Caves Weren't Painted in a Day!

I've heard of artists being late with their commissions, but 15,000 years to finish a painting job seems a trifle over the top.

Scientists are revolutionising our understanding of early human societies with a more precise way of dating cave art.

In several caves in Spain -- where it had been assumed that the art all dated to the same period -- new dating techniques reveal that the paintings were done in several phases, sometimes as much as over 15,000 years (25,000 years ago to just 10,000 BCE).

The dating method involves a technique called uranium series dating. It works on any carbonate substance, such as coral or limestone, and involves measuring the balance between a uranium isotope and the form of thorium that it decays into. The process is lengthy and painstaking -- researchers must scrape off enough of the calcite crust for an accurate dating, while taking care not to harm the art underneath, or even contaminate the sample with the older limestone behind the art.

"This lets us challenge assumptions about the age of cave art," says Alistair Pike, senior lecturer in archaeological sciences at Bristol University, who has helped develop the technique.

Dr Pike and his research team spent two weeks in Spain last year testing the new method in caves, and have just returned from another fortnight's expedition to sample nine more caves, including the so called 'Sistine Chapel of the Palaeolithic', Altamira cave (from which come the bison above and the animals below). The elaborate works in Altamira were thought to date from around 14,000 years ago.

It may have taken Michelangelo four long years to paint his fresco on the ceiling of the Sistine Chapel, but his earliest predecessors spent considerably longer perfecting their own masterpieces.

Rather than being created in one session, as archaeologists previously thought, many of the works discovered across Europe were produced over hundreds of generations who added to, refreshed and painted over the original pieces of art.

In new research published by the Natural Environment Research Council's website Planet Earth, Dr Pike reports that some of the paintings were between 25,000 and 35,000 years old. The youngest paintings in the cave were 11,000 years old.

"We have found that most of these caves were not painted in one go, but the painting spanned up to 20,000 years. This goes against what the archaeologists who excavated in the caves and found archaeology for just one period.

"It is probably the case that people did not live in the caves they painted. It seems the caves they lived in were elsewhere and there was something special about the painted caves."

Given that the researchers often had to crawl through tiny fissures to take their samples, and that some of the art is virtually inaccessible except with modern spelunking equipment, I'd say that something special is a bit of an understatement.

(Left) Black and violet painted horses overlying red figures at Tito Bustillo Cave, Asturias, Spain: it's staggering to think that the horses may be separated from the red signs -- and conceivably even from each other -- by thousands of years.

When we really absorb this new information, it must also change entirely how we look at cave painting* -- and especially its puzzling mix of representational and geometric, sign-like imagery. One single explanation -- whether shamanistic hallucinations or gender-coded bursts of consciousness -- is unlikely to stretch over so many painters over such unimaginably long periods of time.

The death knell of a universal theory for the origins of art, perhaps?


* If, that is to say, these great time differences are confirmed by future work (which may not be taken for granted: I've seen too many scientific flip-flops in archaeology to be sanguine).

And, yes, I know I'm wildly off topic but this was too good to miss. My thanks once again to The Ridger at The Greenbelt , whose Monday Science Links alerted me to this exciting story, first picked up on the blog Pro-Science.