While the phrases are Jamerson-like, the syncopations and the lack of variations and movement aren't all that much. The first person I thought of was Bernard Reed, because the tone and style are dead on to a few songs he's done that I was reminded of immediately.
I did a bit of googling and it led me to Lee Silver, Brunswick Records, etc, for whom Reed did a lot of recording at that time, so my guess is it was indeed him.
http://www.youtube.com/watch?v=vmshGrpNxbs
Compare (bad sound, sorry):
http://www.youtube.com/watch?v=hxjhw672voA http://www.youtube.com/watch?v=ygSnzjrrA5s
