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Comment by Dr. Krishna Kumari Challa on September 16, 2023 at 9:47am

The bottleneck, potentially caused by a period of global cooling, continued until 813,000 years ago, the study said.

Then there was a population boom, possibly sparked by a warming climate and "control of fire", it added.

The researchers suggested that inbreeding during the bottleneck could explain why humans have a significantly lower level of genetic diversity compared to many other species.

The population squeeze could have even contributed to the separate evolution of Neanderthals, Denisovans and modern humans, all of which are thought to have potentially split from a common ancestor roughly around that time, the study suggested.

It could also explain why so few fossils of human ancestors have been found from the period.

However, archaeologists have pointed out that some fossils dating from the time have been discovered in Kenya, Ethiopia, Europe and China, which may suggest that our ancestors were more widespread than such a bottleneck would allow.
The hypothesis of a global crash does not fit in with the archaeological and human fossil evidence.
In response, the study's authors said that hominins then living in Eurasia and East Asia may not have contributed to the ancestry of modern humans.

"The ancient small population is the ancestor of all modern humans. Otherwise we would not carry the traces in our DNA.
Some experts are "extremely skeptical" that the researchers had accounted for the statistical uncertainty involved in this kind of analysis. They said it will "never be possible" to use genomic analysis of modern humans to get such a precise number as 1,280 from that long ago, emphasizing that there are normally wide ranges of estimations in such research.

The authors of the paper said their range was between 1,270 and 1,300 individuals—a difference of just 30.
But sceptics say that the paper was unconvincing".

Our ancestors may have neared extinction at some point but the ability of modern genomic data to infer such an event was "very weak"they say.

"It's probably one of those questions that we're not going to answer in the near future."
Source: AFP

Part 2

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Comment by Dr. Krishna Kumari Challa on September 16, 2023 at 9:43am

Skepticism about claim human ancestors nearly went extinct

Could the lives of the eight billion people currently on Earth have depended on the resilience of just 1,280 human ancestors who very nearly went extinct 900,000 years ago?

That is the finding of a recent study which used genetic analysis modeling to determine that our ancestors teetered on the brink of annihilation for nearly 120,000 years.

However, scientists not involved in the research have criticized the claim, one telling AFP there was "pretty much unanimous" agreement among population geneticists that it was not convincing.
None denied that the ancestors of humans could have neared extinction at some point, in what is known as a population bottleneck.

But experts expressed doubts that the study could be so precise, given the extraordinarily complicated task of estimating population changes so long ago, and emphasized that similar methods had not spotted this massive population crash.

It is extremely difficult to extract DNA from the few fossils of human relatives dating from more than a couple of hundred thousand years ago, making it hard to know much about them.

But advances in genome sequencing mean that scientists are now able to analyze genetic mutations in modern humans, then use a computer model that works backwards in time to infer how populations changed—even in the distant past.

The study, published in the journal Science earlier this month, looked at the genomes of more than 3,150 modern-day humans.

The Chinese-led team of researchers developed a model to crunch the numbers, which found that the population of breeding human ancestors shrank to about 1,280 around 930,000 years ago.

99 percent of ancestors wiped out?
"About 98.7 percent of human ancestors were lost" at the start of the bottleneck.
Part 1

Comment by Dr. Krishna Kumari Challa on September 15, 2023 at 11:06am

Rivers are rapidly warming, losing oxygen: Aquatic life at risk, study finds

Rivers are warming and losing oxygen faster than oceans, according to a  study published in the journal Nature Climate Change. The study shows that of nearly 800 rivers, warming occurred in 87% and oxygen loss occurred in 70%.

The study also projects that within the next 70 years, river systems, especially in the American South, are likely to experience periods with such low levels of oxygen that the rivers could "induce acute death" for certain species of fish and threaten aquatic diversity at large.

