It is most rational to believe there is a 'Bigfoot'

As the Con position, I will be arguing that believing in the existence of Sasquatch as late as European settlement in the US is not the most rational position one can hold concerning Bigfoot. Gigantopithecus blacki (GB hereafter) – My opponent starts by citing this creature as Bigfoot. He does so to show that Sasquatch lived in the distant past so we should not be surprised to find one living in the Americas as late as European settlement. The first problem is that my opponent is assuming too much when claiming GB is analogous to Bigfoot. We simply do not know enough from the fossils to determine whether GB was bipedal or resembles a gorilla or a chimp for that matter. If the animal is a knuckle dragger, then GB does not fit any eye witness accounts of Bigfoot my opponent listed in RD 1, nor would the footprint evidence be valid as it would accompany marks consistent with an animal walking on, or at least using, all four limbs for movement. In addition, we have not uncovered any fossil remains of the creature outside of China, India, and SE Asia, nor have we found any fossil remains less than 300,000 years old (see wiki on GB, opponent's source). Most researchers looking into this species hold the view that GB was not bipedal. One prominent researcher disagreed . http://en.wikipedia.org..., but his work did not muster enough data to pass the peer review process. Pro has only assumed that GB and Bigfoot are one and the same; he has not supported this statement. Although the partial mandibles found do allow for the potential of bipedal movement, we simply do not have the data to confirm this hypothesis. In addition to the above information, we have to consider that if GB managed to cross over to North America in a very small population, then inbreeding depression would likely have occurred . http://en.wikipedia.org... . Some species have a high resistance to inbreeding depression, but GB would not be such a species as many species resistant to inbreeding depression start with and maintain small gene pools such as species that develop on an island (with little competition) or produce an abundance of offspring at a time. GB appears to have been a dominate species covering a large land mass allowing for out breeding enhancement naturally. Such creatures as GB would be very susceptible to inbreeding depression. The cheetah is a great example of inbreeding depression . http://www.telacommunications.com..., but the species did manage to survive. As stated above, the fact that a cheetah can produce 9 and 10 cubs at birth helped it dramatically as did human intervention. GB would not have these advantages as a great ape undiscovered by humans. Another problem with accepting sightings of Bigfoot is the range. Bigfoot sightings in North America alone cover the area as far north as Alberta, Canada and as far south as Florida. . http://bigfootsightings.org... Combining this evidence with the fact that GB would have started with a very small population, coming from a very large population; therefore, subject to inbreeding depression. We have to except that the species managed to flourish for over 300,000 years in order to cover this range without succumbing to human hunters or leaving a trace in the fossil record. Unlike the cheetah, mentioned above, The GB would not be producing 9 to 10 offspring at birth. And even the low cheetah population left an abundant fossil record. To date, no fossils of any great apes, other than humans, have been found in North America. Although the data is limited, the most logical position to hold would be one supported by this data without too much extrapolation, and the data does not suggest that the creature lived in North America, nor that it lived later than 300,000 years ago, nor can we say with much certainty if GB was bipedal like Bigfoot sightings indicate. At this point in history, maintaining the existence of GB in North America is not the most rational position for one to hold. Living Fossils-Yes, we have found creatures alive today that scientists hypothesized were extinct, but this is not the definition of a living fossil. A living fossil is one where a species appears to be very similar to its "fossil" relative. . http://en.wikipedia.org... Nothing in the evolution of life prohibits a parent population from existing alongside a population which branched off at an earlier time. When creatures are found in the fossil record, scientists can only use inductive reasoning to determine extinction. They form a hypothesis and as more data comes to light, the hypothesis becomes stronger or weaker. Nothing in science is absolute, nothing. Some hypotheses are simply stronger than others. The proposed extinct species we have found are usually oceanic creatures like Coelacanth and Chlamydoselachus anguineus or they are small or they live in remote regions of the world like the others my opponent listed (Laotian rock rat, Purple frog). We do not, however, find large land animals. We can say with a high degree of certainty that T-Rex is extinct. We can do so because it is a very large land predator that would leave some noticeable impact on its surrounding environment. Also, the fossil evidence will show no T-Rex bones in latter rock layers. GB fits the category of T-Rex more than that of the proposed extinct species my opponent listed. GB may have been 10 feet tall and weighed over 1,000 lbs and it lived on land. Claiming that a creature of this size maintaining a population capable of allowing for reproduction for the last 300,000 years all the while leaving no indication of its existence (outside of sketchy eyewitness accounts and footprints of dubious quality) is not the most logical position to hold. My opponent speaks of time machines in his argument, and my best guess is that he wishes to show that sightings of a creature prior to knowledge of the existence of such a creature in the fossil record must indicate the sightings are real and creature still lives, or lived up to European exploration of America, or hoaxers had a time machine which is more amazing than accepting Bigfoot. The logical flaw here is that Pro has not established that Bigfoot sightings are really sightings of GB. He has not established that GB resembles proposed Bigfoot sightings. He uses his unsupported claim to support the reliability of the eyewitness accounts. Once he does this, he uses the eyewitness accounts to support his original claim. This is a simple case of circular logic and is, therefore, invalid. Eyewitness Accounts: Eyewitness testimony is notoriously unreliable. . http://agora.stanford.edu... Even in cases where the eyewitness has taken an oath under penalty of law, the account should be viewed with skepticism. In cases with Bigfoot, aliens, pink elephants, and fairies, etc, the witness is free to extrapolate and the more fantastic the claim the more attention it garners. The eyewitnesses may truly believe they saw something fantastic, but without independent verification we have no way to know. The problem with many of these accounts is that they are too old to verify independently or when others try to locate physical evidence of the encounter, it is mysteriously absent. I do not wish to call any of these good people liars, but I must rely on the physical evidence and the knowledge science has gained about great apes in modern times. Using the latter two, I must dismiss the accounts has hoaxes, fabrications, or an overactive imagination. Accepting GB as Bigfoot and claiming the species lived to within the last couple hundred years is not the most logical position to hold.