Given the Neanderthal concepts of humor guiding so many recent movie comedies, the new slapstick farce "Caveman" is obviously a numbskull consummation -- the Neanderthal comedy about Neanderthals. Carl Gottlieb, who directed "Caveman" in a Mexican location from a script by himself and Rudy de Luca, doesn't seem to have a fresh gag or spontaneous gesture in his comical loincloth, but "Caveman" is more competent Exercise in Dumb than "Hardly Working" or "Going Ape." It may tickle kids too young and innocent to have encountered these grunts, pratfalls, vulgarities and anachronisms before.

When Buster Keaton placed himself in prehistoric surroundings in the silent comedy "The Three Ages," he had his own genius to rely on. The comparable Keatonesque role in "Caveman" is played by Ringo Starr, whose inability to carry a comedy on the strength of his own limited persona or pantomimic skills, which are primitive indeed, causes strategic problems Gottlieb must strain to overcome. As Atouk, the outcast of a scroungy tribe dominated by the brutish, growling Tonda, (John Matuszak of the Oakland Raiders, looking plenty intimidating), Ringo plays the traditional comic little guy, destined to survive and prosper by virtue of his cleverness. Booted out of the tribe for attempting to make time with Tonda's voluptuous, complacent mate Lana (Barbara Bach), Atouk goes on to form his own tribe of rejects (which include racial minorities and a set of Neanderthal gays called Ruck and Flok) and overthrow Tonda, still a hulk but too old-fashioned to compete with innovative weapons and tactics.

Although funnier performers are hanging around -- Dennis Quaid as Ringo's sidekick, Avery Schreiber as one of Matuszak's crowd and Jack Gilford as a blind old man -- Gottlieb never takes astute advantage of them. Matuszak is certainly a commanding presence, but he lacks comic polish and unifying ability as severely as Ringo. The best sustained comic performances aren't given by the actors at all; they're contributed by the miniatures of goggle-eyed monsters who are called upon to chase the characters up trees, behind rocks and into caves.

The first title, announcing a setting of "One Zillion B.C.," is a reliable clue to the wit in store. The characters are given a small facetious vacabulary, and there's a tiresome inevitability about the way terms like "macha" (signifying beast or monster) and "pooka" (hurt or yukky, depending on the context) set up a prehistoric "caca."

Gottlieb's most spectacular inspiration is the discovery of the fried egg, which occurs when Atouk and the boys accidently drop a stolen pterodactyl's egg into a hot spring. His lamest idea is a prolonged subplot which obliges Quaid to be pursued by an abominable snowman in "A Nearby Ice Age." Priceless it ain't, but if the kids are determined to enjoy it, the brain damage should be minimal.