It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Friday, April 04, 2025
AMERIKA
Deporting immigrants may further shrink the health care workforce
JAMA
About The Study:
More than 1 million noncitizen immigrants (one-third of them undocumented) work in health care in the U.S. Their ranks include skilled personnel who would be difficult to replace, especially if legal immigration is further restricted. Many health care workers may be removed if President Trump implements plans to deport undocumented immigrants and those losing temporary protected status (e.g., from Haiti and Venezuela).
Corresponding Author: To contact the corresponding author, Lenore S. Azaroff, MD, ScD, email Lenore_Azaroff@yahoo.com.
Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.
US Resident physician intentions regarding unionization
JAMA Network Open
About The Study:
In this survey study, most resident physicians reported either being in a union or supporting unionization at their institution, citing pay and financial security as critical factors in their consideration of unionization. Future research should investigate other factors and whether unionization achieves its goals of increased pay and benefits, work hours, and well-being.
Corresponding Author: To contact the corresponding author, Laura K. Barger, PhD, email lkbarger@hms.harvard.edu.
Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.
About JAMA Network Open: JAMA Network Open is an online-only open access general medical journal from the JAMA Network. On weekdays, the journal publishes peer-reviewed clinical research and commentary in more than 40 medical and health subject areas. Every article is free online from the day of publication.
Journal
JAMA Network Open
Climate change and prehistoric human populations: Eastward shift of settlement areas at the end of the last ice age
A new study sheds light on how prehistoric hunter-gatherer populations in Europe coped with climate changes over 12,000 years ago. Led by scientists from the University of Cologne, a team of 25 prehistoric archaeologists from twenty European universities and research institutions revealed significant shifts in population size and density during key periods at the end of the last Ice Age, specifically during the Final Palaeolithic between 14,000 and 11,600 years ago. The study has been published in PLOS One under the title ‘Large scale and regional demographic responses to climatic changes in Europe during the Final Palaeolithic’.
The results reveal that the first establishment of a larger human population in north-eastern central Europe during the Final Palaeolithic was followed by a dramatic population decline during the last cold period (Greenland Stadial 1) of the Ice Age. This decline reduced the total population of Europe by half. However, the study found that some areas in central Europe show stability or even a slight increase in population size against the general trend. The team interprets this finding as evidence of human migration towards the east in response to worsening climate conditions.
By compiling a comprehensive database on archaeological sites from this period and using a cutting-edge geostatistical method called the Cologne Protocol, the researchers estimated population sizes and densities of prehistoric humans across different regions of Europe. The protocol provides a standardised procedure to estimate prehistoric demographic data, allowing for diachronic comparisons. The identified shifts in regional population sizes provide new insights into how early humans responded to the environmental challenges of their time.
The study focuses on two key periods: Greenland Interstadial 1d-a (GI-1d-a) and Greenland Stadial 1 (GS-1). During GI-1d-a, a warmer period of the Final Palaeolithic, humans continued to repopulate and expand into northern and north-eastern central Europe, making this region the centre of demographic dynamics in Europe for the first time in prehistory. Populations in south-western Europe, particularly in Spain and France, began to decline compared to population estimates for the preceding periods of the Upper Palaeolithic.
When the climate turned much colder during the subsequent GS-1, a climatic period known in the northern Hemisphere as the ‘Younger Dryas’, the total population of Europe decreases by half. But the new study shows that regional dynamics varied considerably: The estimates indicate an increase in population density in some areas of Europe (e.g. northern Italy, Poland and north-eastern Germany) as well as a general shift of populated areas from west to east. “These observations probably reflect the eastward movement of people in response to the very abrupt and pronounced climatic cooling during the Younger Dryas,” explains Dr Isabell Schmidt from the University of Cologne’s Department of Prehistoric Archaeology. “Humans during the Final Palaeolithic apparently responded by migrating to more favourable areas.”
The Cologne researchers are familiar with extreme population declines in Prehistory, such as during the late Gravettian (29,000 to 25,000 years ago), when cooler temperatures reduced populations in western and central Europe by up to two-thirds, leading to the extinction of regional populations.
Although demographic dynamics, particularly in these early phases of human prehistory, are still poorly understood, the new study adds to a growing body of evidence on how prehistoric humans responded to climate change, investigated at the University of Cologne in the framework of the Collaborative Research Centre 806 - Our Way to Europe, which was funded by the German Research Foundation (DFG) from 2009 to 2021. This work is currently being continued by the project HESCOR (Human and Earth System Coupling Research) at the University of Cologne, funded by the Ministry of Culture and Science of the State of North Rhine-Westphalia.
