Just listened to a video with the isolated bass line. Sounds more like Carol Kaye to me, though I wouldn't want to swear to it.
But her lines tend to sound like that, maybe a little stiffer than Jamerson's.
And I've seen videos of her playing live where she plays similarly complex 16th-note runs.
Could easily be either. Or maybe both recorded it, as someone already said. Recording companies often recorded multiple versions of songs they thought had the potential to be hits, replacing some or all of the players from earlier takes. From what I've read, sometimes even the players don't know for sure who was on the released version.