Tuesday, April 5, 2011

Dino petroglyphs again

A month ago, Paul Garner drew my attention to the latest paper from Phil Senter and co-author Sally Cole, this time on a purported Native American petroglyph of a dinosaur at Kachina Bridge in Utah. According to Senter and Cole's analysis, the image that is supposed to be a dinosaur consists of both markings and natural stains. Consequently, it cannot be maintained that it is a dinosaur. Senter and Cole conclude,
Pareidolia is the psychological phenomenon of perceiving significance in vague or random stimuli, e.g., seeing animals in clouds or the face of a religious figure in a food item. The results of this investigation indicate that the dinosaurs of Kachina Bridge are examples of this phenomenon and exist only as pareidolic illusions. They can therefore be added to the list of discredited evidence for the coexistence of dinosaurs and humans.
Paul Garner agreed with their analysis, and posted his own photo of the petroglyph, which frankly doesn't look like much of anything to me.

Two weeks later, much to my surprise, AIG posted a response to Senter and Cole written by Ishmael Abrahams. Abrahams goes through their paper line by line, and the main substance of his critique focuses on the methods. He is dismissive of their techniques (analysis of photographic images of the purported petroglyph), but he is most critical of what Senter and Cole call five "predictions" of the "hypothesis that a given petroglyph depicts a dinosaur." Paul Garner found Abrahams's response "superficial and unconvincing." Believe it or not, I actually think that Abrahams has a point here. Sort of.

Here are the "predictions" that Senter and Cole list in their paper:
(1) the image is a single image, not a composite of separate images, (2) it depicts an animal, (3) its features cannot be reconciled with an interpretation that it depicts a member of the non-dinosaurian local fauna that was contemporaneous with its maker(s), (4) its features depict a specific, identifiable dinosaur, and (5) it is entirely human-made.
Abrahams basically argues that some of these would not be necessary for an artist to depict a dinosaur, and he's right about that. For example, I could draw a dinosaur as a composite image, and I could use features of the rock I was drawing on to help depict that dinosaur. Similarly, I could choose to draw a dinosaur that looked like a lizard or some other common animal, and who's to say that we know all the species of dinosaurs that existed? If there were dinosaurs living with Native Americans in the old west before the white man arrived, why assume they must be identifiable with some dinosaur we know about only from fossils? Couldn't those recent dinosaurs have been a different species that we don't know about?

Insofar as Abrahams goes, I think he has a point, but I think the point only reveals poor wording on the part of Senter and Cole. The problem as I see it is not at all whether an artist could have used creative methods to depict a dinosaur unknown to modern science. Rather, the question at hand is whether a marking on a rock actually depicts a recently-living dinosaur. To conclude that the markings at Kachina Bridge are intended to depict a dinosaur, we're going to need some criteria to make sure we haven't mistaken the image for something else. Seen in that light, Senter and Cole's "predictions" actually make very good criteria. For example, their first and fifth "predictions" help us to make sure that the image didn't just happen to look sort of dinosaur-y due to accidental proximity to stains in the rock or separate petroglyphs. Likewise, "prediction" four helps us to make sure the artist wasn't just making up some fanciful image purely from imagination. "Prediction" three is necessary for us to conclude that the image is a dinosaur and not just some lizard.

Failing to meet these criteria means that we cannot say for certain that the markings at Kachina Bridge depict a dinosaur. We can't be sure that the markings were intended to be a single image or were not merely stains on the rock. We cannot be certain that this image depicts any specific dinosaur. We can't even be sure that the image depicts an animal! Consequently, we ought not promote this image conclusively as a Native American depiction of a dinosaur. All we can say is that in some photos, the markings on that rock look vaguely sauropod-ish, but in other, better photos of the same markings, it doesn't look like much of anything.

So if there's any problem with Senter and Cole's paper, it's a problem of wording, and I think that Abrahams completely misses the point. He bases his rebuttal entirely on hypotheticals - what an ancient artist might have done - rather than on what we can now reliably conclude based on what the unknown artist(s) actually did.

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