Long before the famous duck-rabbit illusion (seen at right), prehistoric
artists were creating mind-bending double images of their own, according to a
new paper presented earlier this year at an international convention on rock
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
Early cave art researcher Henri Breuil
copied this image of overlapping bison and mammoth from the walls of
Font-de-Gaume in France. (Image courtesy of Duncan Caldwell)
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.
The two sides of a
figurine from a site near Cambrai show very different details. On one
side (left), the high back leg and short front leg are characteristic of
depictions of bison. On the other, the tall straight front leg and
grooves depicting long hair in the midriff are typical of mammoths. (Image courtesy of Duncan Caldwell)
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
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.”
A classic version of the duck-rabbit
illustration, contemplated by psychologist Joseph Jastrow in 1899, and
philosopher Ludwig Wittgenstein in 1953. (wikimedia commons)
Another classic shape-shifting image is the “Old Woman-Young Woman” image, where the young woman’s neckband and ear become the old woman’s mouth and eye, respectively. (wikimedia commons)
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.
Magic Is in the Beholder of the Eye
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.”
Unlike other bison-mammoths that depict two distinct but overlapping images, this carving from a spear-thrower
features one image that can be seen two different ways. Above, the
artifact in its natural state. Below, red ovals highlight the position
of the two eyes. (Images courtesy of Duncan Caldwell)
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
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.
Even in the somewhat common technique in prehistoric art of
using “twisted perspective” where an animal’s body will be shown in profile,
but both eyes will be visible on the face in a Picasso-like manner, the eyes
are generally still close together. In addition, that technique seems to be more
common in flat wall art than in full sculpture, where the ability to put one
eye on each side of the sculpture takes care of the perspective problem.
The possibility remains however that pieces of the complete spear-thrower that are now missing would clarify the image further, and show that the image is just a mammoth, plain and simple. For example, in a reconstruction in the book “Mammoths: Giants of the Ice Age,” authors Adrian Lister and Paul Bahn propose that the mammoth’s trunk would have looped back in the lower-left part of the carving, making the lower “eye” the curled up end of the mammoth’s trunk.
A Window Into Stone Age Philosophy?
If Caldwell’s analysis of the mammoth-bison phenomenon is
correct, we begin to get a view not only of what prehistoric people saw, but
also how they thought, and that has the potential to change our perspective and
how we see other artifacts as well.
That perspective shift is also what makes these ambiguity
illusions so appealing in the first place. Nigel Warburton said he chose the
duck-rabbit as the logo for “Philosophy Bites” because it’s also what he likes
about philosophy itself. “Part of what philosophy does,” he said “is, sometimes,
make you see what you already knew in a completely different light.” Perhaps
someone enjoyed the same thought sitting in a cave, some 15,000 years ago.
For More Information
Duncan Caldwell is a fellow at the Marine and
Paleobiological Research Institute in Massachusetts. Follow his varied research
and interests on his personal site.
Nigel Warburton is a Senior Lecturer in Philosophy at The
Open University. His latest book, “Philosophy Bites,” based on the podcasts of the same name, is
available from Oxford University Press.