2001:A Space Odyssey is also the title of a science fiction novel and movie co-written in parallel by Arthur C. Clark and Stanley Kubrick. The movie employed ground-breaking special effects in telling the story of an intervention by aliens in the evolution of man.
100,000 years ago
The story begins as apelike proto-humans are starving to death. As a result of their "education" by the aliens through the use of a mysterious monolith, the proto-humans invent the first weapon, killing a tapir for food using the thighbone of a dead animal. In one of the most famous transitions in movie history, the scene ends when one of the "apes" throws his weapon of bone high in the air, where it is transformed into a nuclear weapon orbiting the Earth in space. The movie thus portrays 100,000 years of human evolution as the change from the most primitive to the most advanced weapon.
Technically advanced humans
The movie continues as a team of scientists travels to a moonbase, and then flies out to a site where an artifact has been discovered. Left by the aliens, the artifact was designed to give off a powerful magnetic field, which had been detected and led to the discovery of the artifact. As the scientists approach the monolith, which has been excavated, the sun rises over the Moon's horizon and the monolith sends a powerful electronic signal into space, triggered by the light of the sun (clever aliens knew once future humans dug it up it would eventually be exposed to the sun - it was actually a sort of alarm system designed to inform the aliens of when we had evolved to the point that we had reached the Moon). Having traced the signal to one of the moons of Jupiter, Earth sends a space mission to find out what is out there. On the way the most advanced computer of the time, H.A.L. 9000 ( Heuristic programmed ALgorithmic computer, or I.B.M. transposed one letter back in the alphabet), goes insane because it has been given conflicting commands: to lie to the humans on the mission about the true purpose of the mission and to make the mission a success. H.A.L. tries to kill all the humans to insure the success of the mission (humans are too likely to introduce human error), but one of them, Dave, survives and dismantles H.A.L.'s upper brain functions.
The movie ends when Dave finds another monolith in orbit around Jupiter, and it turns out to be a star gate to the location of one of the creators of the Monoliths. After Dave travels through a trippy light show light years through space to the aliens' planet, they put him in a familiar environment they have created for him (looks like a hotel room) while he is educated further and advanced to a being pure energy. Dave chooses an appropriate form for a newly born member of a new species (beings of pure energy can apparently choose any form they wish), an embryo (the Star Child), and returns to Earth to halt the impending nuclear war which would have destroyed Earth. The movie also popularized the dramatic introduction to Richard Strauss's tone poem "Also Sprach Zarathustra."