Comment

Comment by Dr. Krishna Kumari Challa on Wednesday

The brain clocks sickness from a mile off

The brain fires up immune cells when sick people are nearby

At the mere sight of a sick person, the brain kickstarts an immune response mimicking the body’s response to an actual infection. In a study, volunteers donned virtual reality headsets to view human avatars with rashes, coughs or other symptoms of illness. Researchers found that the sight of a sick person activates the brain’s ‘salience network’: a collection of regions involved in recognizing and responding to threats. This activity triggered a surge in innate lymphoid cells, which are part of the body’s first line of defence against invaders.

https://www.nature.com/articles/s41593-025-02008-y?utm_source=Live+...

Comment by Dr. Krishna Kumari Challa on Wednesday

Aging dampens lupus by reducing overactive immune genes in older adults

 Researchers have found that certain antiviral genes become less active over time in lupus, revealing why some patients see their symptoms fade as they age.

Lupus, an autoimmune disease, causes the immune system's first-line viral defenses—known as interferons—to attack the body. Nearly every organ is at risk, leading to conditions like kidney and heart disease.

But unlike many other autoimmune or chronic illnesses, lupus can improve as patients reach their 60s and 70s.

By analyzing blood samples from patients across the age spectrum, scientists discovered that aging turns down the activity of certain immune genes in people with lupus, leading to fewer interferons and other inflammatory proteins in the body.

The study found that in healthy adults, inflammation-related genes and proteins rose slowly over the years, a process that has been dubbed "inflammaging." In patients with lupus, however, the expression of these genes and proteins was abnormally high in midlife but decreased as the decades went by.

"Inflammaging seemed to be reversed in the lupus patients", say the researchers.

"But it wasn't fully reversed. The lupus patients still had a greater level of inflammatory signaling compared to healthy adults in older age."

Rithwik Narendra et al, Epigenetic attenuation of interferon signaling is associated with aging-related improvements in systemic lupus erythematosus, Science Translational Medicine (2025). DOI: 10.1126/scitranslmed.adt5550

Comment by Dr. Krishna Kumari Challa on Wednesday

Australopithecus afarensis, which lived between 3.9 and 2.9 million years ago, is widely regarded as either a direct ancestor of modern humans or a species very closely related to a direct ancestor.

Yet, its high degree of sexual dimorphism suggests that early hominins may have lived in social systems that were far more hierarchical and competitive than once thought.

Meanwhile, the less dimorphic A. africanus—which overlapped in time with A. afarensis but first shows up and last appears in the fossil record slightly later, between roughly 3.3 and 2.1 million years ago—may represent a different evolutionary branch on the hominin tree, or perhaps a transitional stage in the development of more human-like social behavior.
We typically place these early hominins together in a single group called the gracile australopiths, a group of species that are thought to have interacted with their physical and social environments in very similar ways.
while that's true to a certain extent—the evidence suggests that both these species may have had social organizations more like gorillas than modern people—the significant difference in the amount of dimorphism in these two extinct species suggests that these closely related hominin species were subject to selection pressures more distinct than the selection pressures applied to any pair of similarly closely related living ape species, highlighting the diversity of ways that our extinct ancestors and close relatives interacted with the world.

 Adam D. Gordon, Sexual Size Dimorphism in Australopithecus: Postcranial Dimorphism Differs Significantly Among Australopithecusafarensis, A. africanus, and Modern Humans Despite Low‐Power Resampling Analyses, American Journal of Biological Anthropology (2025). DOI: 10.1002/ajpa.70093

Part 3

Comment by Dr. Krishna Kumari Challa on Wednesday

Sexual size dimorphism (SSD) isn't just a physical trait—it reveals something deeper about behavior and evolutionary strategy. Consistent with sexual selection theory, high SSD in living primates typically correlates with strong male–male competition and social structures allowing for polygynous mating systems, where one or a few large males monopolize reproductive access to multiple females.

In contrast, low SSD can be found in any species, but tends to be found in those with pair-bonded social structures and low competition for mating opportunities. Modern human populations exhibit low to moderate SSD, where males tend to be slightly larger than females on average but with substantial overlap in size between the sexes.

