The Em Dash: From Shakespeare to ChatGPT

This episode of 99% Invisible, hosted by Roman Mars and reported by Will Aspinall, traces the strange journey of the em dash—a punctuation mark that has evolved from a medieval experiment into a hallmark of literary genius, only to become a suspicious sign of AI-generated text in the age of ChatGPT. The episode centers on Brian Vance, a Portland journalist whose grocery deal newsletter was accused of being AI-written solely because he used em dashes, sparking a deeper exploration of how this single mark became a battleground between human expression and machine mimicry.

0:00The Reddit Accusation That Started It All

Brian Vance runs Stumptown Savings, a Portland-based website and newsletter that tracks local grocery deals. He spends 40 hours a week visiting stores in person to find the best prices, writing dry but essential content like "Safe Catch Elite Wild Canned Tuna, select varieties — two for six." Despite his dedication, a Reddit user accused him of using ChatGPT to write his newsletter. The evidence? Brian used "extra long EM dashes that are not possible to replicate on a normal keyboard." The accusation stung not because it was false—Brian doesn't use AI—but because it revealed how a beloved punctuation mark had become a supposed tell for machine-generated text. The em dash, a horizontal bar roughly the width of a capital M, has long been a favorite of writers who appreciate its flexibility: it can replace commas, colons, semicolons, and parentheses. But in 2025, seeing an em dash in text has become, for some readers, an instant trigger to assume AI authorship.

5:26Bonnie's Forgotten Invention and the Dash's Medieval Origins

Keith Houston, author of "Shady Characters: The Secret Life of Punctuation," explains that punctuation was chaotic for centuries after its introduction around the 3rd century BCE. Rules were inconsistent and varied wildly across contexts. Then came Boncompagno da Signa, a 12th-century Italian scholar of *ars dictaminis* (the formal art of letter writing). Dissatisfied with existing punctuation, he created his own simple system with just two marks. The first, *virgula sursum erecta*, was a forward slash indicating a pause—this eventually dropped to the bottom of the line and became the modern comma. The second, *virgule plana*, was a horizontal dash used to end sentences like a period. This flat dash looked exactly like a modern en or em dash, but using it to end sentences never caught on. For centuries, the dash remained marginal, its grammatical role unclear and therefore malleable. Houston notes that while other punctuation marks like the period, comma, colon, and semicolon had relatively fixed uses, the dash "slid into this new era of printing without necessarily a big weight of opinion behind it," giving writers freedom to experiment.

8:28Shakespeare, Aposiopesis, and the Dash on Stage

The dash found its first dramatic purpose in Elizabethan theater through a technique called *aposiopesis*—an ancient Greek term for speech deliberately broken off mid-sentence. Playwrights used dashes to indicate thinking pauses, interruptions, mid-speech realizations, or sudden changes of subject. Shakespeare's First Folio is filled with dashes, particularly in moments where characters lose their train of thought or are cut off. The episode features a performance of King Lear by Sir John Gielgud, where Lear's fragmented speech—"Fiery? The fiery duke? Tell the hot duke that—No, but not yet: maybe he is not well"—demonstrates how dashes convey a mind grappling with age, bad decisions, and ungrateful children. This theatrical use of the dash to show how a speaker performs words would later influence novelists, who adopted it to bring naturalistic speech patterns to life on the page.

10:15The Novel's Golden Age: Tristram Shandy, Jane Austen, and the Censoring Dash

As the novel emerged as a new literary form in the 18th century, writers broke from classical rules to explore authentic characters with complex inner thoughts and naturalistic speech. The dash became essential for creating the sense of someone dictating their adventures onto the page. Lawrence Sterne's 1759 novel *Tristram Shandy* is the ultimate example—a rambling, satirical work that uses dashes in every conceivable way, jumping in and out of thoughts in what feels like stream of consciousness. The episode notes that a short excerpt contains seven dashes, and the novel's "wayward dash-strewn madness" makes Tristram feel like a fully rounded, flawed human being. Novelists also used dashes for a clever marketing trick: censoring sensitive content. By writing as if their fictional narratives were real letters or memoirs, they would redact names, locations, and dates with dashes—sometimes to protect real identities, but more often to create the illusion of authenticity. Jane Austen used this technique in *Pride and Prejudice* (1813), where dashes redact the letters in the name of Wickham's army regiment, as if protecting the regiment's reputation. This added a tantalizing mystery for readers, who could try to decode the hidden meaning behind the "saucy little dash."

15:05The Dickinson Revolution: Dashes as Mind-Mapping

The 19th century was the golden age of the dash. A 2018 academic study found that dash usage in English rose sharply during this period. Charles Dickens used 703 dashes in *Oliver Twist* (one every 224 words), Herman Melville used one every 129 words in *Moby Dick*, and Charlotte Brontë's *Jane Eyre* reached one dash every 90 words. But no writer is more associated with the dash than Emily Dickinson, who wrote nearly 1,800 poems in Amherst, Massachusetts, many during the Civil War, accompanied by thousands of dashes. Fiona Green, a Cambridge professor who has studied Dickinson for 30 years, explains that Dickinson's dashes are not random—they represent a quick, quick thinker exploiting unfinishedness. Some dashes are straightforward, but others "don't make any sense" and seem to represent "a mind that's absolutely at odds with itself." Dickinson used dashes to move rapidly to the next thought, caring less about completion than capturing unique insights. Her poems are "always in the process, always undecided," and the dash's suspendedness is part of that unfinished quality. When Dickinson died in 1886, her editors Mabel Lewis Todd and Thomas Wentworth Higginson published her first collection in 1890, removing all but 52 of her 1,151 dashes. Green argues this was not a hatchet job but a way to make Dickinson's avant-garde work legible to a 19th-century audience—though it changed how the poems looked on the page, even if it didn't change how they were read aloud, since meter overrides punctuation in her ballad forms.

