Today marks the 50th anniversary of what might be the single greatest day in cinematic Science Fiction history — both Stanley Kubrick’s 2001: A Space Odyssey and Franklin J. Schaffner’s Planet of the Apes were released for their initial theatrical runs . Both films feature interstellar travel, men in ape-like suits, and innovative uses of music to underscore the films’ themes and moods. But they also each touch on similar themes and social constructs from wildly different angles, serving as looking glasses into the fears, anxieties, and mindsets at the forefront of the general conscious of the end of the 1960s.

By April, 1968 had already been a year rife with turmoil on a nataional and world stage. Overseas, The Tet Offensive had just begun in January and the Pulitzer-winning photograph of the execution of Nguyễn Văn Lém would shortly follow; both were key turning points in the public’s opinion of the Vietnam War. The Battle of Khe Sanh would see thousands of young American and Vietnamese men die in a battle fought for unknown strategic reasons. The My Lai massacre occurred in March. Back at home, the civil rights movement would continue to see violence on college campuses, sports arenas, and in the streets, culminating in the assassination of Martin Luther King, Jr. just the day after 2001: A Space Odyssey and Planet of the Apes would premiere. Amidst social upheaval, 1968 also saw the return of manned spaceflight and the development of higher-power computers. The second season of Star Trek, notable for Gene Roddenberry’s cerebral yet hopeful and idealistic picture of the future, had just finished. However, the nation was only a year removed from the Apollo 1 disaster and the Sputnik crisis from ten years prior proved that the “space race” was merely another aspect of the ever-terrifying Cold War. These social conflicts and differing views of scientific progress feature heavily in the thematic thrusts of both films.

What’s incredible about these two films is that the one featuring a murderous, violent artificial intelligence is the one that confers an optimistic view of technological advances. The opening sequence of 2001: A Space Odyssey, about the dawn of man, tells us that the use of tools, such as using a femur bone as a weapon, is a gift. Later in the film, the monolith gives humanity – having evolved from the ape-like primates of the film’s first sequence into a society with tools like spaceplanes and moonbases – an opportunity to discover more of the galaxy. Even HAL 9000, the villainous AI that murders all but one member of the crew, is sympathetic; when HAL dies, it reverts to its first program, singing the song “Daisy Bell” and demonstrating a child-like side. Humanity’s technological achievements are seen as methods of reaching a higher plane of existence, first from beast-to-man, and then from man to advanced ethereal being.

Contrast this with the overt and pervasive cynicism of Planet of the Apes. In the film’s final scene, Taylor, the film’s protagonist, discovers that humanity merely used their technological advances to destroy themselves. Technology is a tool for war, destruction and greed, with Taylor lamenting how mankind managed to send their own into space despite the obvious flaws on earth. The film even tells us in Taylor’s opening monologue how even the mechanical marvel of space travel bends the mind and causes intense loneliness. Scientific advancement is a curse, and one that human nature can’t help but use for evil.

This really is the key difference between these two films – 2001: A Space Odyssey doesn’t share Planet of the Apes co-scribe Rod Serling’s pessimistic view of mankind. The reveal of the Statue of Liberty in the finale of Apes is a gut punch that all of Captain Taylor’s worst fears had come true. Mankind truly couldn’t use their power to help other people. Rather, they destroyed their world and devolved into the mute, primitive vermin we see scattered throughout the Ape community. Humanity was given dominion over the earth and its inhabitants, and it betrayed that authority and was replaced by another species.

Stanley Kubrick and Arthur C. Clarke, on the other hand, view humanity through a much more sympathetic lens. 2001 posits that man, given the gifts of science, will use that privilege to expand their minds and connect with nature and the galaxy. Early man is given a tool, and while they use it for violence, we’re shown through a quick edit that it leads to scientific advancement beyond even what we have in the real world of 2018. While it might be tenuous, there is peace between the Soviets and Americans when their scientists interact in the film’s first act. HAL might have been a technological terror, but in a way its flaws reflect how human it was. Despite its failure, HAL’s primary function was to aid humanity in their quest. Bowman, the last survivor of Discovery One, takes a chance and risks his life to investigate the final Monolith orbiting Jupiter, with his curiosity leading to his advancement into another plane of existence.

This plane of existence is not just spiritual, but also a physical embodiment of what it truly means to not be alone in the universe. The Monoliths represent a creator, a benevolent, god-like being that bestows the means to progress a civilization from a primitive existence into the stars. We’re given a vision of the universe in the film’s vivid, luminous and bizarre climactic moments that is an invitation for humanity in general and Bowman in particular, to embrace their place in the universe. This spiritual connection to the universe being the key to reaching a plane of existence beyond our own.

Planet of the Apes refutes this, as religion and spirituality, much like technological advancements, are shown to be weapons wielded by the self-righteous and power hungry. The Apes’ society mirrors many cultures across the globe. It is a strict caste system that correlates to the social hierarchy in many Asian nations. It is also backed by conservative religious dogma based on the early seeds of the Christian Right in America. The separation of church and state is merely an illusion, as show-trials are used to mock and discredit scientific theory that doesn’t cater to the rules of the Lawgiver. Taylor’s trial before the Ape Assembly mirrors that of the Scopes Trial, putting evolutionary theory up against that of Ape-telligent Design(ed. note: ugh, but also, stealing this), a conflict that is still being fought in US courts today. Serling’s world is one where religion is seen as either an instrument for subjugation or one of explicit authoritarianism, not as a beacon of hope and an opportunity to advance as a society.

50 years later, you’d be hard-pressed to find even one person who doesn’t include either 2001 or Planet of the Apes as one of their five favorite science fiction films. Both films tackle subject matter that was relevant in 1968 and is sadly still relevant in 2018. One film potentially optimistic, the other explicitly pessimistic — both concerned with how humanity will wield science and spirituality. Neither film gives us the answers we truly want — Planet of the Apes paints a future where mankind has destroyed everything, while 2001’s primarily visual storytelling leaves much of its themes up to interpretation. But these films don’t shy away from using science fiction trappings to explore important, complex, and prominent issues, and their vastly different, but equally relevant and authentic approaches and attitudes towards society at large are why we’ll almost certainly celebrate them in another fifty years.