High SSD in living primates can also be associated with intense resource stress—when food is scarce, small healthy females can get enough food to meet their own metabolic needs and store energy for reproduction faster than larger females can, leading to more offspring with smaller mothers in the next generation and a resulting greater difference in male and female size.

The high SSD identified in both Australopithecus species suggests a high degree of competition among males, similar to that of chimpanzees or even gorillas, while the difference between the two fossil species may be due to a difference in the intensity of those forces of sexual selection and/or a difference in the intensity of resource stress in their environments (e.g., a difference in the length of dry seasons with low fruit availability) and its impact on female body size.

In any event, the high SSD in these fossil hominins contrasts sharply with the more balanced size seen in modern humans and offers a glimpse into a different model of early hominin life—one where large size may have been a key factor in male reproductive success for competitive reasons, and small size may have been a key factor for females for energetic reasons.

Part 2

Comment by Dr. Krishna Kumari Challa on Wednesday

Early human ancestors showed extreme size differences between males and females

A newly published study has found that males of some of our earliest known ancestors were significantly larger than females. The pronounced difference in body size present in both Australopithecus afarensis (the East African species that includes the famous fossil "Lucy") and A. africanus (a closely related southern African species) suggests the ancient hominins may have lived in social systems marked by intense competition among males, leading to the substantial size disparity among the sexes.

The research  appears in the July issue of the American Journal of Biological Anthropology. Using a novel approach that overcomes the limitations of incomplete fossil records, the study reveals that both A. afarensis and A. africanus were more sexually dimorphic than modern humans—and in some cases, even more than gorillas.

These weren't modest differences. In the case of A. afarensis, males were dramatically larger than females—possibly more so than in any living great ape. And although both of these extinct hominin species exhibited greater sex-specific size differences than modern humans do, they were also more different from each other in this respect than living ape species are, suggesting a greater diversity of evolutionary pressures acting on these closely related species than we had previously appreciated.

The results add new depth to interpretations of the fossil record. Earlier studies had reached differing conclusions about dimorphism in A. afarensis, with some suggesting it resembled the relatively low levels seen in modern humans. Furthermore, direct comparison between fossil species had not previously been made because investigations were limited by incomplete fossil samples and insufficient statistical power to detect real differences.

This analysis overcomes these issues by using an iterative resampling method that mimics the missing data structure in both fossil species when sampling from skeletal material of living species, allowing the inclusion of multiple fossil individuals even when those individual specimens are fragmentary.

This study provides strong evidence that sex-specific evolutionary pressures—likely involving both male competition for mates and resource stress acting more intensely on female size due to the metabolic constraints of pregnancy and lactation—played a larger role in early hominin evolution than previously thought. 

Part 1

Comment by Dr. Krishna Kumari Challa on Wednesday

About 82% of deaths averted occurred among individuals vaccinated before any infection and 57% during the omicron period. Persons aged 60 years or older accounted for 89.6% of lives saved, with children and adolescents contributing just 0.01%. Sensitivity analyses yielded a range of 1.4–4.0 million deaths and 7.4–23.6 million life-years saved.

Life-year benefits tracked a similar age gradient with individuals over 60 making up 76% of the total years saved, with negligible contributions (<0.5 %) from those under 30. Long‑term‑care residents, who accounted for 11.8 % of deaths averted, only added 2% to life‑years saved. Authors conclude that vaccination offered a clear mortality benefit during 2020–2024, largely among older adults, and describe their estimates as conservative.

John P. A. Ioannidis et al, Global Estimates of Lives and Life-Years Saved by COVID-19 Vaccination During 2020-2024, JAMA Health Forum (2025). DOI: 10.1001/jamahealthforum.2025.2223

Part 2

Comment by Dr. Krishna Kumari Challa on Wednesday

Global analysis finds 14.8 million life-years added by COVID-19 vaccinations

A Stanford University-led investigation into the COVID-19 vaccination effort reports that it averted an estimated 2.533 million deaths and 14.8 million life-years worldwide between 2020 and 2024.

Amidst much controversy in the public sphere, a worldwide vaccination campaign took place to counter the novel and deadly COVID-19 virus as it spread to every corner of the globe. As the pandemic spread, so did misinformation, disinformation, and real-time updates on risk and prevention that occasionally changed as events unfolded.

Around 7 million people died as a direct result of the virus. Estimating the human toll prevented by vaccines remains a crucial question, both for  public education and for future public health planning.

