Charlton Heston plays Taylor, an astronaut on a long mission away from earth. After 2000 earth years (1.5 years to them) he and his crew crash-land on a strange planet, where the humans are treated like feral animals by the intelligent apes that rule the world.

This film has the least secret twist in movie history, so much so that they even spoil it on the DVD case. I always assumed this was because the film is so popular that no effort was made to keep it from people who hadn’t seen the film, as it was assumed everyone had seen it – a bit like the ‘I am your father’ moment in Star Wars. But actually I think it’s more that it’s so poorly handled in the film that there’s no point trying to hide it from people that haven’t seen it.

It’s so obvious the planet they’ve landed on is earth that it’s a wonder it never crosses Taylor’s mind. It’s not just that he chances on a planet with breathable air, abundant water and a temperate climate (we can overlook these things – it is a film after all). He also sees guns, horses, cornfields, apes, humans, finds out there was a human civilization there 2000 years ago (the time he last saw humans alive on earth) and finds a 20th century talking doll near human bones, and he still doesn’t twig. He only realises when he stumbles on the Statue of Liberty in the final scene, when the big reveal happens as if it’s a total surprise. As the statue is shown the score goes silent and the film fades to black, to let us absorb this shocking twist that even the slowest audience member will have known for at least half an hour.

But given everyone knows the twist anyway, it’s not that important that it’s handled so badly. The best aspect of the film is how it holds a mirror up to humans’ treatment of animals by reversing the roles. Having only previously watched the recent prequels, Rise of and Dawn of the Planet of the Apes, I didn’t know much about the future version of this world, but watching the original it’s great to see how many parallels there are, particularly with Rise. Planet is a film about a human having to convince apes he’s intelligent and worthy of respect, and Rise is about an ape doing that in a human world. In a sense this makes Planet the better sci-fi as it provides a hypothetical situation to satirise our own culture. The issues raised in Rise about how we treat animals are more at face value as the cruelty is inflicted on actual animals.

Planet has a further string to the bow of its sci-fi credentials which is its critique of religion. Evolution is objected to by the religious orthodoxy of the day – just as it continues to be in 2015. The religion of the apes is also shown as a system of control by the fanatical Doctor Zaius (Maurice Evans), who knows more than he lets on, and the apes worship an ape god, claiming to have been made in his image. Ring any bells?

But it’s also not aged particularly well, with the silliness of the plot and hammy acting ensuring it falls short of being a truly great film.  Heston gives an almost Shatner-esque performance in the lead role, chewing the scenery in every scene. His voice is so close to that of The Simpsons’ Troy McClure, it’s easy to see why they made the character star in ‘Planet of the Apes: the Musical’ in one episode (see below).

It’s entertaining enough, don’t get me wrong, but when compared to the similarly-themed The Island of Dr Moreau from around the same time, with similar people in animal masks, you can see that these problems with Planet aren’t due to the time it was made. It’s impressive how the prequels managed to remove so much of the absurdity and camp of the original. Part of this is down to technological developments that replace rubber masks with CGI apes that actually look like apes. But it’s mostly due to the fact the whole thing is made far more serious by toning down the acting and thinking things through a bit better.

Planet of the Apes isn’t a masterpiece – it’s too cheesy and daft for that. There are too many unanswered questions and it’s not a universe that feels that well-thought through. But it’s also enjoyable, and highly iconic, having seeped into the popular conciousness and having been endlessly parodied in pop culture. It also provides a mirror to our own behaviour in a futuristic environment, just as good sci fi should. I love you Doctor Zaius!