An Australian magpie. Image Credit: NAPARAZZI, Flickr

<p>During a recent study, a group of magpies removed their GPS trackers, astounding their observers. But were the birds actually trying to help each other?</p>

How magpies outwitted researchers in Australia

A person in the first stages of multiple sclerosis may have trouble gripping objects or experience dizziness, fatigue, and vision problems. Symptoms may get progressively worse. Image Credit: © Minerva Studio/Shutterstock

<p>The underlying cause of multiple sclerosis is not yet known, but Epstein-Barr virus is a possible culprit, Harvard researchers say.</p>

Epstein-Barr infection found to increase risk of multiple sclerosis

Animal Care Supervisor Lisa Dijenno bottle-feeds a manatee named Tober. Image courtesy of ZooTampa

<p>As Florida’s seagrass beds die off, manatees are starving. Can the seagrass–and the manatees–make a comeback?</p>

A day at a Florida manatee hospital

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<p>NOVA Next is NOVA’s award-winning digital publication that provides answers from the cutting edge of science and technology. Launched in 2012, we feature in-depth articles and commentaries from some of the most respected journalists, scientists, and engineers. NOVA Next explores the ideas that are changing the future, from the frontiers of synthetic biology to the politics of personalized medicine.</p><p>Let us know what you think. We’re listening on <a href="http://www.facebook.com/NOVAonline">Facebook</a>, <a href="http://twitter.com/novapbs">Twitter</a>, and email.</p><p>If you’re a journalist and have an idea for a story, send it our way.</p>

NOVA Next is NOVA’s award-winning digital publication that provides answers from the cutting edge of science and technology.

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<p>NOVA Next is NOVA’s award-winning digital publication that provides answers from the cutting edge of science and technology.</p>

cast iron skillet full of Brussels sprout halves and bits of bacon sits on a wooden surface

What happens when you season a cast iron pan

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<p>Ahh, cast iron pans. Love ‘em or hate ‘em, they’ve been around for hundreds of years. With proper maintenance, they can last long enough to become family heirlooms. A cornerstone of this pan’s upkeep is seasoning, the process of baking oil onto the pan. Contrary to the name, you won’t need salt and pepper, but fat. </p><p>To season, you heat the pan covered in fat to scalding temperatures in an oven. What is left behind is a somewhat nonstick surface that not only helps with cooking but <a href="https://www.youtube.com/watch?v=8uaoCPxJa3Q&amp;list=PLnNZYWyBGJ1G82dSY0lEGClN4Ma3oTkWm&amp;index=4">protects the pan from rust</a>.</p><p>You can use the fat of your choice, but one thing to keep in mind is the smoke point, the temperature at which it starts to smoke. That temperature varies from oil to oil. For example, virgin avocado oil has a smoke point of 520 F, but coconut oil smokes at just 350 F. As soon as that temperature is reached, the seasoning process begins. </p><p>There are multiple hypotheses about what’s happening at the molecular level inside that hot oven. The predominant one is that the oil is polymerizing. Fats are made up of different fatty acids, like saturated and unsaturated. When heated, those acids break down into smaller molecules called monomers. And when monomers join together, they form larger molecules <a href="https://www.pbs.org/wgbh/nova/video/beyond-the-elements-indestructible/">called polymers</a>. When this joining happens over and over in an iron skillet, the polymers form a protective layer that keeps water at bay. </p>
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<p>A group of researchers from Chongqing University <a href="https://www.sciencedirect.com/science/article/pii/S2589965120300416">studied this phenomenon</a> in the context of another cast iron cooking tool: the wok. Woks, mainly used in Chinese-style cuisine, are usually round-bottomed. The team hypothesized that the slick surface formed during seasoning is due more to the iron than the oil. To test their hypothesis, the researchers coated a wok with beef tallow and heated it up. As the temperature increased, the fat started to reduce. And the scientists, using X-ray technology, started to see oxygen molecules sneaking into the places where iron was present. With this unexpected guest, iron atoms had to shuffle around to make space, creating small lumps along the surface. The final product is what the team called “iron nanoballs.” </p><p>They point out that these nanoballs didn’t make the wok completely nonstick, but rather made the surface conditionally hydrophobic. That means that it repels water when there isn’t much around, but gets wet when there’s a lot of it. The study authors claim this property comes in handy during cooking, because if the pans are <a href="https://www.pbs.org/wgbh/nova/article/pfas-synthetic-chemicals-water-toxic/">completely nonstick</a>, the fat will lump together, causing uneven cooking. If the surface can get wet, it creates an even layer, and the food can cook evenly as the water evaporates, creating less charring.</p>
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<p data-block-key="lvieb">Here is how oil and heat can form a durable coating.</p>

A dried, twisted old tree against a blue sky

"Methuselah," a bristlecone pine in California long considered to be the world's oldest tree. Image Credit: Yen Chao, Flickr

