Comment

Comment by Dr. Krishna Kumari Challa on July 8, 2024 at 9:45am

Species went extinct on all continents except Antarctica and in all types of ecosystems, from tropical forests and savannas to Mediterranean and temperate forests and steppes to arctic ecosystems.
Many of the extinct species could thrive in various types of environments. Therefore, their extinction cannot be explained by climate changes causing the disappearance of a specific ecosystem type, such as the mammoth steppe—which also housed only a few megafauna species.
Most of the species existed under temperate to tropical conditions and should actually have benefited from the warming at the end of the last ice age.
The researchers point out that the loss of megafauna has had profound ecological consequences. Large animals play a central role in ecosystems by influencing vegetation structure (e.g., the balance between dense forests and open areas), seed dispersal, and nutrient cycling. Their disappearance has resulted in significant changes in ecosystem structures and functions.

Jens-Christian Svenning et al, The late-Quaternary megafauna extinctions: Patterns, causes, ecological consequences and implications for ecosystem management in the Anthropocene, Cambridge Prisms: Extinction (2024). DOI: 10.1017/ext.2024.4

The numbers of extinct and surviving species come from the freely accessible database PHYLACINE 1.2.1, which lists all known mammals that have lived in the past 129,000 years, including those that have gone extinct recently or are only found in captivity.

Part 3

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Comment by Dr. Krishna Kumari Challa on July 8, 2024 at 9:43am

The dramatic climate changes during the last interglacial and glacial periods (known as the late Pleistocene, from 130,000 to 11,000 years ago) certainly affected populations and distributions of both large and small animals and plants worldwide. However, significant extinctions were observed only among the large animals, particularly the largest ones.

An important observation is that the previous, equally dramatic ice ages and interglacials over the past couple of million years did not cause a selective loss of megafauna. Especially at the beginning of the glacial periods, the new cold and dry conditions caused large-scale extinctions in some regions, such as trees in Europe. However, there were no selective extinctions of large animals.

The large and very selective loss of megafauna over the last 50,000 years is unique over the past 66 million years. Previous periods of climate change did not lead to large, selective extinctions, which argues against a major role for climate in the megafauna extinctions.
Another significant pattern that argues against a role for climate is that the recent megafauna extinctions hit just as hard in climatically stable areas as in unstable areas.
Archaeologists have found traps designed for very large animals, and isotope analyses of ancient human bones and protein residues from spear points show that they hunted and ate the largest mammals.
Early modern humans were effective hunters of even the largest animal species and clearly had the ability to reduce the populations of large animals. These large animals were and are particularly vulnerable to overexploitation because they have long gestation periods, produce very few offspring at a time, and take many years to reach sexual maturity.
The analysis shows that human hunting of large animals such as mammoths, mastodons, and giant sloths was widespread and consistent across the world.

It also shows that the species went extinct at very different times and at different rates around the world. In some local areas, it happened quite quickly, while in other places it took over 10,000 years. But everywhere, it occurred after modern humans arrived, or in Africa's case, after cultural advancements among humans.
Part 2

Comment by Dr. Krishna Kumari Challa on July 8, 2024 at 9:41am

The evidence is mounting: Humans were responsible for the extinction of large mammals

The debate has raged for decades: Was it humans or climate change that led to the extinction of many species of large mammals, birds, and reptiles that have disappeared from Earth over the past 50,000 years?

By "large," we mean animals that weighed at least 45 kilograms—known as megafauna. At least 161 species of mammals were driven to extinction during this period. This number is based on the remains found so far.

The largest of them were hit the hardest—land-dwelling herbivores weighing over a ton, the megaherbivores. Fifty thousand years ago, there were 57 species of megaherbivores. Today, only 11 remain. These remaining 11 species have also seen drastic declines in their populations, but not to the point of complete extinction.

A research group  now concludes that many of these vanished species were hunted to extinction by humans.

They present this conclusion in a review article invited by and published in the journal Cambridge Prisms: Extinction. A review article synthesizes and analyses existing research within a particular field.

The researchers incorporated several research fields, including studies directly related to the extinction of large animals, such as:

• The timing of species extinctions
• The animals' dietary preferences
• Climate and habitat requirements
• Genetic estimates of past population sizes
• Evidence of human hunting

Additionally, they included a wide range of studies from other fields necessary to understand the phenomenon, such as:

• Climate history over the past 1–3 million years
• Vegetation history over the past 1–3 million years
• Evolution and dynamics of fauna over the past 66 million years
• Archaeological data on human expansion and lifestyle, including dietary preferences

Part 1

Comment by Dr. Krishna Kumari Challa on July 8, 2024 at 9:31am

The research found that if all car journeys under eight miles were shifted to walking or cycling, there would be a 9.3% reduction in carbon emissions. However, around 55% of all journeys would need to be shifted to achieve this, as most travel is done locally and in cars.

