Impact of paleoenvironmental variability on hominin evolution as documented from a multiproxy perspective in the Turkana Basin, Kenya
Dr. Catherine C. Beck
Members of the HSPDP-WTK13 Project Team
Humans as a species are remarkable generalists but what drove this evolutionary adaptation? Through studying lake sediment cores from key intervals in hominin evolution, the Hominin Sites and Paleolakes Drilling Project (HSPDP) seeks to contribute high-resolution environmental records to test whether climate influenced the evolution of hominins in East Africa. Because of its rich combination of paleoanthropologic and geologic data, a core (WTK13) from the Turkana Basin, Kenya, is an important component of this synthesis. By combining multiple indirect measure of environment and climate (i.e. a multiproxy approach) we aim to quantify how paleoenvironment and paleoclimate changed across the time when the genus Homo was evolving. Using a combination of tephra chronology and paleomagnetic data, the WTK13 core has been dated to 1.87-1.37 Ma. The sedimentology records deposition on a dynamic lacustrine margin becoming more influenced by channel and floodplain processes through time. Multiproxy records provide a window into paleoevironments of the Turkana Basin that operated on shorter time scales than this dominant first-order facies shift. Organic biomarkers, phytoliths, and pollen records track processional cycles (~21 kyr). However, interestingly, the biomarker record suggests that the hydroclimate of the Turkana Basin, while highly variable at the Milankovitch-scale, exhibits no directional trend in the mean values towards wetter or drier conditions. The combined phytolith and pollen records suggest that grasses, albeit with fluctuating abundances of C4 mesophytic and C4 xerophytic taxa, dominated the landscape throughout most of the core. This indicates that despite climatic variability, resource availability may have maintained some general consistency for hominins in the area. Ultimately, the time period spanned by the WTK13 record is significant for our understanding of hominin evolution as it covers an interval of increasing aridity on the African continent as observed in distal marine records. This synthesis demonstrates how paleoenvironment of the Turkana Basin responded to these broader paleoclimatic trends.
Bio:
Catherine Beck’s research focuses on how sediments from the East African Rift Valley preserve changes in paleoclimate and paleoenvironment over Quaternary time-scales. This work is strongly based in field research, and she is particularly interested in coupling the study of lake sediments with paleoecology and stable isotope analyses in an effort to better constrain the conditions in which early hominins evolved. Beck received her bachelor's in geology and archaeology from Tufts University and her master's and doctorate in geosciences from Rutgers University. She has been at Hamilton College since 2015 and when not working, she can be found running over the hills of Central NY.