The world’s oldest tree has competition

<p>High on a ridge in California’s Eastern Sierra, a gnarled bristlecone pine known as Methuselah has reigned over almost five millennia’s worth of snowy winters and blazing summers. Methuselah, whose crooked and weather-beaten boughs make it look more like a sculpture than a living thing, is estimated to be 4,853 years old, based on data from a core sample taken in 1957—making it the oldest tree in the world.</p>
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<p>Until now. This year, an upstart competitor has appeared to challenge California’s grizzly old-timer. Nicknamed Alerce Milenario, or Gran Abuelo, which means great grandfather in Spanish, it sits in a humid valley outside La Unión, Chile. As <a href="https://www.science.org/content/article/world-s-oldest-tree-growing-ravine-chile">reported in Science</a> in May, researcher Jonathan Barichivich says new data suggest the tree might hold a new record: 5,484 years old. (That record excludes clonal trees that share root systems, like aspen colonies, Science specified. In the search for the oldest tree, scientists focus on individuals with just one trunk.)</p><p>Gran Abuelo is an alerce, or Patagonian cypress, a type of conifer related to giant sequoias and coast redwoods. Like their Californian cousins, alerces can grow to very old age; at least one other alerce in southern Chile has been dated at 3,600 years old. That makes the species the second longest-lived in the world—older than sequoias but not quite at the bristlecone pine level. And Barichivich knows alerces well. He grew up around them, including Gran Abuelo, since his grandfather and mother both worked as rangers in the park where Gran Abuelo grows. He says his grandfather discovered the tree around 1972. “It’s a tree that’s very, very close to our hearts,” he told Science.</p><p>Standard practice in dendrochronology, the science of determining tree age, involves <a href="https://www.pbs.org/wgbh/nova/video/trees-climate-records/">counting rings</a> from a thin core taken from the living tree, then comparing those rings to patterns in cores from trees nearby. But Barichivich ran into a problem: Gran Abuelo’s trunk was so wide that his increment borer, the instrument usually used to take age cores, could not reach all the way through. And while in similar cases some dendrochronologists might take samples from the roots to supplement or confirm available data, Barichivich was concerned that that might damage the tree's roots, which have already struggled under the footsteps of curious tourists coming to see their arboreal elder. "It's not the point to make a big hole in the tree just to know that it's the oldest,” he <a href="https://www.livescience.com/possible-oldest-tree-found-chile">told Live Science</a>. “The scientific challenge is to estimate the age without being too invasive to the tree."</p><p>Intead, Barichivich used statistical modeling to estimate Gran Abuelo’s age, drawing on data from fully cored alerces nearby and incorporating possible growth rate variation and fluctuations caused by climate and environment. The result that the model suggested shocked him. The absolute oldest the tree might be was 6,000 years, it said. There was an 80% chance that the tree was over 5,000 years old, with an overall estimated age of 5,484. “It was astonishing,” he told Science.</p>
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<p>Though Science reported on Barichivich’s findings in May, he has yet to publish them fully in a peer-reviewed journal. His fellow dendrochronologists have therefore greeted his claims with a mix of intrigue and doubt. “I fully trust the analysis that Jonathan has made,” Swiss Federal Institute of Technology dendrochronologist Harald Bugmann told Science. “It sounds like a very smart approach.”</p><p>But others remain skeptical. “The ONLY way to truly determine the age of a tree is by dendrochronologically counting the rings, and that requires ALL rings being present or accounted for,” Ed Cook, a founding director of Columbia University’s Tree Ring Laboratory, told the publication via email. Similarly, Peter Brown, who has produced a database of the oldest trees on Earth and serves as Guinness World Records’ consultant on the oldest tree, told <a href="https://www.sfchronicle.com/california/article/California-thinks-its-bristlecone-pine-17201279.php">The San Francisco Chronicle</a> that the project is “awfully interesting,” but he wants to see the details before coming to any conclusions. Plus, <a href="https://www.nationalgeographic.com/environment/article/whats-the-oldest-tree-on-earth-and-will-it-survive-climate-change">he pointed out to National Geographic</a>, Gran Abuelo’s estimated age is over 1,500 years older than the next oldest alerce, which is a pretty big jump. (Barichivich stands by his estimate, citing the “growth-lifespan tradeoff” to Live Science, a theory that posits that slow-growing species tend to live longer—and alerces grow slower than both sequoias <i>and</i> bristlecone pines.)</p><p>Ultimately, Barichivich emphasizes that “the objective is to protect the tree, not to make headlines or break records.” He <a href="https://www.newsweek.com/conservation-tree-chile-oldest-rare-record-broken-protection-alerce-national-park-1709970%E2%80%9D">told Newsweek</a> he was going public with his research out of concern for Gran Abuelo’s wellbeing, estimating that only 28% of the tree is still alive. (Trees possess a remarkable ability to <a href="https://www.bartlett.com/resources/compartmentalization-of-decay-in-trees.pdf">compartmentalize decay</a>, walling off areas that have been invaded by fungi and microorganisms and prioritizing growth in other areas.) Not only do tourists come too close for comfort, he said, but the tree is currently encircled by a platform that is crushing the remaining living roots. He and his colleagues would like to see the park where the tree lives erect a protective net and move the walkway further from those roots. "To me, this tree is like a family member,” he said. “Seeing him like this is breaking my heart.”</p><p>Meanwhile in California, the guardians of Methuselah <a href="https://www.sfchronicle.com/california/article/California-thinks-its-bristlecone-pine-17201279.php">told The San Francisco Chronicle</a> that they’re “not concerned” about the southern challenger but are intrigued by Barichivich’s innovations. “Perhaps there are other older trees out there waiting to be discovered with this new potential dating method,” ranger Andrew Kennedy said. </p><p>That may include in Methuselah’s own backyard. In 1959, a tree ring researcher from University of Arizona collected cores from several of Methuselah’s ancient neighbors, suspecting some might be even older—but died before he could complete his analysis, The Chronicle reports. Then in 2010, another researcher restarted the project, finding one core that seemed to suggest a still-living tree might be 5,062 years old. But that researcher died before the work was complete as well—and then the cores were lost.</p><p>Meanwhile, these most ancient of trees, having witnessed countless births and deaths and virtually all of modern human history, live on.</p>
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<p data-block-key="cafrm">Will a Patagonian cypress in Chile prove older than California’s most elderly bristlecone pine?</p>

