Reading older mysteries by Raymond Postgate has set me to thinking about how the genre has changed over past 170-odd years, since Edgar Allan Poe started spinning stories about C. Auguste Dupin. The mysteries that get written today would have terrified and horrified the readers of Poe’s detective stories. (Hell, some of them terrify and horrify me.) It seems to me that the authors of mysteries have been a wordy arms race ever since those short tales, but how they outdo each other has varied according to public tastes and tolerances for violence. I’ll admit right now that I’m not an expert, just a reader with a dilettante-ish love of the genre.
I see two halves to the history of the mystery genre. The first half, from Dupin to say, the 1950s, was all about the puzzle. (Although, “The Murders in the Rue Morgue” is rather gory.) From Poe to Christie, authors were challenged to come up with fiendishly complicated plots to outdo each other. They created devices like locked room mysteries, butlers who might or might not have done it, and very clever detectives who could not only see, but observe. But eventually, they would have hit the limits of reader credulity (wait, it was the long lost third cousin because of a mysterious inheritance of a porcelain swan?) or they would start “cheating” by hiding clues or introducing new suspects in the last act.
The second half—well, I’m not sure when exactly it began—ushered in an era of gore and psychological terror. Now fictional detectives seem to face a series of increasingly depraved and violent serial killers. Where readers used to ratiocinate with the protagonists, we profile based on modi operandi. The clichés of newer mysteries tend to revolve around the detectives’ almost mystical abilities to infer an entire psychological profile, plus backstory, of the criminal from a few obscure clues. (This broken twig here by the body clearly indicates that the killer is a left-handed Rosicrucian who was attacked by a ferret at the age of three.)
Speaking from personal experience, the only limit with this type of mystery is a reader’s tolerance for gore. I used to be a huge reader of mystery thrillers, but I eventually reached a point where I couldn’t take any more mutilated, almost invariably female corpses. Now, I go back and forth from old to new as I get tired of the clichés. I never seem to tire of a good mystery, no matter when it was written.
A Bookish Type 
Another mystery sub-genre that overlaps the end of the polite-thinky mysteries is the hard-boiled detective of the 20’s-50’s by the likes of Dashiell Hammett and Raymond Chandler. Not a lot of brilliant deduction…just running down leads, stepping on people’s toes, and making snarky remarks to mobsters, bootleggers, and femme fatales until something clicks into place (usually with a fair amount of gunplay). It’s my go-to escapist genre, though I’m less fond of the more splattery, explicit, and criminal-centered crime/noir genre that it evolved into.
LikeLiked by 1 person