Long before the Sumerians pressed reeds into clay, humans may have already taken their first steps toward writing. Forty thousand years ago, in the depths of Ice Age caves, people began leaving behind simple symbols — dots, zigzags, triangles, and ladder shapes. These marks weren’t random doodles. They appeared again and again across Europe, and later even on jewelry buried with the dead. Paleoanthropologist Genevieve von Petzinger believes they may represent humanity’s earliest attempt to store and transmit information: a prehistoric code that could be the ancestor of writing itself.

Hunting for Symbols in the Dark

Between 2013 and 2014, von Petzinger undertook what sounds like the world’s most claustrophobic road trip. She crawled, slid, and squeezed into 52 caves across France, Spain, Italy, and Portugal. Many of these weren’t tourist-ready attractions with paved walkways. Some were nearly forgotten sites with only cryptic notes from the 1970s to guide her. At El Portillo in northern Spain, the “entrance” was a hole at knee level, trickling with water. She slithered inside, caked in mud, until she found two faint red dots — evidence that someone, 30,000 years earlier, had made their mark in the dark.

“I thank God I’m not claustrophobic,” she told New Scientist.

In each cave, she ignored the naive depictions of animals that dazzled earlier generations of archaeologists. Instead, she carefully logged geometric symbols: penniforms (feather-like shapes), tectiforms (posts with roofs), claviforms (key-like signs), hand stencils, grids, squares, zigzags, and dots.

She eventually discovered that 32 distinct symbols kept reappearing across caves worldwide.

For tens of thousands of years, across an entire continent, Ice Age humans kept returning to the same small set of marks. For tens of thousands of years, our ancestors seem to have been curiously consistent with the symbols they used.

The First Emoji Dictionary

Consistency wasn’t all. Von Petzinger noticed that many of the signs weren’t new inventions of Ice Age Europeans. Two-thirds of them already existed elsewhere when modern humans arrived in Europe around 40,000 years ago.

“This does not look like the start-up phase of a brand-new invention,” von Petzinger writes in her book The First Signs: Unlocking the Mysteries of the World’s Oldest Symbols. Instead, the people who crossed into Europe from Africa brought a mental dictionary of symbols with them.

In South Africa’s Blombos Cave, a 70,000-year-old piece of ochre was found, etched with cross-hatching. It’s considered the earliest drawing ever found. In Indonesia, a half-million-year-old shell etched by Homo erectus bears a zigzag pattern. These hints suggest the capacity for symbolic thinking is far older than cave art itself.

Von Petzinger argues that these signs are humanity’s first experiment in abstract communication — a prehistoric emoji system, you can say. “We’ve been building on the mental achievements of those who came before us for so long that it’s easy to forget that certain abilities haven’t already existed,” she said in a TED Talk.

Signs on the Move

When she mapped the symbols, von Petzinger noticed something else: cultural trends. Just like hashtags on social media, certain signs fell in and out of fashion. Hand stencils were hot 40,000 years ago, then declined about 20,000 years later. Penniforms emerged in northern France around 28,000 years ago, spread west, and eventually reached Spain and Portugal.

She suspects the spread happened in two waves. At first, the marks traveled with migrating populations. Later, they moved along trade routes. In other words, Ice Age signs spread the way memes do now — sometimes carried by people, sometimes carried by networks.

What Did They Mean?

Here’s the frustrating part: we may never know.

French prehistorian Jean Clottes insists the marks are inseparable from animal paintings, at least concerning the artworks in Europe. “The signs in the caves are always (or nearly always) associated with animal figures and thus cannot be said to be the first steps toward symbolism,” Clottes was cited as saying by the Bradshaw Foundation.

Other scholars disagree and suggest these markings may indeed represent some form of proto-writing. MIT linguist Cora Lesure and colleagues argue that cave art could represent “converting acoustic sounds into drawings”. The idea is that the images and signs reflect the same symbolic thinking needed for language. In her words, cave and rock art may be “a modality of linguistic expression.”

And then there are the psychedelic theories. South African archaeologist David Lewis-Williams suggested that spirals, grids, and zigzags mirror hallucinations triggered by shamanic rituals. Migraines, too, can produce similar visuals. If he’s right, Ice Age art might be humanity’s first attempt to draw the inside of the mind.

Von Petzinger admits the code may be indecipherable. As Clottes puts it: “Something we call a square, to an Australian Aborigine, might represent a well.” Context matters, and that context is long gone.

But she pushes back against dismissing them as meaningless. “Of course they mean something,” Clottes himself also said. “They didn’t do it for fun.”

Jewelry, Signs, and Systems

When Genevieve von Petzinger flipped over a deer tooth in a French museum, she wasn’t expecting goosebumps. The tooth, part of a 16,000-year-old necklace, carried three etched marks: a line, an X, and another line. She recognized them instantly.

The etched deer teeth necklace showed that the marks weren’t limited to cave walls. They appeared on portable objects, too — worn, carried, shared. Out of 48 teeth, many bore the same symbols found in caves, sometimes strung together into sequences.

These compound signs may hint at an even bigger leap. On cave walls, repeated combinations could be accidental. On jewelry, they look deliberate, almost like letters forming a word.

Whether you call it “writing” depends on definitions. Strictly speaking, writing encodes spoken language, and these symbols fall short of that. But if you define writing as a system for transmitting information across time and space, then von Petzinger’s signs might qualify as the very first.

Cracks in the Old Story

For centuries, archaeologists divided history into two neat halves: prehistory (before writing) and history (after). Writing, we were told, began suddenly around 3400 BCE, when Sumerians pressed reeds into clay. Everything before was darkness rife with speculation.

But the Ice Age signs suggest a slower, less straightforward process. Humans may have been experimenting with abstract symbols for tens of thousands of years before cuneiform.

As Frank Jacobs wrote for Big Think, these signs force us to “abandon the powerful narrative of history as total darkness until the Sumerians flip the switch.” Instead, they show humans “slowly but surely undimming the light many millennia earlier.”

The search isn’t over. Many caves along Europe’s coasts are now underwater, submerged after the last Ice Age. Von Petzinger has teamed up with David Lang, founder of the underwater robotics company OpenROV, to hunt for drowned caves off Spain’s northern coast. Using mini-submarines armed with cameras, they hope to explore unseen spaces that might hold lost panels of signs.

The odds are good. When divers discovered Cosquer Cave off Marseilles in 1985 — its entrance 37 meters below sea level — they found some of the most stunning cave art in Europe. It’s likely that more hidden galleries still wait in the dark.

The Legacy of 32 Signs

Even if we never crack the code, the Ice Age symbols matter. They show that humans long ago learned how to preserve information outside the body — scratched into stone, painted on walls, etched onto teeth.

Von Petzinger points out something crucial: drawing a mammoth takes skill. Drawing a square does not. That simplicity made the signs accessible. Anyone, not just artists, could use them. And that democratization of expression may have been the true revolution.

For the first time, humans no longer had to be in the same place at the same time to share information. Ideas could survive their creators. Knowledge could travel.

That is the essence of writing. And it may have begun not with clay tablets in Mesopotamia, but with a few lines scratched onto cave walls by torchlight, or etched onto a necklace buried with the dead.