Looking down into a pan with a pile of beige mushroom slices

Crimini mushrooms ready to be cooked. Image Credit: joyosity, Flickr

Why you can’t really overcook mushrooms

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<p>You don’t have to be a chef to notice that some foods are more forgiving of kitchen mistakes than others. When you’re cooking vegetables (zucchini, let’s say), if you step out to take a call you might end up with too-soft glop. When you’re cooking meat, if you get distracted you could end up with a hockey puck. But mushrooms are much more forgiving. Even if an unexpected visitor calls you away from a pan of sautéing porcini for an hour, when you come back the mushrooms are likely to still be glossy and tender.</p><p>A few years ago, Dan Souza at Cook’s Science, run by America’s Test Kitchen, set out to confirm this phenomenon <a href="https://www.youtube.com/watch?v=h0fHS8-l_NU">with an experiment</a>. Souza spent 40 minutes steaming half-inch-thick planks of portobello mushroom, zucchini, and beef tenderloin. Every five minutes, he tested each sample with a fancy machine called a “CT3 Texture Analyzer,” which measured how much force would be required to “bite” three millimeters into each one. He also gave them to human tasters to try. Then he recorded the results.</p><p>After five minutes of steaming, the zucchini, beef, and mushroom were all equally tender, requiring about the same force for a “bite.” The mushrooms stayed the same for almost the whole 40 minutes, getting only 57% tougher in total—and still seemed tender to the tasters. In deep contrast, the beef was a whopping 293% more leathery after the same period of cooking. Meanwhile, the zucchini decreased 83% in firmness, turning into vegetable mush. So, what gives?</p>
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<p>The answer, it turns out, is chitin, a fibrous polysaccharide—or cluster of chains of carbohydrate molecules—similar to keratin. It’s found in lobster and shrimp shells, <a href="https://www.pbs.org/wgbh/nova/video/edible-insects/">insect wings</a>, and the cells of fungi. It mostly serves to protect soft tissue in the natural world. (It’s also a great source of dietary fiber.)</p><p>And chitin is remarkably resistant to heat. In 2015, three Japanese researchers <a href="https://www.nature.com/articles/srep11907">published a study</a> exploring the material’s limits, which found that fungal cells with chitinous walls could withstand temperatures up to 380 C (716 F). In contrast, cellulose samples began to warp and eventually dissolved around 300 C. The authors attributed this remarkable strength to chitin’s structure. In mushrooms, chitin takes the form of fine bundles, each of which is made up of sheets that are layered in parallel but run in opposite directions. In α-chitin, the form most common in crustaceans, insects, and mushrooms, those sheets are held together by strong hydrogen bonds, making them even more durable.</p><p>All that is quite different from the molecular makeup of meat and vegetables. When the strands of the protein in meat are raw, they’re soft and flexible. But as they heat up, they contract together, pushing out moisture. The empty space causes the proteins to contract even further, eventually drying the meat out and turning it hard and tough. In vegetables, on the other hand, the hemicellulose and pectin (another polysaccharide) that hold plant cell walls together begin to break down after exposure to heat, releasing the bond between those cells. And, as the Japanese researchers found, they do so at much lower temperatures than chitin does. </p>
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<p data-block-key="fghf3">Mushrooms are remarkably forgiving. Here’s the science of why.</p>

A red orb filled with cloudy blue gas against a black sky

Southern Ring Nebula, as observed in infrared by the James Webb Space Telescope. Image Credit: NASA, ESA, CSA, STScI

