The Plio-Pleistocene Climate History of East Africa and the Role of Environmental Change on Human Evolution: Studies of Leaf Wax Isotopes from Paleolake Sediment

Lupien, Rachel

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Year:: 2019
Contributor:: Lupien, Rachel (creator); Russell, James (Advisor); Herbert, Timothy (Reader); Clemens, Steven (Reader); Dalton, Colleen (Reader); Potts, Richard (Reader); Brown University. Department of Earth, Environmental, and Planetary Sciences (sponsor)
Genre:: theses
Subject:: Paleoclimatology; Limnology; Human evolution; Biochemical markers; Lakes; Isotopes; Africa, East; Sedimentology; Hydroclimate
Extent:: xxvi, 153 p.
DOI: https://doi.org/10.26300/h7yg-fe45

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Abstract:: Early humans, or hominins, relied on their East African environment for food, resources, and habitation, but the nature of the relationship between hominins and climate has been debated for almost a century, and testing various hypotheses on this relationship has proven difficult. My dissertation work investigates the environmental and climatic history of East Africa over the course of the late Pliocene and Pleistocene, 3.3 Ma to present. To characterize vegetation and hydroclimate variability over timescales from millions of years to millennia and test human evolutionary hypotheses, we need terrestrial archives that allow us to quantify both paleoclimate trends and variations that can be clearly compared to the human fossil record. To compare these records through space and time, we require a proxy of environmental change that does not rely on local geological conditions. I use carbon isotopic composition of leaf wax compounds (δ13Cwax) preserved in paleolake sediment, which is determined by the type of plant that produced them, and hydrogen isotopes from the same leaf wax biomarkers (δDwax), which record large-scale water vapor transport histories. Chapter 1 explores the vegetation history of the Baringo Basin, a locale famous for large Pliocene diatomite sequences that coincide with a dramatic hominin turnover event. Chapter 2 focuses on early Pleistocene orbital-scale hydroclimate variations in the Turkana Basin, Kenya. The high-amplitude variability packet discovered in Chapter 2 lead to more questions about the timescale of East African paleoclimate changes and their potential importance to human evolution. Chapter 3 zooms in on two intervals, one from the interval of high-amplitude climate variability and one from a low-amplitude interval, to investigate sub-orbital climate variability and abrupt change, and its potential effects on early humans. Chapter 4 investigates the long-term climate evolution of the late-Plio-Pleistocene by compiling δDwax datasets from four drill cores that provide snapshots into East African rainfall over the last 3.3 Ma. The findings in this dissertation will make a substantial impact on the fields of paleoclimatology and paleoanthropology.
Notes:: Thesis (Ph. D.)--Brown University, 2019

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Rights: In Copyright
Restrictions on Use: Collection is open for research.

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Lupien, Rachel, "The Plio-Pleistocene Climate History of East Africa and the Role of Environmental Change on Human Evolution: Studies of Leaf Wax Isotopes from Paleolake Sediment" (2019). Earth, Environmental and Planetary Sciences Theses and Dissertations. Brown Digital Repository. Brown University Library. https://doi.org/10.26300/h7yg-fe45

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Earth, Environmental and Planetary Sciences Theses and Dissertations

Theses and Dissertations for the Earth, Environmental and Planetary Sciences department.
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