Silent movie question: Der Letzte Mann

I just watched Der Letzte Mann, directed by F. W. Murnau and starring Emil Jannings, last night. I really liked it; it had no intertitles (except one explaining the ludicrously upbeat ending Murnau was forced to tack on by the studio), and thus no dialogue. The camera work was stunning. Anyhoo, my question:

The literal translation of the title is “The Last Man”, but every English title I’ve ever seen refers to this movie as “The Last Laugh”. Does anyone know why this is? Why would they change the title so dramatically?