The possibility that human evolution in Africa has been strongly influenced by Earth's climatic and environmental history over the last several million years has been an important question at the forefront of paleoanthropological research. One fundamental question is: can any of the potential envionmental drivers of evolutionary change be reconstructed with enough precision to allow us to relate them with confidence to the episodes of speciation, extinction and cultural evolution known to anthropologists, and thereby test their relationships in time and space?
This team of paleoanthropologists and earth scientists plans to analyze climate and other environmental histories to provide direct tests of key hypotheses linking environmental history and mammal (including early human) evolution by collecting and analyzing detailed paleoenvironmental data at three key anthropological sites in Africa. They will collect continuous paleoenvironmental records by drilling long sediment cores from ancient lake beds in the northern Afar, Ethiopia (~3.8-2.9 million years ago-Ma), the Baringo Basin, Kenya (~3.2-2.35 Ma), and the Turkana Basin, Kenya (~2.3-1.42 Ma), and relate these records to the outcrops in the same basins that contain early human and other mammal fossils, as well as stone tools in the younger time periods. As a group these basins contain some of the most critical evidence for human evolutionary history in Africa. Although past investigators have reconstructed climate and other environmental histories from the outcrops in which the fossil humans and artifacts have been found, such environmental records are highly discontinuous due to the nature of the sediments where the fossils occur, and are unsuitable for many of the most informative geochemical records available today because of the weathering that has affected outcropping sediments. Drilling lakebeds near the fossil sites gets around these problems, because lake sediments accumulate much more continuously, and because drilling into the subsurface allows unweathered samples to be collected Funding for the drilling costs for this project has been secured from other sources: with the IPG funds the team will analyze the cores to generate quantitative and high resolution records of changes in temperature, precipitation, vegetation, fire and volcanic activity and other factors which may have influenced human evolution.
The primary research goal is to obtain long cores from these basins, each of which span critical intervals in human evolution and are close to hominin fossil and archaeological sites. The researchers will apply state-of-the-art paleoenvironmental and paleoclimate methods to these cores to assemble high resolution records covering much of the past four million years of East African environmental history. The team will then evaluate existing hypotheses and generate new hypotheses linking climate history to early human physical and cultural evolutionary adaptations. The paleoenvironmental and paleoecological data collected from the drill cores will be linked directly in time and space to the nearby fossil human, mammal and stone tool records by way of the numerous volcanic ashes present in both the cores and outcrops, along with other dating techniques. By comparing the new records to similar records from nearby ocean sediment cores the researchers plan be able to distinguish local from global drivers of environmental change and in the process test a series of hypotheses linking key events in human evolution with climate and other aspects of environmental history. Finally, the team will use these new, combined paleoenvironmental and paleoanthropological data sets, combined with novel modeling techniques to better understand how landscape and climate change across various scales of time and space may have affected the availability and predictability of critical ecosystem resources upon which early humans would have depended.
This project will greatly expand our understanding of African climate history and will be an opportunity to invigorate interest in human evolution and its relationship to climate with the US and African public. The project will train many American and African students during its field, analytical and internship/synthesis phases, and will generate numerous informal science learning opportunities through our collaborations with the National Museums of Kenya and Ethiopia and the Smithsonian Institution.
