I have heard it from science magazines, newspapers and various people that the average human only use approximately 10% of their brain.
I'm sure others can explain this better than I can, but here goes.
This is totally not true. Humans DO use 100% of our brain. That science magazine you read was referring to the possible neural connections that people make.
How could a human that has evolved be using less than 100% of its brain unless humans have de-evolved some how? Unless the 'random evolution' somehow 'evolved too far' and now humans have ended up with all this wasted brain space? I dont understand.
No such thing as "devolve". As to the rest, I'll leave them to our resident brainologists.