title: Phytolith-Based Paleoecology and Hominin Landscapes at Oldupai Gorge 2–1.4 Ma
Creators: name: Mwambwiga, Aloyce
Publisher: name: Graduate Studies
Year: 2025
Subjects: subject: Paleoecology
subject: phytolith
subject: Oldowan
subject: Acheulean
subject: paleoenvironment
subject: Archaeology

description: As an interdisciplinary science, archaeology uses knowledge from many sciences, such as chemistry, biology, biochemistry, earth sciences, materials science and many others. Phytoliths are silicon oxide particles produced within and between plant tissues and released into the soil or sediments when the plant dies. Three main questions guide this thesis: 1) How can phytolith analysis characterize paleo-habitats from off-site localities at Oldupai Gorge Bed I-II? 2) Can phytoliths reveal eco-signals that define the Oldowan-Acheulean landscape 2-1.4 million years ago? 3) Was this landscape uneven or homogeneous? Phytoliths are particularly valuable because they will likely survive when other forms of palaeobotanical evidence are lost. To understand human behavioural changes such as the Oldowan-Acheulean transition, we must know the past environments and plant communities from the phytolith data. This research used sediments collected from off-site localities (from non-archaeological digs). The selection of sampling sites was based on proximity to the known geological and archaeological deposits in the Oldupai Basin. A systematic sampling strategy was used, and samples were taken at 20-cm intervals. The phytolith extraction followed the method of Mercader et al. (2018), and the microscopic analysis was done through fresh mounting for 3D classification. Quantitative analysis was done using IBM® SPSS®, while Principal Component Analysis (PCA) used PAleontological STatistics (PAST) software. The focus was on examining the differences and similarities between the two zones (Eastern and Western) from Beds I and II (2–1.4 Ma) across the Oldupai Gorge palaeobasin. In addition, this research emphasizes the importance of phytoliths in the determination of distinct ecological signals that act as a beacon for behavioural transitions. The phytoliths investigated in this study were derived from sediment samples obtained from four localities through the eastern to western sections of the Gorge: Emurutoto (Loc. 7), Engaji Nanyori (Loc. 14), Olaiphtara (Loc. 80), and Emborr Nado (Loc. 61). While many stratigraphic units are characterized by a mixed environment (woodland and grassland environment), the individual stratigraphic assessments from both sides of the Gorge indicate that woody vegetation phytoliths are more frequent than those of grasslands. The climatic and environmental conditions in the past can be determined with the help of phytolith indicators from the woodland and grassland environments found at Oldupai Gorge. The presence of grassland, indicative of phytoliths, points to arid or seasonally dry climates with open savannas. On the other hand, Woodland-indicative phytoliths imply humid climates with dense vegetation. The variations in their proportions are a mirror image of paleoclimatic fluctuations that affected hominin habitats and resources. This analysis helps reconstruct the ecological contexts of early human ancestors. The results suggest that vegetation cover varied within similar zones of the Gorge. The variations could be due to differences in phytolith preservation, post-depositional processes, and dissolution effects. However, the results from this research are consistent with earlier research indicating that during the Oldowan era, Oldupai Gorge Bed I and Lower Bed II had a woodland setting while the Acheulean layers, above Bed II Tuff IID, mostly featured open grasslands.