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Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 9:29am

Two ancient human species came out of Africa together, not one, suggests new study

The textbook version of the "Out of Africa" hypothesis holds that the first human species to leave the continent around 1.8 million years ago was Homo erectus. But in recent years, a debate has emerged suggesting it wasn't a single species, but several. New research published in the journal PLOS One now hopes to settle the matter once and for all.

The debate centers on the Dmanisi fossils, five skulls found in the Republic of Georgia between 1999 and 2005, which belong to some of the oldest humans ever found outside Africa. The problem is that they don't look alike. Some are larger than others, particularly Skull 5, which has a tiny braincase but a massive, protruding face. Some researchers explain this as a difference in sexes within the same species, while others argue that it represents two distinct species living together.

To provide much-needed clarity, researchers studied the teeth of three Dmanisi specimens. The reason is that, generally, skulls are not always the best species identifiers because bone is fragile and can be warped and crushed. Dentition is far more useful because enamel is the hardest biological substance produced by humans, and everything from the shape and size of individual teeth can be used to identify a species.

The team focused on the surface area (dental crown) of the back teeth (premolars and molars) of the Dmanisi specimens that had sufficient dental remains for analysis. They compared these to a database of 122 other fossil specimens, including Australopithecus and several other Homo species. Then, using a statistical sorting tool, they analyzed 583 teeth to create a biological map and determine whether the Dmanisi fossils belonged to a single family or to other branches of our family tree.

The map revealed that these ancient remains were not from a single group. Skull 5, with its large jaw, was grouped with Australopiths, a more primitive ape-like ancestor. The other two specimens were more human-like. Because of this, the study authors support using the names Homo georgicus for Skull 5 and Homo caucasi for the human-like group.
To ensure the differences weren't just between males and females, the team compared the fossils with those of great apes. In some animals, like gorillas, males are much larger than females but still have the same basic teeth. The differences between the Dmanisi teeth were so great that male-female differences within the same group couldn't explain them.
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Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 8:43am

Scientists chart over 140,000 DNA loops to map human chromosomes in the nucleus
Over 140,000 DNA looping interactions were mapped in human embryonic stem cells and fibroblasts, providing a detailed 3D organization of chromosomes within the nucleus. Computational models now predict genome folding from DNA sequence alone, clarifying how chromatin loops influence gene regulation and how genetic variations may alter genome structure and function.

Job Dekker et al, An integrated view of the structure and function of the human 4D nucleome, Nature (2025). DOI: 10.1038/s41586-025-09890-3

Elzo de Wit, Systematic maps reveal how human chromosomes are organized, Nature (2025). DOI: 10.1038/d41586-025-03808-9

Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 8:40am

People are getting their news from AI—and it's altering their views

Large language models increasingly shape public opinion by generating news content and summaries, often introducing subtle communication bias by emphasizing certain viewpoints while minimizing others, even when information is accurate. This bias stems from model design, training data, and market concentration. Current regulations focus on harmful outputs but are less effective against nuanced framing biases, highlighting the need for greater competition, transparency, and user involvement.

 Read the original article.

Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 8:37am

Biodegradable electronics can break down into harmful microplastics
Some materials used in biodegradable electronics, such as PEDOT:PSS, can persist for years and degrade into microplastics, raising environmental concerns. In contrast, polymers like cellulose and silk fibroin degrade more safely. The environmental impact of both material choice and manufacturing processes is significant, highlighting the need for sustainable, circular approaches in electronics production.

Sofia Sandhu et al, End-of-Life usefulness of degradation by products from transient electronics, npj Flexible Electronics (2025). DOI: 10.1038/s41528-025-00411-w

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Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 8:33am

More eyes on the skies can help planes reduce climate-warming contrails

Aviation's climate impact is partly due to contrails—condensation that a plane streaks across the sky when it flies through icy and humid layers of the atmosphere. Contrails trap heat that radiates from the planet's surface, and while the magnitude of this impact is uncertain, several studies suggest contrails may be responsible for about half of aviation's climate impact.
Geostationary satellites detect only about 20% of contrails visible to low-Earth-orbiting satellites, primarily missing smaller, younger contrails. Combining data from geostationary, low-Earth-orbit, and ground-based observations can provide a more complete understanding of contrail formation and evolution, supporting more effective contrail avoidance strategies to mitigate aviation's climate impact.

Pilots could conceivably reduce their planes' climate impact by avoiding contrail-prone regions, similarly to making altitude adjustments to avoid turbulence. But to do so requires knowing where in the sky contrails are likely to form.

To make these predictions, scientists are studying images of contrails that have formed in the past. Images taken by geostationary satellites are one of the main tools scientists use to develop contrail identification and avoidance systems.

But a new study shows there are limits to what geostationary satellites can see.