Scientists know that a warming climate has led to warming and oxygen loss in oceans, but did not expect this to happen in flowing, shallow rivers. They found that rivers are warming up and deoxygenating faster than oceans, which could have serious implications for aquatic life—and the lives of humans. 

Widespread deoxygenation in warming rivers, Nature Climate Change (2023). DOI: 10.1038/s41558-023-01793-3

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Electrons from Earth may be forming water on the moon

A team of researchers, led by a University of Hawai'i (UH) at Mānoa planetary scientist, discovered that high energy electrons in Earth's plasma sheet are contributing to weathering processes on the moon's surface and, importantly, the electrons may have aided the formation of water on the lunar surface. The study was published in Nature Astronomy.

Comment by Dr. Krishna Kumari Challa on September 15, 2023 at 10:55am

Selective removal of aging cells opens new possibilities for treating age-related diseases

A research team  has achieved a significant breakthrough in the treatment of age-related diseases. Their cutting-edge technology offers a promising new approach by selectively removing aging cells, without harming normal healthy cells. This groundbreaking development is poised to redefine the future of health care and usher in a new era of targeted therapeutic interventions.

Aging cells, known as senescent cells, contribute to various inflammatory conditions and age-related ailments as humans age. To address this issue, the research team focused on developing a technology that could precisely target and eliminate aging cells, while sparing normal healthy cells. In their study, the team designed organic molecules that selectively target receptors overexpressed in the membranes of aging cells. By leveraging the higher levels of reactive oxygen species (ROS) found in aging cells, these molecules promote the formation of disulfide bonds and create oligomers that bind together. The research is published in the Journal of the American Chemical Society.

Through self-assembly of these oligomers, the researchers successfully created artificial proteins with a stable α-helix secondary structure. These protein-like nanoassemblies exhibited strong binding affinity to the mitochondrial membranes of aging cells, leading to membrane disruption and subsequent cell self-destruction.

"The selective removal of aging cells by targeting the mitochondria and inducing dysfunction has been successfully demonstrated in their experiments. This approach represents a new paradigm for treating age-related diseases.

This innovative technology offers several advantages, including minimal toxicity concerns and a wide therapeutic window by specifically targeting organelles within cells. It opens up exciting possibilities for designing preclinical and clinical trials in the future.

Sangpil Kim et al, Supramolecular Senolytics via Intracellular Oligomerization of Peptides in Response to Elevated Reactive Oxygen Species Levels in Aging Cells, Journal of the American Chemical Society (2023). DOI: 10.1021/jacs.3c06898

Comment by Dr. Krishna Kumari Challa on September 14, 2023 at 11:32am

Expansion Rate: The Hubble Tension

Comment by Dr. Krishna Kumari Challa on September 14, 2023 at 11:09am

Exposure to One Metal May Cause More Heart Disease Than Smoking or Cholesterol

Lead poisoning has a far greater impact on global health than previously thought, potentially contributing to over five million deaths a year and posing a similar threat to air pollution, modelling research suggested recently. The study, described as "a wake-up call", also estimated that exposure to the toxic metal causes young children in developing countries to lose an average of nearly six IQ points each. Lead pollution has been shown to cause a range of serious health problems, particularly relating to heart disease and the brain development of small children, resulting in leaded gasoline being banned worldwide. But people can still be exposed to the potent neurotoxin via food, soil, cookware, fertilisers, cosmetics, lead–acid car batteries and other sources. The researchers' model estimates that 5.5 million adults died from heart disease in 2019 because of lead exposure, 90 percent of them in low- and middle-income countries. That is six times higher than the previous estimate, and represents around 30 percent of all deaths from cardiovascular disease – the leading cause of death worldwide. It would mean that lead exposure is a bigger cause of heart disease than smoking or cholesterol.

https://www.businesswire.com/news/home/20230911634611/en/Pure-Earth....

https://www.thelancet.com/journals/lanplh/article/PIIS2542-5196(23)00166-3/fulltext

Comment by Dr. Krishna Kumari Challa on September 14, 2023 at 10:01am

Six of nine planetary boundaries now exceeded

A new study updates the planetary boundary framework and shows human activities are increasingly impacting the planet and, thereby, increasing the risk of triggering dramatic changes in overall Earth conditions.

