Understand All

What kind of parasite eats a fish’s tongue and then stays behind as the tongue? In this episode, we unpack Cymothoa exigua, the tongue-eating parasite, how it gets into fish through the gills, why the host can often keep feeding, and what this bizarre case reveals about parasite biology and evolution—listen now before this one gets buried under a hundred half-true versions of the story.

Cymothoa exigua, the tongue-eating parasite, sounds like a horror story — but it’s a real parasitic isopod that can enter a fish through the gills, feed on the tongue, and then function as the tongue itself. In this episode, we unpack the biology, the weird evolutionary trade-offs, and why this fish parasite is famous in marine biology.

• Cymothoa exigua is the only known parasite that physically replaces a host organ in form and function.
• It mostly targets marine fish like snappers in the eastern Pacific.
• Infected fish can often keep feeding, even while their mouths and gills are under chronic stress.
• Humans are not known hosts, and infected fish are generally considered safe to eat.

Chapter labels:
The Fish With a Missing Tongue
How the Parasite Gets In
Why the Fish Still Survives
What This Means for Marine Ecosystems

Related resources:
[More marine biology episodes](/shows/marine-biology)
[Transcript](/transcripts/cymothoa-exigua)
External: [Wikipedia](https://en.wikipedia.org/wiki/Cymothoa_exigua)
External: [Ocean Conservancy on tongue-eating lice](https://oceanconservancy.org/blog/2022/04/28/tongue-eating-louse-eats-tongues/)

If this episode made you rethink what parasites can do, share it with a friend and subscribe for more strange-but-true science stories.

A real epidemic once left people trapped in a strange half-awake state, sometimes frozen in place, and then seemed to disappear before doctors could fully explain it. In this episode on encephalitis lethargica, the sleeping sickness epidemic, we trace the mystery, the Spanish flu connection, the autoimmune theories, and the survivors who later developed post-encephalitic parkinsonism — listen now to hear why this vanished disease still matters.

Encephalitis lethargica, the “sleeping sickness” epidemic, was a global neurological mystery that left some people profoundly sleepy, others frozen in place, and many survivors with long-term movement and psychiatric symptoms. In this episode, we explore the rise, disappearance, and lasting scientific mystery of encephalitis lethargica, including its debated link to the Spanish flu and its relevance to modern autoimmune encephalitis research.

• How encephalitis lethargica spread worldwide between 1915 and 1930
• Why it caused lethargy, movement disorders, and post-encephalitic parkinsonism
• Why the Spanish flu theory remains controversial
• What L-DOPA revealed about frozen brain circuits
• Why EL still matters to neurology and pandemic preparedness

The sleeping epidemic
Vienna and Constantin von Economo
Spanish flu, infection, and autoimmunity
Frozen bodies and L-DOPA awakenings
Why it vanished

Related resources and links:
Internal: [Episode transcript](/episodes/encephalitis-lethargica)
External: [Brain review on encephalitis lethargica](https://academic.oup.com/brain/article/140/8/2246/3970828), [PMC sleep research review](https://pmc.ncbi.nlm.nih.gov/articles/PMC7448964)

If this episode changed how you think about the brain, send it to a friend and leave a review so more people can find it.

One torch, one masked costume, and a royal ball in 1393 nearly ended with the King of France burning alive. In this episode, we unpack the Bal des Ardents, Charles VI, medieval Paris, and the fire that turned a court celebration into a political nightmare—listen now to find out how it happened and why it still matters.

In this episode, we unpack the Bal des Ardents, the 1393 masked ball in Paris where a royal celebration turned into a fire disaster that nearly killed King Charles VI of France. We trace how a courtly entertainment, a flammable costume, and one careless torch exposed the danger, politics, and fragility inside the French court.

• The Bal des Ardents took place on 28 January 1393 at the Hôtel Saint-Pol in Paris.
• Charles VI was already coping with mental illness, which made the event politically explosive.
• Four nobles died when their wild men costumes caught fire.
• The Duchess of Berry helped save the king, while one dancer escaped by jumping into wine.
• The fire became a symbol of courtly excess and instability in medieval France.

Chapter Labels:
The Royal Ball
Charles VI’s Fragile Court
The Torch That Changed Everything
Fire, Panic, and Survival
Why the Ball Became a Political Scandal

Related resources and links:
• Internal: [More episodes on medieval history](/topics/medieval-history)
• External: [BnF: Jean Froissart’s Chronicles](https://essentiels.bnf.fr/fr/livre-feuilleter/03e271f1-c313-4130-bb2f-f65edb3fde9d-jean-froissart-chroniques)
• External: [HistoryExtra on the Ball of the Burning Men](https://www.historyextra.com/period/medieval/ball-of-burning-men-history-facts-what-happened/)

If you enjoyed this episode, share it with a friend who loves strange history, and follow the show for more stories from the past that still feel uncomfortably modern.

One chemist helped turn air into fertilizer for billions of people — and then helped turn the same science toward poison gas. In this episode, we unravel Fritz Haber, the Haber-Bosch process, the rise of synthetic ammonia, and the grim birth of chemical warfare. Listen now to hear how one invention could feed the world and reshape war at the same time.