Dazzling first images from James Webb Space Telescope

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<p>With the world watching, NASA revealed the first images from the James Webb Space Telescope (JWST), marking the<a href="https://www.pbs.org/wgbh/nova/video/james-webb-space-telescope-launch/"> beginning of a new era</a> in our understanding of the universe.</p><p>Instead of orbiting Earth like its <a href="https://www.pbs.org/wgbh/nova/article/hubble-space-telescope-best-images/">predecessor, the Hubble Space Telescope</a>, JWST will orbit the sun at a position about 1 million miles farther out than Earth’s orbit. The space telescope, a project <a href="https://www.pbs.org/wgbh/nova/article/-james-webb-space-telescope-launch-nasa-big-bang/">30 years in the making</a>, launched in December 2021 and arrived at its destination point in January. After a lengthy “unfolding” process, JWST turned its 21-foot mirror on the stars. Today we see its first observations.</p>
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<img alt="Patch of black sky dotted with disc-like galaxies and stars in red and blue tones" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/SMACS2_crop.width-990.png"/>
<figcaption><p>Galaxy cluster SMACS 0723, known as Webb’s First Deep Field, released July 11, 2022. Image Credit: NASA, ESA, CSA, and STScI</p>
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<p><b>Webb’s First Deep Field, Galaxy Cluster SMACS 0723</b></p><p>Teeming with thousands of galaxies, including the faintest objects ever observed in infrared light, this image represents a tiny speck of outer space about the size of a grain of sand held up at arm’s length. The image, taken with JWST’s Near-Infrared Camera (NIRCam), shows the galaxy cluster SMACS 0723 as it appeared some 4.6 billion years ago. That cluster is acting as a “gravitational lens,” bending and distorting light from the galaxies behind it—including some distant red galaxies more than 13 billion years old.</p>
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<img alt='Reddish brown swath at the bottom appears like mountains below a blue, starry "sky" above' class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Carina_Nebula.width-990.png"/>
<figcaption><p>"Cosmic Cliffs" in the Carina Nebula, as captured by the James Webb Space Telescope. Image Credit: NASA, ESA, CSA, STScI </p>
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<p><b>“Cosmic Cliffs” in the Carina Nebula</b></p><p>This massive landscape of cosmic mountains and valleys in the Carina Nebula is known as the “Cosmic Cliffs.” Here the bubbles, cavities, and jets of newborn stars are made visible through the dust in a way that was impossible when the Hubble Space Telescope <a href="https://hubblesite.org/contents/media/images/2010/13/2718-Image.html?news=true">imaged this region</a> of intense star formation. The youngest stars appear as red dots in the darker areas of the dust cloud; others are emitting ‘protostellar’ jets typical of early star birth. This image illustrates the delicate balance of forces at play during the birth of stars. The tallest “peaks” are a staggering seven light-years high. They’ve been slowly eroded by the intense ultraviolet radiation and stellar winds from hot, young stars nearby. As the bright, ionized rim of the cloud moves down, unstable material may collapse to form new stars. But this disturbance can also prevent star formation. Images like these will help JWST researchers understand why stars form at specific sizes and masses, and why some regions host more than others.</p>
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<img alt="Four round, cloudy, pinkish galaxies against a dark sky" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Stephans_Quintet_JWST.width-990.png"/>
<figcaption><p>Composite image of a galaxy group known as Stephan's Quintet. Image Credit: NASA, ESA, CSA, STScI</p>
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<p><b>Stephan’s Quintet</b></p><p>This massive composite image shows the compact galaxy group Stephan’s Quintet in unprecedented detail, with clusters of young, sparkling stars and starburst regions where new stars are being born. The gravitational interactions pull broad trails of gas and dust away from the galaxies, and Webb’s Mid-Infrared Instrument captures huge shockwaves as one of the galaxies, NGC 7318B, slams through the cluster. JWST's instruments also reveal hot gas near a supermassive black hole in the top galaxy and measure its bright outflows in spectacular detail.</p>
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<img alt="Side-by-side images of round nebula with red and blue coloration against black sky" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/Southern_Ring_Nebula.width-990.png"/>
<figcaption><p>The Southern Ring Nebula visualized in near-infrared light (left) and mid-infrared light (right) by NASA’s Webb Telescope. Image Credit: NASA, ESA, CSA, STScI</p>
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<p><b>Southern Ring Nebula</b></p><p>This pair of images of the Southern Ring Nebula shows two powerful perspectives on the same binary star system, a white dwarf and its younger counterpart. Before it became a white dwarf, the older star periodically ejected its outer layers, repeatedly contracting, heating, and pushing out material like a rotating sprinkler. Its partner, which has yet to shed its layers, closely orbits its dimmer companion, helping to distribute the material. In the near-infrared image on the left, the younger, brighter star partially obscures the white dwarf to its lower left. In the mid-infrared image on the right, we can see the white dwarf more clearly, surrounded by dust, a view made possible because of the power of JWST’s instruments.</p>
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<img alt="A graph with a horizontal undulating line with data points along it, set against an image of an exoplanet" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/WASP-96b.width-990.png"/>
<figcaption><p>A transmission spectrum reveals atmospheric characteristics of the gas giant exoplanet WASP-96 b. Image Credit: NASA, ESA, CSA, STScI</p>
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<p><b>Exoplanet WASP-96 b (spectrum)</b></p><p>Although JWST has not captured a direct image of exoplanet WASP-96 b, it doesn’t need one to learn all about this hot, rather puffy, gas giant. Instead, researchers were able to observe the transit of the exoplanet across its star, which is roughly 1,150 light-years away from Earth, and detect changes in the wavelengths of light. This graph is a representation of the data they gathered about WASP-96 b’s atmosphere. The labeled peaks indicate the presence of water vapor, specifically clouds of water droplets. And the gradual downward slope at the left side indicates possible haze. All this tells observers that it’s hot and wet on WASP-96 b—the height of the peaks, compared with other characteristics of this spectrum, suggest an atmospheric temperature of 1,350 F!</p>
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<p data-block-key="hx37d">Images of five targets include the deepest and sharpest infrared image of the distant universe to date.</p>

