What we don’t know is shaped by what we do. Whatever dark matter is, we will look for it assuming an accelerating, expanding universe. However cancer can be truly defeated, we will have to outsmart evolution to do so. And no matter what bizarre creatures are still to be discovered in our densest forest and deepest ocean depths, they are unlikely to ever be Bigfoot, Nessie, or the Chupacabra.

We have found monsters before. As biology has gotten better at tracking down the beasts that elude us, unlikely legends are becoming real animals. Just recently, we finally obtained amazing footage of two very mysterious creatures—the giant squid and the oarfish. They didn’t appear from nowhere either. Over the years biologists and fisherman have found traces of their existence, from fins and tentacles to intact bodies. This is how we find rare creatures in huge areas—we follow the evidence.

Cryptozoological creatures like Nessie and Bigfoot are both (supposedly) large animals living in large areas, and both have decades of “evidence” to suggest that we might film one someday—as we did the giant squid. But practicing biologists still consider these mythic animals’ existence to be highly unlikely. Why? In science, the kind of evidence matters; all unlikelihoods are not created equal.

The methods of science lay out a continuum of knowing, from plain ignorance and necessary uncertainty, to likely truths, to facts so well established “that it would be perverse to withhold provisional assent,” as Stephen Jay Gould famously said. For peer review, replication, and objectivity to make any headway on the continuum, for science to find the right answers to anything, there have to be wrong—or at least unlikely—answers. It’s how we know that vitamin C doesn’t cure the common cold and multi-vitamins are for the most part useless, for example. By blinding, replicating, and ultimately verifying experiments, science moves forward.

It’s possible to move backwards on the continuum as well. The more personal data gets—the more the evidence is anecdotal and neither repeatable nor verifiable—the less likely a theory becomes. Anecdotal support like stories and sightings don’t determine impossibility, but frankly, a body is always better. That is something others can measure and touch; nobody can see exactly what you saw. The fallibility of anecdotal and eyewitness support is why it is very unlikely (if not impossible) that a large ape-human hybrid roams the world’s deep forests and that the Loch Ness is anything other than barren. If that is the true state of Nessie’s and Bigfoot’s biology, how can their existence be so commonsensical in our culture?

Daniel Loxton, co-author with Donald Prothero of the fantastically thorough new book Abominable Science!: Origins of the Yeti, Nessie, and Other Famous Cryptids [Amazon], contends that cryptozoologists don’t assess probability in the same way scientists do, and as a result they get their science backwards. In an email exchange he told me:

A scientist generally starts with the conservative working assumption that proposed new ideas are not true or that hypothetical new entities do not exist, and then revises her probability estimate upwards only when the evidence forces her to do so. A pseudoscientist typically starts with the assumption that a novel proposal seems to be true, and then revises her probability downward as the evidence leaves her no choice—if she is willing to surrender the possibility to any degree at all.

In fact, Loxton went on to tell me, he is unaware of any cryptid, such as Bigfoot or Nessie, or class of evidence that has been abandoned by the cryptozoological community altogether—despite the well-publicized hoaxes and incompatible ideas.

Ultimately, whether an idea in any field of inquiry is unlikely or not depends on the standard of evidence. Here zoology and cryptozoology part ways. Science—psychology in particular—has shown time and again that human perception is easily distorted, and therefore plain eyewitness testimony in biology or zoology holds little weight. In contrast, pseudoscientific endeavors like the continued hunt for Bigfoot use each new eyewitness “sighting” to increase the likelihood just a little. Innumerable eyewitness reports amount to a “likely” conclusion in Bigfoot lore because the existence of Bigfoot was decided upon before it was seen.

Anecdotal and eyewitness data have a fatal flaw—enough stories and sightings can actually make a mythical creature less likely to exist.

Consider Bigfoot. It goes by many names—over 100 by some counts. It supposedly lives on every continent except for Antarctica…in sustaining populations. It should be everywhere. The ubiquity of Bigfoot sightings smashes up against the fact that we have never found any verifiable scat, bones, hair or body. We sometimes hook giant squid—a creature we apparently see far less often than Bigfoot that occupies a much larger area—but a hunter never shoots a Sasquatch. Paradoxically, Bigfoot has been reported too many times to actually exist.

With a different perspective on what “unlikely” means, when science considers the existence of Bigfoot or Nessie or UFOs or psychic powers unlikely, it can be like the denial of “a rock solid established fact, like the existence of France,” to believers, Loxton says. And if you don’t know how the scientific continuum moves, then what “unlikely” means really can be foreign. It certainly feels foreign to value biological theories over “I know what I saw” narratives, says Loxton. “It’s the way we’re built.”

Cryptids persist because “unlikely” means something else to their proponents—the same things that make Bigfoot scientifically unlikely are lauded as nail-in-the-coffin positive evidence for squatchers. Biologists and cryptozoologists interpret unlikelihoods differently enough that a deeply flawed study of “Bigfoot DNA” can be interpreted to say that Bigfoot is both scientifically unlikely and too likely not to exist at the same time.

There are still monsters out there. Some are based on myth and word-of-mouth, others on body parts and dredged decompositions. As long as biology and cryptozoology keep talking past each other, each with their own language of unlikely, what kind of evidence do you think will help us find the next monster?

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Image Credit:

From the exhibition Cryptozoology: Out of Time Place Scale, as shown at the Kansas City Art Institute's Artspace by Kelly Garbato on Flickr

Bigfoot by Marc Dragiewicz