Comment

Comment by Dr. Krishna Kumari Challa on Monday

East Asian human gene that allows adult humans to digest sugars in milk likely came from Neanderthals

A small team of computational and evolutionary biologists  reports that unique lactase genes carried by about 25% of East Asian people may have been inherited from Neanderthals.

In their study published in Proceedings of the National Academy of Sciences, the group compared the genes of thousands of people of African, East Asian and European descent against one another and then against Neanderthal genes.

Prior research has shown that many people of European descent carry genes that allow them to easily digest the sugars (lactose) present in milk, in sharp contrast to people of East Asian descent, who tend to have a high percentage of lactose intolerance.

However, in this new effort, the research team found unique versions of the lactase gene in some East Asian people along with evidence that they may have come from interbreeding between humans and Neanderthals thousands of years ago.

The researchers compared thousands of genomes collected from people of known European, African or East Asian descent, looking for commonalities between people who were lactose intolerant and those who were not. They found that approximately 25% of the East Asian samples studied carried versions of lactase genes not found in the genes of African or European people.

That led them to then compare those lactase genes from East Asians with genes from Neanderthals. They found that the genes in the East Asian samples likely came from the Neanderthals. This was because the genes showed up in the early humans before they had begun to drink the milk of domesticated animals such as cows, which ruled that out as a source of selection.

Exploring how the Neanderthals might have developed the lactase genes, the team found evidence that they may have provided some degree of protection against infections, a finding that would also explain why the genes persisted in East Asians long after the disappearance of the Neanderthal.

Xixian Ma et al, Neanderthal adaptive introgression shaped LCT enhancer region diversity without linking to lactase persistence in East Asian populations, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2404393122

Comment by Dr. Krishna Kumari Challa on Saturday

Supercooling and the subsequent bubble formation were seen more often in narrower bottles. Comparing two bottles of different sizes filled with the same amount of water, the water in the smaller bottle cools down faster thanks to the larger surface it has per unit volume. This increases the chance of water cooling further below 0°C before it starts to freeze.
The second way to prevent trapped liquid pockets is to make sure that not the top surface, but the bottom of the container freezes first. So long as the top surface doesn't freeze over before the rest of the water does, the ice will simply expand into the open space above.
The team found that the shape of the water's surface plays a key role. In untreated glass containers, and in those coated with a layer that attracts water (being hydrophyilic), the water surface curves up against the glass. Thanks to the water molecules at the edge having less freedom to move, this region tends to be the first to freeze.

Water in containers with water-repelling (hydrophobic) coatings instead has a flat surface. Thanks to this, it is much more likely to freeze from the bottom up, preventing trapped liquid pockets from forming and reducing the risk of breakage.
If you don't want shattered bottles in your freezer, choose smaller bottles and ones with more water-repelling surfaces. (Many plastics are more water-repelling than glass—think of the PET bottles that many soft drinks come in, or of hard plastic like the PP used for Dopper bottles.) Beyond avoiding messy kitchen disasters, these new findings will also help with understanding and preventing frost damage in other places, including buildings, roads and historical artifacts.
But I don't recommend plastic bottles at all! This is not  good advice!

Menno Demmenie et al, Damage due to ice crystallization, Scientific Reports (2025). DOI: 10.1038/s41598-025-86117-5

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Comment by Dr. Krishna Kumari Challa on Saturday

To understand this process, the researchers used a special dye, methylene blue, to track freezing in open cylindrical glass containers. The dye easily dissolves in water and turns it blue. The dye becomes transparent when the water freezes, as it gets pushed out of the ice crystals. This allows the researchers to see exactly when and where ice forms.

Having filmed tens of samples of blue-dyed water freezing in a—30°C environment, the researchers cracked the case. Ice breaks glass when the top surface of the water—the one open to air—freezes first. The rest of the water naturally freezes from the outside in, creating a pocket of liquid water surrounded by ice on all sides. When this pocket freezes too, it exerts an extreme amount of pressure on its surroundings, in many cases enough to break glass.
The researchers estimate the pressure exerted by the ice in their experiments to be around 260 megapascals, enough to dent high-strength steel and four times as much as their glass vials can withstand.
By testing glass containers of different sizes and with different surface coatings, the research team discovered that there are two ways to reduce the risk of trapped pockets of water forming.

The first way is to ensure the water gets colder before it begins to freeze. While water can start freezing at 0°C, it is possible for liquid water to get "supercooled" to subzero temperatures. Freezing needs to start somewhere, and the start of the phase transition can be delayed.

Supercooled water freezes differently than water that freezes closer to the freezing point. Rather than growing as a crystalline block, it freezes along fingerlike branches ("dendrites"). In the experiments, this type of freezing turns the dyed water a darker shade of blue before it freezes completely.

