The song was first recorded on 29 January 1964 at the Parthé Marconi Studios in Paris, France - one of the relatively few Beatles tracks not to be recorded at Abbey Road (then EMI) Studios. The band did four takes. Take 1 has never surfaced, but take 2 shows a very different style than the released version. First, the tonality of the song is C# major - a major second higher pitched than the finished product. This gives McCartney's voice a slightly strained timbre - very bluesy, and quite similar to that which can be heard on "She's a Woman" or "I'm Down". In addition, Harrison and Lennon both add backing vocals starting in the second verse ("Oooooh, love me too", "Oooooh, give to you", et cetera) that again parallels the standard blues idiom. (By the way, I've been searching for a predecessor to this take, something that perhaps inspired or influenced the band's decision to experiment with these backing vocals, but I've had a surprisingly difficult time finding an adequate example. If anybody ever reading this has any suggestions, please do comment!)
Miles, Barry. Paul McCartney: Many Years from Now. Henry Holt and Company, New York, NY, 1997.