Sentences have been getting shorter for two hundred years, with or without dialogue
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Somewhere between Chaucer and Chaucer's modern reader, the English sentence lost most of its length, in novels and in genres with no dialogue at all. In novels, one other thing changed over the same two centuries: how much of the page is spoken out loud by its characters.
Start with one writer's career: Agatha Christie. In a Language Log post of December 29, 2017, the linguist Mark Liberman measured the share of characters between quotation marks in seven of Christie's novels, from 1920 to 1973. In 1920, about 49.2 percent of her text was dialogue.
By 1972, that figure had climbed to 79.4 percent. For comparison, Virginia Woolf's To the Lighthouse sits at just 3.3 percent dialogue, while a G.K. Chesterton text from 1908 runs to 60.1 percent: across authors, his figures vary with genre more than with date.
Liberman is careful to call this a rough measure on a small sample, not a controlled study, and he suspects the rise over Christie's career reflects her style's natural progression, or the experience of seeing many of her novels adapted for stage and screen. The numbers should be read that way: suggestive, not definitive.
A separate, larger count looks at two centuries rather than one career. In a blog post of January 10, 2018, .txtLab at McGill computed Flesch readability on about 5,000 English-language novels from the Stanford Literary Lab and Chicago Text Lab collections, and found that readability has risen steadily across two centuries of English fiction.
Per decade, the number of quotation marks, a rough proxy for dialogue, and readability correlate at r = 0.86. Books have gotten easier to read, in other words, and over the same decades more of what's on the page is people talking; whether one caused the other would take more data to show, the authors say.
Sentence length itself tells a similar story from another angle.
A 2025 blog post by the writer Arjun Panickssery lines up some vivid examples: Chaucer and Spenser averaging sentences of roughly 49 to 50 words, against J.K. Rowling and D.H. Lawrence down at 12 to 14.
Even Warren Buffett's own shareholder letters shortened, from 17.4 words per sentence in 1974 to 13.4 by 2013. These are striking numbers, and worth a caveat: they're drawn from a handful of hand-picked authors, not a controlled sample, so the exact slope of the decline shouldn't be taken as precise.
For that, there's Rudnicka, whose peer-reviewed work (first published in 2018, with an arXiv version posted in 2025) measured more than 19 million sentences of American English, from 1810 to 2009, and found sentence length falling in every genre, by slightly different amounts.
The direction Panickssery's colorful examples point to holds up under more careful counting. The exact numbers, understandably, don't match exactly, because a curated set of famous names and a full statistical corpus are never going to agree down to the decimal.
Put the pieces together and the picture is narrower than a chain of cause and effect. Sentence length fell, in fiction and outside it. In novels, .txtLab found dialogue's share and readability rising together over two centuries; and Flesch readability is itself computed from sentence and word length, so the rise in one and the fall in the other are partly the same fact.
Rudnicka's genre-by-genre results are worth returning to here, because they cut against the tidy version of this story. Sentence length falls by slightly different amounts depending on whether a text is fiction, a magazine, a newspaper, non-fiction or a script, and she reads those declines as one larger phenomenon across written English, which she links to colloquialization, mass readership and punctuation.
That is not a dialogue story: the decline shows up in genres with no characters talking at all. Whether dialogue played any part in the shortening of novels, none of these sources claims to settle.
What they agree on, from a twentieth-century mystery writer's fifty-year career, measured in dialogue, to an investor's letters from 1974 to 2013, measured in sentence length, is the direction of travel. Sentences got shorter. In novels, people on the page started doing more of the talking.