Nearly 50,000 years ago, the people of South Africa used milk- and ochre-based paints to adorn themselves, as well as stones and wooden slabs.

The use of paint dates back 250,000 years, but most ancient paints were derived from plants and minerals. The latest evidence is the earliest example of milk-based ochre pigment in southern Africa. Ochre paints have been discovered in both ancient African villages of the Middle Ages and at concurrent European archaeological sites, but never before with milk used as the binding agent.

Researchers at the University of Colorado who studied remnants of the powdery paint suggest ancient peoples sourced their paint base from hunted milk-producing animals -- members of the bovine family, including buffalo, eland, kudu and impala.

"Although the use of the paint still remains uncertain, this surprising find establishes the use of milk with ochre well before the introduction of domestic cattle in South Africa," lead study author Paola Villa, a curator at the University of Colorado Museum of Natural History, explained in a press release.

Earlier artifacts show the use of plant gum and bone marrow to mix ochre before applying it as body paint or as an affixing agent to secure stone tools to wooden shafts.

"Obtaining milk from a lactating wild bovid also suggests that the people may have attributed a special significance and value to that product," Villa added.

Villa and her colleagues found a stone flake they believe was used by modern humans in the Middle Stone Age to either mix or apply milk- and ochre-based paints. The stone flake was found in Sibudu Cave, a rock shelter in KwaZulu-Natal, South Africa's "garden province."

Advanced imaging and high-tech chemical analysis revealed the presence of casein on the stone flake, the main protein in milk. Villa's discovery is detailed in the journal PLOS ONE.

Because many of the indigenous people of South Africa practice body painting, researchers say it's likely the ancient people of the region used milk-based paints to adorn themselves and others.