Fritz Haber’s story is one of science’s biggest double edges: the ammonia synthesis behind the Haber-Bosch process helped make fertilizer at industrial scale and feed billions, but the same chemistry also fed explosives and chemical warfare. In this episode, we unpack how one chemist changed global agriculture, war, and the ethics of scientific progress.

• The Haber-Bosch process turned atmospheric nitrogen into ammonia, transforming fertilizer production and modern food systems.
• That same industrial chemistry also helped Germany produce nitrates for explosives during World War I.
• Fritz Haber became a central figure in chemical warfare, including the first large-scale chlorine gas attacks.
• His legacy still shapes debates about dual-use science, scientific responsibility, and technology ethics.

Chapters:
Why fertilizer starts with air
How the Haber-Bosch process works
From ammonia to explosives
Chemical warfare and chlorine gas
The legacy of dual-use science

Related resources and links:
Internal: Episode transcript
Internal: More episodes on science and ethics
External: Nobel Prize biography of Fritz Haber
External: Science History Institute profile on the Haber-Bosch process
External: BBC coverage of Haber’s pesticide legacy

If this episode changed how you think about food, war, or science, share it with a friend and leave a review so more listeners can find it.

An African man in Oda Nobunaga’s Japan became one of history’s most debated figures: Yasuke, the so-called Black samurai, bodyguard, or something in between. In this episode, we trace the real Yasuke through 16th-century Japan, Jesuit missions, and the thin historical record that turned him into legend—listen now before the myth outruns the evidence.

Yasuke’s story begins with a question that still sparks debate: was he a samurai, a bodyguard, or something in between? This episode follows the African warrior who entered Oda Nobunaga’s world in 16th-century Japan, tracing the Jesuit route that brought him there, the thin historical record around him, and the legend that grew afterward.

• Yasuke appears in the record only briefly, around 1579–1582, but his impact on Japanese history and global history is outsized.
• Contemporary sources point to Yasuke as an attendant or bodyguard, while later retellings elevated him into a samurai legend.
• The Honnō-ji Incident in 1582 is the key turning point that makes his story vanish from the archive.
• Yasuke’s life opens a window into Jesuit missions, Oda Nobunaga, and early Africa-Japan contact.

Chapter labels: Yasuke arrives with the Jesuits; Nobunaga notices the stranger; Samurai, bodyguard, or legend?; Honnō-ji and the missing ending; How myths grow from thin records.

Related resources and links: Internal link: episode transcript; External link: Britannica’s Yasuke biography; External link: Smithsonian Magazine on Yasuke.

If you enjoyed this one, share it with a friend and tell us: what do you think history remembered about Yasuke, and what did it leave out?

What if the most famous masked lawman in American folklore had a real-life predecessor — and he was a formerly enslaved deputy U.S. marshal named Bass Reeves? In this episode, we unpack the Bass Reeves story, the 3,000-arrest legend, and the evidence behind the “real Lone Ranger” claim, so listen now before this history gets flattened into another easy myth.

Bass Reeves was one of the most remarkable deputy U.S. marshals in American history, and his story may have helped shape the legend of the Lone Ranger. In this episode, we dig into Bass Reeves, the Old West, Indian Territory, and the real history behind the “3,000 arrests” claim.

• Bass Reeves was born enslaved and later became a deputy U.S. marshal in Fort Smith.
• He worked under Judge Isaac Parker in Indian Territory, a dangerous frontier jurisdiction.
• The famous Lone Ranger comparison is intriguing, but the direct evidence is thin.
• Reeves’s life adds essential context to African American history and Western history.

Bass Reeves and the Old West
Fort Smith and Judge Isaac Parker
Indian Territory and federal law
The Lone Ranger connection

Related resources and links:
• National Park Service: [Bass Reeves site bulletin](https://www.nps.gov/articles/000/bass-reeves-site-bulletin.htm)
• Encyclopedia of Arkansas: [Bass Reeves](https://encyclopediaofarkansas.net/entries/bass-reeves-1747/)
• Britannica: [Bass Reeves](https://www.britannica.com/biography/Bass-Reeves)
• More episodes: [Our show archive](/shows) | [Black history episodes](/episodes/black-history)

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An enslaved pilot in Charleston Harbor stole a Confederate warship, passed armed forts, and sailed his family to freedom in plain sight. In this episode, we follow Robert Smalls’s escape, the Civil War intelligence he delivered to the Union, and the fight for Black freedom and power that came next — listen now to hear how one night changed history.

Robert Smalls was an enslaved pilot in Charleston Harbor who seized the Confederate steamer Planter, passed armed forts, and sailed his family to freedom. This episode follows the Robert Smalls escape, the Civil War intelligence he delivered to the Union, and how his courage shaped Black military service and Reconstruction politics.

• Learn how Smalls used harbor knowledge, signals, and timing to pull off the escape.
• Hear how the seized warship gave the Union a ship, codebook, and mine maps.
• See why Robert Smalls became a symbol for Black enlistment and leadership.
• Follow his postwar work in South Carolina government and the U.S. House.

