Libet & Free Will - Athletes & Blood-Brain Barrier - Jellyfish Rhythms - GLP1 & Longevity?

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Mar 21, 2026, 7:51:27 AMMar 21

https://www.sciencefocus.com/wellbeing/free-will-neuroscience

How the experiment that nearly killed free will is still haunting neuroscience

Nate Scharping

Whether or not we have free will is a question philosophers have been debating for millennia. In the early 1980s, there was a brief moment when it appeared the debate may finally have been settled.

The potential solution came not from philosophy, but neuroscience.

The answer, somewhat depressingly, was that free will didn’t exist. Experiments carried out by the neuroscientist Benjamin Libet appeared to show decisions being made in the brain before people were even aware of them.

It was as if science had finally revealed the strings of the puppet master controlling our thoughts and actions.

To even casual observers of the history of inquiries into free will, this pronouncement felt premature. Thankfully, they were right.

Scientists today are much more sceptical not only of the idea that free will doesn’t exist, but also of the notion that brain scans will ever definitively prove or disprove its existence. But why?

Ultimately, the question of free will may be best left to philosophers, but that doesn’t mean it’s a topic neuroscientists should ignore.

Experiments into how the human brain makes decisions have led to important insights into neurology and psychology, and have expanded our understanding of the brain’s inner workings.

Those experiments include the ones Libet conducted in the 1980s, which, although viewed in a more critical light now, paved the way for decades of innovative research.

The experiments were simple. Libet attached volunteers to an electroencephalogram (EEG) machine to monitor their brain activity, then placed a button in front of them and asked them to decide when they wanted to press it.

While they were deciding, they had to watch a timer, consisting of a dot moving around the inside of a circle (like a second hand on a clock). Each volunteer had to note the dot’s position when they decided to press the button.

With the EEGs, Libet was looking for something called a readiness potential, a build-up of activity in the brain’s motor cortex that precedes a muscle movement.

He was hoping to see how a volunteer’s awareness of their decision to move (their noting of the dot’s position) lined up with their readiness potential.

https://www.nature.com/articles/d41586-026-00885-2

Brain’s protective barrier stays leaky for years after playing contact sports

Max Kozlov

For decades, scientists have struggled to understand exactly how years of taking hits to the head while playing sports can translate into severe memory loss and dementia later in life.

Now, a study1 published today in Science Translational Medicine reveals that the protective shield known as the blood–brain barrier can be damaged and leaky decades after an athlete retires from sport. This persistent leakiness seems to trigger a long-lasting immune response that is closely tied to cognitive decline, the study finds.

The work is a “very important study that finds the disruption of the blood–brain barrier many years after head trauma”, says Katerina Akassoglou, a neuroimmunologist at the Gladstone Institutes in San Francisco, California, who was not involved in the research.

Part of the difficulty in studying the long-term effects of head trauma is that some neurodegenerative conditions, such as chronic traumatic encephalopathy (CTE), can be diagnosed only by examining neuronal tissue after death, says Matthew Campbell, a specialist in neurovascular genetics at Trinity College Dublin, who co-authored the paper.

Campbell and his colleagues wanted to see whether they could spot warning signs in living athletes by looking at the blood–brain barrier, a dense layer of cells lining the blood vessels that supply the brain. This layer usually keeps harmful substances from leaking out of the blood and into brain tissue.

To investigate, the researchers scanned the brains of 47 athletes who had retired from playing contact sports with a high risk of concussion and repetitive head impact, such as rugby and boxing. They also examined a control group of non-athletes and athletes who had played non-contact sports.

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https://www.quantamagazine.org/the-jellies-that-evolved-a-different-way-to-keep-time-20260320/

The Jellies That Evolved a Different Way To Keep Time

By Marlowe Starling

The passage of the sun across the sky — dawn, day, dusk, night — drives the clock of life. Some species wake with the sun and sleep with the moon. Others do the opposite, and a few keep odd hours. These naturally driven, 24-hour biological cycles are known as circadian rhythms, and they do more than cue bedtime: They regulate hormones, metabolism, DNA repair, and more. When life falls out of sync, there can be dire consequences for health, reproduction, and survival.