Cluster of three purple fireworks exploding against a black sky

Image Credit: Matthew Bellemare, Wikimedia Commons

The science of fireworks

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<p>Fireworks are part of countless celebrations around the world—including United States Independence Day festivities dating back to the very first bash in 1777. But how do those glittering displays actually work? It turns out that the firework shows that dazzle crowds across the country each year are backed up by millennia of engineering—and science that continues to evolve.</p><h3><b>The boom</b></h3><p>The basics of fireworks have remained the same for a thousand years, starting with a recipe believed to have been devised by <a href="https://www.americanpyro.com/history-of-fireworks">Chinese alchemists</a> around 800 CE. The “black powder” they dreamed up is three quarters potassium nitrate and the rest charcoal and sulfur. Stuff that in a paper container, and you’ve got the beginning of a firework. </p><p>When you light that baby, the sulfur melts first, flowing over the potassium nitrate and charcoal and setting them alight. This flame releases gas and energy: an explosion. If there is a conveniently placed hole in the container, the gas escapes and launches the firework skyward before it blasts apart. </p><p>In modern aerial fireworks, black powder is packed into a container connected to a fuse. When the fuse is lit, it burns for a set amount of time to allow the firework to reach a desired altitude, at which point it reaches the “bursting charge.” Inside, all that black powder has been packed with “stars,” small spheres or cubes made of metal salts, in a particular pattern. The exploding powder throws those stars outward, creating intricate spheres or flowers of sparkling light with names like “palm,” “willow,” and “chrysanthemum.” More complicated “multibreak” shells can even burst in two or three phases, sometimes including shells-within-shells, fuses that ignite each other, or explosives that break each section into pieces.</p><h3><b>The ooh and ahh</b></h3><p>We’ve come a long way from the simple Chinese launch-and-boom fireworks of a thousand years ago. These days, modern firework designers can use computer programs to choreograph their shows—sometimes along with music—down to a fraction of a second. They use a mix of virtual modeling, precisely engineered launching brackets, and circuits equipped with computer chips to map out and execute the timing of each firework, its launch angle, and how high it should sail in the air before exploding.</p><p>Plus, 21st century fireworks have something the original Chinese inventors could only dream of: color. In the original versions, which used potassium nitrate as a base of the black powder, the sulfur’s electrons would get excited, jumping into a further orbital away from each atom. When they fell back to their original state, that extra energy would be released as yellow light. </p>
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<p>But in the 1830s, Italian firework makers discovered that using potassium chlorate instead of nitrate opened up a huge realm of sparkling possibilities. The new material delivered oxygen more quickly to the powder, increasing combustion temperature from 1,700 to 2,000 C. And that increased temperature created an opportunity to add a new set of chemicals with higher burn temperatures that could create brighter light—and new colors.</p><p>More specifically, Italian firework innovators began adding metal salts to their works of explosive art. Each of these ionic compounds emits light from a different part of the spectrum when its excited electrons bounce from their outer orbital neighborhood back to home base. Strontium and lithium both make deep reds; calcium blooms orange; sodium glitters yellow; barium radiates green.</p><h3><b>Greener greens, safer reds, and the elusive blue</b></h3><p>All that is good for creating a visual masterpiece—but the new chemicals adding to our oohs and ahhs have some drawbacks. The strontium chloride that creates beautiful red blooms in the night sky can also create carcinogenic fallout. In 2015, researchers looking for more environmentally friendly, chlorine-free options found possibilities in materials like hexamine, a preservative, and 5-amino-1H-tetrazole, an airbag propellant, <a href="https://cen.acs.org/articles/93/web/2015/08/Red-Fireworks-Green.html?ref=search_results">Chemical &amp; Engineering News reported</a>. That could be helpful in military contexts, since red flares used in training can be a regular source of harmful fallout.</p><p>And in 2011, a U.S. Army team of pyrotechnics experts found that boron carbide, “a compound long dismissed as inert” could help replace the toxic, barium-based chemicals currently used in green fireworks, <a href="https://www.nature.com/articles/news.2011.222">Nature reported</a>.</p><p>Environmental and safety concerns aren’t the only challenge left for pyrotechnic artists. There’s still the firework holy grail: the perfect blue. Blue fireworks have always been among the most difficult to develop. They must stand out against the dark night sky, but their signature color is created using a copper gas that burns at a very high temperature. The firework maker's task is to help the color come out without overheating it and causing the color to wash out, turning from blue to white. That makes a really vivid blue firework an aerial feat of chemistry that marks a true master.</p>
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An elderly woman in a red sweatshirt runs down a path in a park

