Saturday, July 18, 2015


The question of tools and materials used to create rock art has received another fascinating contribution with the discovery of a small piece of flat rock with a red ocher pigment on it from a rock shelter in northern KwaZuluNatal province in South Africa that had been occupied by humans during the Middle Stone Age, from roughly 77,000 to 38,000 years ago. An analysis of it found casein, a protein from milk, mixed with the pigment. Casein has long been used as a binder in paint, and the milk itself would provide the liquid vehicle to mix the paint in. Indeed milk paint is a category of do-it-yourself paint that has a long history and it is still sometimes used to give furnishings an antique look. Casein is also a popular binder in glues, being an important component in many white carpenter's glues. A report in the online science journal PLOS/one, and picked up by, reported the discovery and analysis recently.

Stone flake with milk paint, Sibudu, South Africa.
University of Colorado Museum, Boulder, Colorado.

"The researchers, led by Paolo Villa, a curator at the University of Colorado Museum of Natural History, first found casein, a protein found in milk, in a smear of reddish paint on the edge of a stone. The milk would have helped the powder of ochre bind together into a paste that people may have used to paint stone, wood or their bodies. The researchers figured that the mixture was paint, rather than adhesive because milk doesn’t stick that strongly unless the proteins are mixed with lime and heated." (Fessenden 2015:1)

"Gas chromatography/mass spectrometry, proteomic and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS) analyses of residue on a stone flake from a 49,000 year-old layer of Sibudu (South Africa) indicate a mixture of ochre and casein from milk, likely obtained by killing a lactating wild bovid. Ochre powder production and use are documented in Middle Stone Age South African sites but until now there has been no evidence of the use of milk as a binder. Our analyses show that this ochre-based mixture was neither a hafting adhesive nor a residue left after treating animal skins, but a liquid mixture consisting of a powdered pigment mixed with milk; in other words, a paint medium that could have been applied to a surface or to human skin. The significance of our finds also lies in the fact that it establishes the antiquity of the use of milk as a binder well before the introduction of domestic cattle in South Africa in the first millennium AD." (Villa et al 2015:1)

Milk is seemingly a good choice for mixing paint because it combines the vehicle with a very effective binder for the resulting paint. It is interesting that this was so long before the domestication of cattle, and acquisition of the milk would have depended upon hunting or trapping a lactating bovid. Visit these sites for the complete story of this fascinating discovery.


Fessenden, Marissa
2015    In South Africa, People Painted with Cow Milk Long Before They Domesticated Cattle,, July 9, 2015.

Villa, Paola, Luca Pollarolo, Elaria Degano, Leila Birolo, Marco Pasero, Cristian Biagioni, Katerina Douka, Roberto Vinciguerra, Jeannette J. Lucejko, and Lyn Wadley,
2015    A Milk and Ochre Paint Mixture Used 49,000 Years Ago at Sibudu, South Africa, PLOS One (online journal), June 30, 2015.

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