Writers are cutting the em dash because readers treat it as proof of AI

AI detection has claimed its first innocent victim, and it is a punctuation mark.

How a dash became evidence

The em dash spent a century as an ordinary tool of English prose. Now a single one in a paragraph can be enough for readers to declare the whole passage machine written, because large language models happen to use the mark heavily. The accusation needs no evidence beyond the character itself. The dash is the case.

Writers have noticed, and they are responding rationally to an irrational test. They are editing the em dash out of their own prose. Not because the sentence reads better without it, but because keeping it costs credibility with an audience primed to see it as a tell. People are changing how they write to prove a negative.

What informal detection looks like

This is what AI detection actually looks like in practice for most text, most of the time. Not a tool, not a score, not a probability with error bars. A vibe, applied by readers, with no appeal process and no way to prove you wrote something yourself.

Formal detectors at least publish accuracy claims that can be challenged. The informal version runs on pattern matching against whatever surface features people currently associate with model output, and punctuation is the easiest feature to spot. The writer who has used em dashes since school and the writer who pasted from a chatbot produce the same mark, and the reader cannot tell them apart. So both get flagged, and only one of them is guilty.

Where the logic goes next

The uncomfortable part is that this reasoning has already moved past casual reading. The same one-signal logic is being applied to job applications, essays and portfolios by people who have no better signal to go on. A hiring manager or an instructor facing a stack of submissions does not run a forensic analysis; they scan for tells, and the tells are style.

The predictable result is a quiet convergence: human writing edited to look less like model output, while model output keeps absorbing human style. The em dash is the first casualty, not the last.