In Africa, ochre is used for protection from the sun and as a barrier from insects such as mosquitos. It has also been scientifically proven to inhibit the effects of UV radiation. There are many other uses.
Ochre is an umbrella term for a range of earthy, iron-rich rocks composed of iron oxides or oxyhydroxides, such as shales, sandstones, mudstones and specularite.
Why the fuss
Ochre appears in the archaeological record around the same time as anatomically modern humans. Its use became more frequent from about 100,000 years ago at many Middle Stone Age sites.
At the same time, we find other significant developments in the material culture, such as new tool technologies and the use of a wide range of raw materials. Consequently, ochre is often seen as an indicator of “modern human behaviour” and cognitive development through its use as an indicator of symbolic behaviour.
This is reinforced by the preferential use of bright red ochre and ochre powder, as well as the deliberate engraving of ochre. Therefore, archaeological studies of the use of ochre can give fresh insights into the cognitive development of our early ancestors.
Past and present uses of ochre
Current and ethnographic uses of ochre have influenced interpretations of how it was used in the Middle and Later Stone Age. This must be done with caution because ochre has many different uses and we cannot assume that it was used in the same way in the past as it is today. Nevertheless, a great deal is now known about the properties of ochre. Here are some of its confirmed uses:
It was also used to tan hide. Ochre has anti-bacterial qualities which prevent the breakdown of collagen. This helps preserve hides. There is no direct evidence of its use as a hide tanning substance in the Middle Stone Age as no hides are preserved. But traces on the ochre pieces indicate that some pieces were rubbed on soft materials.
It is more commonly known for protection from the sun protection. Ochre-based pastes has been used as protection from the sun as well as a barrier from insects like mosquitos. It has been scientifically proven to inhibit the effects of ultra-violet radiation. It is still used as a sunscreen today, for example, by the Ovahimba in Namibia.
Ochre pigments were, and still are, widely used in paint and artwork. Many of the red and yellow pigments in rock art panels around the world are made with ochre-based paints. There is limited evidence for the creation of ochre paint in the Middle Stone Age, but 30,000 years ago its use as a paint was established.
Connecting the dots
Links between the visible uses of ochre and cognition have not been clearly defined. To reconstruct the technology and processes involved in using ochre, it is important to understand the physical and chemical qualities of this material, whether as pieces or in powdered form. It is then possible to conclude whether ochre was used in the same way in the ancient past as it was in the recent past.
The main ways that ochre was used in the Middle Stone Age was by grinding pieces on coarse sandstone slab to create powder, scoring (or engraving) pieces with sharp tools, or rubbing ochre on soft surfaces, such as animal hide or human skin.
Grinding, to create a powder, is the most common use trace on Middle Stone Age ochre pieces. Red ochre appears to be preferentially ground at many Middle Stone Age sites implying that bright red powder was desired. Additionally, ochre powder has been found on various archaeological artefacts in this period such as stone tools, grindstones, perforated shell beads and bone tools.
The construction of thought-and-action cognitive sequences for activities involving the use of ochre has helped to reconstruct which actions require enhanced cognitive functions.
To model these sequences, each activity performed with ochre must be considered – from collection, to possible modification by heat, to use with other tools, to discard.
By reconstructing the series of actions we can look at the cognitive requirements needed to perform them, such as problem solving abilities, the need to switch attention between two concurrent activities, long range planning and response inhibition.
The requirement for cognitively complex abilities in some of the ochre-related activities in the Middle Stone Age suggests that the people living then had the advanced mental capabilities of people today. Ochre use could be a proxy for cognitive capabilities, and can therefore shed light on the evolution of the modern mind.
This article is based on a submission by the author to the Cambridge Archaeological Journal.
Tammy Reynard receives funding from The Centre of Excellence in Palaeosciences (CoE_PAL), The National Research Foundation (NRF), The Palaeontological Scientific Trust (PAST) and The Mellon Fondation.
Authors: The Conversation