The story of bigfoot precedes any modern documentation. Many old cultures have stories of these hairy men. There must be something to it. I’m more inclined to say they’re more of a demonic embodiment since no concrete evidence ever seems to come up. I don’t know. I’m fascinated by this. The most compelling thing has been the Patterson/Gimlin film; and people are 50/50 on that one.
It's called hypertrichosis:
http://en.wikipedia.org/wiki/Hypertrichosis