Wednesday, December 29, 2010

World's Oldest Optical Illusion Found?

The paper's author, Duncan Caldwell has surveyed the Paleolithic art of several caves in France and discovered a recurring theme that he says can't be simply accidental. Throughout the cave of Font-de-Gaume, and in examples from other sites as well, drawings and engravings of woolly mammoths and bison often share certain lines or other features, creating overlapping images that can be read first as one animal, then the other. Rarely, if ever, do they do the same with other animals.

While images of horses, deer, extinct cattle, and even rhinos often appear in such caves, and often partially or entirely overlap each other, it is only the mammoth-bison pair that Caldwell found regularly appearing superimposed so exactly. For example in the modern drawing below of an image from Font-de-Gaume, one main body shape, underbelly, and set of legs is adorned with signs of both mammoth and bison heads at both ends. These two large, bulbous, "armor-headed herbivores" which share many physical similarities in life, seem to have had some connection for people in this region in art as well.

In a particularly striking example, a small figurine has been given the details of a bison on one side and those of a mammoth on the other. The Paleolithic artist was clearly playing with the similar contours of the two animals and creating a single object that could be flipped to represent one species or the other.

Nice Trick, But Is It an Illusion?

There's a big difference between overlapping images or ambiguous profiles and a proper optical illusion however. Nigel Warburton is a senior lecturer of philosophy at The Open University and co-host of the podcast "Philosophy Bites," which uses the duck-rabbit as its logo. For him, knowing the original context of the image is key. Speaking of the classic version, he said "If somebody had been illustrating a children's book about rabbits, nobody would have seen it as a duck." As he put it, "the fact that a figure can be read in two ways isn't conclusive proof that it was intended to be read both ways."

The duck-rabbit is different because we know that it was created not just to show both animals individually, but to call attention to the strange sensation of one replacing the other. It's to some degree a "reflection on the nature of perception." The mammoth-bison images clearly make use of ambiguous shapes and similarities between the animals, but that doesn't guarantee they were intended as optical illusions.

Source from

For more interesting topics related to archaeology, visit archaeology excavations.

1 comment:

Anonymous said...

Archaeology Excavations (AE) has cut the text of the National Geographic blog in a completely misleading way, leaving the reader with the impression that Nat Geo cast doubt on the claim that Paleolithic artists made optical illusions. The final paragraph of the cropped AE report was not meant to be dismissive in Nat Geo’s original text, where it occurs long before the end, but rather to show balance before presenting incontrovertible evidence. This evidence appears in the following three paragraphs from Nat Geo, which vanished from AE’s corrupted version:

“Perhaps the most dramatic candidate for a mammoth-bison image meeting this requirement and being an intentional illusion isn't on a cave wall, but on a carving from a spear-thrower from the site of Canecaude. In this piece, as Caldwell sees it, it's not that the animals share a contour or a few lines, but that just two small details allow the entire image to be read as either of the two species, and seeing one causes the other to "disappear."

The details in question are the eyes. Caldwell describes how there is "both an upper eye, which turns the crescent beneath it into a tusk, and lower eye, beside the front leg, that transforms the same crescent which we just interpreted as a "tusk", into a bison's overhead horn." Looking back and forth between the eyes then, we are able to see the entire shape transform from one animal to the other, an effect much more like the classic Gestalt shift of the duck-rabbit.

Significantly, it is hard to think of other reasons for the unusual position of the eyes. First of all, their delicately carved shapes show that they were made intentionally, and are not just accidental markings. Secondly, the details of the body of the animal, its tusk/horns, long hair, and legs are all fairly realistically represented showing the artist's ability to make an accurate full profile view if desired."

AE should add the above paragraphs from Nat Geo’s blog to its eclipsed version in order to avoid leaving its readers with a false impression.