Dating correlated microlayers in oxalate accretions from rock art shelters: New archives of paleoenvironments and human activity.

Oxalate-rich mineral accretions, often found in rock shelters around the world, offer important opportunities for radiocarbon dating of associated rock art. Here, sample characterization and chemical pretreatment techniques are used to characterize the accretions, prescreen for evidence of open-system behavior, and address potential contamination. The results provide stratigraphically consistent sequences of radiocarbon dates in millimeter-scale laminated accretions, demonstrating their reliability for dating rock art, particularly symbolic markings commonly engraved into these relatively soft deposits. The age sequences are also consistent with correlations between distinctive patterns in the layer sequences visible in shelters up to 90 km apart in the Kimberley region of northwestern Australia, suggesting their synchronized formation is not entirely shelter specific but broadly controlled by variations in regional environmental conditions. Consequently, these accretions also offer potential as paleoenvironmental archives, with radiocarbon dating of layers in nine accretions indicating four, approximately synchronous growth intervals covering the past 43 ka.

Ages for Australia's oldest rock paintings.

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.

12,000-Year-old Aboriginal rock art from the Kimberley region, Western Australia.

The Kimberley region in Western Australia hosts one of the world's most substantial bodies of indigenous rock art thought to extend in a series of stylistic or iconographic phases from the present day back into the Pleistocene. As with other rock art worldwide, the older styles have proven notoriously difficult to date quantitatively, requiring new scientific approaches. Here, we present the radiocarbon ages of 24 mud wasp nests that were either over or under pigment from 21 anthropomorphic motifs of the Gwion style (previously referred to as "Bradshaws") from the middle of the relative stylistic sequence. We demonstrate that while one date suggests a minimum age of c. 17 ka for one motif, most of the dates support a hypothesis that these Gwion paintings were produced in a relatively narrow period around 12,000 years ago.

Cultural innovation and megafauna interaction in the early settlement of arid Australia.

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.

No turnover in lens lipids for the entire human lifespan.

Lipids are critical to cellular function and it is generally accepted that lipid turnover is rapid and dysregulation in turnover results in disease (Dawidowicz 1987; Phillips et al., 2009; Liu et al., 2013). In this study, we present an intriguing counter-example by demonstrating that in the center of the human ocular lens, there is no lipid turnover in fiber cells during the entire human lifespan. This discovery, combined with prior demonstration of pronounced changes in the lens lipid composition over a lifetime (Hughes et al., 2012), suggests that some lipid classes break down in the body over several decades, whereas others are stable. Such substantial changes in lens cell membranes may play a role in the genesis of age-related eye disorders. Whether long-lived lipids are present in other tissues is not yet known, but this may prove to be important in understanding the development of age-related diseases.

Prussian blue based nanoelectrode arrays for H(2)O(2) detection.

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 x 10(-)(8) M) and a linear calibration range starting exactly from the detection limit and extending over 6 orders of magnitude of H(2)O(2) concentrations (1 x 10(-)(8) to 1 x 10(-)(2) M), which are the most advantageous analytical performances in hydrogen peroxide electroanalysis.