Hollywood Flashback: ‘Soylent Green’ Depicted an Overpopulated Planet With a Dark Secret

This story is part of The Hollywood Reporter's 2023 Sustainability Issue (click here to read more).

In 1970, 20 million Americans participated in the first Earth Day. One of the more alarming predictions that day was from Stanford biologist Paul Ehrlich, who foresaw a future in which "population will inevitably and completely outstrip whatever small increases in food supplies we make," resulting in the starvation death of hundreds of millions.

Hollywood took notice and released a string of eco-disaster films in the years to follow.

In 1972's Silent Running, a science fiction film starring Bruce Dern — and directed by 2001: A Space Odyssey effects master Douglas Trumbull — all plant life on Earth has gone extinct. And 1973's Soylent Green, with Charlton Heston (who had starred in two other sci-fi hits, 1968's Planet of the Apes and 1971's The Omega Man), took Ehrlich's ideas to scary, if campy, extremes.

Helmed by Richard Fleischer (who also directed 1954's 20,000 Leagues Under the Sea for Disney, among countless other titles), Soylent Green was based on the 1966 novel Make Room! Make Room! by Harry Harrison.

That book is set in 1999, when the planet's population is 7 billion and virtually everything, including water, is rationed for all but the ultra-rich.

But Soylent pushed the narrative ahead to 2022 and upped the ante by introducing a processed biscuit, which comes in Soylent Red, Soylent Yellow and the all-new and much more delicious Soylent Green varieties. The name was derived from a reference in Make Room! to "soylent steaks" made from soy beans and lentil.

Heston plays detective Robert Thorn, who, along with his professor sidekick played by Edward G. Robinson — reuniting Heston with his Ten Commandments co-star in what would be Robinson's final film role — investigates the murder of a wealthy Soylent Corporation board member.

THR's review called the film "a continually interesting movie with a largeness of production rare these days." The Hollywood Reporter

In the final sequence, the movie conjures up a dark reveal: Soylent Green isn't made from sea plankton, as the other Soylent products are. As Heston bellows in the film's most iconic moment: "It's people! Soylent Green is made out of people!"

The line ranks 77th on AFI's "100 Years…100 Movie Quotes" list and was parodied in a 1996 Saturday Night Live sketch with Phil Hartman playing Thorn, helping cement the film's place as a sci-fi cult classic.

"[Soylent Green] was one of the best movies I ever did, primarily because of Eddie [Robinson]," Heston said in one of his last interviews before his death in 2008 at age 84. "He was a wonderful actor and lovely man to work with. He was so good in it. He was dying at the time … and he was undertaking to die in the scene. And talking to him, I was weeping. Because of what it was like for him as an actor to lie there, knowing you were never again going to put on makeup and wardrobe and say words for a film. That must have been what he was thinking."

Robinson died Jan. 26, 1973, of bladder cancer. Heston delivered the eulogy at his funeral. Soylent Green opened on April 19.