The researchers discovered that this unusual ice growth results in a large amount of small air bubbles getting trapped within the ice, something which appears to relieve enough pressure to prevent fracturing.
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Comment by Dr. Krishna Kumari Challa on Saturday

Preventing freezer bottle explosions: New insights into ice crystallization and pressure

Have you ever left a bottle of liquid in the freezer, only to find it cracked or shattered? To save you from tedious freezer cleanups, researchers at the University of Amsterdam have investigated why this happens, and how to prevent it. They discovered that while the liquid is freezing, pockets of liquid can get trapped inside the ice. When these pockets eventually freeze, the sudden expansion creates extreme pressure—enough to break glass.

The usual explanation for frost damage is that water expands when it freezes, but this does not explain why half-filled bottles also burst in our freezers. This new work addresses how ice can break a bottle even when it has plenty of space to expand into. Part 1

Comment by Dr. Krishna Kumari Challa on Saturday

Researchers did not observe any instances of fusion, where the membrane of the cell and the membrane of the extracellular vesicle fuse together until the vesicle can enter the target cell.

Typically, endocytosis is facilitated with a protein called clathrin, but clathrin was not involved in the absorption of small extracellular vesicles into their target cells. Instead, it was a pair of proteins called galectin-3 and LAMP-2C, which are found on the membrane surface of the small extracellular vesicles.
The findings revealed that extracellular vesicles derived from several cancer cells are categorized into distinct subtypes.
All the subtypes of extracellular vesicles were primarily internalized by clathrin-independent endocytosis via galectin-3, which was facilitated by an increase in intracellular calcium concentration induced by the binding of extracellular vesicles to the target cells.
This process where a cell secretes a protein that aids in the absorption into a recipient cell from a different cell line is called paracrine binding or paracrine adhesion signaling. It is in contrast to an autocrine binding, which would be a cell secreting a protein so that it can bind to cells from the same cell line.

By better understanding the process by which small extracellular vesicles are brought into target cells, researchers are hopeful that the vesicles could be used to modify recipient cells and develop new cancer-fighting drugs.

Koichiro M. Hirosawa et al, Uptake of small extracellular vesicles by recipient cells is facilitated by paracrine adhesion signaling, Nature Communications (2025). DOI: 10.1038/s41467-025-57617-9

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Comment by Dr. Krishna Kumari Challa on Saturday

Cancer's hidden messengers: How extracellular vesicles aid tumor spread

In recent years, extracellular vesicles have attracted attention as a carrier of intercellular signaling.

Most cells in the body send out little messengers called extracellular vesicles that carry proteins, lipids, and other bioactive molecules to other cells, playing an important role in intercellular communication. But healthy cells are not the only ones that rely on extracellular vesicles. Cancer cells do, too. Small extracellular vesicles that are shed from tumor cells contribute to how cancer spreads to healthy tissue.

These small messengers could be a key to developing new cancer-fighting drugs and therapies, but it has been unclear how exactly the recipient cells absorb the extracellular vesicles and their cargo. Recent research used state-of-the-art imaging to observe the uptake of tumor-derived small extracellular vesicles by target cells. The results were published in Nature Communications on March 12, 2025.

Researchers focused on small extracellular vesicles derived from two different tumor cell lines. Using single-particle imaging with single-molecule detection sensitivity, a high-tech imaging technique, they were able to categorize the small extracellular vesicles into distinct subtypes. They then tracked the internalization pathway of the extracellular vesicles, or how the vesicles were absorbed into their recipient cells.

Most small extracellular vesicles were internalized into their target cells through a process called endocytosis. Previously, researchers suspected that the primary mechanism was fusion. During endocytosis, the target cell's membrane completely surrounds the extracellular vesicle, creating a kind of bubble around the vesicle. This allows it to be absorbed through the membrane so its cargo can be deposited into the target cell.

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Comment by Dr. Krishna Kumari Challa on Saturday

Some scholars have proposed that language capacity dates back a couple of million years, based on the physiological characteristics of other primates. But to the researchers of this study, the question is not when primates could utter certain sounds; it is when humans had the cognitive ability to develop language as we know it, combining vocabulary and grammar into a system generating an infinite amount of rules-based expression.
Human language is qualitatively different because there are two things, words and syntax, working together to create this very complex system. No other animal has a parallel structure in their communication system. And that gives us the ability to generate very sophisticated thoughts and to communicate them to others, they argue.
This conception of human language origins also holds that humans had the cognitive capacity for language for some period of time before we constructed our first languages.

