The Hominin sites and Palaeolakes Drilling Project: testing hypotheses of climate-driven human evolution and dispersal at Chew Bahir, Ethiopia

Abstract

There are numerous hypotheses linking climatic trends, events and variability to human origins, evolution and dispersal. Long palaeoenvironmental records from continental sites that may allow tests of these hypotheses are only now becoming available, but most are distant from fossil human sites. The Hominin Sites and Palaeolakes Drilling Project (HSPDP) aims to obtain long continuous sediment cores spanning critical intervals of evolutionary history from lacustrine sites close to globally significant hominin sites in East Africa. Together, the five sites – Northern Awash and Chew Bahir, Ethiopia; West Turkana, Baringo Basin and Lake Magadi, Kenya – will provide multi-proxy records spanning the last 4 million years. This will allow us to correlate and compare environmental changes to the more fragmentary record of evolution, dispersal, extinction and cultural innovation. The project team will evaluate models of climatic and tectonic forcing of environmental processes and landscape resources. We will test hypotheses linking climate variability to physical and cultural evolution. The project is supported by the International Continental Drilling Program (ICDP), NSF (USA), DFG (Germany) and by NERC (UK). Drilling began in June 2013 in Kenya. NERC funded research focuses on the Chew Bahir site in Ethiopia, where a survey of basin sediments using 2D electrical resistivity tomography was completed in October 2013 and drilling of a 400m core is scheduled for November 2014. A team of UK Quaternary scientists will work with German and Ethiopian colleagues to produce a multi-proxy record which is anticipated will cover the last c. 500,000 years. Detailed analysis will focus on identifying the nature of climate variability during the penultimate glacial-interglacial transition (Termination II: c. 125–135 ka), once an outline chronology has been established. Key proxies are: high-resolution geochemistry; isotopes (δ13C, δ18Ocarb, δ18Odiatom, δ18Oostracod); biomarkers (including GDGTs and compound specific leaf wax δ13C and δD); pollen; diatoms; ostracods and magnetic properties. The chronological framework will be constructed using radiocarbon, Post-IR IR stimulated luminescence and 40Ar-–39Ar dating along with tephrochronology, which will be used to correlate between sites where possible. The record of climatic and ecological change, from Chew Bahir, along with previous data from Lake Tana, will be used as model input to test the hypothesis that periods of high climatic variability correlate with key biological and cultural transitions.