That is a very good question...
I do not believe anyone on earth knows the answer for sure.
And the reason why is very simple: we just don't know how EXACTLY our brains work.
If we did, a lot of problems and brain deseases would have been solved or cured.
There is a lot of speculation about the humans using only a small percentage of their brains. Some say 20%, some say less.
But all of this is only... guessing! :-(
Have you seen any part of the human body that has no function?
Have you seen any part of the human body that works as a spare part? (Like the spare tire in your car's rear trunk?)
The brain consumes a lot of energy. And energy is a very precious thing.
Why would nature keep a large percentage of it without use?
Nature doesn't do that with our livers nor with our hearts. (Try to live without any one of them!)
My own guess would be 100% or something close to that.
Think about it.
;-)
