Can you tell what it is yet?

Here we go again. About six months ago I found myself writing about the great excitement caused by finds of paleolithic art in Germany and France, my point being that the rhetoric generated by these finds ("exquisite", "astonishingly precocious", "pretty sophisticated") was out of proportion to their artistic quality. It wasn't that the objects weren't interesting in scholarly terms, or even that they didn't have a crude kind of artistic integrity. But they were talked up in a way that betrayed an interesting tangle of received ideas.

A residue of the Modernist admiration for "primitive" forms of art had combined with proprietorial academic rivalry ("my bone carving is more important/older/ paradigm-busting than your bone carving") to produce an entirely excessive reaction.

I also thought, to put it bluntly, that quite a few of the experts were seeing things, giving the ancient artists the benefit of the doubt over objects that were at least 10 parts doubt to one part undeniable intention.

You can see something very similar happening with the announcement that "a Sistine Chapel of the Ice Age" has been discovered at Creswell Crags, in Nottinghamshire. The first discoveries of carvings here were made last year, but now a further 96 figures carved on the roof of the cave have been identified - many of them revealed after an English Heritage team had started work early one morning and, for the first time, had seen the roof in slanting natural light. What had been invisible under spotlights was, apparently, thrown into relief by morning sunshine. And, at once, the usual rhetoric was rolled out. "These are masterpieces" said Dr Ripoll, a Spanish expert on cave art. The carvings were praised for their exactitude of representation and their elaboration, and it was noted that they proved Britain was "up there at the top of the cave-art league". One newspaper wrote of a "prehistoric Michelangelo" and the word "spectacular" was used -- an ironic choice given that these carvings have been in public view for years without anyone actually noticing them.

This is partly about journalism, of course. Most of the stories about the Creswell Crags discovery led on the Sistine Chapel comparison and left the fact that the experts themselves are divided about many of the finds for the final paragraphs. There really isn't much mileage in a story headlined "Indeterminate Shapes May Be Ice Age Carvings But Some Doubt Whether They Really Are".

But it is also partly about the creative power of human imagination. This was nicely illustrated by the picture which accompanied most of the reports - of a bird's head carved into the limestone ceiling of Church Hole. It looked to me like a flamingo, though other observers saw similarities to a curlew and even a dodo. Frankly, it was impossible to tell, since there was no way to establish which bit of the weathered incisions constituted the outline.

It was even more difficult to say where exactly the natural irregularities of the rock gave way to man-made marks. This fact was only confirmed by an accompanying drawing designed to bring out the details of the carving - a sketch which seemed highly selective about which divots and bumps were part of the figure and which weren't.

It's possible that all this is a trick of the light. It would be very foolish to rely on a photograph to capture every nuance of a three-dimensional object. But it is a little odd that easily visible marks become faint on the drawing, while invisible ones become sharply pronounced. And since those publicising this find are unlikely to have released their least convincing picture, you can't help wondering how vague some of the other carvings might be. One of the experts - a Dr Pettitt - reportedly conceded that some of the identified works might be only "in the eye of the beholder".

You don't have to doubt the sincerity or professionalism of those involved to point out that some beholders see a lot more than others, and that excitement and expectation can have a marked effect on perception. This makes it particularly intriguing that the bird's head discovered at Creswell Crags should bear such a striking resemblance to a famous image from 20th-century philosophy -- the duck/rabbit figure that Wittgenstein used to make a point about the mental nature of interpretation. Tilt it sideways a little bit and the "beak" becomes "ears", or vice versa. What you see depends on what you have in mind to begin.

Not just the Sistine Chapel of the Ice Age, then, but just possibly an ancient version of Wittgenstein's Trinity College, too.