Brian Wilson calls this the The Beach Boys' anthem. It usually starts off their live shows. Note the Bach style intro to this song. Kind of builds up anticipation, until the beat picks up into what Brian calls a western rhythm. I'm thinking it was inspired by the old Gunsmoke series on TV. At one time Gunsmoke was closing their show with music featuring this exact same bass riff as on California Girls. Then this song came out a little later.