Nov 26 2012

Bigfoot DNA

The Bigfoot community (yes, they still exist) is abuzz with the announcement that Bigfoot/Sasquatch DNA has been analyzed with interesting results. Bigfoot is the alleged large North American furry hominid that roams the deep forest, largely in the Pacific Northwest. It is known only from sightings and ambiguous trace evidence (blurry photographs, footprints, hair samples), but is most famous from the Patterson-Gimlin film (touted by believers, but highly criticized by skeptics).

After decades, however, what we lack is a physical specimen. No one has captured a bigfoot, killed one, found a dead body or skeleton. There is also no fossil evidence supporting the existence of such a creature. Researchers have found biological samples (such as hair or skin) that they claimed were from a bigfoot. The big news today is that a five-year study to sequence and analyze DNA from these samples has now concluded. I predict that the results will be touted by believers but highly criticized by skeptics.

The results have not yet been peer-reviewed or published, so there will definitely need to to be follow up when this occurs. The work was headed by Dr. Melba Ketchum, a geneticist working in Texas. Apparently she was scooped by a Russian collaborator, Igor Butsev, who released the results on his Facebook page. Ketchum was then forced to put out a press release confirming the findings. The press release indicates:

“Our study has sequenced 20 whole mitochondrial genomes and utilized next generation sequencing to obtain 3 whole nuclear genomes from purported Sasquatch samples. The genome sequencing shows that Sasquatch mtDNA is identical to modern Homo sapiens, but Sasquatch nuDNA is a novel, unknown hominin related to Homo sapiens and other primate species. Our data indicate that the North American Sasquatch is a hybrid species, the result of males of an unknown hominin species crossing with female Homo sapiens.

Ketchum further indicates that this alleged hybridization occurred no more than 15,000 years ago. The press release also further clarifies:

“Sasquatch nuclear DNA is incredibly novel and not at all what we had expected. While it has human nuclear DNA within its genome, there are also distinctly non-human, non-archaic hominin, and non-ape sequences. We describe it as a mosaic of human and novel non-human sequence. Further study is needed and is ongoing to better characterize and understand Sasquatch nuclear DNA.”

Until these results are peer-reviewed and published it is difficult to give a definitive critique, but from what is being reported a few things are clear. First, the mitochondrial DNA (mtDNA) is unambiguously human. I suspect these samples come from hair, which retains mtDNA but not nuclear DNA (nuDNA). (Mitochondria are the energy factory of cells, likely evolved from primitive bacteria, and still retain some of their own DNA. Nuclear DNA comes from the nucleus of cells and is the main genetic code of the organism.)

The nuDNA also contains human sequences but also unknown sequences. We are told these do not match Neanderthal, other known early hominids, or any known ape. They are simply unknown. So, in short, we have human DNA (not human-like, but human) mixed in with some unknown sequences. Ketchum concludes from this that the samples are from a hybrid between a human and an unknown primate occurring less than 15,000 years ago.

Let me offer a preliminary alternate hypothesis. The hair samples that contain only human mtDNA are from a human. The samples from which the nuDNA is isolated are also from humans but with some contaminants or some other animal source mixed in. That seems to be a more parsimonious interpretation. I would like to know more about the source of the DNA, but I guess that will have to wait for the full details to be published. The fact that the human DNA is modern human (hence the need for the alleged hybridization to have occurred so recently in the past) is most easily explained as the source simply being modern humans.

Let us also consider the scenario that Ketchum is suggesting – in the very recent past (less than 15,000 years) an unknown primate bred with modern human females (mtDNA comes almost exclusively from the female line) producing the creature we now know as bigfoot. What, then, must the original unknown primate looked like? The result of this pairing then produced fertile offspring, enough to generate a new stable population of bigfeet. It is highly doubtful that the offspring of a creature that looks like bigfoot and a human would be fertile. They would almost certainly be as sterile as mules. Humans could not breed with our closest living relatives, the chimpanzees, or any living ape. It is probable that we could produce fertile young with Neanderthals, but it gets doubtful the further back in our evolutionary history we go – and how far back would we have to go to reach a common ancestor with bigfoot?

The bottom line is this – human DNA plus some anomalies or unknowns does not equal an impossible human-ape hybrid. It equals human DNA plus some anomalies.

Yet Ketchum (somewhat prematurely) suggests:

Government at all levels must recognize them as an indigenous people and immediately protect their human and Constitutional rights against those who would see in their physical and cultural differences a ‘license’ to hunt, trap, or kill them.”

What can be recognized is the process of pseudoscience – anomaly hunting and then backfilling to the desired conclusion. What we don’t have is compelling evidence for a new species.

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