The Inca Empire in South America was one of the most powerful pre-Columbian societies. It was known for the architecture of Machu Picchu, an extensive road network and a system of terraces for agriculture. The society also kept records known as khipu, which involved a system of tying knots to encode sophisticated information.Literacy in this form of writing was assumed to be something that only the highest levels of Inca society could do. But NPR science correspondent Nell Greenfieldboyce shares how a new analysis of a cord made out of human hair may change that assumption. Curious about science history? Email us 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.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy

Feel like summers are hotter than they used to be? It’s not just your imagination. Climate researchers say that average annual temperatures around the country have been trending upwards for the past 50 years — and are still on the rise. But it can be hard to represent those numbers in a way that makes sense to everyday people. So Gulf States Newsroom reporter and New Orleans resident Drew Hawkins wondered: What if he could help people hear those changes for themselves? Turn temperatures into tunes?This episode is part of Nature Quest, a monthly Short Wave segment that answers listener questions about their local environment.Got a question about changes in your local environment? Send a voice memo to shortwave@npr.org with your name, where you live and your question. We might make it into our next Nature Quest episode!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.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy

Deep sea mining for rare earth elements could start as early as 2026, even as 38 countries have called for a moratorium on it. The metals that companies are targeting are used in many green technologies like electric cars and wind turbines – but mining them is destructive to the environment. Some in the mining industry say the mining is necessary to a green transition – and essential to democratizing that transition globally since the supply chain is currently dominated by a single country, China. Meanwhile, some scientists caution against mining before the full scope of environmental damage can be understood. Can there be balance in this environmental and political push-and-pull? Hosts Regina G. Barber and Emily Kwong dive into this debate and talk about what science has to say. Curious about other science controversies? Email us 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.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy

Chocolate may fill grocery store shelves around the world, but the raw product that powers chocolate is far more selective. The majority of chocolate farms are found in West Africa and South America – just 20 degrees north or south of the equator. Each farm produces chocolate of a different flavor. Some cocoa tastes fruitier; others, more floral. Nutty. Earthy. Spicy. But what drives these different flavor profiles? And can it be recreated in a lab? A team led by scientists at the University of Nottingham in the UK sought to find out and published their results in the journal Nature Microbiology this week. Curious about other ways science intersects with food? Email us 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.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy

Thirty years ago, park rangers reintroduced grey wolves into Yellowstone National Park. They wanted to restore the ecosystem and get the elk population, which had decimated the plant community, in check. And it worked – or so the popular narrative suggests. But is it really so simple? Today on the show, we explore how the Yellowstone ecosystem has changed since wolves returned and whether those changes can really be pinned solely on wolves. Plus, how the narrative of the Yellowstone wolf legacy could affect wolf reintroduction elsewhere.Curious about other science controversies? Email us 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.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy

Imagine, you’re a toxic toad hanging around South America. No other animals are gonna mess with you, right? After all, you’re ~toxic~! So if anyone tries to eat you, they’ll be exposed to something called a cardiotonic steroid — and may die of a heart attack. Well, unfortunately, for you, some animals have developed adaptations to these toxic steroids. Evolutionary biologist Shabnam Mohammadi has spent her career studying how these adaptations work — and says even humans have used these toxins to their advantage since ancient Egypt. So today on Short Wave, we get a little… toxic (cue Brittney Spears). Host Regina G. Barber talks to Shabnam about how some predators can get away with eating toxic prey. Curious about biology? Email us 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. Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy

Scientists have mapped less than 30% of the world's seafloor. Experts say that getting that number up to 100% would improve everything from tsunami warnings to the Internet and renewable energy. That's why there's currently a global effort to create a full, detailed map of the seabed by 2030. On today's Sea Camp episode, we talk to Dawn Wright, a marine geographer and chief scientist at the Environmental Systems Research Institute (Esri) about this effort.  We have a newsletter that lets you go even deeper with the marine research each week of Sea Camp. You can sign up here!Curious about ocean science? Email us at shortwave@npr.org.  Listen to Short Wave on Spotify and Apple Podcasts.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy

In this Back To School episode we consider the "List of Life": the criteria that define what it is to be a living thing. Some are easy calls: A kitten is alive. A grain of salt is not.But what about the tricky cases, like a virus? Or, more importantly, what about futuristic android robots?As part of our Black History Month celebration, developmental biologist Crystal Rogers and Short Wave co-host Regina G. Barber dig into what makes something alive, and wade into a Star-Trek-themed debate.Listen to Short Wave on Spotify and Apple Podcasts.Is there something you'd like us to cover? Email us at shortwave@npr.org.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy

Neurotic, anxious robots like C-3P0 from Star Wars' C-3P0 and Marvin from The Hitchhiker's Guide to the Galaxy are a staple of science fiction — but they're not as common in the real world. Most of the time, the chatbots and artificial intelligence "robots" we encounter are programmed to be extraverted, confident and cheerful. But what if that changed?NPR science correspondent Nell Greenfieldboyce dives into the world of robot personality research and talks to a team of researchers that are experimenting with a very different kind of robot temperament.Read more of Nell's reporting on the topic here.Interested in more science news? Let us know 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.Love podcasts? For handpicked recommendations every Friday, subscribe to NPR's Pod Club.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy

A Chinese scientist, He Jiankui, made a shocking announcement to the world in 2018: He had secretly engineered the birth of the first gene-edited babies. The birth of the twins was seen as reckless and unethical by the scientific community. That’s because, among other things, the CRISPR gene-editing technique Jiankui used was so new. NPR science correspondent Rob Stein has been following the controversial world of gene-editing and human reproduction, including some companies’ recent quests to push gene-editing technology forward.Read more of Rob Stein’s reporting on the topic here.Interested in more science news? Let us know 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.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy