Award-winning photographer, filmmaker, and environmentalist Ian Shive gives the inside scoop on a research expedition to the Aleutian Islands. Then, learn how researchers solved a molecular mystery about how our ears turn sound into what you hear.
Award-winning photographer, filmmaker, and environmentalist Ian Shive gives the inside scoop on a research expedition to the Aleutian Islands. Then, learn how researchers solved a molecular mystery about how our ears turn sound into what you hear.
Additional resources from Ian Shive:
Scientists discovered the ear mechanism that turns sound into electrical activity -- and protects our hearing by Grant Currin
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Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/aleutian-island-secrets-and-electrical-ear-activity
CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from curiosity-dot-com. I’m Cody Gough.
ASHLEY: And I’m Ashley Hamer. Today, you’ll hear the exclusive, inside scoop about a research expedition to the incredible Aleutian Islands, with award-winning photographer and environmentalist Ian Shive. Then, you’ll learn about how researchers solved a molecular mystery about how our ears turn sound into what you hear.
CODY: Let’s satisfy some curiosity.
We’ve all seen Alaska on a map. It looks like a really huge chunk of land with a “tail” of islands that trails off to the west, towards Russia. Well those mostly uninhabited islands are called the Aleutian [uh-LOO-shin] Islands, and they’re part of the Alaska Maritime National Wildlife Refuge. Scientists can learn a surprising amount about the health of our planet from studying them, and our guest today is going to tell us how. Ian Shive is an award-winning photographer, filmmaker, and environmentalist, and host of “The Last Unknown,” a new nature special that documents the Aleutian Islands’ incredible natural wonders and wildlife. Here’s why Ian went there.
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So the Aleutian Islands are great for researchers because seabirds basically bring data to them. But that doesn’t mean scientists have an easy job: the entire archipelago is one of the most volcanically active areas in the world. Kinda dangerous. But also kind of important! When those volcanoes erupt — especially the underwater ones — they release nutrients and minerals into the environment, which helps nourish the entire food chain. And that’s not all.
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Yes, volcanoes don’t just destroy — they PROVIDE HABITATS? Who knew? ...they… DO, still, destroy, though.
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Again, that was Ian Shive, an award-winning photographer, filmmaker, and environmentalist, and host of “The Last Unknown,” a new special where you can see the beautiful nature he’s been describing. “The Last Unknown” is streaming now on discovery+. And if you don’t already have discovery+, then please check out the 7-day free trial by visiting discovery-plus-dot-com-slash-curiosity. We’ll include a link in today’s show notes.
Researchers have solved a molecular mystery that underpins an everyday miracle: hearing. They used lasers to study a tiny link in the very long chain of body parts that turn sound into, well, something you can hear.
Deep inside the inner ear are bundles of tiny hairs called stereocilia that help the body turn physical vibrations into the electrical signals the brain can understand. The stereocilia line the inside of a small, fluid-filled organ called the cochlea. Vibrations in the fluid cause the stereocilia to sway, kind of like the tentacles of a sea anemone that’s moving with the ocean current.
The researchers behind this study were interested in these teeny tiny little threads that connect the stereocilia to each other. They’re called tip links, and they’re really important. That’s because tip links control the flow of ions into cells that are connected to the nervous system. This flow of ions encodes the raw data that you eventually perceive as sound.
The researchers had already figured out that tip links are made of two different kinds of proteins. Each stereocilia has 2 strands of one kind of protein attached to it. Each of those strands is attached to a strand of the other kind of protein, and each of those strands is attached to the next stereocilia. Think of it like two acrobats, each hanging from a trapeze and holding the hands and feet of another acrobat in the middle.
To understand the bonds between the strands, the researchers in this study used lasers to pull on them until the bonds between them broke. That let them measure exactly how much force the bonds could handle before they reached a breaking point.
It turns out that the two pairs of strands are both strong and resilient. First, two strands can keep a connection for a lot longer than one strand can. When the researchers pulled on a double strand, the bond lasted ten times longer than when they tried with a single strand. And remember, each stereocilia has two strands, like the two hands of an acrobat.
One reason for that extra strength is that bonds could break and reform in tenths of a second, so if a loud sound caused one bond to break, the other could keep the connection long enough for the broken one to mend itself. If an acrobat loses their grip on one hand, the other hand can stay connected.
Strength isn’t necessarily a good thing, though. A really loud sound can cause both links to break. The researchers think that property serves as a kind of safety release or circuit breaker that protects these hard-to-repair structures from damage.
The experiments led to a really big surprise. Under resting conditions, a tip link only lasted about 8 seconds before breaking. That means that the connections that turn sound into signals in your brain are constantly breaking and reforming themselves. So, thanks to an ever-changing process happening in your ears at the molecular level, you get to hear this podcast. Aww.
Let’s recap the main things we learned today
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CODY: Today’s last story was written by Grant Currin and edited by Ashley Hamer, who’s the managing editor for Curiosity Daily.
ASHLEY: Today’s episode was produced and edited by Cody Gough.
CODY: Join us again tomorrow so Ashley and I can stimulate the stereocilia in your cochlea, to help you learn something new in just a few minutes.
ASHLEY: And until then, stay curious!