Image Credit: David Tett via Centre for Ageing Better

How exercise may help prevent Alzheimer's

<p>Your brain loves it when you exercise. Of course, you yourself may not love every sweaty minute of your kickboxing class or Saturday afternoon run—but your brain revels in it. That’s because exercise doesn’t just increase muscle tone. It doesn’t just goose energy levels and enhance mood, fighting <a href="https://www.pbs.org/wgbh/nova/video/depression-memory-alzheimers/">depression</a> and anxiety. It also heightens problem-solving skills and memory. And, research has increasingly shown, it protects against <a href="https://www.pbs.org/wgbh/nova/video/determined-fighting-alzheimers/">Alzheimer’s disease</a>—both delaying onset of the disease and slowing decline in patients who have already been diagnosed.</p>
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<p>As baby boomers age and more Americans live longer, Alzheimer’s is on the rise. In 2020, some 5.8 million people in the U.S. were living with this most common form of dementia, in which inflammation and tangles of misformed proteins in the brain accompany progressive <a href="https://www.pbs.org/wgbh/nova/video/alzheimers-screening-test/">memory loss</a> and inability to perform day-to-day tasks.</p><p>Despite decades of research, effective treatments for Alzheimer’s have eluded researchers; even a full explanation of what happens inside an Alzheimer’s patient’s brain has remained out of reach. This is in part because the disease is incredibly knotty and multifaceted, says Fang Yu, a researcher at Arizona State University who specializes in applying new dementia science to human trials. Alzheimer’s affects myriad processes in the brain, our most complicated organ, but most treatments developed thus far have only been able to tackle one aspect of the disease at a time, she says. “Even if there is a medication that can help target certain pathways, there are many pathways needed.” </p><p>That’s why Yu’s Alzheimer’s studies have often focused on the power of moving our bodies. Exercise is unique in that it also affects the body and brain in many ways, she says, making it an important intervention for addressing the complexity of Alzheimer’s. </p><p>It’s “something quite special,” agrees Christiane Wrann, a neuroscientist at Harvard University and Massachusetts General Hospital. While you’re dancing, bicycling, or running, it may seem like “you’re doing something that doesn’t have anything to do with the brain,” she says. “But you’re actually getting improvement in cognitive function.”</p>
<h3><b>How does it work?</b></h3><p>Perhaps the most straightforward way in which exercise safeguards against Alzheimer’s is by improving cardiovascular health. The effects of a good sweat session don’t stop at our hearts—they help improve the condition of our other organs and blood vessels as well. Those healthier vessels deliver an upgrade in the connections among brain cells called neurons, Wrann says. With reinforced wiring, it’s easier for nourishing oxygen to get in, for waste products to get out, and for the neurons to talk to one another. And improved fitness of the heart and lungs also seems to help the brain take up glucose more efficiently, which helps keep neurons healthy.</p><p>Plus, <a href="https://www.pbs.org/wgbh/nova/video/cannabis-reverses-brain-aging/">research on mice</a>—a common, if imperfect, source of new Alzheimer’s science, since it’s not possible to ethically conduct some kinds of research on living humans—has shown that exercise is a rare cause of “adult neurogenesis,” or the growth of new neurons in adulthood. Although it’s difficult to prove fully that the same happens in humans, it seems like <a href="https://www.researchgate.net/publication/323624428_The_Role_of_FNDC5Irisin_in_the_Nervous_System_and_as_a_Mediator_for_Beneficial_Effects_of_Exercise_on_the_Brain">one key player is irisin</a>, a hormone manufactured in the muscles in response to exercise, Wrann explains. Irisin is special because it carries a pass to get through the blood-brain barrier, the barricade of tissue and blood vessels that keeps harmful substances from reaching the brain. </p><p>Once inside, <a href="https://www.researchgate.net/publication/354038429_Exercise_hormone_irisin_is_a_critical_regulator_of_cognitive_function">irisin helps the brain</a> create a neurotransmitter called BDNF, which is important to hippocampus health. The hippocampus is a center of learning and memory in the brain, and Alzheimer’s patients’ hippocampi tend to shrink as their health declines, Yu says. The ability to sprout new cells in the hippocampus, and to prune away connections that aren’t needed anymore—two processes that BDNF supports—is key to stabilizing and protecting it.</p>
