Isn’t it nifty when a movie’s title both names the protagonists and describes them? In writer-director Tamara Jenkins’ The Savages, which has already been nominated for a raft of awards, Laura Linney and Philip Seymour Hoffman play the Savage siblings. Wendy and Jon aren’t “savage” in the cave-dwelling, primal-chest-beating sense: If anything, they’re overeducated. (He’s a professor of “the theater of social unrest,” and she’s a New York playwright making ends meet as a temp.) But they are a bit feral when it comes to human connection and communication. Their upbringing didn’t help: Dad was a jerk, and Mom took off and never returned. Now, Wendy pops prescription drugs, tells casual lies, and sleeps with her married neighbor, while Jon lets his Polish girlfriend’s visa expire because he can’t commit.

The movie is about what happens when, together, these lonely misfits face one of America’s toughest rites of passage: taking responsibility for a parent who can’t care for himself. Their estranged dad (Philip Bosco), who’s been living in the upscale seniors’ paradise of Sun City, starts exhibiting Parkinson’s-related dementia just as his longtime girlfriend dies, leaving him homeless. It’s up to Wendy to bring him back to wintry Buffalo, where her brother has reserved a spot in a nursing home — if she can handle changing Dad’s diapers on the plane.

Linney and Hoffman are both superb actors, and they develop a convincing rapport. Wendy’s the manic one, fretting sentimentally about her father’s comfort even though she barely seems to know him. A straight man of sorts, Hoffman plays Jon so depressive and low-key that it takes a while for us to realize he’s no more mature than his sister. When the two bicker over who’s the bigger loser in life, it’s hard not to sympathize with Dad — who, sitting beside them, switches off his hearing aid.

The Savages has a lot in common with Jonathan Franzen’s best-selling novel The Corrections, in which three confused siblings try to cope with their aging father’s decline. But Franzen delved into the father’s mind and made him an indelible character. As the novel’s reader comes to understand what it means to this organized, capable engineer to lose his mind, the message about mortality hits home.

In her script, by contrast, Jenkins limits what we know about Lenny Savage to a few hints that he was violent toward his kids. He doesn’t talk much, and his children don’t ask him about his past or reminisce about their own, which leaves an odd void at the center of the film. Maybe Jenkins would rather withhold info than risk indulging in TV-movie clichés about adults recovering from an abusive childhood. But with the father a cipher, Jon and Wendy’s arguments have an unpleasantly tinny, echoing quality, like dialogue from a self-conscious play. Their anger has no context, no history.

The film’s humor seems stilted, too, and occasionally turns cloying. (It’s an awkwardness that marred Jenkins’ other autobiographical feature, 1998’s Slums of Beverly Hills.) Jenkins leaves overly big spaces around her laugh lines. And she tries to milk too much comedy from ironic contrast. It’s darkly funny when the Savages glance from a hospital TV playing an upbeat bleach commercial to a catheter bag slowly filling with their father’s urine. But when Jenkins keeps using exactly the same device — panning from a realtor chirpily selling Mr. Savage’s former abode to Wendy grimly emptying his drawers; or from a silly Sun City stage show to the Savages in the audience, both absorbed in books on dementia — the satire wears thin.

We get the point: Americans don’t like to confront aging, dirt or death. Or human savagery. But, with its overcontrolled jokes and audience manipulation, The Savages doesn’t really confront those things, either. As an unsentimental look at dilemmas that affect more and more people each day in this graying nation, it’s a movie that matters. But it’s hard not to wish its one-liners came with more insight.