. The questions reflect many of the important current conceptual and technical pre-occupations of ecology. For example, many questions concerned the dynamics of environmental change and complex ecosystem interactions, as well as the interaction between ecology and evolution. The questions reveal a dynamic science with novel subfields emerging. For example, a group of questions was dedicated to disease and micro-organisms and another on human impacts and global change reflecting the emergence of new subdisciplines that would not have been foreseen a few decades ago. The list also contained a number of questions that have perplexed ecologists for decades and are still seen as crucial to answer, such as the link between population dynamics and life-history evolution. Synthesis. These 100 questions identified reflect the state of ecology today. Using them as an agenda for further research would lead to a substantial enhancement in understanding of the discipline, with practical relevance for the conservation of biodiversity and ecosystem function. © 2013 The Authors. Journal of Ecology © 2013 British Ecological Society.