For over 3 billion years, the interaction between life (represented by the planetary boundary, Biosphere Integrity) and climate have controlled the overall environmental conditions on Earth. Human activities, for example replacing nature with other land uses, changing the amount of water in rivers and in soil, the introduction of synthetic chemicals to the open environment, and the emission of greenhouse gases to the atmosphere all influence these interactions.

Respecting and maintaining interactions in the Earth system so that they remain similar to those that have controlled Earth conditions over the past ~12,000 years are critical for ensuring human activities do not trigger dramatic changes in Earth conditions—changes that likely would decrease the Earth's ability to support modern civilizations.

The nine "planetary boundaries" represent components of the global environment that regulate that stability and livability of the planet for people. The degree of breaching of the safe boundary levels is caused by human-driven activities impacting the components.

The planetary boundaries framework applies the newest scientific understanding of the functioning of the Earth system to identify a "safe operating space" for humanity by proposing limits for the extent to which human activities can be allowed to impact critical processes without risk of potentially triggering irreversible changes in the Earth conditions that support us.

For the first time, metrics for all boundaries are presented. Six of the boundaries are found to be transgressed, and transgression is increasing for all boundaries except the degradation of the Earth's ozone layer. A global focus on climate is not enough. Development of Earth system models that accurately reproduce interactions between boundaries, especially Climate and Biosphere Integrity, is an urgent priority.

The trend of increasing transgression of the boundaries is worrying.

Crossing six boundaries in itself does not necessarily imply a disaster will ensue but it is a clear warning signal. We can regard it as we do our own blood pressure. A BP over 120/80 is not a guarantee of a heart attack but it increases the risk of one. Therefore, we try to bring it down. For our own—and our children's—sakes we need to reduce the pressure on these six planetary boundaries.

The study, published in Science Advances, represents the third update of the framework carried out by 29 scientists from eight different countries.

Katherine Richardson, Earth beyond six of nine Planetary Boundaries, Science Advances (2023). DOI: 10.1126/sciadv.adh2458. www.science.org/doi/10.1126/sciadv.adh2458

Comment by Dr. Krishna Kumari Challa on September 14, 2023 at 9:37am

Exploit steals passwords by tapping into keystrokes

Add one more threat to the list of risks you take when you use your phone to conduct business at a local shop.

Researchers from universities in China and Singapore uncovered a security gap that permits snoops to lift your password by identifying your keystrokes.

Researchers are calling Wiki-Eve "the first WiFi-based hack-free keystroke eavesdropping system."

The cyberattack demonstrated by the researchers is made possible thanks to a feature in wireless communications called BFI, beamforming feedback information. BFI permits devices to more accurately transmit feedback about their location, sending signals specifically towards the routers that are to receive them, instead of dispersing them omnidirectionally. But one vulnerability of BFI, a component of the 802.11ac WiFi standard (also known as WiFi 5), is that it transmits data in cleartext. That means there is no need for physical hacking or cracking of an encryption key. The researchers devised a means of identifying a user's device and capturing the cleartext transmissions. Unlike older side-channel attacks, Wiki-Eve does not require planting rogue programs that trick a user into logging on to an illegitimate site. It also does not require setting up additional links to sense a target user's keystrokes. "Since BFI is transmitted from a smartphone to an AP [access point] in cleartext," the researchers said, "it can be overheard by any other Wi-Fi devices switching to monitor mode." Researchers said Wiki-Eve "achieves 88.9% inference accuracy for individual keystrokes and up to 65.8% top-10 accuracy for stealing passwords of mobile applications." Keystroke inference is the determination of what key is being pressed based on BFI data. As a user glides over keys on a keypad, the variations in wireless signals between device and base station can be tracked and identified with the aid of a deep-learning model. The team ran tests using numerical passwords since they are easier to decipher than alphanumeric passwords. They demonstrated Wiki-Eve by successfully lifting WeChat Pay passwords from a subject in a nearby conference room. Wiki-Eve joins a long list of side-channel attack methods. Such methods include acoustic cryptanalysis that interprets sounds produced by a device during transmission, cache attacks that probe access patterns, electromagnetic analysis that uses radiation to decipher information, and thermal attacks that track temperature variations to reveal activities. The study assumed users were engaging in activity over an unprotected network, common in public spaces such as coffeeshops, airports, train stations and other gathering places offering free WiFi.

