Prehistoric Painters Planned Ahead

13 October 2011 2:01 pm

C. S. Henshilwood et al., Science

Paint shop. Prehistoric humans had everything they needed to mix ochre pigments in abalone shells 100,000 years ago.

When Vincent Van Gogh moved to the southern French town of Arles in 1888, he painted nearly 200 vivid canvasses before cutting off his left ear in a fit of madness. This artistic explosion was possible in part because Van Gogh kept his brushes, paints, and palette constantly at the ready. A new discovery in South Africa suggests that prehistoric human painters also planned ahead, using ochre paint kits as early as 100,000 years ago. But just what they used the paints for is still a matter of debate.

Red or yellow ochre, an iron-containing pigment found in some clays, is ubiquitous at early modern human sites in Africa and the Near East. Some researchers think the earliest known art comes from the site of Blombos in South Africa, about 300 kilometers east of Cape Town, where pieces of ochre incised with an abstract design have been dated to 77,000 years old. Scientists have found even earlier signs of ochre use at Blombos and other sites as old as 165,000 years, but solid evidence that the pigment was used in artistic or other symbolic communication has been lacking.

In this study, Christopher Henshilwood of the University of Bergen in Norway and his colleagues report two ochre-processing "toolkits" at Blombos, dated to 100,000 years ago with a technique called optically stimulated luminescence, which measures how long grains of sand in archaeological layers have been hidden from sunlight. The toolkits, found only 16 centimeters apart in the same layer, were very similar: Both consisted of abalone shells filled with a mixture of ochre, crushed bone, and charcoal, the group reports today in Science. Inside both shells were chunks of ochre-stained quartzite rock apparently used to grind the mixture. One of the shells also had part of the forearm bone of a canid, possibly a wolf or fox, which the team thinks might have been used to stir the paint or transfer it out of the shell.

The two shells appear to be components of an ochre workshop, the team concludes. And they infer that the Blombos humans followed a specific series of steps to create the ochre paint, including grinding the pigment into a powder, heating the bone before crushing and adding it to the mix, and then putting the paint into the shells where it was gently stirred.

But what the ancient craftsmen used the paint for is "not self-evident," Henshilwood and colleagues write in their report. They suggest that it might have been used for decorating skin or clothing or for protecting the skin. (Ochre is known to repel mosquitoes and other insects.) They contend that the discovery shows aspects of modern behavior such as advance planning and "an elementary knowledge of chemistry."

Henshilwood's group rejects the suggestion, made for some other ochre finds, that Blombos residents might have used the substance as glue to haft stone tools into handles because a key ingredient in such adhesives—resin or wax—was not present in the shells.

The new discoveries are "astonishing" and "extraordinary," says archaeologist Lyn Wadley of the University of the Witwatersrand, Johannesburg, in South Africa. She agrees the shells are evidence that these early modern humans could "multitask and think in abstract terms about the qualities of the ingredients that they manipulated."

Nevertheless, Wadley, who has experimented with the adhesive properties of ochre mixtures, says that the ochre at Blombos could have been used as an adhesive even without resin or wax, especially because it contains crushed bone: "Bone glue was used by cabinetmakers well into the mid-20th century."

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