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<p>A series of studies at Wrann’s lab in Boston has also shown that, at least in mice, irisin produced during exercise has powerful anti-inflammatory effects in the brain. That could be an important insight because some new research points to <a href="https://www.pbs.org/wgbh/nova/article/brain-inflammation/">inflammation</a>, rather than previously implicated amyloid plaques, as a possible cause of neuron death in Alzheimer’s. Inflammation is caused by the immune response to negative stimuli—not just viruses or bacteria but also, for example, misfolded proteins in the brain. In an Alzheimer’s patient, the immune system may respond to the presence of these plaques by attacking them, Wrann explains, and in its enthusiasm, it may also attack the synapses that connect neurons. “If it gets completely out of control, you have this ‘friendly fire’ that causes damage to the neurons,” she says. But her research indicates irisin may bind to receptors on specialized cells deep within the brain, calming that inflammatory response.</p><p>And one last piece of the puzzle is <a href="https://www.pbs.org/wgbh/nova/article/healing-sleep/">sleep</a>—not a type of exercise in itself, but caught up in something of a love triangle with exercise and Alzheimer’s disease. When it comes to dementia prevention, sleep and exercise may work together, says neuroscientist Miranda Chappel-Farley, a Ph.D. candidate at University of California, Irvine. Studies have shown that more exercise leads to better quality sleep, which is an important protective factor itself against Alzheimer’s. And people getting better sleep are more likely to feel up to exercising. Together, they create a powerful bulwark against dementia and represent a lifestyle factor ignored at your peril, says Chappel-Farley, who cautions against “targeting exercise but not paying attention to sleep.” </p>
<h3><b>What kind of exercise is best?</b></h3><p>Aerobic exercise seems to be the champion when it comes to protection against Alzheimer’s and maintaining executive function. Of course, most of the mice participating in Alzheimer’s trials run on their wheels, but that doesn’t mean you have to. Biking, dancing, swimming, or any activity that gets your heart rate up is a good candidate, Yu says. That’s because it has the potential to increase BDNF levels; spur blood flow and shore up blood vessels; and decrease “white matter hyperintensities,” abnormal changes that affect how the brain transmits electrical signals.</p><p>Newer research also indicates that resistance-based muscle-building exercise may support a broad spectrum of cognitive functions. That effect seems especially promising in patients who have already been diagnosed with Alzheimer’s, where it may help slow their decline, adds Yu, who often works with dementia patients. There, the goal is not improvement but slowing deterioration. “And that’s basically what my research has shown: that exercise can level and stabilize,” she says.</p><p>Tai chi and other types of movement that incorporate mindfulness also decrease stress and inflammation and improve sleep, she adds. And some research suggests that a mix of many types of exercises may provide stronger improvement than a single activity. In a review of <a href="https://europepmc.org/article/med/34004389">71 studies of exercise and dementia</a>, Yu and her colleagues found the most consistently effective exercise was “mixed component,” a blend of muscle-building and aerobic workouts.</p><p>Still, “it’s important to highlight that there’s a lot we don’t know yet,” says Chappel-Farley, since exercise comes in so many forms and can be adjusted by duration, intensity, frequency, and timing. “It’s not totally clear which might be best.” Does it take a certain amount of exercise for our brains to reap the benefits? Are there any findings in the extensive mouse research on this topic that can’t be transferred to humans? </p><p>Wrann says that data is encouraging so far, indicating that the more you exercise the more benefit you’ll experience. And really, what’s the risk? “My big message is that exercise is good for you,” Yu agrees. “Even if in the future we find that it doesn’t prevent Alzheimer’s for everyone, it’s still good for your health and quality of life.”</p><p>But Wrann also remains mindful of people who can’t exercise because of a disability or physical limitations, or who may develop Alzheimer’s despite getting plenty of exercise; there’s still no silver dementia bullet. While it’s unlikely that researchers could develop a drug that can affect the body in as many ways as exercise can, she’s hopeful about irisin’s potential as a source of new drug therapies. Because it’s a powerful anti-inflammatory that can already wriggle through the blood-brain barrier, she wonders if it might be possible to use irisin to create a drug that goes even beyond the positive effects of exercise. Inflammation in the brain seems to be central to many neurological conditions. That way, she says, “we could reach people with Alzheimer’s disease—or beyond.”</p>
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<p data-block-key="eldwf">Exercise could be a powerful defense against Alzheimer’s disease. Three dementia researchers explain how it works.</p>

