Like "The Hangover" and about as funny, "Year One" is its premise. It's maybe a concept comedy on the page, but the constituent scenes more closely resemble sketches than a piece of a whole, and the whole is less than the sum of its parts. There's no build, there's no arc, there's just a sparse minefield of successful one-liners and gags, and dangerous stretches between. The best that can be said is that the comedic personalities play exactly as you would expect between Black and Cera, but the script rarely offers them the opportunity to work together so much as beside one another.
The two play Hunter Zed and Gatherer Oh respectively, though the advertised caveman humor lasts all of about twenty minutes before the pair becomes unwittingly entwined in decidedly safe Bible parody. Cue the prostitution and foreskin jokes.
The environments are not as interesting as the mashed-up land of the lost, and because Black and Cera play their characters with on the nose modern sensibility, the prehistoric comedy is mostly demoted to an aesthetic gimmick. Many of the best jokes, besides having been in the trailer, do have fun with the premise, but lack the searing wit or intelligent wherewithal to comprise a smart comedy about dumb characters, rather than a lowbrow comedy about large-brow characters, which is what it is.
David Cross, who plays antagonist Cain (to Paul Rudd's Abel), has proved himself hilarious time and again through not only his own material and "Arrested Development," but has carved himself some unexpectedly interesting roles from the most awful material ("Alvin and the Chipmunks" springs to mind), but disappointingly never clicks in "Year One" either. The dialogue doesn't offer him the bite he's great at playing with and never sounds quite natural coming from him.
The script was maybe a placeholder at some point. With so many proven comedians lined up for the parts, it'd seem a safe bet that the funny would work itself out naturally, and there's evidence of improv throughout, but no one seems able to overcome what's on the page. As also in "The Hangover," the middling final product is a testament to the importance of not just a high joke per minute ratio in comedy writing, but in story. Last summer's "Tropic Thunder" had a strong premise that often didn't need to rely on gags because the plot itself was clever.
"The Hangover" attempts the same, but less intelligently and ultimately less successfully. "Year One" is a different type of comedy altogether, a straightforward concept mined for all it's worth over an hour and a half.
Ramis, who once directed "Caddyshack" and "Groundhog Day," has been struggling to strike gold again, and is more recently responsible for the dreadful "Bedazzled" and decent "Analyze This/That" films. Needless to say, "Year One" isn't his return to form. His direction is nondescript and though the actors give it their all, the script was too stagnant from inception to be saved.
So, if you have to pick just one prehistoric comedy this summer, make it "Land of the Lost."