Journal
PLOS One
Method of Research
Data/statistical analysis
Subject of Research
Not applicable
Article Title
Large scale and regional demographic responses to climatic changes in Europe during the Final Palaeolithic
Article Publication Date
2-Apr-2025
Researchers from MARE ULisboa discover that the European catfish, an invasive species in Portugal, has a prolonged breeding season, enhancing its invasive potential
Gonadosomatic-index (GSI) of female (dark colour) and male (white colour) European catfish Silurus glanis specimens in relation to water temperature (dashed line) in the Lower River Tagus (LRT). The box represents the interquartile range (IQR; 25th and 75th percentiles), and the line within the box is the median. Whiskers represent the 75th percentile + 1.5 × IQR and the 25th percentile + 1.5 × IQR. Water temperature values are shown as mean and extracted from the SNIRH database ( https://snirh.apambiente.pt/). Numbers in brackets denote the number of female and male individuals used in the analysis, separated by a slash.
Credit: Gkenas, C., Sequeira, V., Ribeiro, D., Gago, J., Dias, D., Verma, C.R., Kumkar, P. and Ribeiro, F.,
The European Catfish is the largest freshwater fish in Europe, reaching up to 2.8 meters in length and 130 kg in weight. It was first detected in Portugal in 2014. As a top predator, it has no natural enemies and exhibits high fecundity, with females capable of producing up to half a million oocytes (unfertilized eggs). “This is not new information, as this invasive species reaches large sizes, and there is a direct relationship between abdominal cavity volume and the total number of oocytes produced,” said Christos Gkenas, a researcher at MARE-ULisboa and the study’s lead author. “What surprised us was that this fish has a prolonged breeding season, lasting almost five months, and that its oocytes are quite large, reaching over 3 mm in diameter.”
Over two years, from January 2022 to November 2023, nearly 700 catfish were captured using electrofishing and gill nets. The researchers found that the species spawns between February and June. This strategy allows its offspring to have different survival opportunities when facing extreme hydrological events (e.g., spring floods) and helps avoid competition for food resources among juveniles. The study also determined that European Catfish individuals reach sexual maturity at around 70 cm in length (approximately three years of age), which is considered early given that the species can live up to 70 years.
“Our work is crucial for controlling this species' population because our efforts should focus on removing larger individuals, which have higher fecundity,” said Filipe Ribeiro, the study's lead researcher, also from MARE-ULisboa. “The density of these animals is particularly high in protected areas, such as the International Tagus Natural Park. In October, as part of the LIFE-PREDATOR project, we removed approximately 1,200 kg of Catfish—about 100 individuals—in just three days from a small 10 km stretch of the Ponsul River.”
“The establishment of capture and removal teams to reduce Catfish populations is essential to mitigate the impact of this massive invader in Portugal,” Ribeiro concluded.
The LIFE-PREDATOR project titled “LIFE Predator – Preventing, Detecting, and Reducing the Spread of Silurus glanis in Southern European Aquatic Systems to Protect Aquatic Biodiversity” is funded by the European Union’s LIFE Program, is coordinated by the National Research Center in Italy and involves 11 researchers from three countries and will continue until August 2027.
Logistic regression curve of the proportion of mature female (upper panel) and male (lower panel) European catfish Silurus glanis specimens with total length in the Lower River Tagus (LRT). The solid line represents the model-predicted values, the dashed lines represent the corresponding 95% confidence intervals, and the red lines indicate the respective values in the Figure.
Histological sections of reproductive active ovaries of European catfish Silurus glanis: a) ovary with CA and AVTG oocytes, b) ovary with several PG and AVTG oocytes, c) ovary with EVTG oocyte, d) oocyte with PG, CA and AVTG oocytes. AVTG – advanced vitellogenic oocyte, CA – cortical alveoli oocyte, EVTG – early vitellogenic oocyte, PG – primary growth oocyte.
Credit
Gkenas, C., Sequeira, V., Ribeiro, D., Gago, J., Dias, D., Verma, C.R., Kumkar, P. and Ribeiro, F.
Bacteria may have adapted to oxygen well before Earth’s atmosphere was saturated with it, according to a new study. Researchers who traced microbial evolution over billions of years – using machine learning and other methods – show that the evolution of oxygen tolerance predated the Great Oxidation Event (GOE) and may have been crucial not only for the origin of oxygenic photosynthesis in Cyanobacteria but also for the evolution of the planet’s atmosphere. The findings underscore the dynamic relationship between biological evolution and Earth's geological history. Microbial life has dominated Earth’s history for at least 3.7 billion years. However, given the sparse presence of the planet’s first lifeforms in the fossil record, particularly in deep geological time, little is known about their evolution. In lieu of fossil evidence, researchers use geochemical records of microbial biological activity to estimate the ages of key bacterial lineages and their metabolic innovations. The GOE, ~2.4 billion years ago (Ga), marked the accumulation of atmospheric oxygen. This transformative event is thought to have been driven by the emergence of oxygenic photosynthesis – an evolutionary innovation attributed to Cyanobacteria that likely arose ~3.22 Ga. Yet despite this innovation that predated the GOE, it is thought that most life remained anaerobic until the GOE, when atmospheric oxygen levels began to rise. The extent to which aerobic life existed before the GOE remains a subject of debate and the evolutionary timelines of oxygen-adapted bacterial lineages remain poorly constrained.
