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1.
Richard S. Vachula Yongsong Huang James M. Russell Mark B. Abbott Matthew S. Finkenbinder Jonathan A. O'Donnell 《Boreas: An International Journal of Quaternary Research》2020,49(3):514-525
Our understanding of the timing of human arrival to the Americas remains fragmented, despite decades of active research and debate. Genetic research has recently led to the ‘Beringian standstill hypothesis’ (BSH), which suggests an isolated group of humans lived somewhere in Beringia for millennia during the Last Glacial, before a subgroup migrated southward into the American continents about 14 ka. Recently published organic geochemical data suggest human presence around Lake E5 on the Alaskan North Slope during the Last Glacial; however, these biomarker proxies, namely faecal sterols and polycyclic aromatic hydrocarbons (PAHs), are relatively novel and require replication to bolster their support of the BSH. We present new analyses of these biomarkers in the sediment archive of Burial Lake (latitude 68°26′N, longitude 159°10′W m a.s.l.) in northwestern Alaska. Our analyses corroborate that humans were present in Beringia during the Last Glacial and that they likely promoted fire activity. Our data also suggest that humans coexisted with Ice Age megafauna for millennia prior to their eventual extinction at the end of the Last Glacial. Lastly, we identify fire as an overlooked ecological component of the mammoth steppe ecosystem. 相似文献
2.
William R. Dickinson 《Quaternary Research》2011,76(2):201-210
Discovery of the Monte Verde archeological site in Chile overturned the previous consensus that the first Americans into the New World from Asia were the makers of Clovis projectile points, and rejuvenated the hypothesis that migration through the Americas occurred largely on portions of the Pacific continental shelf exposed by Pleistocene drawdown in eustatic sea level. The postulate of travel along a paleoshoreline now hidden underwater is an attractive means to posit pre-Clovis human movement southward from Beringia to Chile without leaving traces of migration onshore. Geologic analyses of the Pleistocene paleoenvironment at Monte Verde and of the morphology of the potential migration route along the continental shelf raise questions that have not been fully addressed. The periglacial setting of Monte Verde may call its antiquity into question and the narrowness of the Pacific continental shelf of the Americas makes it unlikely that people could travel the length of the Americas without impacting ground still onshore and no farther inland than Monte Verde itself. Geological perspectives on Monte Verde and coastal migration jointly suggest that the Clovis-first hypothesis for peopling the New World may have been abandoned prematurely. 相似文献
3.
In the Nearctic ecozone (temperate, subarctic, and arctic environments) hunter–gatherers often have to rely on diets with inadequate caloric intakes during certain times of the year. Although the Neotropic ecozone has different and less extreme conditions, it can also be nutritionally challenging. While the tropical forests offer a more stable diet (in terms of carbohydrates, proteins, and fat availability), high altitude biomes, such as the central Andes, can challenge human populations to metabolize proteins properly in certain times of the year. Guinea pigs (Cavia porcellus) may have been incorporated in the Andean diet because they represented an additional source of fat, especially when carbohydrates were short in supply. 相似文献
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5.
Across North and South America, the final millennia of the Pleistocene saw dramatic changes in climate, vegetation, fauna, fire regime, and other local and regional paleo-environmental characteristics. Rapid climate shifts following the Last Glacial Maximum (LGM) exerted a first-order influence, but abrupt post-glacial shifts in vegetation composition, vegetation structure, and fire regime also coincided with human arrival and transformative faunal extinctions in the Americas. We propose a model of post-glacial vegetation change in response to climatic drivers, punctuated by local fire regime shifts in response to megaherbivore-driven fuel changes and anthropogenic ignitions. The abrupt appearance of humans, disappearance of megaherbivores, and resulting changes in New World fire systems were transformative events that should not be dismissed in favor of climate-only interpretations of post-glacial paleo-environmental shifts in the Americas. Fire is a mechanism by which small human populations can have broad impacts, and growing evidence suggests that early anthropogenic influences on regional, even global, paleo-environments should be tested alongside other potential causal mechanisms. 相似文献
6.
