R&B and rock and roll groups in the 1950s emphasized rhythm, so their backup bands generally consisted only of the standard swing band rhythm section of guitar, piano, bass, and drums supporting a vocalist, and in some cases omitting the keyboards. The bass guitar took over from the double bass in the 1950s, and had almost completely taken over the bass role in the 1960s. As the 1960s progressed the term "rhythm section" as used in a pop music context sometimes came to refer to just the bass and drums. For example, Paul McCartney and Ringo Starr of the Beatles were referred to as the band's rhythm section.