A question that I simply had to answer on FB…everyone else was addressing the fact that it’s fine that stories without elements of the supernatural are considered horror, but not talking about underlying reasons why. Genre is often a marketing category–not a logical one. I realized that I’ve actually read broadly enough across the history of horror to actually answer this (although I’m probably wrong on at least a couple of points):
In the 70s and 80s, horror became pretty rigid as a genre, being mostly a marketing category to sell scantily clad, screaming (and perhaps plucky) young women and tough men with lots of grit (and perhaps hubris) against an uncaring universe. Wicked thrills, some good plot twists, some gross-out and splatter. A lot of what we think of as horror now got retconned into the genre later (the Alien series–SF). There were a few outliers who didn’t fit the mold, a lot of them British (Clive Barker). Mostly women got moved into the dregs of Gothic, fantasy, and plain ol’ fiction (I think Anne Rice was the main exception–Tanith Lee was fantasy at the time, although she was in a lot of Weird Tales–while writers like Toni Morrison or Shirley Jackson were fiction). Mostly non-supernatural horror got shunted into suspense or literary fiction (The Silence of the Lambs, Fowles’s The Collector), although if you were a name in horror, everything you wrote was de facto horror (Misery and The Eyes of the Dragon by King, which by another name would be thriller and fantasy today).
A lot of the short fiction from the time is all over the place, and is quite wonderful. But the novels were more rigidly controlled. I’m pretty sure that the writers of the time would have written more widely if they’d been able to sell those novels.
In the 90s, things opened up, but slowly, as the sales numbers of the horror genre declined, and you see stuff like more women, more horror marketed toward younger audiences (Goosebumps), more historical horror (Kim Newman), more regional horror, horror getting translated and coming in from Japan, etc., more diverse writers with more diverse stories. The 2000s is when it starts getting properly Messed Up, with metafictional horror (House of Leaves, John Dies at the End), literary horror (Dan Simmons, Let the Right One In), nihilistic horror, worldwide horror…I think the 90s and 2000s are my favorite decades since the 1890s.
So what you have now is a genre blossoming into the broadness of the short fiction that has been the particular gold in the horror genre mines, to create a more diverse, unpredictable genre that still dips deep into the 80s horror tropes from time to time…and a lot of pulp/KDP fiction that’s trying to be The Silence of the Lambs with monsters (professional detective/agent/cop discovers monsters!). It’s a really interesting time to be writing in the genre.
If you, too, would live in interesting times…check out my cheesy 80s horror novella By Dawn’s Bloody Light, the first in the Fairy’s Tale series. Three women, the queen of the fairies, and the serial killer who won’t know what hit him.