In the study, "Global Estimates of Lives and Life-Years Saved by COVID-19 Vaccination During 2020-2024," published in JAMA Health Forum, researchers conducted a comparative-effectiveness analysis to quantify life-saving effects attributable to vaccination from December 2020 through October 1, 2024.

Nearly 8 billion individuals (the 2021 world population) served as the study cohort, partitioned by seven age tiers: community versus long-term-care residence, and pre-omicron versus omicron periods.

Investigators estimated deaths averted by multiplying stratum-specific population, projected infection proportion, infection fatality rate, and vaccine effectiveness; life-year gains combined those results with life expectancy and a health-status adjustment factor.

Findings show 2.533 million lives saved, equating to one death averted per 5,400 vaccine doses. Life-year gains reached 14.8 million, or one life-year per 900 doses.

Part 1

Comment by Dr. Krishna Kumari Challa on Wednesday

Rigid and negative thought patterns linked to increasing political polarization online

The ideological divide between opposing political groups has been drastically increasing in various countries worldwide. This phenomenon, known as political polarization, can lead to greater social division, extremism and political violence.

Researchers  recently carried out a study aimed at better understanding the psychology of political polarization and, more specifically, the thought patterns associated with extreme and opposing political views. Their findings, published in Communications Psychology, unveiled a link between the rising political polarization online and distorted ways of thinking often associated with some mental health disorders, including anxiety and depression.

Distorted thinking appeared to precede polarization in some cases. This suggests that how we think—emotionally and cognitively—may be a key driver of polarization, not just what we believe. Of course, their observations do not imply causality.

Andy Edinger et al, Cognitive distortions are associated with increasing political polarization, Communications Psychology (2025). DOI: 10.1038/s44271-025-00289-4

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Comment by Dr. Krishna Kumari Challa on Tuesday

Scientists grow novel 'whole-brain' organoid

Researchers have grown a novel whole-brain organoid, complete with neural tissues and rudimentary blood vessels—an advance that could usher in a new era of research into neuropsychiatric disorders such as autism.

The research, published in Advanced Science, marks one of the first times scientists have been able to generate an organoid with tissues from each region of the brain connected and acting in concert. Having a human cell-based model of the brain will open possibilities for studying schizophrenia, autism, and other neurological diseases that affect the whole brain—work that typically is conducted in animal models.

Anannya Kshirsagar et al, Multi‐Region Brain Organoids Integrating Cerebral, Mid‐Hindbrain, and Endothelial Systems, Advanced Science (2025). DOI: 10.1002/advs.202503768

Comment by Dr. Krishna Kumari Challa on Tuesday

Changes in female body odor during ovulation elicit measurable reactions in men, finds study

Researchers explored how female body odor can influence behaviors in men. They found that certain scent compounds in female body odor increased during ovulation and can subtly influence how men feel.

When these scents were added to armpit odor samples, men rated them as more pleasant and faces associated with the samples as more attractive. The scents also seemed to reduce stress. The team states this is not evidence of pheromones in humans, but that smell might subtly shape how people interact.

This study show something measurable and interesting is happening, analogous to the idea of pheromones.

The researchers  identified three body odor components that increased during women's ovulatory periods. When men sniffed a mix of those compounds and a model armpit odor, they reported those samples as less unpleasant, and accompanying images of women as more attractive and more feminine.

Furthermore, those compounds were found to relax the male subjects, compared to a control, and even suppressed the increase in the amount of amylase (a stress biomarker) in their saliva. These results suggest that body odor may in some way contribute to communication between men and women.

Previous studies by different groups have already discovered that female body odor changes throughout the menstrual and that the changes in the ovulatory phase can be perceived by men and are reported as being pleasant. But the specific nature of these odors went unidentified and is something this latest study managed to achieve.

 These tests were done "blind," meaning the participants did not receive any hints about what they were smelling or why, with some participants being given nothing at all as a measure of control.

This way, psychological factors and expectations were reduced or eliminated.

But the researchers say they cannot conclusively say at this time that the compounds they found which increase during the ovulation period are human pheromones. 

Human ovulatory phase-increasing odors cause positive emotions and stress-suppressive effects in males, iScience (2025). DOI: 10.1016/j.isci.2025.113087

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