A painstaking investigation of Europe’s cave art has revealed 32 shapes and lines that crop up again and again and could be the world’s oldest code

Spot the signs: geometric forms can be found in paintings, as at Marsoulas in France Philippe Blanchot / hemis.fr / Hemis/AFP

When she first saw the necklace, Genevieve von Petzinger feared the trip halfway around the globe to the French village of Les Eyzies-de-Tayac had been in vain. The dozens of ancient deer teeth laid out before her, each one pierced like a bead, looked roughly the same. It was only when she flipped one over that the hairs on the back of her neck stood up. On the reverse were three etched symbols: a line, an X and another line.

Von Petzinger, a palaeoanthropologist from the University of Victoria in Canada, is spearheading an unusual study of cave art. Her interest lies not in the breathtaking paintings of bulls, horses and bison that usually spring to mind, but in the smaller, geometric symbols frequently found alongside them. Her work has convinced her that far from being random doodles, the simple shapes represent a fundamental shift in our ancestors’ mental skills.

The first formal writing system that we know of is the 5000-year-old cuneiform script of the ancient city of Uruk in what is now Iraq. But it and other systems like it – such as Egyptian hieroglyphs – are complex and didn’t emerge from a vacuum. There must have been an earlier time when people first started playing with simple abstract signs. For years, von Petzinger has wondered if the circles, triangles and squiggles that humans began leaving on cave walls 40,000 years ago represent that special time in our history – the creation of the first human code.


If so, the marks are not to be sniffed at. Our ability to represent a concept with an abstract sign is something no other animal, not even our closest cousins the chimpanzees, can do. It is arguably also the foundation for our advanced, global culture.

The first step to check her theory was to fastidiously document the signs, their location, age and style, and see if any patterns emerged. For this, von Petzinger would have to visit as many caves as she could: archaeology’s focus on paintings of animals meant the signs were often overlooked in existing records.

Black tectiforms at Las Chimeneas, Spain D v. Petzinger

It wasn’t easy or glamorous work. Gaining access to caves in France, where a lot of Stone Age art is located, can be devilishly complicated. Many are privately owned and sometimes jealously guarded by archaeologists. For the full set of symbols, von Petzinger also had to visit many obscure caves, the ones without big, flashy paintings. At El Portillo in northern Spain, all she had to go on was a note an archaeologist made in 1979 of some “red signs”; no one had been back since. At first, von Petzinger couldn’t even find the entrance. Eventually, she noticed a tiny opening at knee level, trickling with water. “Thank God I’m not claustrophobic,” she says. After 2 hours sliding through mud inside the mountain, she found two dots painted in pinkish ochre.

Between 2013 and 2014, von Petzinger visited 52 caves in France, Spain, Italy and Portugal. The symbols she found ranged from dots, lines, triangles, squares and zigzags to more complex forms like ladder shapes, hand stencils, something called a tectiform that looks a bit like a post with a roof, and feather shapes called penniforms. In some places, the signs were part of bigger paintings. Elsewhere, they were on their own, like the row of bell shapes found in El Castillo in northern Spain (see picture below), or the panel of 15 penniforms in Santian, also in Spain.

At El Castillo in Spain, a black penniform and bell-shapes D v. Petzinger

“Our ability to represent a concept with an abstract symbol is uniquely human“

Perhaps the most startling finding was how few signs there were – just 32 in all of Europe. For tens of thousands of years, our ancestors seem to have been curiously consistent with the symbols they used. This, if nothing else, suggests that the markings had some sort of significance. “Of course they mean something,” says French prehistorian Jean Clottes. “They didn’t do it for fun.” The multiple repetitions of the P-shaped claviform sign in France’s Niaux cave “can’t be a coincidence”, he argues.

Thanks to von Petzinger’s meticulous logging, it’s now possible to see trends – new signs appearing in one region, sticking around for a while before falling out of fashion. Hand stencils, for example, were fairly common in the earliest parts of the Upper Palaeolithic era, starting 40,000 years ago, then fall out of fashion 20,000 years later. “You see a cultural change take place,” says von Petzinger. The earliest known penniform is from about 28,000 years ago in the Grande Grotte d’Arcy-sur-Cure in northern France, and later appears a little to the west of there before spreading south. Eventually, it reaches northern Spain and even Portugal. Von Petzinger believes it was first disseminated as people migrated, but its later spread suggests it then followed trade routes.

The research also reveals that modern humans were using two-thirds of these signs when they first settled in Europe, which creates another intriguing possibility. “This does not look like the start-up phase of a brand-new invention,” von Petzinger writes in her recently published book, The First Signs: Unlocking the mysteries of the world’s oldest symbols (Simon and Schuster). In other words, when modern humans first started moving into Europe from Africa, they must have brought a mental dictionary of symbols with them.

That fits well with the discovery of a 70,000-year-old block of ochre etched with cross-hatching in Blombos cave in South Africa. And when von Petzinger looked through archaeology papers for mentions or illustrations of symbols in cave art outside Europe, she found that many of her 32 signs were used around the world (see “Consistent doodles”). There is even tantalising evidence that an earlier human, Homo erectus, deliberately etched a zigzag on a shell on Java some 500,000 years ago. “The ability of humans to produce a system of signs is clearly not something that starts 40,000 years ago. This capacity goes back at least 100,000 years,” says Francesco d’Errico from the University of Bordeaux, France.

