Seasons of Change: Investigating the Role of Seasonality in the Oldowan-Acheulean Transition

The nature of the relationship between climate change and hominin biological and cultural change is critical to understanding the processes of evolution within the Homo lineage. The relationship between the climatic and palaeoanthropological records has been the focus of intensive research; however, the different scales at which both climate and evolutionary change operate has meant that identifying the mechanisms involved is particularly challenging. The climatic record as inferred from lacustrine, marine, and terrestrial cores explores change over the coarse resolution of geological time, whereas individual fossils and artefacts reflect episodes of behaviour at the scale of a lifetime or shorter. As a result, we cannot be sure how broad patterns of climate change are imposing changes in the selective conditions that shape hominin morphology and behaviour. This dissertation aims to provide a preliminary exploration of how this gap might be bridged by using seasonality and inter-annual variability as lenses through which to explore a critical period in the archaeological record: the Oldowan-Acheulean transition. The thesis, entitled “Seasons of Change: Investigating the Role of Seasonality in the Oldowan-Acheulean Transition”, aims to show that a substantial component of the structure of the archaeological record can be plausibly explained by differences in the season of tool use. According to a model in which early lithic technologies are only used in processing activities, we would expect greater investment in lithic reduction during wetter parts of the year, when (plant) resource patches are more dispersed across the landscape but predictably accessible within the year, and when modern hunter-gatherers display the greatest frequency of movement between these patches. In this context, I also explore the hypothesis that Early Acheulean bifaces evolved to function as specialised core forms associated with wet season foraging activities, and that they were less important in dry season foraging (especially butchery contexts). The dissertation first explores the nature of lithic variability in the archaeological record (Chapter 1), before constructing a behavioural ecological framework for the role of seasonality in this process (Chapter 2). It then turns to the climatic record around the Oldowan-Acheulean transition, and how this might have been experienced by hominins within their lifetimes. Chapter 3 examines existing research on biface function, pointing out the gap in our understanding of their use in the Early Acheulean, and especially the utility of flakes released in their manufacture. In Chapter 4, I present an experimental methodology for comparing the efficiency of material use in flake manufacture between bifaces and Oldowan core forms, and present the comparative morphology of the flakes obtained in the experimental study in Chapter 5. These data suggest that reduction of large flake blanks—which predominate in the Early Acheulean—allows for the production of increased small flake cutting edge relative to core size. This is especially true of handaxe manufacture. In Chapter 6, I show that these patterns are identifiable in the Early Acheulean record of Koobi Fora, as part of longer-term (but non-linear) trends towards the increasing efficiency of flake production. Chapters 7 and 8 provide quantitative assessments of the technological structure of the Oldowan and Early Acheulean records from published data, alongside preliminary explorations of seasonality at individual sites according to their palaeoecological and taphonomic signatures. It is argued that investment is indeed greater in wet season contexts within the Oldowan (a case that also seems to encompass transitional sites), and that bifaces are rare in likely dry season contexts within the Early Acheulean. The implications of the study for our understanding of early hominin behaviour are discussed in Chapter 9. While more data are needed for each period, the results broadly support the hypothesis that bifaces functioned as effective cores in the face of increased structured mobility during the wet season, and highlight the additional insights that can be derived from balancing the scales of analysis in the palaeoanthropological record.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2024

Author dc:creator

• Clark, James

Advisor dc:contributor.advisor

• Mirazón Lahr, Marta

• Early Stone Age
• Oldowan
• Acheulean
• Seasonality
• Experimental Archaeology
• Technological Variability

Licence

• https://www.repository.cam.ac.uk/bitstreams/4c9f59e7-81b9-429d-9d7d-610281f80275/download
• https://creativecommons.org/licenses/by-nc/4.0/

Language dc:language

eng

Author Identifier

0000-0001-7338-7144

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/390778