Dr Peter Griffith

Bio

I am a graduate of U.C.C.. Having completed my PhD in Palaeoecology at the University of Cambridge, I am currently an IRC postdoctoral fellow in Department of Archaeology. I am interested in the evolution and diversification of our species (Homo sapiens) in Africa. In particular, I am curious about how palaeoenvironmental changes in East Africa shaped Middle Stone Age (MSA) population structure, and their influence on our species’ apparently unrivalled capacity for ecological plasticity and specialisation. My research focuses on synthesising habitat reconstructions and archaeological records to help clarify the selective pressures experienced by MSA groups 

Abstract

Palaeoenvironmental records from East Africa associated with the emergence and diversification of Homo sapiens, show localised and divergent ecological responses to cyclical global palaeoclimatic changes. This is hypothesised to have created a climate-driven mosaic of regional ecological enclaves linked by semi-contiguous geographic corridors. This so called ‘refugium network’ may have been crucial in sustaining regional human populations during the late Quaternary Period, as it did for many species of plants and animals, while also encouraging dynamic demographic and behavioural responses to environmental challenges. Consequently, establishing the nature of these putative human refugia is an essential element in understanding the ecological plasticity and specialisation of early modern humans, including the differential success of African populations prior to their expansions into Eurasia. Evidence of the spatio-temporal continuity of refugia and studies of human ecology within them, particularly during the last interglacial period (MIS 5e [~130-120 thousand years ago]) in East Africa, has hitherto been lacking. This obscures the trajectories and diversity of modern human behavioural changes during the Middle Stone Age (MSA) period, including their underlying environmental and demographic context. 

This project’s priority is to publish findings from archaeological and palaeoenvironmental studies conducted in the highlands of the Kenyan Central Rift (KCR) as part of the fellow’s PhD research. Palaeoenvironmental reconstructions and geoarchaeological investigations were conducted at MSA sites with key stratified last interglacial-glacial sequences in the Nakuru Basin. 

Investigations of mobility and demographically determined aspects of stone tool technology were correlated with records of local habitat change to infer changes in landscape use, human habitat preferences, and intra-regional site connections over time. This provides a more nuanced appraisal of the ecological and social conditions driving changes in the archaeological record of the study area over time. 

Phytolith analysis was used to reconstruct past spatio-temporal vegetation changes, believed to be strong determinants of the habitats exploited by hunter-gatherers. Interpretations of vegetation changes are supported by studies of modern plant phytolith taxonomic-morphological relationships in indicator species particular to different vegetation zones of the Afromontane phytochorion. 

This project will report findings that marked changes in palaeovegetation composition and human ecological preferences occurred in the basin over time: from xeric grassland to Afromontane forest, extending our understanding of long-term vegetation dynamics in forest and savanna communities in the area back to MIS 5. Sub-regional comparisons suggest the basin remained ecologically stable compared to adjacent lowland areas. Results also dispute the long-held view that MSA groups exclusively tracked the ecotonal boundary between montane forest and savanna. Together these findings will be used to highlight far greater levels of plasticity in terms of how humans exploited these environments than had previously been recorded. Findings also lend support to the idea that the steep climatic gradients found in the basin formed a buffer to severe regional aridity, allowing the KCR to act as refuge for humans and as a pivot, linking sub-regions. 

 

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