Pigeon Magnetic Detection - Fish Sleep - Vision Model - GLP1 Rapid Weight Loss

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May 30, 2026, 7:11:34 AMMay 30

https://www.sciencenews.org/article/pigeon-navigation-iron-liver-cells

Homing pigeons may use a surprising navigation mechanism

By Elizabeth Pennisi

Homing pigeons don’t rely on gut instinct to return to the roost. But a nearby organ — the liver — might point the way.

White blood cells in the birds’ livers accumulate iron and act as an internal compass when clouds block the sun that normally helps them navigate, researchers report May 28 in Science. While scientists generally agree that some animals use Earth’s magnetic field to guide migrations, they had not pinned down how, and the new work offers a surprising explanation.

For decades, researchers have fiercely debated first if and then how birds sense magnetic fields and use them for navigation. One prominent idea involves proteins in their eyes undergoing a reaction in magnetic fields. No one has been able to prove exactly how this so-called “quantum effect” is in play. Other animals that orient using Earth’s magnetism, such as bats and sharks, lack the proteins, so the debate languished unresolved.

Ornithologist Martin Wikelski of the Max Planck Institute of Animal Behavior in Radolfzell, Germany, and immunologist Christian Kurts of the University of Bonn in Germany stumbled on another idea more than a decade ago at a conference coffee break. Kurts mentioned how frustrated he was that immune system cells called macrophages in mouse spleens would stick to magnetic columns in instruments used to separate different types of cells, ruining his experiments.

The reason the macrophages were sticking, he discovered, was that they accumulated and recycled damaged red blood cells’ iron atoms, which aligned in magnetic fields.

https://www.nytimes.com/2026/05/27/science/fish-sleep-a-lot-like-us-they-even-nap.html?searchResultPosition=17

Fish Sleep a Lot Like Us. (They Even Nap.)

By Sara Novak

Whether tucked away in a colony of coral, hidden in the darkness of an aquatic cave or floating catatonic just above the ocean floor, fish take opportunities for rest and recovery, just as we do.

Like humans, most fish are diurnal, meaning they sleep mostly at night; while they don’t have eyelids, and therefore can’t shut out the darkness, light does disrupt their sleep. And just like us, when they snooze they’re motionless and slow to respond to environmental stimuli. If you deprive them of sleep, they will make up for the loss by sleeping longer the next night.

Now, a new study, released this month in Nature Communications, shows just how much fish sleep really does resemble our own. By tracking eye movements of zebrafish, the researchers were able to identify four different substates of sleep, akin to the “stages” of sleep that scientists have described in humans.

“There’s complexity to their sleep structure,” said Jennifer Mengbo Li, a co-author of the study and a neuroscientist at the Max Planck Institute for Biological Cybernetics in Germany.

Three of the four substates happen at night, lasting a total of 10 hours. The first — and deepest — is characterized by a stone-cold stare. As the waking hours near, a second, lighter substate sets in: The zebrafish’s eyes twitch, sideways in the same direction, before moving slowly back to center. In the third substate, entered as morning approaches, both eyes turn to the same side and stay there.

During the fourth and final substate, which takes place in brief bursts during the day, the zebrafish’s eyes move back and forth, as if sweeping the surroundings for potential risks. But the eyes can be deceiving: These five-to-10-minute naps are deep enough that much of the brain activity is suppressed, and the zebrafish are hard to wake up.

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https://www.thetransmitter.org/vision/unbelievably-beautiful-evidence-extends-nobel-prize-winning-model-of-vision/

‘Unbelievably beautiful’ evidence extends Nobel Prize-winning model of vision

By Claudia López Lloreda

Neurons in the visual cortex decode an object’s orientation—horizontal, vertical or anything in between—using information from non-orientation-tuned neurons in the thalamus, according to David Hubel and Torsten Wiesel’s Nobel Prize-winning work in cats in the 1950s and ’60s. In other species, though, the process remained unclear. Thalamic neurons in mice, for example, show orientation selectivity, subsequent studies suggested.