Chapter labels:
Charleston Harbor and the Planter
The Night of the Escape
What the Union Got
From War Hero to Lawmaker

Related resources: [Transcript](/transcript), [Listen next: Reconstruction and Black political power](/episodes/reconstruction), [National Park Service biography](https://www.nps.gov/people/robert-smalls.htm), [Smithsonian Magazine feature](https://www.smithsonianmag.com/history/thrilling-tale-how-robert-smalls-heroically-sailed-stolen-confederate-ship-freedom-180963689/).

If Robert Smalls surprised you, share this episode and send it to one friend who loves untold history.

A volcanic eruption in 1883 was heard 3,000 miles away—and that was only the first strange thing Krakatoa did. In this episode, we follow the Krakatoa eruption, the tsunamis, the atmospheric pressure wave, and the global climate effects that turned one island disaster into worldwide chaos, so listen now before you think you already know the story.

In 1883, Krakatoa didn’t just erupt — it sent a shockwave through the atmosphere, the oceans, and the world’s news network. This episode follows the Krakatoa eruption heard 3,000 miles away, the tsunamis that followed, and the strange global climate effects that made sunsets look like art and disaster at the same time.

• The Krakatoa eruption reached VEI 6 and ranks among the most powerful volcanic events in recorded history.
• Sound from the final blast was reported thousands of miles away, and the pressure wave circled the globe.
• Tsunamis caused most of the death toll, with coastal villages in Java and Sumatra devastated.
• Ash and sulfur in the stratosphere changed skies worldwide and cooled the planet for years.

Chapters:
The Island Before the Blast
The Sound That Traveled the Planet
Tsunamis, Collapse, and Human Loss
Ash, Sunsets, and Global Climate Effects

Related resources: USGS Krakatau 1883, NOAA/NCEI Krakatau eruption overview, Royal Society archive on the 1883 event, and our internal episode transcript and archive.

If this story grabbed you, share it with a friend, subscribe for more science history, and tell us which part of Krakatoa surprised you most.

In 1859, a solar storm known as the Carrington Event sent telegraph wires sparking and set the stage for the biggest “what if” in space weather history. In this episode, we explore how a repeat Carrington Event could threaten the modern grid, power lines, satellites, GPS, and the systems that keep daily life running — listen now to hear why the Sun is still a risk we can’t ignore.

The Carrington Event was a 1859 solar storm so powerful it sparked telegraph wires and became the benchmark for a worst-case geomagnetic storm. In this episode, we unpack what happened, how coronal mass ejections drive space weather, and why a repeat could stress the modern power grid, satellites, GPS, and communications.

• The 1859 event remains the largest geomagnetic storm in the instrumental record.
• Telegraph systems literally sparked, shocked operators, and sometimes worked with batteries disconnected.
• A modern Carrington-level storm could disrupt transformers, navigation, and timing systems.
• Monitoring from NOAA and NASA gives warning, but extreme storms still carry real risk.

Chapter labels: Richard Carrington’s telescope | Telegraphs on fire | From CME to geomagnetic storm | What a repeat could do now

Related resources and links: [More episodes on space weather](#/space-weather), [Subscribe to the show](#/subscribe), [NOAA Space Weather Prediction Center](https://www.swpc.noaa.gov), [NASA Solar Dynamics Observatory](https://sdo.gsfc.nasa.gov)

If this story changed how you think about the Sun, share it with a friend and tell us what system you think would fail first.

Gregor MacGregor sold London a country that did not exist — and people actually bought the dream. In this episode, we unpack the Poyais scam, the fake country, the forged maps, the Poyais bonds, and the devastating trip that exposed how far a confidence game can go. Listen now to see how a made-up nation fooled investors, settlers, and an entire financial world before the truth caught up.

Gregor MacGregor sold London a country that did not exist, and the Poyais scam became one of history’s most infamous confidence games. In this episode, we unpack how fake sovereignty, forged land grants, Poyais bonds, and glossy promotional materials turned a fiction into a financial and human disaster.

• Poyais was a fabricated Central American state promoted in the 1820s for investment and emigration.
• MacGregor used maps, guidebooks, and official-looking documents to manufacture legitimacy.
• The fraud reached the London capital market through Poyais bonds and settlement sales.
• Settlers arrived in 1822–1823 and found wilderness, not a functioning colony.

Gregor MacGregor and the invention of Poyais
How fake documents created trust
London bonds and investor deception
The settlers who discovered the truth
Why Poyais still matters

Related resources: [Episode transcript](#transcript) | [Britannica overview](https://www.britannica.com/story/the-craziest-scam-gregor-macgregor-creates-his-own-country) | [Cambridge Core study](https://www.cambridge.org/core/journals/enterprise-and-society/article/whats-in-a-fraud-the-many-worlds-of-gregor-macgregor-18171824/18C69E0C9D7E0878A96E17E2B0B9E12F)

If this story made you rethink how legitimacy gets built, share it with a friend and leave a review with your favorite moment.