W. George Lovell 《Geoforum》2006,37(1):31-40
In Memory of Fire, a poetic narration of the history of the Americas from pre-Columbian times to the late 20th century, Eduardo Galeano furnishes readers with over 1200 of his trademark vignettes, some 35 of which pertain to Guatemala. Galeano evokes disparate aspects of the geography of Guatemala, past and present, in grounded miniatures of time, place, and episode. His sketches of the experiences of Maya peoples allow us to see them as survivors of three cycles of conquest: (1) conquest by imperial Spain; (2) conquest by local and international capitalism; and (3) conquest by state terror. Composed in the literary mode of creative non-fiction, Memory of Fire serves as an inspirational classroom text, exposing students not only to factual detail but also a powerful artistic imagination. 相似文献
7.
Assunta Florenzano Anna Maria Mercuri Aurora Pederzoli Paola Torri Giovanna Bosi Linda Olmi Rossella Rinaldi Marta Bandini Mazzanti 《Geoarchaeology》2012,27(1):34-47
This paper presents the study of parasite remains recovered in pollen samples collected from archaeological layers. Laboratory treatment enabled us to obtain very high concentrations of both pollen and parasite eggs from the same samples. The case study of the site of Piazza Garibaldi in Parma, a town in the Po plain, is reported. The site was a sacred area in Roman times and a market square in Medieval times (10th–11th century A.D.). Pollen, seeds, and fruits from the latter phase were collected from four Medieval pits and one cesspit. After a palynological treatment including sieving, floating, and light acetolysis, abundant quantities of parasite eggs were extracted. Human and animal parasite eggs belonging to Trichuris, Ascaris, Taenia/Echinococcus, Capillaria, Dicrocoelium, and Diphyllobothrium were found. The analyses of animal and plant remains identified in the same samples suggested that the pit infillings consisted of waste, human and animal excrements, deteriorated plant food, and refuse of grapes. Therefore, parasite remains help the interpretation of archaeobotanical data in identifying human behaviors and site functions. 相似文献
8.
Kidong Bae 《Quaternary International》2010,211(1-2):103-112
Assemblages classified as ‘Upper Paleolithic’ in the Korean peninsula are diverse in their composition, including not only some blade industries but also conventional ones continued from earlier Paleolithic periods. This has often been explained as the result of an indigenous development. However, the ‘heterogenic’ character of Upper Paleolithic industries is the result of the continuing influx of modern human populations via two different routes: (1) from Siberia and (2) from southern China. Blade technology from Siberia appeared in the Korean peninsula around 35 000 BP and coexisted with core and flake stone industries carried by modern humans from southern China and Southeast Asia throughout the Upper Paleolithic. This explanation is based on the current observation of patterns of Upper Paleolithic industries in East Asia. Blade industries have been found only in the northern part of East Asia while none have been reported in southern China, although modern Homo evidently dispersed via two different routes from the Near East. The ‘North-South Model’ of Modern Homo migrations into the Korean peninsula is supported by a genetic analysis of the Y-chromosome of the modern population in this region. Continuing influx of modern human population from both origins to the peninsula can explain the consistent presence of Upper Paleolithic industries that appear heterogenic. 相似文献
9.