New mouse findings—realized by imaging individual synapses on cortical neurons and distinguishing which inputs come from the thalamus versus the neighboring cortex during visual processing—help resolve the discrepancy. Signals coming into the primary visual cortex, or V1, from the thalamus are not orientation tuned, but those from other parts of the cortex are, confirming that orientation tuning occurs in the visual cortex, the new study reveals.

This study is the first “to get a map of thalamic receptive field location at the level of seeing almost all the spines that receive thalamic input,” says Jose Manuel Alonso, professor of biological and vision sciences at the State University of New York College of Optometry, who was not involved with the work. “This is unbelievably beautiful.”

What’s more, the Hubel and Wiesel model of orientation selectivity “is preserved through evolution,” Alonso adds.

“In the mouse, this pathway from the thalamus to the V1 is really organized as the Hubel and Wiesel suggested it should be,” says Anton Arkhipov, investigator at the Allen Institute, who was not involved with the study.

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https://www.scientificamerican.com/article/retatrutide-results-spark-questions-about-how-rapid-weight-loss-affects-the-body/

New powerful GLP-1 drugs drop a lot of weight fast. How does that affect health?

By Bethany Brookshire

Once people understood glucagonlike peptide 1 (GLP-1) drugs’ potential for weight loss, the race among pharmaceutical companies was on. Among the current options, Wegovy can help people lose an average of 10 percent of their body weight in a year, while people taking Zepbound have had about a 15 percent loss, on average, in the same period. Soon the most powerful GLP-1 treatment to date could hit the market: retatrutide.

Already popular on the online peptide gray market, the new drug, originally developed by Eli Lilly, caused participants in a recent clinical study to lose more than a quarter of their body weight over 80 weeks at the highest dose—results comparable to bariatric surgery. U.S. Food and Drug Administration approval could soon follow.

But bodies don’t just drop weight with no potential adverse effects. Weight loss on its own can change muscle, bone and more. As new-generation GLP-1 drugs promote higher rates of loss, clinicians want to ensure that the desire to shed pounds and see improvements such as better cardiovascular health are balanced with the very real risks that may come with the treatment.
Fat, Muscle or Bone?

People typically lose weight when they eat fewer calories than their body expends. A common way to cut calories is to diet, while bariatric surgery removes or changes part of the gastrointestinal tract to reduce food—and therefore calorie—absorption.

GLP-1 is a gut hormone released in response to a meal that helps people feel full. It also increases insulin release and reduces glucose in the blood. Semaglutide (sold as Ozempic and Wegovy by Novo Nordisk) binds to the hormone’s receptor for longer periods of time, making people feel fuller for longer and eat less. Newer versions of GLP-1 drugs, such as tirzepatide (sold as Zepbound and Mounjaro by Eli Lilly) and Novo Nordisk’s upcoming drug CagriSema target more than one type of gut hormone receptor, while retatrutide hits three.

https://www.theguardian.com/society/2026/may/30/poor-sleep-linked-rising-cancer-risk-under-50s

Andrew Gregory in Chicago

Poor sleep may be fuelling the global rise in under-50s being diagnosed with cancer, two large studies suggest.

The number of younger people diagnosed with the disease has risen by almost 80% in three decades. Worldwide cases of early-onset cancer increased from 1.82m in 1990 to 3.26m in 2019, while cancer deaths among people in their 40s, 30s or younger rose by 27%.

Experts are still trying to understand the reasons behind the increase. However, research presented at the world’s largest cancer conference, the American Society of Clinical Oncology’s annual meeting in Chicago, suggests irregular sleeping patterns in younger people may be a contributing factor.

Two studies led by MD Anderson Cancer Center in Houston, Texas, one of the world’s leading cancer research organisations, analysed health data for more than 18 million adults in the US aged between 18 and 50.

Researchers found that people with poor sleeping patterns were more likely to develop early-onset bowel, breast, uterine or ovarian cancer. In some cases, under-50s diagnosed with insomnia were three times more likely to develop cancer within five years.

“These findings suggest that sleep disruption may represent a clinically relevant, potentially modifiable risk factor in early-onset cancer risk stratification and warrants further investigation,” the researchers said.

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