Bigfoot, also known as Sasquatch, is a giant ape-like creature that is said to roam the Pacific Northwest. There is scant physical evidence that such creatures exist, but Bigfoot buffs are convinced that they do, and that science will soon prove it.

While most sightings of Bigfoot occur in the Northwest, the creatures have been reported all over the country. There are many native myths and legends of wild men in the woods, but Bigfoot per se has been around for only about 50 years. Interest in Bigfoot grew rapidly during the second half of the 20th century, spurred by magazine articles of the time, most seminally a December 1959 "True" article describing the discovery of large, mysterious footprints the year before in Bluff Creek, California.

Eyewitness evidence

By far the most common evidence for Bigfoot is eyewitness reports. Unfortunately, this is also by far the weakest type of evidence. Psychologists and police know that eyewitness testimony is notoriously unreliable, and that people are simply not very good at accurately describing something they saw — especially at a distance in low light and when the subject is partially hidden by trees and foliage (as most Bigfoot reports are).

Anyone can be mistaken, and pilots, policemen, priests, and public officials are no exception. Most Bigfoot researchers admit that the vast majority of sightings are mistakes or hoaxes (up to 95 percent, by some estimates).

Still, they insist that a Bigfoot must be hiding in that tiny portion of sightings and reports that can't be easily explained. The most famous image of a Bigfoot is the short film taken in 1967 by Roger Patterson and Bob Gimlin. Shot in Bluff Creek, Calif., it shows a dark, man-sized and man-shaped figure striding through a clearing.

Widely considered a hoax, it remains to this day the best evidence for Bigfoot. However this poses a serious blow to the film's credibility: if it's real, and these Bigfoot creatures are really out there wandering in front of people with cameras, it's very suspicious that better films and videos haven't emerged since Lyndon Johnson's administration.

These days almost everyone has a 5 megapixel, HD camera in their pocket with their iPhones or other devices. At no time in history have so many people had high-quality cameras on them virtually all the time. If Bigfoot exist, logically the photographic evidence for them should improve over the years. Yet it hasn't. Photographs of people, cars, mountains, flowers, sunsets, deer, and everything else have gotten sharper and clearer over the years; Bigfoot is a notable exception.

One possibility is that there is some supernatural explanation, such as that Bigfoot somehow emits special, unknown light waves that inexplicably cause the beasts to always appear out of focus in photographs, no matter how good the camera is. The more logical explanation suggests that these things don't exist, and that photographs of them are merely hoaxes and misidentifications. [News: Did Hiker Film Bigfoot, Black Bear or 'Blobsquatch'?]

In his book "Big Footprints," veteran researcher Grover Krantz (Johnson Books, 1992) discussed alleged Bigfoot hair, feces, skin scrapings and blood: "The usual fate of these items is that they either receive no scientific study, or else the documentation of that study is either lost or unobtainable. In most cases where competent analyses have been made, the material turned out to be bogus or else no determination could be made."

When a definite conclusion has been reached through scientific analysis, the samples have invariably turned out to have ordinary sources — "Bigfoot hair" turns out to be elk, bear, or cow hair, for example, or "Bigfoot blood" is revealed to be transmission fluid. Sometimes alleged Bigfoot samples are subjected to DNA analysis and are deemed "unknown" or "unidentified." However "unknown" or "unidentified" results do not mean "Bigfoot." There are many reasons why a DNA sample might come back unknown, including that it was contaminated or too degraded by environmental conditions. Or it could simply mean that the animal it came from was not among the reference samples that the laboratory used for comparison. We have no reference sample of Bigfoot DNA to compare it to, so by definition there cannot be a conclusive match.

In fact, genetics provides another reason to doubt the existence of Bigfoot: there cannot just be one elusive creature, there would need to be tens of thousands of them in order to assure enough genetic diversity to maintain the species. With so many of them out there,  surely at least one of the creatures would be killed by a hunter or hit by motorist on a highway, or even found dead (by accident, disease, or old age) by a hiker or farmer at some point. Yet no bodies, bones, or anything else have been found.

Hoaxers have further contaminated the problem of sorting fact from fiction. Dozens of people have admitted faking Bigfoot prints, photographs, and nearly every other type of Bigfoot evidence. One man, Rant Mullens, revealed in 1982 that he and friends had carved giant Bigfoot tracks and used them to fake footprints for decades. Which are real? Which are fake? Often the Bigfoot experts themselves can't agree.

The lack of good evidence hasn't dampened the enthusiasm of Bigfoot buffs; they have all they need in sighting reports, fuzzy photos, inconclusive hair samples, and footprints to keep the search going. Until better evidence comes along, old evidence will be rehashed and re-examined­ — and unless Bigfoot is proven to be alive, the search will continue.