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SPONSORED BY  | | | | December 3, 2024: Friends sharing microbiomes, the name for that feeling when a word's on the tip of your tongue, and why birds look so goofy when they run. —Andrea Gawrylewski, Chief Newsletter Editor | | | Polar Bear on pack ice in Svalbard, Norway. Schafer & Hill/Getty Images | | | • The Arctic could experience its first so-called "ice-free" day within the next few years, according to a new analysis. (Ice-free means the Arctic sea ice cover shrinks below 1 million square kilometers, or 386,102 square miles, on the surface of the ocean.) | 3 min read | | | Scientists used a computer simulation to study birds' strange running style--modeling the gait of a Common Emu ( Dromaius novaehollandiae). All birds employ "ground running," where they always keep one foot on the ground even as they gain speed. Humans use aerial running and pick up our feet to move faster. The researchers showed that the emu's posture makes grounded running more efficient than aerial running at certain speeds.
How it works: Birds have a crouched body position, with their hips and knees tucked into their feathery bodies. This alignment favors ground running. Using the simulation, the researchers were able to "adjust" the emu's leg anatomy and prevent the tendons from storing energy as they tested which gaits were most efficient for moving at various speeds. (You can try this yourself by crouching down and trying to run.)
What the experts say: If birds run this way, then it's likely that birds' prehistoric dino ancestors, such as the petite velociraptors, hunted their prey in this (terrifying) crouched run position, says Pasha van Bijlert, an evolutionary biomechanics graduate student at Utrecht University and Naturalis Biodiversity Center in the Netherlands. | | | Graphic by Brown Bird Designs | | | The feeling of knowing a word, but not being able to summon it up, is appropriately called tip-of-the-tongue (TOT) state. Long thought to be partial recollection, the latest research shows that the phenomenon is sometimes just an illusion. College students were given a set of questions and reported for each one whether they were in a TOT state or not. Those who felt that the answer was on the tip of their tongue were no more likely to come up with the right answer than those who did not.
How it works: One possible explanation for TOT is that the question triggers a feeling of familiarity, and the brain tries to make sense of it by signaling that we must have seen or learned this thing before. Exactly WHY this feeling happens remains a…what's that word again? Oh yes: mystery.
What the experts say: The brain may be "signaling: 'something relevant is here in memory–let's do a search,'" says Anne Cleary, a psychologist at Colorado State University. Some research has revealed that TOT feelings correlate with curiosity to learn the real answer. | | | SPONSORED CONTENT BY NMDP | The Future of Blood Stem Cell Transplants Is Here | Blood stem cell transplants using cells from a donor offer a promising cure for people with blood cancers or disorders. Before, not everyone had a suitable donor, leaving many without options for a cure. Now science is changing what's possible. Learn more. | | | • "Given the vastness of the cosmos and the fact that its physical laws allowed life to emerge at least one place—on Earth—the existence of life elsewhere is effectively guaranteed," writes Christopher K. Walker, professor of astronomy at the University of Arizona. But so far, we haven't found any. Because of the sheer gulf between us and the rest of the universe, we may never encounter alien life. "This doesn't mean we should stop looking—only that we should manage our expectations and prepare for a long and lonely voyage through space and time before meeting them, either virtually or physically," he says. | 5 min read | | | It's hard to share photos like the one above of the sad polar bear on a dwindling patch of ice. For one, it's heartbreaking. But in the case of climate change, I think it's important that we face up to the dramatic changes that many habitats--especially at high latitudes--are experiencing because the planet is warming rapidly. Human industry is having an outsized impact on plant and animals. Some species will be able to adapt, yes. Others won't. | Thank you for being part of our circle of science-curious readers! Email me anytime: newsletters@sciam.com. Same time tomorrow. | —Andrea Gawrylewski, Chief Newsletter Editor | | Subscribe to this and all of our newsletters . | | | | Scientific American
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