Alex Bledsoe is the author of five novels, including Dark Jenny and The Hum and the Shiver. A Tennessee native, he now lives in Wisconsin.

I’m old enough to remember the literally grim state of science fiction before Star Wars. The books, movies and TV shows may have had their humorous moments (or more likely, moments that were intended to be humorous but actually fell flat: see the WWII-ish humor of Forbidden Planet), but pre-1977, humor and science fiction were considered contradictory. After all, the future would be a serious place.

The problem is that humor goes to the core of humanity (and I mean “humanity” in the broad sense). SF always runs the danger of absurdity, and by acknowledging this with humor, you can get the reader/audience on your side. By pretending it isn’t goofy, you alienate them (see? I made a pun! “Alienate!”).

My favorite joke in all of science fiction filmdom isn’t in Star Wars, or E.T., or any of the intentionally humorous SF films like Men in Black. It occurs in 1968′s Planet of the Apes, and is so audacious that it still astounds me that someone thought of it, actually filmed it, and allowed it to stay in the final film.

Astronaut Taylor (Charlton Heston) is brought before a tribunal of orangutans led by the devious Dr. Zaius. It’s totally Kafkaesque: Taylor has no defense for his crime, which is essentially being who he is, a human being who can speak. Nonetheless, chimpanzee Drs. Cornelius and Zira do their best to bring logic to the table, against which the orangs have no real defense except shouting.

And then the moment of magic.

As Zira continues her speech, the two subservient judges repeatedly bellow “Objection!” to which Zaius responds “Sustained!” One puts his hands over his eyes, another put his hands over his ears and the third covers his mouth. They visually recreate the famous “See no evil, hear no evil, speak no evil” monkey illustration.

It’s a brilliant visual moment, and in the context of the story it’s an even greater triumph. In a scene, and a film, which could easily stray into somber self-importance, we get a joke that’s simultaneously fully meta (in the context of the story, the actual joke means nothing) and fully relevant (the image of power, especially power based in religion, ignoring logic and common sense is always relevant).

There are a lot of other jokes in the film, most of them familiar sayings that have been slightly tweaked (i.e., “Human see, human do”). They’re more in the service of the central conceit (“A planet where apes evolved from men!”) than actual attempts at inducing laughter. But they get the audience chuckling with the film, not at it.

In fact, the famous Statue of Liberty climax would not be nearly so chilling without the jokes. For comparison, see the climactic moment of another Heston-starring SF film, Soylent Green. That film has an unrelenting seriousness, so much so that the final (very grim) revelation has now become a punchline. In contrast, watching the end of Planet of the Apes–even over 40 years later and knowing what’s coming–is not funny at all.