Most film franchises start at a place that not only shapes their box-office future but also their expanded universes. Without the original Frankenstein in 1931, would the doctor's stitched-together creation ever have met the Wolf Man and tangled with other Universal monsters in the '40s? Without Honey Ryder, would James Bond have had the opportunity to jump in bed with Pussy Galore and Dr. Holly Goodhead? And where would Jar Jar be without Ponda Baba, Kardue'sai'Malloc and other Mos Eisley cantina patrons to pave the way?

Most film franchises also start without any plans to survive beyond the production of the initial outing. When the first Planet of the Apes movie premiered on Feb. 8, 1968, nobody was sketching future installments involving underground mutants, a return to present-day Earth or an rebellious uprising that looked an awful lot like the violent aftermath of the civil rights movement.

Back when the film started shooting in May 1967, producer Arthur P. Jacobs simply wanted to bring Pierre Boulle's 1963 novel – which he purchased the rights to before it was even published – to the screen. Over the next decade, the first Planet of the Apes movie spawned four sequels, a TV series, comic books, lunchboxes, trading cards, a Saturday-morning cartoon, action figures and more.

But it all started in a more humble and less ambitious place: to tell the story of a group of explorers who visit a planet where apes and humans have reversed roles.

After several rewrites, the script by Michael Wilson and The Twilight Zone mastermind Rod Serling was given a green light, framing the story around astronauts who crash on a planet more than 2,000 years in the future. Only one eventually survives the ordeal, Taylor (played by Charlton Heston), who is captured by talking apes. Some – like Roddy McDowall's chimpanzee Cornelius and his psychologist fiancee, Zira (Kim Hunter) – are friendly and inquisitive; others are suspicious of the strange man who can speak (Maurice Evans' skeptical orangutan, Dr. Zaius). And many more, mostly the brute gorillas serving as military, are downright hostile.

Watch the 'Planet of the Apes' Trailer

The film's famous ending – in which Taylor realizes he's been on Earth the entire time after spotting the remains of the Statue of Liberty poking out of a desolate shoreline – instantly became an indelible image for moviegoers. Within weeks of its wider opening in April, Planet of the Apes was a box-office smash, quickly making back its nearly $6 million budget on its way to more than $30 million over the years.

Franklin J. Schaffner was handpicked as director by star Heston, but his previous output included mostly TV shows. He was suddenly elevated to the A-list, next helming 1970's Patton, which earned both him and the movie Academy Awards. The groundbreaking ape makeup by John Chambers won a special Oscar, while Planet of the Apes was nominated for its costume design and original score. The movie also eventually entered the National Film Registry.

But its greatest legacy has been its ability to continue to thrive in the succeeding decades. In addition to the original sequels – Beneath the Planet of the Apes (1970), Escape From the Planet of the Apes (1971), Conquest of the Planet of the Apes (1972) and Battle for the Planet of the Apes (1973) – Planet of the Apes was remade in 2001 by Tim Burton and then re-imagined a decade later for a new movie series, starting with Rise of the Planet of the Apes.

The template – fundamentally following a premise but diverted to suit individual outings' requirements – was laid out in the first film: some sociopolitical commentary, a dash of humor, thrilling set pieces, the absurdity of a world where talking apes are the ruling class. It's easy to see why the movie and series were such a hit with shell-shocked audiences in the middle of wars at home and overseas. It's escapism, sure, but it's escapism with a message.

That might seem like applying too much gravitas to a franchise about talking monkeys that increasingly targeted young viewers, but the original Planet of the Apes remains a cornerstone film of the late '60s: subversive, even in its occasional obviousness, and expert genre moviemaking in a new pioneering age. All these years later, its influence – inside and outside the genre of science-fiction films – runs deep. Few movie series before or since have had this sort of lasting impact on the filmmaking landscape.

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