Ochre use at Sibudu Cave and its link to complex cognition in the Middle Stone Age
Date
2014-03-05
Authors
Hodgskiss, Tamaryn Penny
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Abstract
Ochre is found at many Middle Stone Age (MSA) sites and its use is often attributed
by archaeologists to enhanced mental abilities and symbolism. However, the links
between the visible uses of ochre, cognition and symbolism have not been clearly
demonstrated. Here it is argued that by understanding ochre processing technology and
some of the stages involved in using ochre, one can determine the skill, knowledge and
cognitive abilities required to execute those activities. In order to understand the usetraces
found on ochre, and to enable the identification of them, as well as the types of
ochre used, experiments were first performed with geological ochre specimens. Ochre
pieces collected from the Sibudu surrounds were used experimentally for a variety of
grinding, scoring and rubbing activities. All use-traces created on the ochre piece during
an activity were macro- and microscopically examined, recorded and compared.
Experimental ochre pieces ground against a coarse or fine-grained slab develop
parallel striations. Grinding results in significant changes to the surface shape of the
ochre, and often results in faceted edges. Scoring can be performed with the intention to
create powder, or to create a design. The incisions created from scoring often do not
reach all the edges of the used surface and they regularly have frayed terminations. A
frayed incision termination shows that the incision was created by multiple scoring
strokes. When ochre is scored to manufacture powder the incisions that are generated
are parallel groups of grooves with erratically oriented grooves as well. Grooves created
through both grinding and scoring have microstriations within them and they show a
range of profile shapes. The most common use-wear from rubbing ochre on soft
materials is smoothing, edge rounding and polish. Microstriations and metallic lustre
occasionally form during rubbing. The collection of utilised experimental ochre formed a
comparative collection for the examination of the Sibudu ochre.
The main body of this research comprises a study of the Middle Stone Age ochre
assemblage from Sibudu, KwaZulu-Natal, South Africa. Sibudu has a large Middle Stone
Age ochre assemblage of over 9000 pieces of ochre from layers dating between ~77 ka
and ~37.6 ka. All pieces were examined to determine the types of ochre used and to
inspect all use-traces present on the pieces. The assemblage comprises 5449 ochre pieces
iv
>8 mm, including 682 pieces with markings from use. The pre-Still Bay (~77 ka) and
Howiesons Poort (~65–62 ka) layers have the highest percentage of utilised pieces.
Bright-red ochre was preferentially selected for use throughout most of sequence. There
is evidence of the preferential selection of specific types of ochre for use in the Sibudu
assemblage. Shale and pieces with medium hardness values are common throughout the
sequence. Grain sizes change through time – pieces with clayey grain sizes are favoured
during the Still Bay and Howiesons Poort, whereas silty grain sizes are preferred in the
younger Middle Stone Age occupations. High frequencies of bright-red amongst the
utilised pieces, coupled with high frequencies of yellow or orange pieces with no
evidence of use, suggest that colour choices were deliberate and not a product of postdepositional
heating. Chemical analysis of a sample of utilised pieces indicates that they
all contain iron, silicon, aluminium and calcium; many pieces contain hematite and some
contain maghemite.
Use-traces were divided into activity categories, based on experimental results.
Combined grinding and rubbing is the most frequent activity for which ochre pieces
were used. Grinding and rubbing use-wear also occurs independently on many pieces.
Scored pieces are rare, but are more frequent in the pre-Still Bay (~77 ka) industry than
elsewhere in the sequence. Some of the incisions appear to be deliberate engravings, and
parallel lines and fan-like marks are the most often repeated patterns. Use-traces
acquired during powder-producing activities predominate, implying a desire to create
ochre powder. Powder-producing activities were mainly performed with bright-red
pieces, while minimal scoring is mainly present on brown-red pieces. Pieces with mica
inclusions are not common, but were frequently used for powder-producing activities.
Once the activities performed with ochre were established, thought-and-action
sequences, or cognigrams, were constructed. This helped establish the steps involved in
each activity and the temporal and physical distance between the commencement of a
task to its completion. Inferential sequences were constructed to establish the
procedures and knowledge needed to complete an activity, thereby establishing the
cognitive prerequisites. Cognitive interpretations are made using the concept of
enhanced executive functions of the brain. The construction of the inferential thoughtv
and-action sequences showed that the various ways that ochre was used have different
cognitive requirements.
Powder-production alone is not an indicator of complex cognitive processes,
although some planning, foresight and knowledge of materials is required. Some of the
powder was used in the creation of hafting adhesives, which is a cognitively demanding
process requiring attention-switching ability, response inhibition and abstract thought.
Grinding ochre and then rubbing the piece on a soft material for the direct transfer of
powder does require some complex mental abilities, such as multi-tasking and switching
attention. Scoring a piece of ochre with a sharp tool does not necessitate enhanced
executive functions, but some engravings demonstrate foresight, intentionality and an
awareness of space and symmetry that may demonstrate abstract thought.
This research provides a complete description of the Middle Stone Age ochre
assemblage at Sibudu, and establishes the way that ochre was used at the site. This
contributes to the debate on the advent of enhanced behaviours in the past by providing
insight into the cognitive abilities required by the ochre users. It offers a method of
analysing ochre use in the past by drawing on cognitive theory and the visible
applications of ochre. Both simple and complex cognitive abilities were required for
ochre activities at Sibudu. The requirement for cognitively complex abilities in some of
the ochre-related activities at Sibudu suggests that the people living there during the
MSA had advanced mental capabilities like modern humans living today. This research
shows how ochre use can be employed as a proxy for cognitive capabilities, and can
therefore shed light on the evolution of the modern mind.