Thomas M. Soniat Eileen E. Hofmann John M. Klinck Eric N. Powell 《International Journal of Earth Sciences》2009,98(1):99-114
The eastern oyster (Crassostrea virginica) is affected by two protozoan parasites, Perkinsus marinus which causes Dermo disease and Haplosporidium nelsoni which causes MSX (Multinucleated Sphere Unknown) disease. Both diseases are largely controlled by water temperature and salinity and thus are potentially sensitive to climate variations resulting from the El Niño-Southern Oscillation (ENSO), which influences climate along the Gulf of Mexico coast, and the North Atlantic Oscillation (NAO), which influences climate along the Atlantic coast of the United States. In this study, a 10-year time series of temperature and salinity and P. marinus infection intensity for a site in Louisiana on the Gulf of Mexico coast and a 52-year time series of air temperature and freshwater inflow and oyster mortality from Delaware Bay on the Atlantic coast of the United States were analyzed to determine patterns in disease and disease-induced mortality in C. virginica populations that resulted from ENSO and NAO climate variations. Wavelet analysis was used to decompose the environmental, disease infection intensity and oyster mortality time series into a time–frequency space to determine the dominant modes of variability and the time variability of the modes. For the Louisiana site, salinity and Dermo disease infection intensity are correlated at a periodicity of 4 years, which corresponds to ENSO. The influence of ENSO on Dermo disease along the Gulf of Mexico is through its effect on salinity, with high salinity, which occurs during the La Niña phase of ENSO at this location, favoring parasite proliferation. For the Delaware Bay site, the primary correlation was between temperature and oyster mortality, with a periodicity of 8 years, which corresponds to the NAO. Warmer temperatures, which occur during the positive phase of the NAO, favor the parasites causing increased oyster mortality. Thus, disease prevalence and intensity in C. virginica populations along the Gulf of Mexico coast is primarily regulated by salinity, whereas temperature regulates the disease process along the United States east coast. These results show that the response of an organism to climate variability in a region is not indicative of the response that will occur over the entire range of a particular species. This has important implications for management of marine resources, especially those that are commercially harvested. 相似文献
10.
The drainage history of South America, since its breakup and separation from Africa about 100 Ma, shows an exceptionally compelling and pervasive tectonic control that should be true of all the continents, disruption by continental ice sheets excluded.Virtually all of South America's present major drainage developed after its separation from Africa. First, broad domes and aulacogens affected rivers such as the lower Amazon, the São Francisco, Uruguay, Rio de la Plata and their tributaries, and the Colorado and Negro in Argentina. Later the Mid-Miocene uplift of the Andes greatly enlarged the Amazon system and also created the present Magdalena and Paraguay Rivers and most of the Orinoco System. Of all these the Amazon is unique in that its “Andean event” can be dated both at its headwaters and offshore. Of all the major South American rivers, the Paraná seems to have the most perfect adjustment to structure, and probably developed after outpouring of the Serra Geral basalts in the late Cretaceous. Examination of the offshore record of South America's passive margin contributed significantly to this analysis, although megashears, plate convergence and impinging oceanic currents have destroyed the offshore record of many rivers.In this era of global geology the ages and paleodrainage of entire continents deserve far more attention from the geologic community than they have received. 相似文献
11.
Ezequiel García Morabito Carla M. Terrizzano Roland Zech Marcela Yamin Lorenz Wüthrich Marcus Christl Víctor A. Ramos Negar Haghipour Jos M. Corts 《地学学报》2021,33(1):30-45
Understanding deformation associated with active thrust wedges is essential to evaluate seismic hazards. In this study, we investigate the spatial distribution, timing, and rates of deformation across the central Andean backarc of Argentina, where deformation and shortening have been assumed to occur within a narrow wedge‐front zone. The combined results of our geomorphic mapping, topographic surveying, and 10Be exposure dating demonstrate that fault activity related to the growth of the Andean orogenic wedge is not only limited to a narrow thrust front zone but also occurs in the Andean wedge interior. There, internal structures with deformation rates of ca. 1.3 mm/year have been active during the last ~140 ka. Widely distributed deformation implies that seismic hazards may have been underestimated in the internal part of the Andean orogen. 相似文献
12.
Recent investigations of a limestone solution cave on the Queen Charlotte Islands (Haida Gwaii) have yielded skeletal remains of fauna including late Pleistocene and early Holocene bears, one specimen of which dates to ca. 14,400 14C yr B.P. This new fossil evidence sheds light on early postglacial environmental conditions in this archipelago, with implications for the timing of early human migration into the Americas. 相似文献
13.