Calculated by dividing the carbon reduction percentage by the percentage of journeys altered, the emission reduction sensitivity for this change would be just 0.17—the lowest recorded in the study.

By contrast, if all flights of less than 1,000 miles were moved to rail, there would be a 5.6% reduction in emissions but only 0.17% of journeys would be affected—resulting in a sensitivity value of 33.2.

At the top end, theoretically limiting everyone who flies now to one return flight abroad per year would have a value of 158.3, as so few journeys would be affected.

The researchers stress that the potential changes are only suggestions meant to make us realize and reassess the impact of our long-distance travel, rather than concrete policy proposals.

While efforts to move local journeys to more sustainable modes of transport are really positive, by omitting aviation emissions from national statistics—as is the case at the moment in nearly all countries—we are not getting a holistic picture and ignoring a large part of the problem.

A call to rethink our travel's carbon impact

The researchers also hope that their findings can act as a driver for policymakers to look at changes in how effort is assigned when dealing with the impact of travel on the environment.

The research also offers the public an insight into the impact that changing their behavior could have.

The important thing both at the policy and personal level is that we prioritize the relatively fewer longer distance trips—especially flights—in order to realize the largest reductions.

Casting a long shadow: the role of long distance travel in carbon emissions from and decarbonisation of passenger travel, Nature Energy (2024). DOI: 10.1038/s41560-024-01561-3 , www.nature.com/articles/s41560-024-01561-3

Part 2

Comment by Dr. Krishna Kumari Challa on July 8, 2024 at 9:28am

True scale of carbon impact from long-distance travel revealed

The reality of the climate impact of long-distance passenger travel has been revealed in new research.

Despite only accounting for less than 3% of all trips by UK residents, journeys of more than 50 miles (one way) are responsible for 70% of all passenger travel-related carbon emissions.

The disparity is even greater when international travel is singled out: International journeys are only 0.4% of total trips, but are responsible for 55% of emissions.

The new research, published recently in the journal Nature Energy, also shows that targeting long-distance travel may be a more effective way of tackling emissions than current efforts focusing on local and commuter journeys.

While the number of long and short distance domestic journeys by car has fallen slightly over the last 25 years, international air travel has increased significantly, driven by an increase in trips for leisure and visiting friends and family.

The scale of the impact of long-distance travel is very large indeed. That just less than 3% of our trips are responsible for around 60% of miles and 70% of emissions shows how important long-distance travel is in the fight to combat climate change. Worryingly, long-distance trips, especially flights, have been growing; however, they offer opportunities too.

Using a new metric they have created, called emission reduction sensitivity, the research team has calculated which types of travel could be changed to maximize a reduction in carbon emissions from passenger travel while affecting as few people or trips as possible.

Part 1

Comment by Dr. Krishna Kumari Challa on July 6, 2024 at 1:32pm

WHO agency says talc is 'probably' cancer-causing

The World Health Organization's cancer agency on Friday classified talc as "probably carcinogenic" for humans, however an outside expert warned against misinterpreting the announcement as a "smoking gun".

The decision was based on "limited evidence" that talc could cause ovarian cancer in humans, "sufficient evidence" it was linked to cancer in rats and "strong mechanistic evidence" that it shows carcinogenic signs in human cells, the WHO's International Agency for Research on Cancer (IARC) said.

Talc is a naturally occurring mineral which is mined in many parts of the world and is often used to make talcum baby powder.

Most people are exposed to talc in the form of baby powder or cosmetics, according to the Lyon-based IARC.

But the most significant exposure to talc occurs when talc is being mined, processed or used to make products, it added.

The agency said there were numerous studies which consistently showed an increase in the rate of ovarian cancer in women who use talc on their genitals.

But it could not rule out that the talc in some studies was contaminated with cancer-causing asbestos.

"A causal role for talc could not be fully established," according the agency's findings published in The Lancet Oncology.

 Leslie T Stayner et al, Carcinogenicity of talc and acrylonitrile, The Lancet Oncology (2024). DOI: 10.1016/S1470-2045(24)00384-X

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Comment by Dr. Krishna Kumari Challa on July 6, 2024 at 1:20pm

Scientists identify thousands of high-risk cancer gene variants

More than 5,000 genetic variants that enable certain cancers to thrive have been identified by scientists, along with a potential therapeutic target to treat or even prevent these cancers from developing.

Researchers from the Wellcome Sanger Institute, and their collaborators at The Institute of Cancer Research, London, and the University of Cambridge assessed the health impact of all possible genetic changes in the "tumor protection" gene, BAP1. They found around a fifth of these possible changes were pathogenic, significantly increasing the risk of developing cancers of the eye, lung lining, brain, skin, and kidney.

