Okay, I've probably posted about this before, but it's fun to put them back to back, so what the hell.
From 1964, please enjoy The Beatles and their utterly sublime and guitar driven "I Feel Fine."
And from 1961, and its place on John Lennon's portable home jukebox, please enjoy the suspiciously similar six-string figure on bluesman Bobby Parker's "Watch Your Step."
I should add that there's a certain irony in the fact that just as Lennon appropriated the earlier riff for his own purposes, Parker's record is a fairly transparent attempt to clone Ray Charles' "What I'd Say."
Ah, the folk process at work...