Oldest pigment factory dates back 100,000 years

This work was published in the journal Science on 14 October.

Red, yellow and black ochre, most often made up of iron oxides, was used by prehistoric men in Africa and Europe for at least 200,000 years. However, the techniques used to prepare and store it prior to the Upper Paleolithic (40,000-10,000 years) had remained unknown so far. In 2008, two sets of tools and ochre fragments were recovered from Blombos Cave³ in South Africa, at levels dated to 100,000 years ago. The first "toolkit" consisted of a large shell, more specifically an abalone shell, covered in a 5 mm-thick layer of red ochre and containing a used fragment of pigment and a quartzite flake (rock made of quartz crystals). The content of this shell was preserved by a pebble showing percussion marks. The "kit" also included a quartzite slab and quartz flakes showing pigment residues and traces of use as grinders or crushers. An elongated bone, probably used to mix or apply the pigment, the shoulder blade of a seal and a herbivore's vertebra completed the set. The second "toolkit" consisted of an abalone, with a layer of pigment inside. It also contained a small block of ochre-stained quartzite, as well as a fragment of red mineral showing traces of abrasion and cuts.

By thoroughly examining the fragments of ochre and the residues present on the unearthed tools and shells, the researchers have been able to reproduce the recipes developed by prehistoric men to make their pigments. In particular, they evidenced the deliberate use of three types of rocks containing high quantities of haematite and goethite⁴, two of the most common iron oxides. By either breaking and crushing these rocks or abrading them using quartzite grinders, the artists of the time produced a pigment powder. The discovery of spongy bone fragments suggests that bone marrow was used as a binding agent. In addition, the presence of a circular trace formed after drying the pigments on the surface of the best-preserved shell indicates that the mixture was liquid. Finally, the shells were used several times to mix and store pigments.

This workshop is the oldest evidence of the production and preservation of coloring agents. Its discovery brings a substantial contribution to current knowledge in this field. The complexity of the techniques used implies cognitive abilities to plan and perform complex tasks, such as combining raw materials of various types and origins, using fire to facilitate the extraction of bone marrow -- and shells as containers or palettes. As far back as 100,000 years ago, artists already had expertise on the coloring properties of various minerals, especially iron oxides.

What was the purpose of these coloring pastes ? The absence of resin, gum or wax seems to rule out their use as adhesives for hafting tools. They more likely served for the coloring of materials (rock, skin, human body), their preservation and/or protection (tanning of skins, body protection against sunlight), for the creation of abstract or figurative paintings, or as medicines and food supplements.

1 -- From prehistory to the present: culture, environment and anthropology' unit (CNRS/Université Bordeaux 1/Ministère de la Culture et de la Communication).  This work has been supported by a grant from the European Research Council (ERC).

2 -- Laboratory of the Center for Research and Restoration of the museums of France (CNRS/Ministère de la Culture et de la Communication).

3 -- This archeological site was known for the discovery of some of the world's oldest abstract prints and shell ornaments dated to 90,000-75,000 and 75,000 years ago, respectively.

4 -- Haematite: iron oxide with chemical formula: Fe2O3; Goethite: hydrated iron oxide with chemical formula: FeO2H.