6 stinking cool facts about dog noses

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<p>Did you know that dogs can use their cold, wet (and cute!) noses to sense sources of heat and thermal radiation? </p><p>That discovery, via a <a href="https://www.science.org/content/article/new-sense-discovered-dog-noses-ability-detect-heat">2020 study from Sweden</a> that challenged dogs to choose between a warm and cool object across a room, makes them only the second mammal known to possess that superpower. (The other is a vampire bat.)</p><p>And that’s not all dogs' noses can do. Read on for six reasons why dog noses are among nature’s most amazingly engineered instruments—instruments whose power humans are <a href="https://www.pbs.org/wgbh/nova/video/electronic-nose-imitate-dog-nose/">now trying to recreate</a>:<br/><br/> 1. Dogs' <a href="https://www.pbs.org/wgbh/nova/article/dogs-sense-of-smell/">sense of smell</a> is between 10,000 and 100,000 times as potent as humans’. This power comes in part from the up to 300 million olfactory receptors dogs carry around in their noses, compared to our mere 6 million. And the part of the canine brain that is dedicated to smells is 40 times larger than ours, proportionally speaking.<br/><br/>2. Dogs can smell continuously, even while they’re breathing in and out. In contrast, when a human smells a scent (sniffs a rose, for example) we inhale that odor and breathe in oxygen through the same passage. But if a dog smells the same flower, air “splits into two different flow paths, one for olfaction and one for respiration," Brent Craven, a Pennsylvania State University bioengineer who has modeled <a href="https://anatomypubs.onlinelibrary.wiley.com/doi/full/10.1002/ar.20592">canine olfaction anatomy</a> using high-resolution MRIs, <a href="https://www.pbs.org/wgbh/nova/article/dogs-sense-of-smell/">told NOVA</a>.</p><p>Craven and his colleagues found that a portion of the air dogs inhale gets ushered into a specialized area at the back of the canine nose reserved for odor detection, while the rest of it continues rushing toward the lungs. And when dogs exhale, that air departs through nose slits in a unique aerodynamic pattern that also guides new air in, creating a cycle of breath that continuously supplies the in-house laboratory in the back of the canine nose with new material. In <a href="https://pubmed.ncbi.nlm.nih.gov/8735662/">one study from the University of Oslo</a>, a dog on a hunt sniffed continuously for a full 40 seconds, across 30 respiratory cycles!</p><h4><b>Watch: This Device Smells Diseases by Imitating a Dog's Nose</b></h4>
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<p>3. Dogs can <a href="https://vcahospitals.com/know-your-pet/how-dogs-use-smell-to-perceive-the-world">wiggle their nostrils independently</a>, which helps them figure out which direction a scent is coming from. Humans can only wiggle their nostrils simultaneously. (Try it. We’ll wait.)</p><p>4. Dogs are great at interpreting all the information coming in through their noses in fine detail. In her book “Inside of a Dog,” canine cognition researcher Alexandra Horowitz writes that humans might taste a teaspoon of sugar added to a cup of coffee. But a dog could detect the same teaspoon of sugar in a million gallons of water—enough to fill two Olympic-sized pools.</p><p>And to take the sugar metaphor further, “if we humans walk into a bakery, we can say, ‘someone’s baking a pie in here,’” canine search specialist Lynne Engelbert <a href="https://www.pbs.org/wgbh/nova/article/cremation-ashes-sniffing-dogs-california-wildfire/">told NOVA</a>. “A dog would walk in and say, ‘Oh, someone’s baking a pie in here, and it has apples, and butter, and cinnamon, and nutmeg.”</p>
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<p>5. Dogs can connect a human with the scent they leave behind with exceptional precision—and even help diagnose sick humans with a variety of diseases. Forensic chemist Ken Furton, who has studied dog olfaction for more than 25 years, once blew up a car with colleagues and then asked detection dogs to pick out human scent from the resulting debris. The dogs were able to sniff the small amount of shrapnel and correctly identify the people who had been in contact with the bomb pre-explosion 82% of the time.</p><p>More recently, Furton and his colleagues looked at whether dogs might be trained to identify COVID-19 patients—and found they could do so with 97.5% accuracy. “I was shocked,” he told NOVA. And <a href="https://faseb.onlinelibrary.wiley.com/doi/abs/10.1096/fasebj.2019.33.1_supplement.635.10">one 2019 study</a> indicated humans’ best friends can sniff out cancer with a similarly high 97% accuracy rate.</p><h4><b>Watch: Cannabis-Sniffing K-9's: Out of a Job?</b></h4>
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<p><br/>6. Dogs can not only identify human remains–they can sniff out <i>already cremated</i> remains from among other ashes. Dogs in the American West are now being trained to <a href="https://www.pbs.org/wgbh/nova/article/cremation-ashes-sniffing-dogs-california-wildfire/">look for the cremated remains</a> of homeowners’ loved ones when those homes are lost to the region's increasingly fierce wildfires. The non-profit Alta Heritage Foundation brings specially trained search dogs and archaeologists to the site of a house destroyed by fire, using canine colleagues to narrow down where the lost ashes might be buried and then archeological techniques to excavate them. </p><p>The ashes are often the only thing his clients want to recover from their houses, Alta Heritage founder Alex DeGeorgey told NOVA. So being able to find their loved ones’ ashes within the ashes of a house is both powerful and continually surprising. “I’ve done this hundreds of times,” DeGeorgey says of cremation ash recovery, “and I still marvel that we’re able to do it.”</p>
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<p data-block-key="dc0rk">Dogs can sniff out disease and analyze new odors even as they exhale. But how?</p>

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