Spain’s Cave Paintings Made by Neanderthals, Uranium-Series Tests Show

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Panel of Hands cave painting Altamira, Spain: Photo by Pedro Saura

Cave art in Europe began 10,000 years earlier than previously thought, according to new analysis techniques.

The paintings could have been created by the first anatomically modern human Europeans, or they could be Neanderthal art.

This adds to a growing body of research suggesting that the cognitive development of Neanderthals was much more sophisticated than previously assumed.

World Heritage Site Cave Art Tested

An interdisciplinary multinational team of researchers used their modern techniques on fifty paintings in caves in northern Spain.

Samples came from eleven caves, including the UNESCO World Heritage Sites at Altamira, El Castillo and Tito Bustillo.

The evidence produced demonstrates that the paintings in these caves are older than those in France, previously thought to be Europe’s oldest cave art.

Locations of the caves sampled: 1, Pedroses; 2, Tito Bustillo; 3, Las Aguas; 4, Altamira; 5, Santiàn and El Pendo; 6, El Castillo, La Pasiega, and Las Chimeneas; 7, Covalanas and La Haza: Image by Pike, et al.

Decoded Science interviewed Dr Paul Pettitt, Reader in Palaeolithic Archaeology at the University of Sheffield and member of the team whose paper is published June 15, 2012 in Science. Dr. Pettitt’s PhD was in Neanderthal behaviour, and he has been consulted in relation to Neanderthal sites and ochre art worldwide.

Neanderthal Red Ochre Disks

Asked if he agrees that these paintings suggest that Neanderthals may have occupied these caves and created the earliest European paintings in them, Dr. Pettitt said, “We know that Neanderthals were occupying these caves before Homo sapiens, and the relatively early dates we have obtained for several pieces of art render it possible that Neanderthals produced them. The study does not unequivocally demonstrate this but given what we know about the timing of the extinction of Neanderthals in northern Spain and the subsequent arrival of our own species one certainly cannot rule out Neanderthal authorship.”

The creation of art is one of a number of important markers of cognitive development in the evolution of modern humans. Art may also be demonstrative of symbolic behaviour, and may be associated with the development of language.

So-called ‘red disk’ paintings in El Castillo cave, where the maximum age was determined by Uranium-Series testing: Image by Pedro Saura

Asked  about the non-figurative paintings he believes are by Neanderthals, Dr. Pettitt suggests that the fact that they are repeated in several different caves implies that they deliberately convey meaning and are not just experimental marks.

They are made with red pigment – ochre – either spat onto the cave wall or applied with the hand, and do not obviously depict anything. While they are relatively simple they are repeated in a number of caves, and for this reason it is likely that they were deliberate and had some kind of meaning to their creators. Thus they are unlikely to be simple doodles or graffiti,” he said.

The sources of the pigments used to make the paintings were local, Dr. Pettitt confirmed. “Ochre can be obtained from caves in the local vicinity. At this stage we have no evidence that these pigments were being carried around in northern Spain, but based on evidence from elsewhere this is possible.”

Testing Paleolithic Cave Paintings

Ochre paintings cannot be tested by normal scientific means because they are not organic, and because taking samples would damage the art. Dr Pettitt has been outspoken in the past about the shortcomings of radiocarbon dating as a method for dating cave art, suggesting that more reliable methods could be found to fully understand the successive artists that occupied caves over several millennia.

When asked whether the ochre pigments or the calcite formations on top of the pigments had been tested, Dr. Pettitt said, “there is no way to date red pigments directly. Thus uranium-series was used to date the time of formation of the stalactites, which as they directly overlie the pigments in all cases provide minimum ages for them.”

The Uranium-Series Disequilibrium Method

The U-series disequilibrium method is based on the radioactive decay of radionuclides within the naturally occurring decayed chains. There are three such decay chains, each starts with an actinide nuclide … and ultimately ends with different stable isotopes of lead,” the researchers explain. This method usefully allows dating in calendar years.

Member of research team taking samples from scarf stalactites: Image by Rodrigo de Balbin Behrmann

The tests were made on calcite precipitation or flowstone that has formed over the pigments placed on the rock by the artists, in the expectation that this would contain miniscule uranium deposits. Samples usually no larger than a grain of rice were carefully removed with a scalpel, with precautions taken to avoid contamination.

In some areas miniscule stalactites had formed over the ochre images; in a number of instances a second sample was taken further down these stalactites. In every case where this was done, the second sample dated earlier than the first, confirming that this is a reliable method. In an instance where the cave artist had decorated a larger stalactite which had later broken, samples were able to be taken from the bedrock, giving a useful earliest date.

When the samples had been processed in the laboratory it was established that those taken among the red disks in the El Castillo cave date back to at least 40,800 years ago, at least 10,000 years earlier than previously thought. Anthropologists are now left with further material to support growing evidence that Neanderthals were more like Homo sapiens than previously credited, and may now consider what further implications may be taken using these new results.

Cave paintings key dates timeline linked to examples: Image by Pike et al

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