The core rhythm, a loop that Apple re-creates live on a metal percussioninstrument, began as her banging with scissors on the things that sit on her desk at home.
Two wooden blocks, as any toddler knows, work fine as a percussioninstrument, and give any Neanderthal half a gourd and a bit of animal skin and you've got a proto-Ringo.
In each case the timbres were extracted from individual vocal performances, percussion hits or instrument riffs performed during the Grateful Dead's concert at the Carousel Ballroom 44 years ago.