Board Thread:Theories and Speculation/@comment-26061639-20150131220909/@comment-2043993-20150208203501

I think you're on to something here, it would certainly fit with what we've seen in the series and would be interesting to have another way to learn senjutsu than from animals.

But I personally don't think anyone would have taught Hashirama how to control natural energy, certainly he would have heard about it (Jugo's Clan perhaps?) but a sensei to teach him would be hard to come by in the Warring States Period.