Elucidating the material culture of early people in arid Australia and the nature of their environmental interactions is essential for understanding the adaptability of populations and the potential ...causes of megafaunal extinctions 50-40 thousand years ago (ka). Humans colonized the continent by 50 ka, but an apparent lack of cultural innovations compared to people in Europe and Africa has been deemed a barrier to early settlement in the extensive arid zone. Here we present evidence from Warratyi rock shelter in the southern interior that shows that humans occupied arid Australia by around 49 ka, 10 thousand years (kyr) earlier than previously reported. The site preserves the only reliably dated, stratified evidence of extinct Australian megafauna, including the giant marsupial Diprotodon optatum, alongside artefacts more than 46 kyr old. We also report on the earliest-known use of ochre in Australia and Southeast Asia (at or before 49-46 ka), gypsum pigment (40-33 ka), bone tools (40-38 ka), hafted tools (38-35 ka), and backed artefacts (30-24 ka), each up to 10 kyr older than any other known occurrence. Thus, our evidence shows that people not only settled in the arid interior within a few millennia of entering the continent, but also developed key technologies much earlier than previously recorded for Australia and Southeast Asia.
The site of Shuidonggou Locality 2 offers important evidence for the Late Paleolithic sequence of north China. The site not only contains one of the earliest instances of ornamental freshwater shell ...and ostrich eggshell beads in the region, but also stone artifacts with features arguably resembling the Initial Upper Paleolithic (IUP) blade technology found farther north. The appearance of these innovative archaeological forms have been attributed to the arrival of hominin populations, possibly modern humans, into the region during Marine Isotope Stage 3. Yet, the chronology of the site remains debated due to ambiguities in the existing dates. In this study, we conduct a systematical radiocarbon analysis of charcoal and ostrich eggshell samples obtained throughout the site sequence. Both acid-base-acid and the more stringent acid-base-oxidation pretreatment methods were applied to the charcoal samples. The resulting ages follow an age-depth relationship that is consistent with the stratigraphic profile. In line with previous stratigraphic assessments, Bayesian age modeling suggests that site formation history can be split into two phases: an early phase 43-35 cal kBP associated with a lacustrine depositional environment, and a later phase 35-28 cal kBP associated with rapid terrestrial silt accumulation. The chronology of the archaeological layers containing IUP-like artifacts are placed at 43-39 cal kBP and 35-34 cal kBP respectively. This finding supports the interpretation that an IUP-like blade technology appeared in the SDG region by at least ~41 ka.
The problem of the degradation and aging of bioorganisms is herein considered from the viewpoint of statistical physics. Two typical timescales in biological systems-the time of metabolic processes ...and the time of the life cycle-are used. A kinetic equation describing the small timescales of the systems' characteristic processes in is proposed. Maintaining a biosystem in a time-stable state requires a constant inflow of negative entropy (negentropy). Ratios are proposed to evaluate the aging and degradation of systems in terms of entropy. As an example, the aging of the epithelium is studied. The connection of our approach to the information theory of aging is discussed, as well as theoretical constructions related to the concept of cooperon and its changing with time.
Fire is an essential component of tropical savannas, driving key ecological feedbacks and functions. Indigenous manipulation of fire has been practiced for tens of millennia in Australian savannas, ...and there is a renewed interest in understanding the effects of anthropogenic burning on savanna systems. However, separating the impacts of natural and human fire regimes on millennial timescales remains difficult. Here we show using palynological and isotope geochemical proxy records from a rare permanent water body in Northern Australia that vegetation, climate, and fire dynamics were intimately linked over the early to mid-Holocene. As the El Niño/Southern Oscillation (ENSO) intensified during the late Holocene, a decoupling occurred between fire intensity and frequency, landscape vegetation, and the source of vegetation burnt. We infer from this decoupling, that indigenous fire management began or intensified at around 3 cal kyr BP, possibly as a response to ENSO related climate variability. Indigenous fire management reduced fire intensity and targeted understory tropical grasses, enabling woody thickening to continue in a drying climate.
