Sedges as bedding in Middle Stone Age Sibudu
Date
2013-07-30
Authors
Sievers, Christine
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Abstract
Cyperaceae (sedge) nutlets dominate the archaeobotanical assemblage of fruits and
seeds recovered from the Middle Stone Age deposits at the rock shelter Sibudu,
KwaZulu-Natal, South Africa (Sievers 2006). My aim is to investigate the
implications of the nutlet presence in terms of human behaviour and to demonstrate
that the nutlets were likely brought into the shelter on sedge culms (stems)
deliberately harvested by people and informally placed on the shelter floor to
provide “bedding”, a surface for working, resting or sleeping. I use various
empirical and experimental approaches to confirm the use of sedges for bedding at
Sibudu as early as ~77 000 years ago, almost 50 000 years earlier than any
previously identified archaeological bedding. The bedding consists of the sedges
Cladium mariscus subsp. jamaicense, Scleria natalensis, S. melanomphala, Cyperus
sp. and a panicoid grass, identified through Scanning Electron Microscopy
To investigate repeated and deliberate burning of bedding at Sibudu, I use
experimental micromorphology and I compare the signatures of the Sibudu
sediments with burned fresh sedge and grass bedding. I undertake further fire
experiments, also in open air situations, to answer questions about burning sedge
beds and the taphonomic implications. Experimental sedge bedding fires are hot and
brief. The matrix beneath the fires affects the temperatures achieved both on the
surface directly under the fire, and at depths of 2 cm and 5 cm below the surface; an
ash matrix conducts heat more effectively than a matrix of 1–2 mm sized particles
and allows for carbonisation of buried nutlets. The burning of dry and green bedding
indicates that once the bedding is burning, the temperatures are sufficient to
carbonise sedge nutlets below both dry and moist bedding.
The methodological innovations I introduce are the use of experimental
micromorphology to address an archaeobotanical question and the use of GIS-based
coexistence analysis of southern African archaeobotanical data to make
interpretations about past climate. The analysis develops previous palaeovegetation
research in the area (Sievers 2006; Wadley et al. 2008) and provides an
environmental context for people/plant activities at Sibudu.
Description
A thesis submitted to the Faculty of Science,
University of the Witwatersrand, Johannesburg,
in fulfilment of the requirements for the degree of
Doctor of Philosophy
2013