One of the unexpected delights of the computer-animation revolution is that it hasn’t been dehumanized by all the digital dazzle. The ”Toy Story” films, ”Shrek,” ”Monsters, Inc.,” ”Jimmy Neutron: Boy Genius,” and now Ice Age — each of these movies is a jaw-dropping technical achievement, yet also brimming with funny and sophisticated pop prankishness. At the beginning of ”Ice Age,” Scrat, a snaggletoothed fuzzball of neurotic energy, tries to bury his precious acorn, a task that will elude him in various ways throughout the film, rendering him a kind of pip-squeak Wile E. Coyote. This homage to the late, great Chuck Jones doesn’t stop there. The very setting of ”Ice Age” is a winterized version of the Road Runner’s playfully abstract jungle-gym desert.
As Scrat pounds that acorn into the white glacier beneath him, the ice breaks — spectacularly — forming a crack that zigzags up a mountain, provoking a chain-reaction avalanche, all of it presented with such matter-of-fact geologic chaos that you’re amused and amazed at the same time. The animation in ”Ice Age” has a funky, laws-of-physics tactility that makes your average hand-drawn cartoon look about as textured as Colorforms. The story itself is only good, not great, as Manny (Ray Romano), a paternally gruff woolly mammoth, and Sid (John Leguizamo), a chatterbox sloth with a speech impediment as spittle-happy as Sylvester’s, team up with the treacherous saber-toothed tiger Diego (Denis Leary) to return a human infant to its tribe. With lesser actors, the characters might have been trumped by the landscapes, but Leguizamo, lisping even more avidly than he did in ”Moulin Rouge,” and Leary, lowering his voice to give Diego both menace and poignance, sear the movie with their personalities. (Romano, in a less showy role, is a bit colorless.) ”Ice Age” never matches the brilliance of ”Toy Story” or the heartfelt heft of ”Shrek,” but it’s an antic and sweet-spirited pleasure.