Human activities have an impact on extant biotic communities, and may have had just as important an impact in the past. We assess human impact on limpet assemblages during the Upper Palaeolithic in Asturias (north‐west Spain). The intensely exploited genus Patella exhibited a marked size decrease and a change in species assemblage composition, substituting the larger species P. vulgata for the smaller P. depressa. The present Patella assemblages in the upper tidal level exhibit the same pattern as those of the Epipalaeolithic (approx. 12 000 to 6000 years before the present). Although climate change may have contributed to such species replacement, spatial differences between close areas with different densities of Palaeolithic human settlements indicate unequivocal human impact. Present Patella species sampled from the region exhibit genetic signatures of past bottlenecks in mitochondrial DNA, which also indicate recent demographic expansion, suggesting that old impacts have been sufficiently important to leave genetic traces in current populations. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
14.
Walter Alvarez 《地学学报》2001,13(5):333-337
Recent evidence indicates that beneath the Caribbean a tongue of sublithosphere mantle is flowing from the Pacific to the Atlantic, dragging the overlying lithosphere eastward: (i) Shear-wave splitting results from beneath the Andean subduction zone and Venezuela suggest mantle flow eastward through the Caribbean. (ii) Volcanic chemistry in Central America indicates a slab source beneath Nicaragua, but a different source in Costa Rica, above the proposed Pacific outflow. (iii) An extinct volcanic arc accreted to the margins of the Caribbean swept eastward through the Caribbean gap between North & South America. The 1982 'continental undertow' model requires shallow-mantle flow through the Caribbean gap from the Pacific to the Atlantic, if continents have deep roots and if shallow-mantle flow beneath oceans is decoupled from convection at deeper levels. The new evidence from the Caribbean is thus compatible with the continental undertow model, and perhaps with other models involving decoupled shallow flow. 相似文献
15.
Bronwen S. Whitney Ruth Dickau Francis E. Mayle J. Daniel Soto José Iriarte 《Quaternary Research》2013
We present a multiproxy study of land use by a pre-Columbian earth mounds culture in the Bolivian Amazon. The Monumental Mounds Region (MMR) is an archaeological sub-region characterized by hundreds of pre-Columbian habitation mounds associated with a complex network of canals and causeways, and situated in the forest–savanna mosaic of the Llanos de Moxos. Pollen, phytolith, and charcoal analyses were performed on a sediment core from a large lake (14 km2), Laguna San José (14°56.97′S, 64°29.70′W). We found evidence of high levels of anthropogenic burning from AD 400 to AD 1280, corroborating dated occupation layers in two nearby excavated habitation mounds. The charcoal decline pre-dates the arrival of Europeans by at least 100 yr, and challenges the notion that the mounds culture declined because of European colonization. We show that the surrounding savanna soils were sufficiently fertile to support crops, and the presence of maize throughout the record shows that the area was continuously cultivated despite land-use change at the end of the earth mounds culture. We suggest that burning was largely confined to the savannas, rather than forests, and that pre-Columbian deforestation was localized to the vicinity of individual habitation mounds, whereas the inter-mound areas remained largely forested. 相似文献
16.
The routes and timing of human occupation of the Tibetan Plateau (TP) are crucial for understanding the evolution of Tibetan populations and associated paleoclimatic conditions. Many archeological sites have been found in/around the Tarim Basin, on the northern margin of the Tibetan Plateau. Unfortunately, most of these sites are surface sites and cannot be directly dated. Their ages can only be estimated based on imprecise artifact comparisons. We recently found and dated an archeological site on a terrace along the Keriya River. Our ages indicate that the site was occupied at ~ 7.0–7.6 ka, making it the earliest well-dated archeological site yet identified in the Tarim Basin. This suggests that early human foragers migrated into this region prior to ~ 7.0–7.6 ka during the early to mid-Holocene climatic optimum, which may have provided the impetus for populating the region. We hypothesize that the Keriya River, together with the other rivers originating from the TP, may have served as access routes onto the TP for early human foragers. These rivers may also have served as stepping stones for migration further west into the now hyper-arid regions of the Tarim Basin, leading ultimately to the development of the Silk Road. 相似文献
17.
