At first glance, it doesn’t look like much: a few uneven lines etched into the soft, chalky outer layer of a small, thin flint flake. But a group of archaeologists claims those uneven lines are a deliberate marking, making the 3.5cm-long flake the latest piece of evidence for symbolic thought among Neanderthals.

Kiik-Koba Cave overlooks the Zuya River in the Crimean Mountains. First excavated in the 1920s, the sediment layers that filled the cave contained evidence of a long history of Neanderthal occupation. The engraved flake came from a layer dating to between 35,486 and 37,026 years old. Archaeologists found the skeleton of a Neanderthal infant in the same layer, leaving no doubt about who lived at Kiik-Koba when the stone tools were made and used.

Several recent discoveries, including cave art and shell jewelry at sites in Spain, leave little doubt that Neanderthals were capable of symbolic thinking. Archaeologists want to understand more about the origins and development of symbolism in both modern humans and our hominin relatives. But interpreting the evidence is sometimes a challenge, because early symbolic objects are, by their nature, relatively simplistic. That makes it easy to dismiss a real symbolic marking as an accident or to make a fuss over the symbolic meaning of an accidental mark.

At Middle and Lower Paleolithic sites across Europe and the Middle East, for example, archaeologists have found several flint and chert flakes with lines etched into the stones' chalky outer layer—the cortex. It’s hard to tell, in most cases, whether those incisions are deliberate markings with meaning or random scratches picked up during use, manufacture, or excavation.

To help figure things out, University of Bordeaux archaeologist Ana Majkic and her colleagues developed a set of questions about the shapes and features of etched lines, the context in which the stone flake was found, and other factors. Archaeologists can assign points based on the answer to each question, and the total score suggests how likely it is that the markings were deliberate and symbolic or produced by some other process. Majkic and her colleagues tested the framework on the Kiik-Koba flake.

Hasty, but purposeful

The 13 lines etched in the chalky outer layer of the flake look messy and haphazard at first glance; some are straight, some are slightly curved, and many of them overlap or are superimposed over others. It’s hard to make out individual lines with the naked eye. But microscopic analysis tells a different story.

It turns out that the lines were etched with a pointed stone tool, which produced clean-edged incisions with a V-shaped cross-section that shows up clearly under a microscope. Some of those cross-sections are asymmetrical in a way that hints at a right-handed craftsman holding the etching tool. Most of the lines have clear starting points where the grooves are deeper but then fade toward the far ends.

That rules out other possible explanations for the marks on the flake, according to Majkic and her colleagues. The lines don’t match the kinds of marks a retouching tool would leave on the flake, and the fact that they were etched with a pointed tool rules out accidental cut marks.

By looking at which lines cross or cover others, Majkic and her colleagues were able to see the order in which the marks have been made. They numbered them L1 through L13. In some cases, the craftsman apparently added a second line to lengthen one that came up too short; in the diagram, L2 seems to have been added over L1 to lengthen it. And new lines were added in between older ones, presumably to fill in blank space.

Majkic et al. 2018

Majkic et al. 2018

The marks are concentrated in the center of the flake, and except for the two mistakes of L7 and L8, they don’t reach the edge. The Neanderthal who etched the lines into this flake seems to have done so with the intent of creating a color contrast between the center and the edges, much the way artists today use hashing to shade parts of an image rather than filling them in with solid color.

At one point, the engraver appears to have switched to another tool to get a deeper line. Most of the first 10 lines show microscopic parallel marks on the sides of the groove, probably caused by slight protuberances on the sides of the tool. But lines L9 and L10 were pretty shallow, and the last three lines were made by a different tool or by the same tool held at a different angle—the lines are deeper.

So the marks on the Kiik-Koba flake weren’t the product of idle scratching—these lines were made deliberately—but they were still hasty work. As noted above, two of the lines, L7 and L8, are relatively shallow and, unlike all the others, reach all the way to the edge of the flake.

“They probably correspond to mistakes in the positioning of the tool due to the speed of execution of the overall pattern,” wrote Majkic and her colleagues. Under a microscope, the shape of the two lines reveals quick motions made in rapid succession.

That kind of work would have required good hand-eye coordination, fine motor skills, and attention to detail—but most importantly, it would have required intent.

What does it mean?

The flake probably isn’t meant to be read like a barcode with the position or number of the lines conveying a detailed meaning, like a number or a name. Several of the lines cover or cross others; with the naked eye, it’s hard to pick individual lines out of the overall pattern.

“It is rather the contrast between the whitish background and the heavily hashed center of the cortex that may have been used to recall [a piece of] information to the flake user or eventually communicate one when the tool was passed to somebody else,” wrote Majkic and her colleagues.

It’s possible that the hashing was just meant to make the smooth surface of the flake easier to grip, but Majkic and her colleagues say that’s unlikely, because the Kiik-Koba flake is too thin to stand up to the kind of vigorous movements that would require a thumb-grip. And a craftsman who just wanted to put a grip on a stone tool wouldn’t have taken such care to stick to the center of the flake and avoid the edges. The impact was meant to be visual, not functional, Majkic and her colleagues argue.

The marks could just be meant to denote ownership, but a similar flake from the same layer of the Kiik-Koba cave is unmarked, which suggests that the Neanderthals who lived here didn’t label their tools as a general rule. And although the sharp flake seems to have been used for something—it bears a slight fracture on its right side and some microscopic scars along its edge—it’s not clear exactly what its purpose was. So it’s hard to say what was special about this flake or what the marking was meant to convey. But Majkic and her colleagues say it’s a clear example of symbolism.

“For the time being, the results of this study add to the growing body of evidence that Neanderthal cultural adaptations, particularly those at the end of their cultural trajectory, included practices that could be consistent with symbolic interpretations,” they wrote.

PLOS ONE, 2018. DOI: 10.1371/journal.pone.0195049 (About DOIs).