The role of geophytes in stone age hunter-gatherer subsistence and human evolution in the greater cape floristic region

Singels, Elzanne

The role of geophytes in stone age hunter-gatherer subsistence and human evolution in the greater cape floristic region

Doctoral Thesis

2021

Abstract

It has been hypothesised that an adaptive shift to a starch-rich diet was an important driver in human evolution and supported the energetic requirements to sustain brain development throughout hominin evolution. Plants that possess underground storage organs (geophytes) have been put forward as the likely source of starch. Geophytes comprise a large portion of the plant diversity in the Greater Cape Floristic Region (GCFR), where significant archaeological evidence of the evolution of human modernity has been identified in the Middle Stone Age (MSA). It is thought that the resources available in this region during this time period fuelled the progression and development of complex language, art and tool production in early modern humans. The overall objective of this thesis is to determine the importance of geophytes in early modern human diets and the impact they might have had on human behaviour and cognition. The role of geophyte resources in Stone Age hunter-gatherer subsistence was evaluated by firstly creating an ecological and environmental framework of data to evaluate the geophyte resource base. Secondly, the archaeological evidence available on actual hunter-gatherer foraging behaviour was evaluated using this framework, together with novel methods of macrobotanical analysis and experimental archaeological methods. It was found that the nutritional quality of geophytes is high, even in comparison to domesticated crops such as potatoes. The desirability of geophytes to a forager would rely on many factors, apart from nutritional quality, however. Geophyte resources on the coastal plain of the GCFR are dense and diverse. This diversity encompasses variation in the quality of the nutrients contained in the USOs and the optimum time throughout the year they would be most profitable to harvest. Geophytes could have been available during a large portion of the year throughout the GCFR. The archaeological evidence shows just how widespread and complex geophyte foraging and processing were during the Holocene, although there is a relative lack of evidence in the MSA. The novel method presented to determine the energy cache offered by geophytes and the seasonality of geophyte foraging shows great promise to improve our understanding of foraging choices and hunter-gatherer mobility across the region. All Stone Age processing methods tested experimentally improved the nutritional quality of USOs, but veldfire produced the most profound nutritional quality improvements of all methods tested. Geophytes could have supplied the dense and predictable resource cache that made the GCFR a reliable environment for human evolution, despite climatic and vegetational shifts. The efficient exploitation of geophyte resources throughout the Stone Age could have altered early human behaviour and cognitive development.

Keywords

archaeology

Reference:

Collections

PhD / Doctoral

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