Board Thread:Theories and Speculation/@comment-25547449-20160805204709/@comment-1512913-20160806125001

@Namikaze, all we know from has been said is that Shinju grew on Earth, it bore a fruit, Kaguya ate it, got chakra. Humans originally didn't have chakra, since Kaguya has been said to be the progenitor, mother, first person to wield etc. of chakra. Canonically, besides having grown thanks to human blood soaked into Earth, we have no more details or ideas how the Shinju came to be and how did it get to have a fruit which grants chakra.

But in the anime filler, it was said that the Shinju was draining natural energy from the nature and humans (yes, natural energy was stated, not chakra, since there was none yet), so I suppose natural energy + human blood = chakra fruit = chakra? Or something like that...