We have discovered a 2–4 year periodicity in geomagnetic secular variation (SV) from data of 110 world magnetic observatories. The periodicity in the horizontal component (H) is most prominent and appears to be globally uniform in different regions, on all continents, and in both hemispheres. The quasi-periodic short-wavelength variations show up in the vertical component (Z) as well but locally superpose on long-wavelength regional anomalies. We presume that the short-period fluctuations may be produced by instability of the eccentric dipole (ED) axis proceeding from the analysis of the SV field and optimization modeling of the dipole field with varied ED parameters. 相似文献
18.
Dunia H. Urrego Brittany A. Niccum Christopher F. La Drew Miles R. Silman Mark B. Bush 《第四纪科学杂志》2011,26(1):28-36
Three pollen and charcoal records from three lakes lying at 3400 m elevation in southern Peru provided a record of landscape change spanning the last ca.18 000 cal. a BP. The tree line lay close to the site between ca. 16 000 and 12 000 cal. a BP, with Polylepis woodlands growing near the lakes. Progressively drying conditions led to increased fire after 12 000 cal. a BP, coinciding with a decline in Polylepis cover and Andean forest relicts as puna grasslands expanded. A strong decrease in the rate of sediment deposition between ca. 12 000 and ca. 4400 cal. a BP was interpreted to indicate the presence of sedimentary hiatuses. With the return of wet conditions after 4400 cal. a BP, forests did not reassemble around the lakes. Instead, fire‐maintained grasslands dominated the landscape. Humans probably induced the intensified fire activity during the late Holocene and thereby deflected local successions. The modern fragmented landscape, with Polylepsis woodlands existing in fire‐resistant pockets above the general limit of the Andean tree line, resulted from the intensification of human land use practices during the last 4400 cal. a BP. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
19.
In situ U‐Th/Pb (LA‐ICP‐MS) monazite ages from the Hindu Kush of NW Pakistan provide new petrochronologic constraints on the tectonic evolution of the Himalaya–Karakoram–Tibet orogen. Monazites from two adjacent garnet + staurolite schist specimens yield multiple age populations that record the major Mesozoic and Cenozoic deformational, magmatic and metamorphic events along the southern margin of Eurasia. These include the accretion of the Hindu Kush–SW Pamir to Eurasia during the Late Triassic, followed by the accretion of the Karakoram terrane in the Early Jurassic. Younger Jurassic and Cretaceous ages record the development of an Andean‐style volcanic arc along the southern Eurasian margin, which ended with the docking of the Kohistan island arc and the emplacement of the Kohistan–Ladakh batholith during the Late Cretaceous. The initial Eocene collision of India with Eurasia was followed by widespread high‐temperature metamorphism and anatexis associated with crustal thickening within the Himalaya system in the Late Oligocene and Early Miocene. 相似文献
20.
Mantle diapirism contributes considerably to the formation of newly formed basins and surrounding centrifugally vergence fold-thrust belts in the Mediterranean and Caribbean regions. Mantle diapirism results from density inversion in the geosphere of astenosphere+lithosphere geosystem. Such inversion has become a driving force in the background of increasing heat flow caused by the heat-resistant convergence of Africa and Eurasia (in the case of the Mediterranean region) and North and South Americas (Caribbean region) in the Cenozoic. Mantle diapirism is caused by unstable gravity in the periods of tectonomagmatic activations. The analytical solution of the problem yields the critical parameters coupling the mantle flow dynamics and surface relief evolution. The difference between the structures and evolutions for Mediterranean and Caribbean regions is the following. In the Mediterranean region, the mantle diapirism produces newly formed basins of intercontinental seas at the final stage of Africa–Eurasia convergence (in the Cenozoic). In the Caribbean region, intensive mantle diapirism first disjoined the North and South Americas in the Mesozoic, and then played the same role as in the Mediterranean for the convergence of these continents in the Cenozoic. 相似文献