The Patterson-Gimlin film is the most compelling piece of evidence for Bigfoot's existence, which also means it's been subject to intense scrutiny. It's been dissected frame by frame by Bigfoot believers and skeptics alike, all of them looking for evidence to prove or disprove the creature's existence. Unfortunately for enthusiasts, no clearer footage has been found. Questionable Bigfoot pictures are all anyone has to go on, even though smartphones are ubiquitous and it seems like somebody ought to have caught better footage by this point.
But the question of "is Bigfoot real?" still persists, in part because the Patterson-Gimlin film is so interesting. It doesn't look quite like a human in a gorilla costume, but its shakiness, lack of focus, and aged film grain mean viewers also never get a good look. Anthropologists and other experts have studied the film extensively, and Patterson himself died still swearing it was genuine. There's compelling evidence for both sides, lending this longstanding evidence of Bigfoot credibility even decades after its creation.
Part of the reason that Roger Patterson and Bob Gimlin were in the area where they shot the infamous 1967 footage is that they were creating a docudrama about a historical encounter with the famed Bigfoot. They went out into the woods that day to search for Bigfoot tracks, as there were numerous sightings of the creature in that area.
While filming a docudrama does give the two an excuse for carrying a camera into the woods, it also raises some questions about authenticity. If Patterson and Gimlin were just scouting for tracks, what are the odds they'd run into a creature few people have ever seen with a camera on hand to record the encounter? Making a documentary about something that may or may not exist and happening to stumble onto that thing in the process sounds suspicious to a lot of skeptics.
Even to someone who hasn't studied biomechanics (the movement of living things), it's pretty clear that the gait of the figure in the Patterson-Gimlin film isn't naturally human. The way the figure swings its arms and the degree to which it lifts its feet have been studied sine the film's creation, with scientists unsure whether it's a deliberate fake or genuine footage of an inhuman creature.
Dmitri Donskoy, a biomechanics expert, reportedly thought the creature was unlikely to be human because of its strange movement in the Patterson-Gimlin film. While some of the evidence is less convincing if the film speed is changed, that so many experts in the field have seen the footage and deemed Bigfoot inhuman lends it a lot of credibility.
Film speed isn't something most people consider, but it's crucially important in the discussion of the Patterson-Gimlin film. Patterson usually recorded at 24 frames per second, but failed to note what speed the Bigfoot footage was recorded at. As experts have noted, if the footage is filmed at 24 frames per second, the speed matches a human's walk. But playing the footage of Bigfoot in comparison to earlier footage of horses on the tape at 24 frames per second makes the horses' movement look strange, indicating that it may not have been shot at that speed.
But that raises the question of why the speed would have been changed for this particular footage. Was it done to make the walk look unnatural, or was it a mere mistake?
As one of the most compelling pieces of evidence for the existence of Bigfoot, the Patterson-Gimlin film has been extensively analyzed by filmmakers. Computer analysis has made this all the more interesting, as analysts can now compare the tracks associated with the figure in the film with the film itself, and reach new conclusions about what's happening in the footage.
Reconstructions have given the figure in the film an intermembral index (which can be used to predict limb length, important in movement) of 88. For comparison, a human's intermembral index is around 71, while a gorilla's, the largest of apes, exceeds 100. Even considering for margin of error and the use of football pads or other artificial bulk, the intermembral index far exceeds that of a human, implying that, whatever the figure is, it's not human.