Episodes

  • How did these flowers evolve to survive a megadrought?

    How did these flowers evolve to survive a megadrought?
    Mar 20 2026
    A multi-year megadrought in the Western U.S. has claimed untold populations of wild plants. Amid the conditions, some have survived. Scientists have produced a stunningly complete picture about how populations of one particular flower – the scarlet monkeyflower – made it through.

    In a new study published in the journal Science, a team of scientists spent decades studying and sampling select populations of scarlet monkeyflowers in California and Oregon. Through genetic sequencing, the team discovered that the populations that did best went through genetic changes in a short time period. This is known as rapid evolution.

    The team found that three of the populations that recovered the BEST adapted their stomata to open less, so they could conserve more water. Stomata act like a plant’s pores, managing gas exchange and water loss. This allowed the scarlet monkeyflowers to hunker down in the drought and survive.

    Interested in more stories about rapid evolution? Email us your question at shortwave@npr.org.

    Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.

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    This episode was produced by Jeffrey Pierre, Rachel Carlson and Hannah Chinn. It was edited by Christopher Intagliata and Rebecca Ramirez. Aru Nair checked the facts. The audio engineers were Becky Brown and Robert Rodriguez.

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    8 mins
  • A dietitian and doctor review RFK Jr's new food pyramid

    A dietitian and doctor review RFK Jr's new food pyramid
    Mar 18 2026
    The new food pyramid was released earlier this year. It emphasizes protein, full-fat dairy and what Health and Human Services Secretary Robert F. Kennedy Jr. calls “healthy fats.” These guidelines influence the standards for school lunches, food labeling and programs like SNAP. Today on the show, Short Wave co-host Emily Kwong chats with registered dietitian nutritionist Shana Spence, and Dr. Sarah Kim, a diabetes specialist, about the new guidelines. Plus, NPR’s Reflect America fellow Kadin Mills unpacks how the new food pyramid could change school lunch trays.

    Check out more of Kadin’s coverage about the changes in dietary guidelines.

    Interested in more health science? Email us your question at shortwave@npr.org.

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    13 mins
  • ‘Black rain’ in Iran and the environmental cost of war

    ‘Black rain’ in Iran and the environmental cost of war
    Mar 17 2026
    US-Israeli airstrikes on oil depots culminated in ‘black rain’ in Iran early last week – a phenomenon usually caused by large amounts of soot, carbon and other pollutants in the air. Usually, rain leaves the atmosphere cleaner than it was before. But in this case, the rain left Tehran’s residents with sore throats and burning eyes. Oily, sooty residue was all over the city. So, we talked to an environmental pollution expert to find out: What’s in this ‘black rain’, what are its potential short- and long-term environmental and health effects, and what could recovery look like?

    Interested in more science behind current events? Email us your question at shortwave@npr.org.

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    13 mins
  • This is your brain on pleasure (even the guilty kind)

    This is your brain on pleasure (even the guilty kind)
    Mar 16 2026
    It’s likely you have at least one “guilty pleasure.” Maybe it’s romance novels. Or reality TV… Playing video games… or getting swept into obscure corners of TikTok. Neuroscientists say the pleasure response helps us survive as a species. So why do we feel embarrassed by some of the things we love the most? Even if you don't have these negative emotions, experiencing – and studying – pleasure is not as straightforward as it might seem. For a long time, neuroscientists thought the concept of "pleasure" referred to a singular system in the brain. But as research into the subject grew, scientists realized that pleasure is really a cycle of "wanting" and "liking" – each with separate neural mechanisms. Today on the show, producer Rachel Carlson explores this cycle with researchers, who weigh in on the science of pleasure. Even the kind that makes us feel guilty.

    Read more of Rachel’s story on guilty pleasures.

    Interested in more brain science? Email us your question at shortwave@npr.org.

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    14 mins
  • An icy mystery: What are lake stars?

    An icy mystery: What are lake stars?
    Mar 13 2026
    When producer Berly McCoy was out on her local frozen lake, she saw something she'd never seen before. There were dark spidery, star-shaped patterns in the ice and they freaked her out. So, we called an expert to find out more about them. In today’s episode, geophysicist Victor Tsai tells us about lake stars and how he became the first person to scientifically prove how they form. Plus, he explains how knowing more about lake stars can potentially give us clues about the presence of water on Europa, one of Jupiter’s icy moons.

    Read Victor Tsai’s full paper on lake stars here.

    Have a question about something in the environment? Email us at shortwave@npr.org.

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    12 mins
  • We saved gray whales from extinction. Why are so many dying again?

    We saved gray whales from extinction. Why are so many dying again?
    Mar 11 2026
    In 1999 hundreds of gray whales washed up along the west coast of North America. More in 2000. They lost an estimated 25% of their population. But then the whale population recovered and people moved on. Until it happened again in 2019. And 2020, and 2021. It’s still happening today. Host Regina G. Barber dives into this mystery with marine ecologist Joshua Stewart, who explains how scientists like himself solved it – and the tough questions that came up along the way.

    Check out our Sea Camp series and our limited run Sea Camp newsletter, featuring deep dives into research, cute critters and games!

    Interested in more ocean mysteries? Email us your question at shortwave@npr.org.

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    13 mins
  • Sibling order may affect sexuality and identity

    Sibling order may affect sexuality and identity
    Mar 10 2026
    Today, guest host Selena Simmons-Duffin is exploring a detail very personal to her: How the number of older brothers a person has can influence their sexuality.

    Scientific research on sexuality has a dark history, with long-lasting harmful effects on queer communities. Much of the early research has also been debunked over time. But not this "fraternal birth order effect." The fact that a person's likelihood of being gay increases with each older brother has been found all over the world – from Turkey to North America, Brazil, the Netherlands and beyond. Today, Selena gets into all the details: What this effect is, how it's been studied and what it can (and can't) explain about sexuality.


    Interested in the science of our closest relatives? Check out more stories in NPR's series on the Science of Siblings.

    Email us at shortwave@npr.org — we'd love to hear from you.

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    12 mins
  • What crocodile bones teach us about dinosaurs

    What crocodile bones teach us about dinosaurs
    Mar 9 2026
    Paleontologists have often determined how old a dinosaur was by counting the growth rings in its bones. Just like with trees, it was thought that each ring corresponded to a single year of age. But researchers who studied crocodiles at an outdoor recreation center near Cape Town appear to have poked a hole in that approach. In the crocodiles, which are some of the closest living relatives of dinosaurs, there was more than one growth ring laid down per year. The results contribute to a growing debate over the best way to age animals.

    Read more of freelance science reporter Ari Daniel’s story here.

    Interested in more on the future of science? Email us your question at shortwave@npr.org.

    Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.


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    11 mins