Jack Black didn't become a caveman overnight for his new film Year One. "I ate a lot of prehistoric food," he told us at the premiere this week. "You know, mutton. I drank from rivers ... raw fish, and a lot of sushi." As for his co-star Michael Cera, he told us the most cavemanlike thing about him was his "muscular build." Aw. View our Party Lines slideshow for more caveman antics.