The horses in the Pech Merle cave in southern France, painted during the Earth's last Ice Age around 25,000 BCE, have long had a special fascination for anthropologists, mainly because of their mysterious spots.

The black markings, which some scientists believe were painted using a spitting technique, cover the entire flank and neck of one of the two horses, while fainter spots can be seen on the other.

Until now, scientists only had DNA evidence of monochrome horses - mainly bay and black - living in Europe in that period, and had therefore assumed that the spots had a shamanistic or spiritual significance – or were simply the artistic license of an imaginative caveman.

But new DNA evidence gathered and analyzed by an international team of researchers has found that spotted horses did indeed exist in Europe in what is known as the Upper Paleolithic period, 50,000 to 10,000 years ago.

According to the findings published on Monday in the Proceedings of the National Academy of Sciences, ancient artists were simply drawing what they saw around them.

Identifying the spot-gene

The team - which included scientists from Britain, Germany, Mexico, the United States, Spain and Russia - was led by Melanie Pruvost of the Department of Evolutionary Genetics at the Leibniz Institute for Zoo and Wildlife Research (IZW) and the Department of Natural Sciences at the German Archaeological Institute in Berlin.

"We had a project on the domestication of the horse, and were looking at this particular color variation in pre-domesticated horses," Arne Ludwig, one of the German researchers, told Deutsche Welle.

"Then an American scientist came up to me at a conference in Leipzig and said, 'Do you know that we have identified the genetic mutation for spotted horses?' So, since we knew about the Pech Merle paintings, we looked for evidence of that mutation from that time."

By analyzing bones and teeth of 31 horses in Siberia and Europe dating back as many as 35,000 years, researchers found that six shared a gene associated with a type of leopard spotting seen in some modern horses.

Hunted horses

Archeologists believe that horses were only domesticated about 6,000 years ago, which means that the horses depicted in Pech Merle were hunted, not bred.

"We assume that the people who did these cave paintings were horse-hunters," said Ludwig. "They needed to be able to observe their environment very precisely. Their whole culture was practically based on hunting horses, because horses were the most common large mammals at the time."

Patrick Skinner, archeologist at Cambridge University, says the findings reinforce current theories of how humans interacted and perceived animals at the time. "The characteristics of the animals were very important for how the Upper Paleolithic people interacted with them," he told Deutsche Welle. "So the new evidence reinforces the idea that they aren't just painting animals for the sake of painting animals. It's their idiosyncratic behaviors that make them important."

It is difficult to judge how common the spotted horses were, based on the handful of samples tested, but Ludwig thinks the percentages suggest they were "not rare." This is also a new insight, since many researchers had considered a spotted coat unlikely for Paleolithic horses.

The ability to genotype Stone Age animals is a relatively new tool for archeologists, and the team behind the discovery are confident that, as more and more genetic codes are identified, we will soon know much more about the appearance of these animals.

Losing their religion?

French archeologist Jean Clottes, president of the International Federation of Rock Art Organizations, is convinced that the new discovery does nothing to damage the spiritual dimension of the cave art, or the creative reputation of the Stone Age artist. He points out that spots depicted on the Pech Merle horses also appear above and below the animals, not just on them - so, he argues, they must have had another meaning too.

"This does not change our perceptions at all," he told Deutsche Welle. "It's interesting, because it shows that the Pech Merle horses were not a figment of the imagination. Fine, but this works for those two horses, and that's it. We've known for a hundred years and more that these people painted animals which existed."

Ludwig agrees. "There's no way you could rule out that these spots generally have a ritual, shamanistic or religious value for the people in those days," he says. "But that's just speculation. All we can say now as geneticists is that these horses existed then."

"The discovery doesn't prove anything for or against any interpretation," adds Clottes. "There are hundreds of cave paintings and the majority of the animals represented are naturalistic, and this is another example. So what? But there are also what we call composite animals - for example, a head of a horse with horns. These are fantastical."

But Ludwig also notes that it is striking how the proportions of tan and spotted horses match the numbers depicted in cave art. "The types of horse that were painted the most – the brown ones – were also the genomes we found most often," he said. "Even if it's a small sample, it does fit."

Author: Ben Knight
Editor: Cyrus Farivar