Language is both a cognitive system and a communication system. Prior to 135,000 years ago, it did start out as a private cognitive system, but relatively quickly that turned into a communications system.
So, how can we know when distinctively human language was first used? The archaeological record is invaluable in this regard. Roughly 100,000 years ago, the evidence shows, there was a widespread appearance of symbolic activity, from meaningful markings on objects to the use of fire to produce ocher, a decorative red color.
Like our complex, highly generative language, these symbolic activities are engaged in by people, and no other creatures. As the paper notes, "behaviors compatible with language and the consistent exercise of symbolic thinking are detectable only in the archaeological record of H. sapiens.
So Language was the trigger for modern human behavior. Somehow, it stimulated human thinking and helped create these kinds of behaviors. If we are right, people were learning from each other [due to language] and encouraging innovations of the types we saw 100,000 years ago.
To be sure, as the authors acknowledge in the paper, other scholars think there was a more incremental and broad-based development of new activities around 100,000 years ago, involving materials, tools, and social coordination, with language playing a role in this, but not necessarily being the central force.

Shigeru Miyagawa et al, Linguistic capacity was present in the Homo sapiens population 135 thousand years ago, Frontiers in Psychology (2025). DOI: 10.3389/fpsyg.2025.1503900

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Comment by Dr. Krishna Kumari Challa on Saturday

The new paper examines 15 genetic studies of different varieties, published over the past 18 years: three used data about the inherited Y chromosome, three examined mitochondrial DNA, and nine were whole-genome studies.

All told, the data from these studies suggest an initial regional branching of humans about 135,000 years ago. That is, after the emergence of Homo sapiens, groups of people subsequently moved apart geographically, and some resulting genetic variations have developed, over time, among the different regional subpopulations.

The amount of genetic variation shown in the studies allows researchers to estimate the point in time at which Homo sapiens was still one regionally undivided group.
The studies collectively provide increasingly converging evidence about when these geographic splits started taking place.

The first survey of this type was performed by other scholars in 2017, but they had fewer existing genetic studies to draw upon. Now, there are much more published data available, which, when considered together, points to 135,000 years ago as the likely time of the first split.
This new meta-analysis was possible because quantity-wise we have more studies, and quality-wise, it's a narrower window [of time].
Many linguists think all human languages are demonstrably related to each other.
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Comment by Dr. Krishna Kumari Challa on Saturday

Genomic study indicates our capacity for language emerged 135,000 years ago

 When did human language as we know it emerge? A new survey of genomic evidence suggests our unique language capacity was present at least 135,000 years ago. Subsequently, language might have entered social use 100,000 years ago.

Our species, Homo sapiens, is about 230,000 years old. Estimates of when language originated vary widely, based on different forms of evidence, from fossils to cultural artifacts. The authors of the new analysis took a different approach. They reasoned that since all human languages likely have a common origin—as the researchers strongly think—the key question is how far back in time regional groups began spreading around the world.

The logic is simple: Every population branching across the globe has human language, and all languages are related.

Based on what the genomics data indicate about the geographic divergence of early human populations. So we can say with a fair amount of certainty that the first split occurred about 135,000 years ago, so human language capacity must have been present by then, or before.

The paper based on this argument, "Linguistic capacity was present in the Homo sapiens population 135 ...," appears in Frontiers in Psychology.

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Comment by Dr. Krishna Kumari Challa on Saturday

Scientists propose another possibility with this research. The researchers first investigated how droplets of water developed different charges when divided by a spray or splash.

They found that larger droplets often carried positive charges, while smaller ones were negative. When the oppositely charged droplets came close to each other, sparks jumped between them. The researchers call this "microlightning," since the process is related to the way energy is built up and discharged as lightning in clouds. The researchers used high-speed cameras to document the flashes of light, which are hard to detect with the human eye.

Even though the tiny flashes of microlightning may be hard to see, they still carry a lot of energy. The researchers demonstrated that power by sending sprays of room-temperature water into a gas mixture containing nitrogen, methane, carbon dioxide, and ammonia gases, which are all thought to be present on early Earth.
This resulted in the formation of organic molecules with carbon-nitrogen bonds, including hydrogen cyanide, the amino acid glycine, and uracil.

The researchers argue that these findings indicate that it was not necessarily lightning strikes, but the tiny sparks made by crashing waves or waterfalls that jump-started life on this planet.
On early Earth, there were water sprays all over the place—into crevices or against rocks, and they can accumulate and create this chemical reaction, they say. We usually think of water as so benign, but when it's divided in the form of little droplets, water is highly reactive.

Yifan Meng et al, Spraying of Water Microdroplets Forms Luminescence and Causes Chemical Reactions in Surrounding Gas, Science Advances (2025). DOI: 10.1126/sciadv.adt8979. www.science.org/doi/10.1126/sciadv.adt8979

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