The oldest known painting kits, used 100,000 years ago in the stone age, have been unearthed in a cave in South Africa.
Two sets of implements for preparing red and yellow ochres to decorate animal skins, body parts or perhaps cave walls were excavated at the Blombos cave on the Southern Cape near the Indian Ocean.
The stone and bone tools for crushing, mixing and applying the pigments were uncovered alongside the shells of giant sea snails that had been used as primitive mixing pots. The snails are indigenous to South African waters.
Other bones, including the shoulder blade of a seal, were among the ingredients for making the pigments. The bones were probably heated in a fire and the marrow fat used as a binder for the paint.
Along with ancient flakes of charcoal, researchers found a "high water mark" on the shells' inner wall, evidence that an unknown liquid, probably urine or water, was added to make the paint more fluid.
The remarkable discovery, reported in the journal Science, throws light on the capabilities and rituals of Homo sapiens who occupied the cave from at least 140,000 years ago. The cave's entrance was blocked by sand 70,000 years ago.
"This is the first known instance for deliberate planning, production and curation of a compound," Christopher Henshilwood at the University of Bergen told Science, adding that the finding also marked the first known use of containers. "It's early chemistry. It casts a whole new light on early Homo sapiens and tells us they were probably a lot more intelligent than we think, and capable of carrying out quite sophisticated acts at least 40,000 to 50,000 years before any other known example of this kind of basic chemistry," he added.
One of the toolkits, which was found next to a pile of different instruments, was more complex and particularly well preserved, with its intact shell coated with red pigment. A second shell, found close by, was broken, but its grinding stone was coated with red and yellow pigments, suggesting it had been used more than once.
Henshilwood's team said the tools were evidence for an "ochre-processing workshop" run by early humans, who gathered the colourful mineral oxides from sites about 20 miles away.
Piecing together the process from the instruments they found, Henshilwood said the artists used small quartzite cobbles to hammer and grind the ochres into a powder, which was then poured into the shell and mixed with charcoal, burnt and broken bone, and the unidentified liquid.
One of the artists' kits came with a slender bone from the front leg of a dog or wolf. One end of the bone had been dipped in ochre, leading the scientists to conclude it was used as a primitive paintbrush.
"You could use this type of mixture to prepare animal skins, to put on as body paint, or to paint on the walls of the cave, but it is difficult to be sure how it was used," said Francesco d'Errico, a study co-author at the University of Bordeaux. "The discovery is a paradox because we now know much better how the pigment was made than what it is used for."
Tiny grooves at the bottom of the shells may be scratch marks caused by sand grains when the artist mixed the paint with a finger. "From time to time they were scratching the bottom when their finger was moving some of these little grains," said d'Errico.
The team has unearthed other artefacts from early humans at the cave. In 2004, it uncovered a collection of 75,000-year-old decorative shell beads at Blombos cave, some of which had been painted with ochre.
"Twenty thousand years after these painting kits were left behind, humans at Blombos were certainly using pigments for symbolic purposes. It is clear they knew all the sources for these red and yellow pigments. This was a tradition for them," said d'Errico.