To address this gap, Adrián Davín and colleagues constructed a species tree of Bacteria using 1,007 genomes spanning bacterial taxonomy. Then, using machine learning and phylogenetic reconciliation, Davín et al. identified distinct evolutionary signatures for oxygen adaption in bacterial genomes and predicted lineages where ancestorial transitions from anaerobic to aerobic lifestyles occurred. This allowed the authors to trace the evolution of oxygen use in bacteria across deep time. According to the findings, early aerobic bacteria emerged before the GOE, around 3.22 to 3.25 Ga, suggesting that aerobic metabolism evolved in some lineages – likely the ancestors of cyanobacteria – before oxygenic photosynthesis emerged. Following the GOE, there was an intense diversification of aerobic metabolism, which contributed to higher rates of diversification in oxygen-adapted lineages compared to anaerobic ones.
Bacterial evolution and oxygen adaptation: A timeline built from genomic, fossil, and chemical data. Colors show oxygen states: anaerobic (blue), aerobic (red), and proportion of aerobic lineages in modern bacterial phyla (purple shades). Analysis includes mitochondria and plastids to leverage eukaryotic fossil data. Land plants and animals are shown for time reference.
Microbial organisms dominate life on Earth, but tracing their early history and evolution is difficult because they rarely fossilize. Determining when exactly a particular group of microbes first appeared is especially hard. However, ancient sediments and rocks hold chemical clues of available nutrients that could support the growth of bacteria. A key turning point was when oxygen accumulated in the atmosphere around 2.3 billion years ago. Scientists have used this oxygen surge and how microbes adapted to it to map out bacterial evolution.
In a new study published in Science, researchers from the Model-Based Evolutionary Genomics Unit at the Okinawa Institute of Science and Technology (OIST) and their international collaborators have constructed a detailed timeline for bacterial evolution and oxygen adaptation. Their findings suggest some bacteria could use trace oxygen long before evolving the ability to produce it through photosynthesis.
The researchers focused on how microorganisms responded to the Great Oxygenation Event (GOE) some 2.3 billion years ago. This event, triggered in large part by the development of oxygenic (oxygen-generating) photosynthesis in cyanobacteria and carbon deposition, fundamentally changed Earth’s atmosphere from one mostly devoid of oxygen to one where oxygen became relatively abundant, as it is today.
Until now, establishing accurate timescales for how bacteria evolved before, during, and after this pivotal transition has been difficult due to incomplete fossil evidence and the challenge of determining the maximum possible ages for microbial groups – given that the only reliable maximum limit for the vast majority of lineages is the Moon-forming impact 4.5 billion years ago, which likely sterilized the planet.
The researchers addressed these gaps by concurrently analyzing geological and genomic records. Their key innovation was to use the GOE itself as a time boundary, assuming that most aerobic (oxygen-using) branches of bacteria are unlikely to be older than this event – unless fossil or genetic signals strongly suggest an earlier origin. Using Bayesian statistics, they created a model that can override this assumption when data supports it.
This approach, however, requires making predictions about which lineages were aerobic in the deep past. The team used probabilistic methods to infer which genes ancient genomes contained, and then machine-learning to predict whether they used oxygen. To best utilize the fossil record, they leveraged fossils of eukaryotes, whose mitochondria evolved from Alphaproteobacteria, and chloroplasts evolved from cyanobacteria to better estimate how and when aerobic bacteria evolved.
Their results indicate that at least three lineages had aerobic lifestyles before the GOE – the earliest nearly 900 million years before – suggesting that a capacity for using oxygen evolved well before its widespread accumulation in the atmosphere. Intriguingly, these findings point to the possibility that aerobic metabolism may have occurred long before the evolution of oxygenic photosynthesis. Evidence suggests that the earliest aerobic transition occurred in an ancestor of photosynthetic cyanobacteria, indicating that the ability to utilize trace amounts of oxygen may have allowed the development of genes central to oxygenic photosynthesis.
The study estimates that the last common ancestor of all modern bacteria lived sometime between 4.4 and 3.9 billion years ago, in the Hadean or earliest Archaean era. The ancestors of major bacterial phyla are placed in the Archaean and Proterozoic eras (2.5-1.8 billion years ago), while many families date back to 0.6-0.75 billion years ago, overlapping with the era when land plants and animal phyla originated.
Notably, once atmospheric oxygen levels rose during the GOE, aerobic lineages diversified more rapidly than their anaerobic counterparts, indicating that oxygen availability played a substantial role in shaping bacterial evolution.
“This combined approach of using genomic data, fossils, and Earth’s geochemical history brings new clarity to evolutionary timelines, especially for microbial groups that don’t have a fossil record,” Prof. Gergely Szöllősi, leader of the Model-based Evolutionary Genomics Unit, highlighted.
“Our work also shows that modelling microbial traits from their genomes using machine learning works well for studying the spread of aerobic metabolisms and might also be a useful approach for exploring how other traits emerged and interacted with the planet's shifting environment across geological time,” Dr. Tom Williams, a researcher from the University of Bristol’s School of Biological Sciences, explained.
