[@Kalleth]
Very good points, but there are many tribes hidden away from civilization, and we dont find them.

Cave systems, some run for miles and miles.

I believe Bigfoot is real, Giant Ape hybrid offspring of Gigantopithicus. 
I believe there are many of them.

The Goverment just came sorta clean on the U.F.O. encounters, maybe they know something about Sasquatch lol hidden away