Deviations from the novel

The film deviated from the original French novel in a number of ways:

• The hero is not a French journalist named Ulysse Mérou, but an American astronaut named Colonel George Taylor.
• The humans wear primitive clothing of animal skins, although they were naked in the novel.
• The technology and general settings of the apes' towns are more primitive than in Boulle's original concept. This was a deliberate decision to reduce design and construction costs. Architectural elements were based on observations of ancient cave cities.
• The apes speak perfect English, while they spoke a wholly different language in the book. Ulysse has to learn it to get acquainted, while in the movie, Taylor has a throat wound which prevents him from speaking at first.
• The Planet of the Apes is indeed Earth, although in the original novel it is a different planet that is very similar. However, Earth is featured later in the novel which followed a similar path as the earth in the film. (Boulle would later go on to say that he wished he had thought of Serling's ending.

Arthur C. Clarke's novel, published after the film's release,

but begun in May 1964 and substantially completed by December 1965 when the film was in production,

seems to explain the ending of the film more clearly.

Clarke's novel explicitly identifies the monolith as a tool created by an alien race that has been through many stages of evolution,

moving from organic forms, through biomechanics, and finally has achieved a state of pure energy.

These aliens travel the cosmos assisting lesser species to take evolutionary steps.

The novel explains the hotel room sequence as a kind of alien zoo -

- fabricated from information derived from intercepted television transmisions from earth -

- in which Dave Bowman is studied by the invisible alien entities.

Kubrick's film leaves all this unstated.