We propose to form nanoelectrode arrays by deposition of the electrocatalyst through lyotropic liquid crystalline templates onto inert electrode support. Whereas Prussian Blue is known to be a ...superior electrocatalyst in hydrogen peroxide reduction, carbon materials used as electrode support demonstrate only a minor activity. We report on the possibility for nanostructuring of Prussian Blue by its electrochemical deposition through lyotropic liquid crystalline templates, which is noticed from atomic force microscopy images of the resulting surfaces. The resulting Prussian Blue based nanoelectrode arrays in flow injection analysis mode demonstrate a sub-part-per-billion detection limit (1 × 10-8 M) and a linear calibration range starting exactly from the detection limit and extending over 6 orders of magnitude of H2O2 concentrations (1 × 10-8 to 1 × 10-2 M), which are the most advantageous analytical performances in hydrogen peroxide electroanalysis.
Abstract
The brittleness and relatively poor adhesion properties of CrN materials have been extensively addressed by developing Ni/CrN composites with a separate Ni phase. However, conditions at the ...Ni/CrN interfaces, which are the key features leading to the enhanced toughness, remain poorly understood. The present work addresses this issue by investigating the effect of interface orientation on adhesion strength and fracture toughness of Ni/CrN interfaces using first-principles calculations. To this end, we build seven Ni/CrN interface models, including Ni(100)/CrN(100), Ni(110)/CrN(110), Ni(110)/CrN(111), and Ni(111)/CrN(111), with different interface orientation and stacking orders. The results demonstrate that the interface orientation plays a predominant role in determining the mechanical properties of the Ni/CrN interfaces, while the effect of stacking order can be neglected. The Ni(111)/CrN(111) interface is demonstrated to provide the greatest adhesion strength, interfacial stability, and fracture toughness among the Ni/CrN interfaces considered, and is therefore the preferred orientation for Ni/CrN composite applications.
Brown bears are one of the few large carnivore species that survived the final Pleistocene wave of extinctions, perhaps in part owing to their wide ecological plasticity, variety of forms and ...polyphagia. Although the brown bear has become a well‐studied system, many questions remain regarding the ecological, trophic and genetic diversity throughout their distribution. For example, knowledge about Asiatic Russian brown bears from the Late Pleistocene arctic tundra steppe, an ecosystem with no analogue in modern times, is sparse. Here we compared diets, morphometry and genetic affinities of Late Pleistocene bears based on broadly sampled subfossil remains from Asiatic Russia. Collecting sites included the Ural Mountains, the lower reaches of the Irtysh River, the upper reaches of the Ob River, the Altai Mountains of western Siberia, the Indigirka–Kolyma Lowlands and northwestern Chukotka. An extremely large bear specimen from the middle Indigirka (41 090 14C a BP) that lived in landscapes of treeless shrubs and wet meadows had a diet composed principally of large herbivorous mammals. A bear from western Chukotka (25 880 14C a BP), much smaller in size, had a diet close to that of modern brown bears. These two Late Pleistocene NE Russian brown bears may comprise a previously undiscovered, but extinct, genetic lineage. At the end of the Pleistocene (MIS 3 and MIS 2), the brown bears from the Ob River Valley and Urals lived in periglacial forest‐steppes and those from the southern Urals in conditions of periglacial steppe. Brown bears from the Ob River valley and Urals, as well as ancient Altai bears, were characterized by a varied diet, from polyphagia to vegetarianism. In living brown bears, the proportions of different dietary foods are primarily related to food availability, which depends on the geographical zone and climatic conditions. We conclude that the same was true for Late Pleistocene brown bears of NE Siberia.
In this study we analyzed the morphometry, diets, and genetic diversity of Late Pleistocene bears from Asiatic Russia and compared them with Holocene and modern bears from these regions. Based on broadly sampled subfossil remains, we find considerable differences in size and diet that largely differ by region and are likely associated with availability of type of foods and their abundance. We find evidence from two particularly large Late Pleistocene brown bears from North‐East Siberia that had a mostly carnivorous diet and that represent a previously undiscovered, but likely extinct, genetic lineage.
Naturalistic depictions of animals are a common subject for the world's oldest dated rock art, including wild bovids in Indonesia and lions in France's Chauvet Cave. The oldest known Australian ...Aboriginal figurative rock paintings also commonly depict naturalistic animals but, until now, quantitative dating was lacking. Here, we present 27 radiocarbon dates on mud wasp nests that constrain the ages of 16 motifs from this earliest known phase of rock painting in the Australian Kimberley region. These initial results suggest that paintings in this style proliferated between 17,000 and 13,000 years ago. Notably, one painting of a kangaroo is securely dated to between 17,500 and 17,100 years on the basis of the ages of three overlying and three underlying wasp nests. This is the oldest radiometrically dated in situ rock painting so far reported in Australia.
PDF