Lacking watches, many species keep time using an internal system — a set of interacting genes and their protein products that effectively keeps track of a 24-hour period — that is calibrated by sunlight. This kind of circadian clock is widespread, found even in single-celled algae, which suggests that biological timekeeping evolved billions of years ago. Across animals, most species have the same genetic system, using genes known as CLOCK, BMAL1, and CRY, or recognizable homologues. This form of biological clock mechanism appears even in ancient lineages, including sponges and some jellyfish.

But is this the only way to do it? In a pea-size jelly off the coast of Japan, biologists are examining a different kind of timekeeping.

Somewhere over the course of their evolution, the class of hydrozoans — which includes certain kinds of jellyfish, hydras, and colonial siphonophores such as the Portuguese man-of-war — lost the genes that operate circadian clocks in the rest of the animal kingdom. Yet a newly discovered hydrozoan jellyfish species has a mysterious circadian clock that regularly tracks 20-hour periods, suggesting that its mechanism evolved independently. The findings, published (opens a new tab) in PLOS Biology in January 2026, push the limits of what chronobiologists consider “circadian.”

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https://www.science.org/content/article/hormone-linked-morning-sickness-may-help-reduce-alcohol-intake

Hormone linked to morning sickness may help reduce alcohol intake

By Catherine Offord

For most people, Oktoberfest means guzzling liters of beer inside a giant tent. But for one research group in Denmark, it’s a chance to study how our bodies know when we’ve had enough.

In a preprint posted on bioRxiv last week, researchers combined a small study of people at Germany’s fall beer festival with mouse experiments, genetic analyses, and blood tests from drunk medical students as well as people with alcohol dependence. Their findings, though preliminary, hint that a hormone commonly associated with morning sickness might also have a role in limiting humans’ alcohol consumption.

“I found it fascinating,” says Marlena Fejzo, a women’s health scientist at the University of Southern California who has studied GDF15, the hormone involved. Though the study relies mostly on associations and can’t prove cause and effect, it “lends support” to the idea that GDF15 stops us from overconsuming harmful substances, she adds.

GDF15 rises sharply during early pregnancy and is thought to contribute to vomiting and feelings of sickness. Some researchers think it evolved as a protective mechanism: Nausea may help an expectant parent avoid unfamiliar or spoiled food that could harm the fetus. But GDF15 is also present in people who aren’t pregnant and has been linked to appetite suppression. It has even attracted interest from the pharmaceutical industry as a potential antiobesity drug.

Matthew Gillum, an endocrinologist at the University of Copenhagen, began to wonder about the hormone’s effect on alcohol intake after collaborating on a study of revelers at the Roskilde music festival. That research measured blood hormone levels in young men who’d spent a week binge drinking and eating junk food and found multiple changes—including a rise in GDF15.

https://www.sciencenews.org/article/glp1-medications-microdose-longevity

GLP-1 microdosers are chasing longevity

By Jamie Ducharme

More than 10 percent of U.S. adults take GLP-1 drugs. But not all of them are taking full doses. Around one in seven users has “microdosed” injections, a recent survey by the health tracking app Evidation found. Some take tiny portions for practical reasons, such as cutting costs. Others have loftier ambitions: They hope to harness the drugs’ powerful effects to achieve better health and longer lives without losing a lot of weight or experiencing side effects such as GI issues and muscle loss.

Medications such as Ozempic and Wegovy mimic the body’s GLP-1 hormone, which helps regulate appetite, metabolism and blood sugar. That has made the drugs blockbuster treatments for type 2 diabetes and obesity. But to date, “there is no rigorous scientific data to support microdosing,” says bariatric medicine specialist Katy Williams of the University of Missouri Health Care in Jefferson City.

That hasn’t stopped some intrepid biohackers from trying it, though. Companies like AgelessRx, a longevity-focused telehealth clinic, explicitly sell GLP-1 microdoses for this purpose, advertising them as “a powerful new path to promoting long-term wellness.”

There is some research to suggest GLP-1s can promote healthy aging by improving overall health. The drugs have been found to reduce inflammation and oxidative stress, lower risks of major cardiovascular problems, lower cancer risk and more. Such findings have prompted scientists to study the drugs as potential treatments for illnesses as diverse as Alzheimer’s disease and arthritis. Some experts have even wondered whether the drugs’ systemic effects might slow cellular aging and prevent age-related chronic conditions, potentially making them the first true longevity drugs to hit the market.

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