Ruth Walker of the Christian Science Monitor opens her recent article on nonfiction titles with a letter to The Economist. Under the inspired headline “Colonic Irritation,” John Hansen of Cambridge, Massachusetts writes, “SIR – Your list of books of the year (December 7th) left me wondering when exactly, in the history of book publishing, did it become mandatory for all non-fiction titles to include a colon and a subtitle?”

He’s right. The best-of list is riddled with colons. So is last week’s bestseller list. There’s been a colon outbreak in the world of nonfiction titles.

Blame Malcolm Gladwell, says Richard Davies in an article for AbeBooks. The success of The Tipping Point: How Little Things Can Make A Big Difference has echoed in colons throughout American nonfiction. Moreover, “: How” rose in popularity, and the phrase “Changed America” took hold since The Tipping Point‘s publication.

Blame SEO, says Ian Williams of The Guardian. Publishers must use colons “to put as many keywords in the title as possible to get the click-on traffic for online buyers.”

Etymologically, a colon used to refer to an independent clause. The word, derived from Latin and Greek, has been in use since 1540 and abused since 2000.

Now it refers to the punctuation mark that separates two independent clauses, or whatever authors and publishers want to define as independent clauses so that they can cram a lot of information into one title. Whatever gives the sales force, buyers, and customers a bunch of information all in one go seems like a really good idea.

Walker applauds Sheryl Sandberg for using an imperative phrasal verb in her title, Lean In: Women, Work, and the Will to Lead. Some other recent bestselling titles that employ the colon include I Am Malala: The Girl Who Stood Up for Education and Was Shot by the Taliban, George Washington’s Secret Six: The Spy Ring That Saved the American Revolution, and HRC: State Secrets and the Rebirth of Hillary Clinton.

Williams calls this the “colonisation” of nonfiction. He says we’re trying to warn readers that the book isn’t what they’re expecting:

You can forgive Herman Melville for adding “or, The Whale”, to Moby Dick, since, firstly it has no colon, and secondly, when he published it no one would have had a clue what it was all about. However, Moby Dick: How Ishmael Lost His Shipmates and Found His Soul While Chasing Jungian Archetypes Around the Globe and Carrying Out Experimental Marine Mammal Research, does not really cut the wasabi for the sushi.

Better still, imagine trying to get a plot summary behind a colon for one of Dickens’s discursive novels, or for that matter, imagine summarising War and Peace in a snappy subtitle. No, it’s all gone too far. We must all cleanse our colons.