I wonder how many of you have spent a good deal of time in the wilderness and realize how vast our country and the world is. There are still many untouched places on the planet, despite what Al Gore would have you think.
For instance, I could walk an hour from my home and probably get into country were no people have been for years.
Here is a perfect example. Recently in Africa they discovered that the " endangered " lowland gorilla existed in very large numbers in a part of the Congo. They estimate that 125.000 of these large silverbacks are in that area, doubling the number they previously thought to exist in the world.
Now if will all the science we have this is a recent find, what makes you think that a semi intelligent humanoid couldnt exist without detection.