On one level, come on, it's Paul McCartney. He is literally one of the most famous people on the planet. For all his fame, though, we're willing to bet that it's his songwriting and singing you think of first when you think about Sir Paul, not his bass playing. However, the truth is McCartney's melodic basslines played an enormously, though often unrecognized, role in the Beatle's sound. Go ahead and listen to "Yesterday" again, only this time, pay special attention to the bassline. Hear how it gently guides the song, never intruding? You're hearing the work of a master bass player, and although it might seem obvious, there is no way you can talk about the history of the instrument without giving it up for Paul McCartney. The Beatles may not have ever actually been "bigger than God" as they claimed, but they're as close as any band will ever get, and Paul's four strings are a big reason why.