As someone with a master’s degree in primatology and a lot of real-world experience in primate behavior, I have a LOT of problems with the conventional methods for looking for Bigfoot/Sasquatch. My opinion on whether this cryptid exists (probably no in North America, probably yes in the Himalayas) aside, I do believe that most of the popular shows and bigfoot hunters are going about it all wrong. In the first of undoubtedly many posts on this subject, I’d like to tackle the issue of activity patterns and eye shine.
Almost every bigfoot hunting show and publicized excursion I’ve seen has its investigators focus on finding bigfoot at night. And yet, almost every bigfoot believer asserts that it is some sort of unidentified large ape. So why would it be nocturnal? There are currently no nocturnal apes and only one species of nocturnal monkey, the owl monkey. It is a characteristic of the haplorrhine group in general (the primate suborder consisting of monkeys, apes, and tarsiers which likely split from the strepsirrhines containing lemurs, lorises, and pottos in the Paleocene around 63 million years ago) to be diurnal. Therefore, a nocturnal great ape would have evolved its nocturnality secondarily, which would require some sort of very extreme evolutionary pressure to do so. Considering that in most places’ bigfoot is thought to exists it is probably one of the largest animals around, predation pressure is unlikely to be the reason. So, some other extreme pressure would have to be the cause.
In keeping with searching for bigfoot at night, a lot of bigfoot searchers use eyeshine to search. Using eyeshine is a very popular method of looking for many nocturnal animals. While in Vietnam I met a team of researchers searching for the tiny nocturnal loris. They claimed that looking for eyeshine was the only possible means of finding the animals in the jungle. Eyeshine is caused by the presence of a reflective layer of tissue in the back of the eye known as the tapetum lucidum, which drastically improves night vision. It is an important adaptation in everything from dogs to deer. However, there is not a single monkey or ape that possesses a tapetum lucidum. It is, in fact, one of the defining traits of the suborder Haplorrhini (mentioned above) to lack the tapetum lucidum. The trait was lost at the split between suborders around 63 million years ago. If bigfoot is a great ape, he should not have eyeshine!
So, we are left with a few options. If bigfoot is a great ape that diverged recently from the other great apes, he must have secondarily evolved nocturnality and a tapetum lucidum. This is incredibly unlikely. Aside from being extremely unparsimonious, the evolutionary pressures would have to be extreme. The only monkey we know of that is nocturnal, the owl monkey, did NOT re-evolve the tapetum lucidum. Instead it just evolved giant eyes. The tapetum lucidum is a very specialized structure, it would be almost impossible for it to evolve again. So is bigfoot not a great ape then? Did he evolve from some other animal? Not likely. That would go against every other piece of evidence we have for him. Bigfoot’s defining feature is being a bipedal strider like a human, and that trait has never evolved in mammals outside the primate lineage.
My conclusion, and the only one I think is acceptable, is that we are looking for bigfoot in the wrong place and the wrong time. If he exists, he is likely to be a diurnal or crepuscular animal with no eye shine. If we are serious about finding bigfoot, I suggest we look for him the way we do other great apes. Search in the early morning hours when activity begins and look for signs of night nests. Perhaps our insistence on looking at night is why finding bigfoot has proven so elusive. Any self-respecting great ape, including bigfoot, should be tucked away in their night nests!