I am back. Most popular theories are the following:
1)The Brown bear (Ursus arctos) and the Black bear (Ursus americanus) might be misidentified when standing upright. But the general outline (the head
particulary) is so much different. Also, as much as bear tracks look like human prints "the wrong way around" (big toes are on the inside of the
stride and their feet turn inward), Bigfoot tracks have always been reported as huge "human" prints.
2)Hoaxes of both sightings and tracks are much more common than you can imagine. Some well-documented prints, however, would have required both a very
elaborate foot (complete with dermal ridges and sweat pores) and somebody capable of exerting at least 450 pounds of pressure in compact soil for at
least a mile.
3)A Gigantopithecus blacki, or an evolved form. It was a huge-jawed ape who lived in what is now China about 500.000 years ago. It is only known form
jaw fragments and isolated teeth. Its estimated height was 9-10 feet tall and weight was more than 700 pounds. However, no weight bearing bones have
been found, yet, and is possible that the teeth and jaws were disproportionate to the body size.
4)A Paranthropus robustus, or an evolved form. It was an exclusively African hominid whose youngest remains have been dated to be 850.000 years old.
However, since post cranial weight bearing bones have been found, its size was way too small to make up a credible Bigfoot candidate (95-145
pounds).
5)An homegrown variety of American primate is extremely unlikely: see my previous post
here.
As for biography, there's a wealth on books on the topic. Too bad many of them are plainly written in a hurry or by people without much knowledge.
Some good titles are these:
Ivan Sanderson "Abominable Snowmen: Legend Come to Life" (Philadelfia: Chilton, 1961)
Gordon Strasenburgh Jr. "Paranthropus: Once and Future Brother" (Aarlington, Va.: G.R. Strasenburgh Jr., 1971)
Roderich Sprague and Grover Krantz, eds, "The Scientist Looks at the Sasquatch" (Moscow: Univeristy of Idaho Press, 1979)
Also, there's a wealth of information in the "Cryptozoology" periodical, with articles by Renè Dahinden, Grover Krantz and Donald Baird.
I can also suggest this one book about cryptozoology as whole:
George Eberhart "Mysterious Creatures: a Guide to Cryptozoology" (Santa Barbara, Ca.: ABC Clio,2002).
Many of these books and magazines are very, very hard to find nowaday. Eberhart's book contains a wealth of knowledge, is currently available, but
it's impossibly priced.
on Vancouver Island in BC for years now.
There is a wildlife biologist here who has been collecting evidence, John Bindernagel, B.S.A., MS,
Ph.D.. 
