Constraining the chronology and ecology of Late Acheulean and Middle Palaeolithic occupations at the margins of the monsoon

South Asia hosts the world’s youngest Acheulean sites, with dated records typically restricted to sub-humid landscapes. The Thar Desert marks a major adaptive boundary between monsoonal Asia to the east and the Saharo-Arabian desert belt to the west, making it a key threshold to examine patterns of hominin ecological adaptation and its impacts on patterns of behaviour, demography and dispersal. Here, we investigate Palaeolithic occupations at the western margin of the South Asian monsoon at Singi Talav, undertaking new chronometric, sedimentological and palaeoecological studies of Acheulean and Middle Palaeolithic occupation horizons. We constrain occupations of the site between 248 and 65 thousand years ago. This presents the first direct palaeoecological evidence for landscapes occupied by South Asian Acheulean-producing populations, most notably in the main occupation horizon dating to 177 thousand years ago. Our results illustrate the potential role of the Thar Desert as an ecological, and demographic, frontier to Palaeolithic populations.Results - Sediment sequence. - Luminescence dating. - Palaeoenvironmental studies. - Lithic artefacts. Discussion Method

Assessment of trace metal contamination in a historical freshwater canal (Buckingham Canal), Chennai, India

The present study was done to assess the sources and the major processes controlling the trace metal distribution in sediments of Buckingham Canal. Based on the observed geochemical variations, the sediments are grouped as South Buckingham Canal and North Buckingham Canal sediments (SBC and NBC, respectively). SBC sediments show enrichment in Fe, Ti, Mn, Cr, V, Mo, and As concentrations, while NBC sediments show enrichment in Sn, Cu, Pb, Zn, Ni, and Hg. The calculated Chemical Index of Alteration and Chemical Index of Weathering values for all the sediments are relatively higher than the North American Shale Composite and Upper Continental Crust but similar to Post-Archaean Average Shale, and suggest a source area with moderate weathering. Overall, SBC sediments are highly enriched in Mo, Zn, Cu, and Hg (geoaccumulation index (Igeo) class 4– 6), whereas NBC sediments are enriched in Sn, Cu,Zn, and Hg (Igeo class 4–6). Cu, Ni, and Cr show higher than Effects-Range Median values and hence the biological adverse effect of these metals is 20%; Zn, which accounts for 50%, in the NBC sediments, has a more biological adverse effect than other metalsfound in these sediments. The calculated Igeo, Enrichment Factor, and Contamination Factor values indicate that Mo, Hg, Sn, Cu, and Zn are highly enriched in the Buckingham Canal sediments, suggesting the rapid urban and industrial development of Chennai MetropolitanCity have negatively influenced on the surrounding aquatic ecosystem

Reply to Stojanowski et al.

In the accompanying Comment1, Stojanowski et al. challenge the evidence for inter-group conflict at Nataruk2. They make two arguments—first, that the lesions in three crania are due to soil compression; second, that there is a correlation between body position and age, reflecting different burial traditions. We believe that their interpretation is incorrect on both counts

Transglutaminase 2 in cartilage homoeostasis: novel links with inflammatory osteoarthritis.

Transglutaminase 2 (TG2) is highly expressed during chondrocyte maturation and contributes to the formation of a mineralised scaffold by introducing crosslinks between extracellular matrix (ECM) proteins. In healthy cartilage, TG2 stabilises integrity of ECM and likely influences cartilage stiffness and mechanistic properties. At the same time, the abnormal accumulation of TG2 in the ECM promotes chondrocyte hypertrophy and cartilage calcification, which might be an important aspect of osteoarthritis (OA) initiation. Although excessive joint loading and injuries are one of the main causes leading to OA development, it is now being recognised that the presence of inflammatory mediators accelerates OA progression. Inflammatory signalling is known to stimulate the extracellular TG2 activity in cartilage and promote TG2-catalysed crosslinking of molecules that promote chondrocyte osteoarthritic differentiation. It is, however, unclear whether TG2 activity aims to resolve or aggravate damages within the arthritic joint. Better understanding of the complex signalling pathways linking inflammation with TG2 activities is needed to identify the role of TG2 in OA and to define possible avenues for therapeutic interventions

Geochemical evaluation of sea surface sediments along the continental shelf, south east coast of India

241-251Present study consists geochemical variations and spatial distribution of trace elements (Fe, Mn, Cr, Co, Cu, Ni, Pb and Zn) of the ocean floor sediments collected along the continental shelf off East coast Tamil Nadu (Chennai to Velanganni) during the 2009 southwest monsoon period. Results indicate sand dominance with abundant calcareous debris and shell fragments. Normalisation of trace metals with Al signifies a geogenic sediment origin. Enrichment factor (EF) of trace metals namely Co, Cr, Cu, Ni, Pb, Mn and Zn exhibit an increasing trend Pb>Cr>Co>Zn>Ni>Cu>Mn indicating high values of Pb, Cr, Co and Zn due to the anthropogenic source. However, contamination factor (CF) and pollution load index (PLI) point less than 1 indicating negligible contamination during the 2009 southwest monsoon period

The first dated evidence for Middle-Late Pleistocene fluvial activity in the central Thar Desert

The Thar Desert, located in western South Asia, marks a major global biogeographic boundary and a major adaptive threshold for the eastward expansions of modern humans from Africa across Asia. Examining the framework of palaeoenvironmental change in this region, both in terms of the regional manifestation of global climate change and the physical geography of the landscape, is therefore important to understand how modern humans first engaged with this significant shift in ecology. Here, we present evidence for the oldest chronometrically dated evidence for fluvial activity within this region, located at the Nal Quarry site in the central Thar Desert. We use luminescence dating of alluvial facies to demonstrate phases of fluvial activity at the site at ∼172–174, 140–150, 79–95 and 26 thousand years ago. This result substantially extends existing evidence for fluvial activity within the Thar Desert, as well as overlapping with evidence from the southern and eastern Thar desert indicating increased fluvial activity during the Last Interglacial (Marine Isotope Stage 5), whereas the cessation of fluvial deposition at Nal Quarry is contemporaneous with the onset of activity within the Ghaggar-Hakkra channel in the northern and western Thar Desert. Critically, the phases of fluvial activity identified at Nal overlaps with substantial behavioural change across South Asia, as well as the wider expansion of modern humans across the continent. This research illuminates a dynamic fluvial landscape that existed in the late Middle Pleistocene and early Late Pleistocene at a key threshold for modern human dispersals.1. Introduction 2. Fluvial landscapes of the pleistocene Thar Desert 3. The Nal Quarry site 4. Stratigraphy and chronology 5. Discussio