WHAT do you call a comedy without a single laugh?

The punchline is: Harold Ramis’s ramshackle road movie through the Paleolithic era headlined by Jack Black and Michael Cera, two of the most gifted comic actors of their generations.

Black is an unstoppable force of nature, who brought his nervous energy to light up High Fidelity, The School Of Rock and Kung Fu Panda.

Cera adopts a more laidback, laconic delivery that perfectly suited Juno and Nick & Norah’s Infinite Playlist.

But put the actors side-by-side in Year One as hunter-gatherers with a nose for adventure, and the results are painful.

“The upside-down prisoner has to pee,” whimpers Cera as warm urine trickles over his face, up his nose and into his mouth in a throwaway scene that perfectly encapsulates the sophistication and artistry of Ramis’s vision.

Pelt-clad primitives Zed (Black) and Oh (Cera) are incompetent and lazy, and don’t pull their weight like the other men in their village.

Zed cannot master his bow and arrow, and is a woeful hunter.

Likewise, Oh fails to fulfil his duties as a gatherer. Nor can he turn the head of the object of his affections, Zed’s sister Eema (Juno Temple).

Inevitably, the friends are banished from the tribe and embark on a quest of self-discovery through an ancient world riddled with danger.

Foolishly, the script begins at the dawn of mankind and merrily incorporates biblical references, which beg unfavourable comparisons with Life Of Brian.

Monty Python’s film may be 30 years old, but it boasts more chuckles and guffaws in the opening five minutes than Year One can muster in its lifeless entirety.