In an ancient seaside cave on the South African coast, archaeologists have found what may be the earliest known drawing created by a human.
This ancient piece of art is about 73,000 years old, its discoverers say. It’s on the smooth, concave side of a grindstone tool that’s only 1.5 inches long, and experiments in a French laboratory suggest it was created with a pointed piece of ochre.
The markings are not much to look at it. They consist of six relatively straight lines that are intersected by three wavy lines to form a rough crosshatch pattern.
But the simple red drawing predates any other known abstract or figurative drawings from Africa, Europe and Indonesia by 30,000 years, according to a report this week in the journal Nature.
Francesco d’Errico, an archaeologist at the University of Bordeaux in France who worked on the study, said the find came as a surprise to the research team.
“It adds a new dimension to what these people were doing and reinforces the hypothesis that they had a symbolic culture,” he said.
The drawing was discovered as part of the excavation of Blombos Cave, which lies 190 miles east of Cape Town on the southern coast of South Africa. Teeth found in the cave indicate that it was used as a temporary residence by early modern humans as far back as 100,000 years ago.
The grindstone was found in sedimentary layers that have been dated to between 77,000 and 73,000 years ago. These layers also contained 67 shell beads, including some that had been colored with ochre.
Archaeologists had also found evidence that visitors to the cave were processing ochre to create a liquid pigment and storing it in abalone shells as much as 100,000 years ago.
However, the drawing still came as a surprise.
It was first spotted by Luca Pollarolo, an archaeologist and honorary research fellow at the University of Witwatersrand in Johannesburg.
Pollarolo had already examined thousands of flakes pulled from the cave as part of his work to better understand the technology used to produce stone tools. The markings on this particular flake looked odd to his trained eye, so he passed it along to the leaders of the dig — Christopher Henshilwood and Karen van Niekerk of the University of Bergen in Norway.
The researchers’ first step was to determine whether the lines were just part of the stone tool or if they had been put there by humans. Microscopic and chemical analyses confirmed that the lines were chemically different from the rock, and that they were made of ochre.
Next, the researchers wanted to know how the ochre lines had gotten onto the rock. Was it painted? Was it drawn?
To answer this question, they brushed rocks with ochre paint and drew on rocks with ochre crayons (pieces of ochre that have been sharpened to a point on one end).
It was painstaking work.
“It may appear as a fun activity to an outsider, but in reality it is a time-consuming endeavor in which you alternate experiments with a lot of time at the microscope,” D’Errico said.
Ultimately, the team determined that the ochre lines were almost certainly made by drawing, not by painting.
Finally, the authors wanted to know whether the pattern was deliberately drawn to convey meaning or it was simply the result of processing ochre. Previous work had shown that these ancient people also used ochre as a glue additive and perhaps as a sunscreen.
To test this, they tried grinding ochre in a way that would match the pattern on the grindstone, but this produced less than one milligram of ochre powder — hardly worth the effort. This led them to the conclusion that there was not a utilitarian purpose to the lines.
Reaction to the study has been mixed among the archaeological community.
Adam Brumm, an archaeologist at Griffith University in Australia, said the authors’ claim was premature.
“To make this argument they would need to find and date more such artifacts, not just one among several thousand other unmarked stones,” he said.
Brumm added that there are other explanations for how the lines could have gotten there.
“For example, the red lines could simply be from sharpening an ochre ‘crayon’ on the grindstone,” he said.
His colleague Maxime Aubert, an archaeologist and geochemist at Griffith University, shared his skepticism. Although the study authors have shown that the ochre was applied to the stone on purpose, the reason for it remains unclear, he said.
“To me, it fails to demonstrate that the crosshatched patterns were intentionally made by humans as a sign of symbolic representation,” he said.
However, Pat Shipman, a retired professor of anthropology at Penn State, said the authors made a convincing case that the drawing was deliberately made.
“The hashtag or crosshatched shape often appears in rock art and quite similar shapes have been scratched into pieces of ochre from the same cave,” Shipman said. “Though they have, so far, only the one piece, I would not be surprised if more are discovered since the one they have recognized so far is part of a larger object.”
Indeed, the researchers report that each red line ends abruptly at the stone’s edge, suggesting that the drawing is a small part of a bigger — and perhaps more complex — pattern.
This is not the first controversy to originate from Blombos Cave. Researchers are also divided on whether several pieces of engraved ochre demonstrate symbolic thinking by the cave’s ancient inhabitants.