The findings, published recently (5 July) in Nature Genetics, are freely available so that they can be immediately used by doctors to help diagnose patients and choose the most effective therapies for them. Importantly, as all possible variants were assessed, the findings benefit individuals from diverse ethnic backgrounds, who have historically been underrepresented in genetics research.

The team also uncovered a link between certain disruptive BAP1 variants and higher levels of IGF-1, a hormone and growth factor. This discovery opens the door to developing new drugs that could inhibit these harmful effects, potentially slowing down or preventing the progression of certain cancers.

The BAP1 protein acts as a powerful tumor suppressor in the body, protecting against cancers of the eye, lung lining, brain, skin, and kidney. Inherited variants that disrupt the protein can increase a person's lifetime risk of developing these cancers by up to 50%, typically occurring around middle age.

Andrew J. Waters et al, Saturation genome editing of BAP1 functionally classifies somatic and germline variants, Nature Genetics (2024). DOI: 10.1038/s41588-024-01799-3

Comment by Dr. Krishna Kumari Challa on July 6, 2024 at 12:26pm

Scientists visualize magnetic fields at atomic scale with holography electron microscope

A research team  has achieved a major breakthrough in the observation of magnetic fields at unimaginably small scales.

The team used Hitachi's atomic-resolution holography electron microscope—with a newly developed image acquisition technology and defocus correction algorithms—to visualize the magnetic fields of individual atomic layers within a crystalline solid.

Many advances in electronic devices, catalysis, transportation, and energy generation have been made possible by the development and adoption of high-performance materials with tailored characteristics. Atom arrangement and electron behavior are among the most critical factors that dictate a crystalline material's properties.

Notably, the orientation and strength of magnetic fields right at the interface between different materials or atomic layers are particularly important, and often help explain many peculiar physical phenomena.

Toshiaki Tanigaki et al, Electron holography observation of individual ferrimagnetic lattice planes, Nature (2024). DOI: 10.1038/s41586-024-07673-w

Comment by Dr. Krishna Kumari Challa on July 6, 2024 at 12:15pm

Researchers find a way to protect microbes from extreme conditions

Microbes that are used for health, agricultural, or other applications need to be able to withstand extreme conditions, and ideally the manufacturing processes used to make tablets for long-term storage. Researchers have now developed a new way to make microbes hardy enough to withstand these extreme conditions.

Their method involves mixing bacteria with food and drug additives from a list of compounds that the FDA classifies as "generally regarded as safe." The researchers identified formulations that help to stabilize several different types of microbes, including yeast and bacteria, and they showed that these formulations could withstand high temperatures, radiation, and industrial processing that can damage unprotected microbes.

In an even more extreme test, some of the microbes recently returned from a trip to the International Space Station, coordinated by Space Center Houston, the researchers are now analyzing how well the microbes were able to withstand those conditions.

What this project was about is stabilizing organisms for extreme conditions. Scientists are really thinking about a broad set of applications, whether it's missions to space, human applications, or agricultural uses.

Synthetic extremophiles via species-specific formulations improve microbial therapeutics, Nature Materials (2024). DOI: 10.1038/s41563-024-01937-6

Comment by Dr. Krishna Kumari Challa on July 6, 2024 at 12:10pm

 Fungi and lichens pose deadly threat to 5,000-year-old rock art

The Negev desert of southern Israel is renowned for its unique rock art. Since at least the third millennium BCE, the hunters, shepherds, and merchants who roamed the Negev have left thousands of carvings (petroglyphs) on the rocks. These figures are mostly cut into desert varnish: a thin black coating on limestone rock, which forms naturally. Many represent animals such as ibexes, goats, horses, donkeys, and domestic camels, but abstract forms also occur.

Now, a study published in Frontiers in Fungal Biology has revealed that the petroglyphs are home to a community of uncommon specialist fungi and lichens. Unfortunately, these species may pose a serious threat to the rock art in the long term.

Scientists show that these fungi and lichens could significantly contribute to the gradual erosion and damage of the petroglyphs. They are able to secrete different types of acids that can dissolve the limestone in which the petroglyphs are carved. In addition, the fungi can penetrate and grow within the stone grains, causing an additional mechanical damage.

Can anything be done to protect the petroglyphs from the slow but destructive work of the observed micro-colonial fungi and lichens? This is unlikely, cautioned the authors.

These natural weathering processes cannot be stopped, but their speed of the weathering process depends heavily on whether and how the climate will change in the future. What we can do is to monitor the microbial communities over time and most importantly, document these valuable works of art in detail.

Diversity of fungi associated to petroglyph sites in the Negev desert, Israel, and their potential role in bioweathering, Frontiers in Fungal Biology (2024). DOI: 10.3389/ffunb.2024.1400380

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