Researchers analyzed contrail images taken with geostationary satellites, and compared them with images of the same areas taken by low-Earth-orbiting (LEO) satellites. LEO satellites orbit Earth at lower altitudes and therefore can capture more detail. However, since LEO satellites only snap an image as they fly by, they capture images of the same area far less frequently than geostationary (GEO) satellites, which continuously image the same region of Earth every few minutes.

The researchers found that geostationary satellites miss about 80% of the contrails that appear in LEO imagery. Geostationary satellites mainly see larger contrails that have had time to grow and spread across the atmosphere. The many more contrails that LEO satellites can pick up are often shorter and thinner. These finer threads likely formed immediately from a plane's engines and are still too small or otherwise not distinct enough for geostationary satellites to discern. The study highlights the need for a multiobservational approach in developing contrail identification and avoidance systems. The researchers emphasize that both GEO and LEO satellite images have their strengths and limitations.

Observations from both sources, as well as images taken from the ground, could provide a more complete picture of contrails and how they evolve.

With more 'eyes' on the sky, we could start to see what a contrail's life looks like, the researchers conclude.

 Marlene V. Euchenhofer et al, Contrail Observation Limitations Using Geostationary Satellites, Geophysical Research Letters (2025). DOI: 10.1029/2025gl118386

Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 8:24am

PFAS concentrations can double with every step up the food chain
PFAS concentrations increase twofold on average with each step up the food chain, resulting in significantly higher levels in top predators and humans. Analysis of 119 global food webs shows substantial variation among PFAS compounds, with some newer alternatives magnifying even more than legacy chemicals. These findings highlight the need for compound-specific regulation and further research into health impacts.

The authors examined 119 aquatic and terrestrial food webs across the globe, finding that top predators such as large fish, seabirds, and marine mammals can accumulate PFAS concentrations exponentially larger than the environments in which they're found. The study is published in the journal Nature Communications.

PFAS concentrations double, on average, with each step up the food chain.

Known as "forever chemicals," PFAS are from a family of more than 12,000 man-made compounds.
These chemicals are prized for their heat resistance and water-repelling properties, and are used in cleaning products, food packaging, non-stick pans, clothing, and fire-fighting equipment.

Since being discovered by the American chemical company DuPont in the 1930s, PFAS are now detectable in the bloodstream of almost every human being on the planet.

Unlike other chemicals, PFAS never break down, meaning that throughout the world right now, they're building up in environments, plants, and animals on land and in the ocean.

For humans, sitting as we do at the top of the food chain, this means our diets can be an important pathway for PFAS exposure.

Given what we know about PFAS toxicity from other studies, these extreme accumulation rates in top predators suggest serious health risks. This creates a cascading ecological risk: Apex predators face disproportionately high exposure even in relatively low-contaminated environments.

Some compounds—including chemicals marketed as safer alternatives to existing products—showed even higher magnification than the chemicals they were designed to replace.

 Lorenzo Ricolfi et al, Unravelling the magnitude and drivers of PFAS trophic magnification: a meta-analysis, Nature Communications (2025). DOI: 10.1038/s41467-025-65746-4

Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 8:16am

How chirality goes from the molecular level to the cellular one

Researchers have discovered how right-handed molecules in our cells can give rise to cells that are not symmetrical about their central axes. This discovery is a key step toward determining why most of our organs lack left–right symmetry.

It's conceivable that if some molecules that make up our cells were twisted in the opposite direction, our hearts would be on the right side of our bodies rather than on the left.

That's because the difference between the left and right sides of our organs may originate from the "handedness," or chirality, of cells, which in turn comes from the chirality of molecules in cells.

However, the link between the chirality of molecules and cellular chirality is largely unknown. Many molecules in cells are chiral, including DNA and some amino acids and proteins, but it's not clear which ones convey their chirality to cells.

 By studying the chiral behaviours of individual cells, researchers have found that the cells' scaffolding, or cytoskeleton, gives rise to the cell's chirality. The findings are published in the journal eLife.

When single cells were placed on a substrate, their nuclei and surrounding cytoplasm rotated in a clockwise direction when viewed from above. This rotational motion is driven by the concentric pattern of the actomyosin filaments that make up the cytoskeleton.

This finding implies that the cell nucleus can rotate even when there is no chiral orientation of the cytoskeleton on a cellular level.
To confirm whether this mechanism was driving the rotation, the team created a 3D theoretical model of a cell and evaluated the effect of the molecular chirality of actin and myosin on it. The results revealed that the molecular scale torque generated by individual components of the cytoskeleton can generate rotation, even when cell-level chiral structures were absent.

These results help fill in a critical link in the chain from molecules to organs and bodies, the researchers say.

 Takaki Yamamoto et al, Epithelial cell chirality emerges through the dynamic concentric pattern of actomyosin cytoskeleton, eLife (2025). DOI: 10.7554/elife.102296

Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 8:11am

Scientists who use AI tools are publishing more papers than ever before

Science is entering a massive publishing boom, in large part due to artificial intelligence. New research published in the journal Science has revealed that scientists who use large language models (LLMs) like ChatGPT are producing significantly more papers across many fields. The technology is also helping to level the playing field for researchers whose first language isn't English.

