Fish otolith microchemistry: Snapshots of lake conditions during early human occupation of Lake Mungo, Australia

The δ18O, Strontium/Calcium and Barium/Calcium values recorded in golden perch otoliths collected from two evaporative lakes, modern Lake Hope and ancient Lake Mungo, have been used to reconstruct changes in water composition and environmental conditions during the life of the fish. Lake Hope was filled by floodwaters in 1989 and 1990, then a period of lake drying was followed by a natural fish death event in 1994. Otoliths from these fish have δ18O profiles reflecting the earlier floods, and the progressive evaporation of the lake. Sr/Ca ratios start to follow the δ18O trend only after evaporation is well advanced, probably after the fish became stressed. Otoliths from a period of early human occupation at Lake Mungo, 14C age range ca. 37–42 cal kBP, record a different history. Most otoliths show a relatively stable δ18O profile throughout the life of each fish, with no evidence of significant lake flooding or drying. Sr/Ca ratios are similarly stable, indicating that over a period of ca. 5 ka evaporation and inflow remained in relative balance. All the otoliths have high Ba/Ca ratios during the early years of the fish, likely a juvenile biological effect in common. The Mungo otoliths differ, in also showing a rise in Ba/Ca ratios in the outermost layers, as yet unexplained. One Mungo otolith, 14C dated at ca. 19.3 cal kBP, does show evaporation and stress trends in δ18O and Sr/Ca ratios respectively, consistent with other evidence that Lake Mungo was subject to frequent drying at that time.Funding support for the radiocarbon dates was provided by the Australian Archaeology Association and an Australian Research Council Discovery Grant (DP150100487)

New ages for human occupation and climatic change at Lake Mungo Australia

Australia’s oldest human remains, found at Lake Mungo, include the world’s oldest ritual ochre burial (Mungo III) and the first recorded cremation (Mungo I). Until now, the importance of these finds has been constrained by limited chronologies and palaeoenvironmental information. Mungo III, the source of the world’s oldest human mitochondrial DNA, has been variously estimated at 30 thousand years (kyr) old, 42–45 kyr old and 62 +/- 6 kyr old. while radiocarbon estimates placed theMungo I cremation near 20–26 kyr ago. Here we report a new series of 25 optical ages showing that both burials occurred at 40 +/- 2 kyr ago and that humans were present at Lake Mungo by 50–46 kyr ago, synchronously with, or soon after, initial occupation of northern and western Australia. Stratigraphic evidence indicates fluctuations between lake-full and drier conditions from 50 to 40 kyr ago, simultaneously with increased dust deposition, human arrival and continent-wide extinction of the megafauna. This was followed by sustained aridity between 40 and 30 kyr ago. This new chronology corrects previous estimates for human burials at this important site and provides a new picture of Homo sapiens adapting to deteriorating climate in the world’s driest inhabited continent

New ages for human occupation and climatic change at Lake Mungo, Australia

© 2003 Nature Publishing Group, a division of Macmillan Publishers Limited.Australia's oldest human remains, found at Lake Mungo, include the world's oldest ritual ochre burial (Mungo III) and the first recorded cremation (Mungo I). Until now, the importance of these finds has been constrained by limited chronologies and palaeoenvironmental information. Mungo III, the source of the world's oldest human mitochondrial DNA, has been variously estimated at 30 thousand years (kyr) old, 42-45 kyr old and 62 +/- 6 kyr old, while radiocarbon estimates placed the Mungo I cremation near 20-26 kyr ago. Here we report a new series of 25 optical ages showing that both burials occurred at 40 +/- 2 kyr ago and that humans were present at Lake Mungo by 50-46 kyr ago, synchronously with, or soon after, initial occupation of northern and western Australia. Stratigraphic evidence indicates fluctuations between lake-full and drier conditions from 50 to 40 kyr ago, simultaneously with increased dust deposition, human arrival and continent-wide extinction of the megafauna. This was followed by sustained aridity between 40 and 30 kyr ago. This new chronology corrects previous estimates for human burials at this important site and provides a new picture of Homo sapiens adapting to deteriorating climate in the world's driest inhabited continent.James M. Bowler, Harvey Johnston, Jon M. Olley, John R. Prescott, Richard G. Roberts, Wilfred Shawcross and Nigel A. Spoone

Bacteriophage targeting of gut bacterium attenuates alcoholic liver disease

Chronic liver disease due to alcohol-use disorder contributes markedly to the global burden of disease and mortality. Alcoholic hepatitis is a severe and life-threatening form of alcohol-associated liver disease. The gut microbiota promotes ethanol-induced liver disease in mice, but little is known about the microbial factors that are responsible for this process. Here we identify cytolysin-a two-subunit exotoxin that is secreted by Enterococcus faecalis-as a cause of hepatocyte death and liver injury. Compared with non-alcoholic individuals or patients with alcohol-use disorder, patients with alcoholic hepatitis have increased faecal numbers of E. faecalis. The presence of cytolysin-positive (cytolytic) E. faecalis correlated with the severity of liver disease and with mortality in patients with alcoholic hepatitis. Using humanized mice that were colonized with bacteria from the faeces of patients with alcoholic hepatitis, we investigated the therapeutic effects of bacteriophages that target cytolytic E. faecalis. We found that these bacteriophages decrease cytolysin in the liver and abolish ethanol-induced liver disease in humanized mice. Our findings link cytolytic E. faecalis with more severe clinical outcomes and increased mortality in patients with alcoholic hepatitis. We show that bacteriophages can specifically target cytolytic E. faecalis, which provides a method for precisely editing the intestinal microbiota. A clinical trial with a larger cohort is required to validate the relevance of our findings in humans, and to test whether this therapeutic approach is effective for patients with alcoholic hepatitis