Stone Age Color, Glue ‘Factory’ Found

A once-thriving 58,000-year-old ochre powder production site has just been discovered in South Africa. The discovery offers a glimpse of what early humans valued and used in their everyday lives.

The finding, which will be described in the Journal of Archaeological Science, also marks the first time that any Stone Age site has yielded evidence for ochre powder processing on cemented hearths — an innovation for the period. A clever caveman must have figured out that white ash from hearths can cement and become rock hard, providing a sturdy work surface.

“Ochre occurs in a range of colors that includes orange, red, yellow, brown and shades of these colors,” project leader Lyn Wadley told Discovery News. “Yellow and brown ochre can be transformed to red by heating them at temperatures as low as 250 degrees Celsius (482 degrees Fahrenheit).”

Wadley, who authored the study, is a professor in the School of Geography, Archaeology and Environmental Studies and in the Institute for Human Evolution at the University of the Witwatersrand. She said ochre has been found on bone awl tools probably used for working leather, so it is possible that the ancients sported colorful leather clothing and other leather goods.

Red-hot leather clothing is still found in stores today, but the probable wearers then were a far cry from today’s fashion elite.

Ochre is derived from naturally tinted clay that contains mineral oxides. In addition to coloring objects, it makes a compound adhesive when mixed with other ingredients, such as plant gum and animal fat.

“This glue would have attached stone spear or arrowheads to hafts, or blades to handles for cutting tools,” Wadley explained.

Ochre can also be used as body paint and makeup, as a preservative and as a medicinal component, so it could have served many different functions during the Stone Age.

Wadley analyzed the ochre “factory” at the large Sibudu rock shelter north of Durban in KwaZulu-Natal, South Africa. The site consisted of four cemented hearths containing the ochre powder. The cement workstations could have held grindstones and/or served as storage receptacles for the powder, according to Wadley, who also excavated about 8,000 pieces of ochre in the area.

She believes the natural material was collected just over a half a mile away from the site, where it would have been heated and ground or just ground directly onto coarse rocks.

Francesco d’Errico, director of research at the National Center of Scientific Research at the University of Bordeaux, said pigment material is found in bits and pieces at various early sites. However, not much was known in detail before about how it was processed and used.

Based on the nature of the cemented ash and the geology of the Sibudu site, d’Errico believes that people 58,000 years ago intended to produce large quantities of red pigment in a short time frame.

He now thinks ochre pigment was a “fundamental constitute of Middle Stone Age culture, and that its production likely involved the work of several members of the group.”