The National Geographic Channel is using humor to sell it's ambitious new special Stonehenge Decoded. Christopher Guest has resurrected his Spinal Tap alter ego for National Geographic Channel, lead guitarist Nigel Tufnel, to expound on his theories about how Stonehenge came to be. Naturally, even as he's promoting the special and National Geographic, his tongue is firmly planted in cheek as he disses the findings of the scientists and purports to be an expert on the subject.

Guest as Tufnel is interviewed by straight man -- comic actor -- Jim Piddock, leading to riotous takes by Nigel about dinosaurs, the secret language of potatoes, the pyramids and other weighty affairs. Here's one of the videos (after the jump), so you can see what I mean:

As fans of Guest know, in the film This Is Spinal Tap, the group's attempt to create a set resembling Stonehenge is ruined when Tufnel's sketch of the design includes measurements in inches rather than feet. When the Stonehenge pieces arrive, they're too small to impress anyone. In the film, Michael McKean's character, David St. Hubbins explains, "I think that the problem may have been... that there was a Stonehenge monument on stage that was in danger of being crushed...by a dwarf."

The director of Best in Show and A Mighty Wind (among others), Christopher Guest (who's also married to Jamie Lee Curtis), has recently directed a series of hilarious commercials for DirecTV, and is working on a new feature film.