Engraved Ochre at Blombos Cave Hints at Symbolic Thought

Blombos Cave sits in a cliff face along the southern coast of South Africa, roughly 300 kilometres east of Cape Town. First excavated in 1991, the shelter contains a deep sequence of Middle Stone Age deposits dating from roughly 100,000 to 70,000 years ago, sealed beneath layers of windblown sand until reoccupation during the Later Stone Age. Groundwater rich in calcium carbonate seeping through the roof created an alkaline environment that exceptionally preserved organic remains, bone implements, and thousands of mineral fragments.

Among the recovered materials are more than 8,000 pieces of iron-rich ochre, an earthy pigment mineral. In 2002, researchers reported the recovery of two shaped pieces from the site's Still Bay layers. Each piece had been smoothed by scraping and grinding before being incised with deliberate geometric patterns, featuring cross-hatched designs framed by parallel lines. A 2009 study reported thirteen additional incised ochre pieces from levels dated to about 75,000 to 100,000 years ago, alongside a bone fragment bearing eight parallel incised lines. While analysing stone tools from the cave, researchers also identified a silcrete flake marked with nine red cross-hatched lines drawn using an ochre crayon about 73,000 years ago, recognized as an early instance of human drawing.