Well, let's look at the data....
We have centuries of time with people walking/hiking all over every square inch of this country. And during all that time, people have run into every imaginable north American vertebrate. Yet, with all those man hours, NOT ONE PIECE of documentable evidence of the existence of this thing has been found.
Surely they die and leave bones lying around? We find bones from rarer animals than this. And if you respond with the "bigfoot bury their dead" reply...how is it that we have found thousands of Amerindian burial sites and can't find a single bigfoot burial?
The only "documentation" is of such poor quality or has been later revealed to be faked (including the most famous "walking bigfoot" film). How is it that competent photographers with thousands of dollars worth of equipment spend thousands of hours out in the woods and get great photos of very rare and elusive animals, but NOT ONE has ever taken a decent photo of these very camera shy animals? Have you seen the recent photo documentation of jaguars in Southern AZ? Why hasn't someone been able to get such a remote camera shot of a bigfoot from the "heart of their range", where ever that is supposed to be.
Can bigfoot tell when the person taking the photo has a junky camera or is incapable of focusing? If so, it has the same mind-reading ability as the Loch Ness Monster!
Why aren't credible scientists (vertebrate biologists) really looking for this thing? Why hasn't a hunter shot one? It would be worth a fortune! I can promise you that if I saw something like that and I had a rifle, there would be a specimen in the Smithsonian museum - not in a roadside carnival.
Humans have created the existence of "half man/half beast" throughout history. These stories are found in every society (bigfoot, yeti, bunyip, etc). Mermaids are an example of exactly the same thing.
In fact, the consistency with which societies have created these things is further evidence of their non-existence. They are rumored to exist on every continent and yet never has a piece of evidence been found.
They are better examined as a sociological or cultural phenomena than as a scientific reality. You could argue that they are part of current mythology. I think the interesting question is why humans "need" to imagine/create a half human/half beast?
These creations predate the (outdated) concept of the "missing link", so it isn't a desire to fill in gaps in an evolutionary record. I suspect they originally were created to warn people of the dangers of the wild. Oddly, today, they seem to represent the persistance of "wildness" in countries where the mystery of the wild has been lost.
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Chris Harrison
San Antonio, Texas