Anthony Hopkins literally makes a monkey of himself in "Instinct," a sloppily structured, snoozily paced psychodrama about living in harmony with nature and all the rest of that tree-hugging hooey.

Inspired by "Ishmael," a philosophical novel about a conversation between a man and a gorilla, the movie is also basically a dialogue. But this is between a scientist who has lived as a gorilla and a cocksure psychiatrist (Cuba Gooding Jr.) who believes in man's dominion over the animals.

Director Jon Turteltaub and writer Gerald DiPego, who previously collaborated on "Phenomenon," would suggest that we are not nearly as well suited for running the world as the gentle gorilla is. The point certainly has some merit, though it's made more convincingly in "The Planet of the Apes," to say nothing of the recent remake of "Mighty Joe Young."

Hopkins is behind bars again as the dangerously deranged Ethan Powell, a once-peaceable primatologist awaiting trial in a maximum-security prison for the criminally insane. Sedated and shackled, Powell has retreated into himself and refuses to speak. Indeed, he has been mute since murdering two Rwandan park rangers a year or so earlier.

Enter Theo Caulder (Gooding), an ambitious young psychiatrist who sees Powell's case as a chance to advance his career. There's sure to be a bestseller in his future, too, if only he can persuade Powell to talk about what precipitated the killings. Though his initial attempts fail, there's really little doubt that the pair will be chattering like a naked Eskimo's teeth in no time at all.

Caulder's mission is made all the more difficult by the prissy warden, sadistic guards and inept medicos of the Harmony Bay Correctional Facility. The inmates may be psychotics who pee in their pants, but they are portrayed as more civilized than their overseers.

The point, hardly a new one, is repeatedly hammered home in flashbacks contrasting the prison's beastly overseers with enchanting footage of Rwanda's loving mountain gorillas. While they and their world are wondrous, the disheveled Hopkins never really looks contented in their midst. He looks more like he could use a drink, a hot bath and a can of insecticide.

Gooding, a generous, outgoing actor, is hardly the embodiment of an uncaring buppie careerist. On the other hand, he almost convinces us that his association with Hopkins's aging jungle boy has provided him with an emotional cathartic. "You taught me to live outside the game," he exclaims. Or maybe just outside the game preserve.

Instinct (126 minutes, at area theaters) is rated R for violence and profanity.

CAPTION: A primatologist (Anthony Hopkins) goes mute after murdering two park rangers in "Instinct."

CAPTION: Cuba Gooding Jr. plays psychiatrist on the make to Anthony Hopkins's scientist-turned-madman.