December 13, 2023: AI makes a map of 500,000 smells, and researchers create a complete atlas of all permafrost on Earth. Plus, is cannabis safe for teens? —Andrea Gawrylewski, Chief Newsletter Editor | | | A machine learning model has predicted smells for 500,000 molecules never synthesized before. To do this, researchers trained a neural network with 5,000 known odorants to emphasize 256 odor dimensions based on their effect on the odor of a molecule. The model created a giant map of odors, each molecule's coordinates determined by its chemical properties and described by descriptor terms like "beefy" or "jasmine." Why this is so cool: The model, called the Principal Odor Map, was able to complete a task that would take a human 70 years to finish. Plus, when the researchers compared the model's scent classifications to assessments by humans, the results matched.
What the experts say: Since most smells are mixes of multiple odor molecules, "mixture perception is the next frontier," says Emily Mayhew, a Michigan State University food scientist. | | | To create this chart, researchers compressed the 256-dimensional data into two dimensions: principal component 1 (PC1, shown on the x axis) and principal component 2 (PC2, shown on the y axis). Together, PC1 and PC2 capture 28 percent of the information contained in the full data set. Credit: Source: Modified version of a chart from "A Principal Odor Map Unifies Diverse Tasks in Olfactory Perception," by Brian K. Lee et al., in Science, Vol. 381; September 1, 2023. (Reproduced with permission.) | | | Researchers have created a free atlas of the world's permafrost, which documents the global distribution of this frozen ground, how it's changing in a warming climate, and how local people use and live on the land. The nearly 160-page document is loaded with dozens of maps, high-resolution images, and charts and graphs, and is easy to get lost in. You can explore the full atlas here.
Why this matters: Arctic permafrost soils are among the largest carbon stores in the world. And they play into an important positive feedback loop: As air temperatures rise, permafrost thaws during the summer months (normally it would remain frozen year-round) and releases stored carbon into the atmosphere. The released gases are potent greenhouse gases that heat the planet further, thawing even more permafrost.
What the experts say: "Many things are changing, especially now and especially in the Arctic. They're changing very rapidly, so this will need to be a living document," says Paul Overduin, a geoscientist at Germany's Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, in the latest episode of Science, Quickly, where you can hear from the scientists who assembled the atlas. | | | • A genetic analysis of underground microbes from as deep as 1.5 kilometers beneath the surface reveals two survival strategies: Some microbes eat everything they come across, and the others rely on scavenging or symbiotic relationships to survive. | 5 min read | | | • Male songbirds perform a daily vocal workout—if they want to impress potential mates. | 4 min read | | | • Ten years after cannabis was first legalized for recreational use in adults, scientists are struggling to provide evidence-based recommendations about the risks to young people. | 9 min read | | | • Mysterious green displays in the sky dubbed "mesospheric ghosts" can sometimes accompany the dramatic red atmospheric lights called sprites. | 3 min read | | | Red sprites above a supercell thunderstorm as lightning illuminates the cumulonimbus cloud below near Hay Springs, Nebraska. Credit: John Sirlin/Alamy Stock Photo | | | • Misleading forensic and expert evidence is too often behind life-ruining court decisions. The integrity of courtroom statistics needs to be improved, writes David Robert Grimes, a scientist and author of Good Thinking: Why Flawed Logic Puts Us All at Risk and How Critical Thinking Can Save the World (The Experiment, 2021). "Juries and Judges need to be educated on standards of scientific and statistical evidence, and to understand what to demand of expert testimony," he says. | 4 min read | | | • When this researcher questioned the use of risky vascular procedures, her colleagues pushed back, aggressively. | ProPublica | | | • Science writer Ed Yong reflects on lessons from reporting on the pandemic. | The New York Times | | | • If we had to name this era of uncertainty we're living through, what would we call it? | The New Yorker | | | It's a day for maps! If you enjoyed our foray into smell and permafrost cartography today, check out this collection of maps by Charles-Joseph Minard, the 19th-century French civil engineer. His most famous map, which depicts the march and retreat of Napoleon into Russia, launched my interest into different ways to display data information. | —Andrea Gawrylewski, Chief Newsletter Editor | | Subscribe to this and all of our newsletters . | | | | Scientific American
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