In a cave a long time ago someone took a crayon and left a series of red criss-crossed lines on a piece of grindstone. What the purpose of those lines were has been lost in the march of 73,000 years of human evolution, but what researchers do believe is that those faint marks of ochre are humankind’s earliest evidence of a drawing.

The discovery of an artefact in the southern Cape that is believed to be the earliest evidence of a drawing predates previously found drawings from Europe and Southeast Asia by a least 30,000 years and, according to researchers, this provides further evidence that the cradle of humankind’s cognitive development, which birthed art, lies in Africa.

The artefact was found in the Blombos Cave, in the southern Cape, in South Africa, in 2013. But it would take another five years and some hardcore forensic testing before researchers concluded that the six lines on the piece of grindstone, or silcrete flake, were intentionally placed there by human hand.

The team’s discovery and findings were announced on Wednesday in the journal Nature.

“Before this discovery, Palaeolithic archaeologists were for a long time convinced that unambiguous symbols first appeared when Homo sapiens entered Europe, about 40,000 years ago, and later replaced local Neanderthals,” said Professor Christopher Henshilwood, a researcher at both Wits and Bergen universities and the lead author on the paper, in a statement.

“Recent archaeological discoveries in Africa, Europe and Asia, in which members of our team have often participated, support a much earlier emergence for the production and use of symbols.”

It was archaeologist Dr Luca Pollarolo, an honorary research fellow at Wits University, who happened across the discovery while painstakingly sifting through thousands of flakes that had been excavated from Blombos Cave.

Realising that they might have something, the team turned to Professor Francesco d’Errico of the PACEA lab of the University of Bordeaux, France, to see if he could work out if the marks were part of the matrix of the rock or if they were in fact man-made.

D’Errico’s team examined the piece by using Raman spectroscopy and an electron microscope. They were able to confirm that the lines had in fact been applied to the stone.

They also discovered that the grindstone was initially used to grind ochre.

The team then experimented on how the ochre could have been drawn onto the rock.

They tried different painting and drawing techniques and concluded that the 73,000-year-old piece was made with an ochre crayon that had a tip that was between 1 and 3 millimetres thick – about the size of a modern pencil.

The lines, they discovered, abruptly end at the edge of the flake, suggesting that the pattern may have extended over a larger surface.

These are not the first examples of art to have been found at the Blombos site. In 2002 Henshilwood and his team announced the discovery a piece of ochre that had been etched with lines, similar to those drawn on the piece of grindstone.

The ochre, which was dated to between 70,000 and 100,000 years old, was believed at the time to be the earliest known example of art.

Since then the discovery of a freshwater shell in Trinil, Java, with an etched zig-zag pattern on it, has pushed back the date of the earliest known engraving to 540,000 years ago. But it is suspected that this pattern was made by a human forebear, Homo erectus.

Besides etched ochre, archaeologists have found shell beads covered in ochre and sophisticated leaf-shaped stone spear points at Blombos. The discovery of the earliest known example of a drawing, says Henshilwood, adds the “fourth leg chair” to human modernity arising in Africa.

“The big message here is that Africa is the birthplace of modern humans,” he says.

Henshilwood suggests that Blombos Cave’s location on the coast might have had a part to play in why its inhabitants began experimenting with early forms of expression.

“People living on the coastline had access to a lot of food; you have hippo, kudu, bontebok and what they can get from the sea,” he said.

“They don’t have to scavenge around for food any more, so they have a lot of time on their hands.”

The use of symbols is seen in archaeological sites right along the West Coast of South Africa, he adds. Many of these symbols are the criss-cross patterns found in Blombos and this, he suggests, shows that humans were creating social networks related to symbols.

Professor Lyn Wadley of Wits University, however, is cautious of the team’s findings.

“It would not be a surprise to find that people at Blombos were able to draw 73,000 years ago; it is perfectly feasible. Yet, despite the authors’ extensive use of scientific methodology to recreate the markings on the flake, and despite the indisputable presence of other remarkable artefacts at Blombos, I am not convinced of intentional ‘drawing’ on the flake based on the present evidence,” she said.

Her concern is that the grindstone was once used to grind ochre, and this might have had an influence on the results of the experiments.

“Given the flake’s history, I should therefore like to see additional experiments using, for example, ground surfaces and pieces of ochre, but replicating activities other than drawing. Since the original hypothesis is that drawing rather than any other activity is represented, there is circularity in the analytical process that experiments only with drawing,” she added.

“If, after performing a variety of activities with grindstones, grindstone fragments and pieces of ochre, the only marks to match the archaeological ones are from drawing with an ochre crayon, then I should be convinced that the present interpretation is the most likely one.”

D’Errico agrees that more experimenting needs to be done but stands by his findings.

“A number of facts go against the accidental interpretation. All the lines are extremely thin and have a constant width. None of the flakes bearing traces of ochre from other sites, interpreted as residue left by hammers made of ochre, show a similar pattern,” he explained.

But the search for more of these early drawings is set to continue.

Henshilwood is assembling a multidisciplinary team that will include climatologists and even psychologists that will be examining that period in the past when humans began to act and think more like us.

“We will be going back, and maybe we will find the rest of the silcrete flake,” says Hensilwood. DM