Nonetheless, something quite special seems to have happened in ice age Europe. In various caves, von Petzinger frequently found certain symbols used together. For instance, starting 40,000 years ago, hand stencils are often found alongside dots. Later, between 28,000 and 22,000 years ago, they are joined by thumb stencils and finger fluting – parallel lines created by dragging fingers through soft cave deposits.

Etched teeth

These kinds of combinations are particularly interesting if you’re looking for the deep origins of writing systems. Nowadays, we effortlessly combine letters to make words and words to make sentences, but this is a sophisticated skill. Von Petzinger wonders whether the people of the Upper Palaeolithic started experimenting with more complex ways of encoding information using deliberate, repeated sequences of symbols. Unfortunately, that’s hard to say from signs painted on cave walls, where arrangements could be deliberate or completely random. “Demonstrating that a sign was conceived as a combination of two or more different signs is difficult,” says d’Errico.

Etched deer teeth from Saint-Germain-de-la-Rivière, France D v. Petzinger

It was while she was grappling with this conundrum that von Petzinger found out about the necklace of red deer teeth. It was found among other artefacts in the grave of a young woman who died some 16,000 years ago in Saint-Germain-de-la-Rivière, in south-west France. From a description in a book, von Petzinger knew that many of the teeth had geometric designs carved into them. So she travelled from Canada to the National Museum of Prehistory in Les Eyzies-de-Tayac, where the teeth were held, in the hope that they might be a missing piece of her puzzle.

The moment she flipped the first one, she knew the trip had been worthwhile. The X and straight lines were symbols she had seen together and separately on various cave walls. Now here they were, with the X sandwiched between two lines to form a compound character. As she turned each tooth over, more and more decorations were revealed. In the end, 48 were etched with single signs or combinations, many of which were also found in caves. Whether or not the symbols are actually writing depends on what you mean by “writing”, says d’Errico. Strictly speaking, a full system must encode all of human speech, ruling the Stone Age signs out. But if you take it to mean a system to encode and transmit information, then it’s possible to see the symbols as early steps in the development of writing. That said, cracking the prehistoric code (see “What do they mean?“) may prove impossible. “Something we call a square, to an Australian Aborigine, might represent a well,” says Clottes.

For d’Errico, we will never understand the meaning of the symbols without also considering the animal depictions they are so often associated with. “It is clear that the two make sense together,” he says. Similarly, cuneiform is composed of pictograms and counting tallies. A ration, for instance, is represented by a bowl and human head, followed by lines to denote quantity.

Von Petzinger points out another reason to believe the symbols are special. “The ability to realistically draw a horse or mammoth is totally impressive,” she says. “But anybody can draw a square, right? To draw these signs you are not relying on people who are artistically gifted.” In a sense, the humble nature of such shapes makes them more universally accessible – an important feature for an effective communication system. “There’s a broader possibility for what they could be used for, and who was using them.”

More than anything, she believes the invention of the first code represents a complete shift in how our ancestors shared information. For the first time, they no longer had to be in the same place at the same time to communicate with each other, and information could survive its owners.

The quest is far from over. Von Petzinger plans to expand her Stone Age dictionary by adding in the wealth of signs on portable objects, in caves on other continents and maybe even those found beneath the waves (see “Diving for art“). “We only have part of the picture now. We are on the cusp of an exciting time.”

What do they mean? Geometric marks left alongside murals of animals have attracted the curiosity and scrutiny of archaeologists for decades, although it’s only recently that one researcher, Genevieve von Petzinger, has begun systematically cataloguing them all into a searchable database to try to determine their significance (see main story). For French prehistorian Henri Breuil, who studied cave art in the early 20th century, the paintings and engravings were all about hunting and magic. In the abstract symbols, he saw representations of traps and weapons – meanings that were intrinsically linked to the larger paintings. In the 1960s, the French archaeologist André Leroi-Gourhan declared that lines and hooks were male signs, whereas ovals and triangles were female. Some of this interpretation has stuck. Circles and inverted triangles are still often cited in the literature as representations of the vulva. It is worth noting that many of the earlier scholars studying cave art were men, which may have led to gender biases in their interpretations. “It’s interesting that it was predominantly male archaeologists doing this work early on, and there were a whole lot of vulvas being identified everywhere. This could have been a product of the times, but then again, many cultures do place importance on fertility,” says von Petzinger. Later, South African archaeologist David Lewis-Williams proposed a neuropsychological interpretation for some symbols. Like many of his peers, Lewis-Williams believes that at least some Stone Age art was made during or after hallucinogenic trips, perhaps as part of shamanic rituals. If so, the symbols could simply be literal representations of hallucinations. Some studies suggest that drugs and migraines can both provoke linear and spiral patterns, not unlike those seen in ice age art. But the sad truth is that without a time machine, we may never really know what our ancestors were communicating with these signs.

Diving for art Some of the most stunning cave art in Europe was only discovered in 1985, when divers found the mouth of the Cosquer cave 37 metres below the Mediterranean coastline near Marseilles in southern France. Its entrance had been submerged as sea levels rose after the last ice age. Chances are, other similar caves are waiting to be discovered. So von Petzinger has teamed up with David Lang of OpenROV in Berkeley, California, which makes low-cost, underwater robots. Next year, they plan to use them to hunt for submerged cave entrances off Spain’s north coast. The region is rich in painted caves, many close to the shoreline, so it seems likely that others could be hiding below the waves. If they find any, the pair will send in the remote-controlled mini-submarines, armed with cameras, to safely explore the new sites.

This article appeared in print under the headline “Hidden symbols”