Jingyang Hu et al, Password-Stealing without Hacking: Wi-Fi Enabled Practical Keystroke Eavesdropping, arXiv (2023). DOI: 10.48550/arxiv.2309.03492

Comment by Dr. Krishna Kumari Challa on September 13, 2023 at 12:44pm

'Hybrid' Brain Cells Have Been Discovered Hiding Inside Our Heads

An international team of scientists has found a whole new brand of brain cell hiding amongst neurons and their supporting units.

Surprisingly, the new cell type has characteristics of both, allowing it to serve an active role in neurological functions while still providing assistance to the nervous tissues around it.

Astrocytes are abundant cells in the brain that wrap around neuronal connections like 'glue'. For many years, neuroscientists assumed these cells were wholly passive, present only to protect neurons. The field was revolutionized when evidence arose that astrocytes may contribute to neuronal 'firing' by secreting glutamate, the brain's main neurotransmitter. But while studies in the lab suggest astrocytes are capable of releasing and absorbing glutamate, their role in a living, healthy brain is still being investigated. In exploring that hypothesis further, researchers from various institutions in the United Kingdom and Europe have stumbled upon a radical hybrid cell in the brains of mice. In between neurons and astrocytes, we now have a new kind of cell .

https://www.nature.com/articles/s41586-023-06502-w

Comment by Dr. Krishna Kumari Challa on September 13, 2023 at 12:41pm

Paleontologists May Have Found A Missing Branch Between Dinosaurs And Birds

Amidst remains of turtles and fish preserved in a southeastern China fossil bed, scientists have uncovered the skeleton of a dinosaur with curious bird-like features. Estimated to be roughly 30 million years older than any confirmed bird fossil, the finding could tell us a thing or two about the first critical steps into their evolution.

Researchers compared the new fossil, named Fujianvenator prodigiosus, with the remains of other dinosaurs from that time and more modern ones to identify the animal's place within the dino-bird family tree. The researchers determined the pheasant-sized and likely feathered Fujianvenator prodigiosus belonged to the ancestral group avialae which includes modern birds and their most closely related dinosaur ancestors. Remains of early bird ancestors like this are hard to come by, so they each hold important clues to the evolution of birds and the environment of Earth they experienced. 

For decades, the preserved 150-million-year-old remains of a dinosaur called Archaeopteryx defined a critical early moment in the evolution of modern birds.

Now, researchers aren't so sure, finding the famously feathered creature has more in common with a group called Deinonychosauria than Avialae. With few other convincing bird-like fossils from this time, researchers can only guess at what such an early bird might have looked like. Appearing just a few million years after Archaeopteryx, Fujianvenator might have at least a few answers, straddling the line between ancient dinosaur and more modern birds. The pelvis of Fujianvenator has features that are more similar to the less-bird-like dinosaurs, including the strange four-winged Anchiornis. This means that the morphological transition from arms to wings started really early on in bird ancestors, while legs were still doing different things, and suggests Fujianvenator branched off in a different direction than the one that led to birds.

This is the first time a potential swamp avialan has been identified. All the other avialans paleontologists have discovered so far have features of being tree dwellers.

https://www.nature.com/articles/s41586-023-06513-7

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