The growing use of AI in scientific research has sparked concerns about shoddy work and machines making things up. But this new analysis also reveals that papers produced with LLMs use more complex language and cite a wider array of sources.

They found that when scientists use AI, their productivity soared. The biggest jump was in the social sciences and humanities, where output increased by 59.8%, while biology and life sciences saw a 52.9% increase. Meanwhile, in physics and math, the scientists report a 36.2% boost. "LLM adoption is associated with a large increase in researchers' scientific output," wrote the research team in their paper.

One of the most fascinating findings was the massive increase in productivity from non-English-speaking countries. Most top journals require manuscripts to be written in high-level English, which has long disadvantaged these scientists. But with AI handling some of the workload, researchers from Asia saw their output jump by as much as 89% in some cases.
However, the study authors also issued a warning regarding AI and quality. While the machines can make papers sound more professional, this can be a trap. Historically, sophisticated writing was a sign of high-quality research, but now the opposite can sometimes be true. The study found that the more complex the AI-generated writing was, the less likely the paper was to be high quality. In other words, good writing can mask weak ideas.

The clear message from the study authors is that we can no longer judge a paper by how smart the language appears. "As traditional heuristics break down, editors and reviewers may increasingly rely on status markers such as author pedigree and institutional affiliation as signals of quality, ironically counteracting the democratizing effects of LLMs on scientific production."

To safeguard scientific integrity, the researchers propose several measures, including that institutions implement deeper checks and even specialized "AI-based reviewer agents" to help distinguish between human writing and machine-generated writing.

 Keigo Kusumegi et al, Scientific production in the era of large language models, Science (2025). DOI: 10.1126/science.adw3000

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Comment by Dr. Krishna Kumari Challa on December 23, 2025 at 8:06am

 Natural daylight can help people with diabetes improve blood sugar levels

People with type 2 diabetes may be able to improve their blood sugar by doing something as simple as sitting by a window for a few hours each day. In a study published in Cell Metabolism, scientists showed that natural daylight helps maintain healthy glucose levels.

Daylight is known to be a mood enhancer and also beneficial for our health. However, according to the research team, most people living in Western societies typically stay indoors around 80% to 90% of the time under artificial light, which is not as bright or dynamic as sunlight. This is important because the human body operates on circadian rhythms, internal 24-hour clocks that orchestrate a range of biological processes, such as digestion and temperature regulation. These are synchronized by light, and a lack of natural light is a risk factor for type 2 diabetes.

Previous studies have shown that artificial light at night disrupts these rhythms and that daylight outdoors can improve the body's response to insulin, which helps control blood sugar levels. But no prior research examined how natural light entering a window affects people with diabetes.

To test this, researchers recruited 13 volunteers with type 2 diabetes to examine how their bodies responded to both natural window lighting and artificial indoor lighting. The participants spent two separate 4.5-day periods in a controlled office environment. In one session, they sat at a desk facing large windows from morning to late afternoon.
In the other, they were in the same room, with the windows blocked and only standard office lights. All participants ate similar meals three times a day and performed the same exercises at the same time across the two sessions. They also continued taking their medication.

The results revealed that while average glucose levels were similar across the two sessions, the participants spent significantly more time in the normal glucose range when exposed to natural daylight. The body's metabolism also changed. In daylight, the volunteers burned more fat for energy and fewer carbohydrates.

The researchers also took muscle biopsies and grew muscle cells in the lab. They found that genes involved in their internal cellular clocks were better aligned to the time of day under natural light. This suggested that sunlight was acting as a signal to keep the muscles "on time," making them better at processing nutrients.

Although this study involved only a handful of people, the results indicate that natural daylight can help reduce the sharp peaks and swings in blood sugar that often affect those with this condition. It offers a simple, natural way to support people with type 2 diabetes alongside existing treatments.

Jan-Frieder Harmsen et al, Natural daylight during office hours improves glucose control and whole-body substrate metabolism, Cell Metabolism (2025). DOI: 10.1016/j.cmet.2025.11.006

Comment by Dr. Krishna Kumari Challa on December 21, 2025 at 10:05am

Scientists observe 'extraordinary' seven-arm octopus
A rare deep-sea encounter captured footage of the seven-arm octopus, Haliphron atlanticus, at 700 meters depth in Monterey Bay. This species, with females reaching up to 4 m and 75 kg, primarily inhabits the ocean's twilight zone and feeds on gelatinous animals such as jellyfish, supporting previous observations of its unusual diet.

Hoving, H.J.T. and S.H.D. Haddock. 2017. The giant deep-sea octopus Haliphron atlanticus forages on gelatinous fauna. Scientific Reports, 7: 44952. https://doi.org/10.1038/srep44952

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