Bones, Stones, Genes and Mud: testing hypotheses of climate change and human origins Seminar

Event details

Climatic change is widely acknowledged to have played a role in the emergence of modern humans in Africa and their subsequent dispersal into Asia. Fossil and genetic data are broadly in agreement about the time of their first appearance ~200,000 years ago, but the timing of subsequent human expansion beyond Africa is contentious. Dispersal from Africa is often linked to climate change at ~60,000 years ago, despite increasing evidence for earlier presence of modern humans in Asia. Similarly, there is a range of views on the possible mechanisms linking climate change to human evolution and dispersal. In this talk I describe some of our current work towards resolving these issues using lacustrine sedimentary records from Ethiopia. Lake Tana, in the north Ethiopian highlands, close to the early H. sapiens sites of the Middle Awash and to postulated dispersal routes, shows a deep seismic and near-continuous lake-sediment record of climatic change for the last 150,000 years The record of geochemical proxies shows variable climate at the end of the penultimate glacial, followed by stable moist climate during the last interglacial, conditions that would favour population growth and range expansion, supporting recent models and growing evidence for early dispersal of modern humans from Africa. As part of the Hominin Sites and Paleolakes Drilling Project, we recovered 280 m cores from the Chew Bahir basin, in the rift valley of south Ethiopia, close to the site of the earliest known Homo sapiens fossils. The cores extend to at least 300,000 years, providing a potential record of environmental history spanning the origin of H. sapiens.