Hollywood has always been obsessed by disaster scenarios, the bigger the better. I grew up in the 1970s, when it seemed like there was a new disaster picture out every year.
Nearly every summer, there was a movie where something huge and on fire would fall on top of Charlton Heston. And if Charlton Heston wasn't available, they'd find some other ageing movie star to stand at the top of a burning skyscraper - or on the rail of a sinking cruise ship - to face a violent and painful end.
These pictures were always chock-full of former movie stars - Fred Astaire was in The Towering Inferno, Shelly Winters was in The Poseidon Adventure - and there was something creepy and almost Freudian about watching the big calamitous scenes where half of the cast, made up of faded stars of the past, was swept away by tidal waves and skyscraper fires. It was as if Hollywood's neurotic obsession with being young and hip was being acted out, symbolically, by killing as many elderly stars as possible.
That was the psychological message, anyway, behind those disaster pictures: the old stars are dead and irrelevant. Bring on the new.
Disaster movies are decidedly out of fashion these days. Maybe there isn't a big enough backlog of yesterday's stars to populate a cast.
Right this minute, Hollywood is concentrating on producing movies about zombies. Zombie movies are today's disaster pictures.
We're in what might be called the entertainment industry's Zombie Moment, and it's "cross platform", meaning there are movies about zombies, and there are popular TV shows about zombies, and there are video games about zombies.
Now, I'm not licensed to practise psychology in the state of California - or any other state, though I like to put it that way because it implies otherwise — but it's not hard to guess that when a town is uniformly obsessed with the idea of the walking dead, something is up in the collective unconsciousness.
Add to that the recent remarks by George Lucas and Steven Spielberg, who both predicted massive, wrenching contractions in the movie business, and the excellent new book from super-producer Lynda Obst, Sleepless in Hollywood, whichdescribes her slow realisation that the Hollywood she knows is facing collapse and calamity, and you don't have to be a licensed mental-health professional to know that the patient is experiencing severe anxiety.
When big-time feature guys like Lucas, Spielberg and Obst talk about changes in the movie business, you know they're serious. And what are they saying? That a lot of movies are about to become television. Spielberg's hit movie Lincoln, for instance, came awfully close, he said, to being an HBO movie. If you're in the movie business, that's a scary thing to think about.
Folks in the television business shouldn't be smug, either. There isn't room, really, for all of those TV channels - not, certainly, at current valuations and current levels of compensation. As the TV industry moves closer to what they're calling "a la carte pricing" - meaning consumers are going to stop being force-fed a lot of channels they don't want and start being allowed to choose - a lot of the fat is going to get squeezed out. Which specific fat? Who knows? But there are shows on right now that are marked down in the book of the walking dead.
Hollywood is thinking a lot about the undead these days because Hollywood is scared that it's becoming the undead. All Hollywood - the writers, actors and directors who make stuff; the lawyers, agents and managers who yell at each other; and everyone else who works in this town - is at risk here.
And that's pretty much what makes zombie movies, like World War Z, so thrilling and scary: we're all potential zombies. The monster we fear isn't a creature like Godzilla rising from the sea, but our friends and neighbours and co-workers - ourselves, really - turning into crazy-eyed undead killers.
The thing about a zombie picture is that you never really know who is going to get it next. One minute you're normal, the next minute you're walking the streets with red eyes and looking for brains to eat.
Whether it's a disaster movie in the 1970s or a zombie picture in 2013, one thing remains true: like any patient with neurotic and paranoid tendencies, the true subject of every story Hollywood tells is Hollywood itself.
Rob Long is a writer and producer based in Hollywood
On Twitter: @rbcl