21:48The Backlash: Swift, Byron, and the Grammar Police

The em dash has faced criticism for centuries. Jonathan Swift mocked excessive dash use in a satirical poem: "In modern wit, all printed trash / Is set off with numerous breaks and dashes." An anonymous reviewer for the British Critic complained about Lord Byron's poetry, saying dashes "occur without any reason whatsoever, sometimes twice or thrice in one line and never less than a dozen times in a page." Even Jane Austen's editors removed over 6,000 em dashes from *Pride and Prejudice*, according to researcher Cressy Cornice. The Chicago Manual of Style warns writers with the rhyme: "If in doubt, edit them out." Even Fiona Green, despite her love of Dickinson, admits that some prose writers use dashes to "sound lyrical" when they should be "more decisive about what they're saying." The dash's multipurpose nature, she argues, can be "a way of not making decisions"—a semicolon or comma would force a writer to articulate the exact connection between thoughts.

24:44The AI Problem: How ChatGPT Made the Dash a Suspect

The em dash's latest crisis began when users noticed that large language models like ChatGPT, Claude, and Gemini use em dashes with "reckless abandon." Younger generations started calling it the "ChatGPT hyphen." When podcaster Theo Vaughn asked OpenAI CEO Sam Altman about this, Altman claimed the company's "personality team" added more em dashes because users liked them, and now "we have too many." But industry insider Sean Gedeke believes the real story is more complex. GPT-3.5, released in November 2022, didn't use many em dashes—it was trained on publicly available web data, blogs, pirated books, and around 600,000 Enron emails (which probably didn't contain many em dashes). By July 2024, however, the models were producing em dashes prolifically. Gedeke suspects the change came when AI companies began training on print books. Court documents from a lawsuit against Anthropic (creator of Claude) revealed that the company used "destructive scanning"—buying millions of books, cutting the pages out of their bindings, and digitizing them. If these training sets included 19th-century literature with its heavy dash usage, the models would naturally adopt those stylistic habits. The result: a punctuation mark that once made writing feel human now triggers suspicion, even though its presence in AI text is simply a reflection of centuries of human literary tradition.

37:28The Am Dash: A Human Counterattack

Rather than avoiding em dashes to evade AI accusations, a Sydney-based creative agency called Coco Gun has proposed a different solution: a redesigned punctuation mark called the "am dash." Co-founder Ant Melder explains that the am dash looks like an em dash but with curved ends—"like an em dash with serifs" or "a suave 20s-style pencil mustache." It functions exactly like an em dash but is virtually impossible for AI to generate because language models work on probability, and the likelihood of ChatGPT using an am dash is infinitesimally small. To use it, writers must download two custom fonts developed by Coco Gun: "Times New Human" (serif) and "Ariel" (sans). Typing "am-hyphen" inserts the mustachioed dash. Since its release in May 2025, thousands of people have downloaded it. Melder acknowledges the challenge of getting the am dash accepted by Unicode (which currently contains almost 160,000 characters) and admits that if it becomes widely used, AI models might eventually learn to mimic it. But for now, he sees it as a "flag in the sand"—a low-stakes, eccentric, deeply human gesture that signals "this text was typed by a person." Roman Mars notes that the sheer eccentric humanity of the project is what makes it appealing, even if it's a David-and-Goliath battle against the vast data centers of AI.

Conclusion

This episode matters because it uses a single punctuation mark to illuminate something profound about how we read, write, and think in the age of AI. The em dash's journey—from a medieval experiment to Shakespeare's stage, from Dickinson's mind-mapping to ChatGPT's overuse—shows that the tools we use to express ourselves carry centuries of meaning. Fiona Green's closing reflection is the episode's emotional core: the hard parts of writing—the rabbit holes, the misreadings, the struggle to find the right word—are precisely what make us human. Outsourcing those struggles to a machine, she argues, means surrendering the process that "rewires your brain" and "sends you out as a different human." The em dash controversy is ultimately not about punctuation at all—it's about what we value in communication, and whether we're willing to fight for the messy, imperfect, deeply human act of putting thoughts into words.

Key takeaways

• The em dash originated in 12th-century Italy as Boncompagno da Signa's *virgule plana*, a horizontal dash used to end sentences, but it didn't catch on for centuries.
• Shakespeare and Elizabethan playwrights used dashes for *aposiopesis*—deliberately broken-off speech—to convey interruptions, thinking pauses, and mid-sentence realizations.
• 18th-century novelists like Lawrence Sterne and Jane Austen used dashes to create naturalistic dialogue and to censor names and locations, adding an illusion of authenticity to fiction.
• Emily Dickinson's nearly 1,800 poems contain thousands of dashes that represent a "quick, quick thinker" exploiting unfinishedness—her editors removed all but 52 of 1,151 dashes in the first published collection.
• The em dash has faced backlash for centuries, from Jonathan Swift to the Chicago Manual of Style, which warns: "If in doubt, edit them out."
• ChatGPT's heavy use of em dashes likely stems from training on 19th-century print books, which were digitized through "destructive scanning" (cutting books apart to feed them into scanners).
• The "am dash"—a redesigned em dash with curved ends—was created by Sydney agency Coco Gun as a human signal that text was written by a person, since AI models are extremely unlikely to generate it.