EARLY in ''Planet of the Apes,'' the 1968 science-fiction film that spawned four sequels, two television series and all manner of gimcrackery through the 1970's, a tall, lithe astronaut named Taylor corrects the misimpression of two intellectual chimpanzees who are trying to determine who this supposedly primitive human is and where he fits into the cosmic puzzle.

''I am not the missing link,'' he informs them. Having crashed-landed a spaceship on an unknown planet he believes to be 320 light years from Earth, Taylor, portrayed with abrasive strength by Charlton Heston, and a cowering band of mutant humans have been rounded up by ferocious gorilla cavalrymen and tossed in a cage as if they were -- well, gorillas.

Throughout all five films, the species are at each other's throats, with all sorts of ethnic overtones hanging out. Interestingly, though, this culture clashing had no negative effect on the films' popularity as family entertainment. Critics hold that the science-fiction settings gave the ''Planet'' movies latitude to confront dicey social situations in ways that may have turned off audiences of more conventional movies. Whatever the case, watched end to end in a new set of videos from Fox, together with a highly informative documentary, ''Behind the Planet of the Apes,'' the films reflect an extraordinary accommodation of messages burning to be dramatized in the era of Vietnam protest and violent racial unrest, on one hand, and the restraints and sweeteners required for a family movie on the other.

Adapted from the novel by Pierre Boulle and written by Rod Serling and Michael Wilson, who had been blacklisted in 1951 for supposed Communist connections, ''Planet of the Apes'' was relentlessly promoted from the time it was just a concept by the producer Arthur P. Jacobs. Hollywood, however, found the idea of costumed apes uncomfortably close to Saturday-morning cartoons. Only Richard D. Zanuck, the head of 20th Century Fox, was willing to make the film.