COG3 Seminar - Kevin Uno (Columbia/Lamont)
Molecules in mud: Reconstructing Neogene Hominid Environments from Molecular Biomarkers in Terrestrial and Marine Sediments
Kevin T. Uno
Lamont-Doherty Earth Observatory of Columbia University
Today, humans rely on grasses like corn, wheat, and rice as a primary food source and for feeding livestock. Our dependence on grasses as a food source has deep roots in our evolutionary history: we evolved in concert with grassland ecosystems in Africa over the past 7 million years. Despite the well-documented association between human evolution and grasslands, little is known about the origin of grasses in Africa, especially before 10 million years ago. When and how did grasses rise to ecological dominance?
In this talk, I will present carbon isotopic evidence that shows C4 grasslands began to spread across Africa in the late Miocene, which resulted in major dietary changes in large mammals. Prior to appearance of C4 grasses at ~10 Ma, isotopic methods for differentiating grasses and woody vegetation are not useful because both plant functional types utilized the C3 pathway. To address this challenge, new methods are needed to explore the history of grassland evolution in Africa, which stretches back through the Neogene, beginning ~23 Ma, and perhaps earlier.
I will describe emerging techniques for reconstructing past ecosystems, including vegetation and fire—the latter of which plays a key role in maintaining modern grasslands—using non-isotopic methods. These methods rely on molecular biomarkers, which when combined with existing isotopic methods, will enable me to reconstruct the rise of grasslands in Africa from the Neogene to present and explore the relationships between climate, ecosystem, and evolutionary change.
About this Series
The Chemical Oceanography, Geology, Geochemistry, and Geobiology Seminar [COG3] is a student-run seminar series. Topics include chemical oceanography, geology, geochemistry, and geobiology. The seminars take place on Fridays from 11am to 12pm or 10am to 11am EST.