Date of Award

Fall 2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Anthropology

First Advisor

Sargis, Eric

Abstract

The advent of tool-making has long been associated with expanding grasslands in Africa. My dissertation reconstructs paleoenvironments at Gona, in the Afar region of Ethiopia, between ~3–1 Ma (1) to make inferences about how hominins were utilizing the paleo-landscape and interacting with mammalian communities and (2) to investigate whether the environment was influential in the development of stone tools. This time period spans the origin of our genus Homo and the evolution of Homo erectus, and it provides evidence of increased behavioral complexity (stone tools), brain expansion, and the acquisition of large nutrient-rich food sources (animal carcasses). Because of the scarcity of fossil and artifact-bearing deposits, little is known about the paleoenvironment during this time. There is an opportunity to address this at Gona, with its long record of Early Stone Age (ESA) archaeology, including among the earliest stone tools (Oldowan), evidence of carcass processing at ~2.6 Ma, and early Acheulean assemblages at 1.7 Ma. The emergence of the Acheulean is noteworthy for the standardized and purposeful technique which required a preconception of form (Semaw et al., 2009). Mammalian fossils throughout this sequence that are relatively understudied have the potential to help interpret the context in which these anatomical and behavioral changes occurred, specifically between ~3–1 Ma.I collected bovid tribal abundance, ecomorphological, and stable isotope data to reconstruct habitats throughout four intervals and analyzed them temporally and spatially in association with stone tools. As part of the Gona Research Project, my study complements and contributes to ongoing taphonomic, lithic, and geologic studies to provide a significant contribution to better understand the origin and evolution of stone tool technology. Tool use is a key innovation linked to behavioral and cognitive advances that led to the evolution of our species. The first chapter introduces the central concepts and explains the dissertation format. Chapter 2 provides the geological, paleontological, and archaeological context for the fossil and archaeological localities included in this dissertation. I discuss the research design used in this dissertation and place these localities into four temporally constrained study intervals or units that range from 2.96 to 0.81 Ma, spanning the emergence of Acheulean technology at Gona. Chapter 3 reports new stable carbon and oxygen isotope enamel values from large herbivores. I reconstruct faunal diets through analyses of ?13Cenamel from fossil assemblages of paleontological and archaeological contexts and then compare them to a large dataset of published stable carbon isotopes from enamel and pedogenic carbonates from eastern Africa to place my observations at Gona in a regional framework. Using community assemblage data and the proportion of grazers (as indicated by taxa with high ?13Cenamel values), I find that the habitats at Gona had more C4 grassy resources between ~3-1 Ma than all other contemporaneous fossil and archaeological localities in eastern Africa. Statistically significant increases in carbon values in the Lower Acheulean study interval provide further evidence for increased exploitation of grassy habitats. Alcelaphini bovids in particular are significantly enriched in ?13Cenamel values in archaeological contexts compared to paleontological contexts during the Lower Acheulean study interval. Alcelaphini from archaeological contexts in the Lower Acheulean study interval are also significantly enriched in ?13Cenamel values compared to Alcelaphini from archaeological contexts in the Oldowan study interval. Chapter 4 presents the results of my bovid ecomorphological analyses of multiple elements and bovid tribal abundances. I find more open ecomorphs and Alcelaphini bovids in archaeological compared to paleontological contexts suggesting an increased reliance on open environments during the Lower Acheulean study interval. These data demonstrate an increase in open settings at the emergence of the Acheulean and a long-term increase in edaphic grasslands at Gona, with a marked increase at ~1.26 Ma. Chapter 5 summarizes the conclusions of this study and the implications for hominin behavior. These new data from Gona fill a significant gap in the eastern African Plio-Pleistocene paleoenvironmental record. I provide a nearly continuous sequence of paleoenvironmental and behavioral land use patterns by early Homo during the Early Stone Age. Overall, this study supports the hypothesis that the Acheulean technology was an adaptation to increased grasslands in eastern Africa.

Download

Share

COinS