Reconstructing the African background to human expansions in Eurasia: New research in the Shungura Formation, Ethiopia Jean-Renaud Boisserie a, d, * , Anne Delagnes b , Yonas Beyene c , Mathieu Schuster d a Pale ´obiodiversite´ et Pale ´oenvironnements, UMR CNRS 5143, USM 0203, de´partement Histoire de la Terre, Muse ´um National d’Histoire Naturelle, 8 rue Buffon CP 38, 75231 Paris Cedex 05, France b Institut de pre ´histoire et de ge´ologie du quaternaire, UMR CNRS 5199 – PACEA, universite´ Bordeaux I, avenue des Faculte ´s, 33405 Talence Cedex, France c Department of Archaeologyand Paleontology, Authority for Research and Conservation of Cultural Heritage, Ministry of Culture and Tourism, P.O. Box 13247, Addis Ababa, Ethiopia d Institut de pale´oprimatologie et pale´ontologie humaine, e´volution et pale´oenvironnements, UMR CNRS 6046 – IPHEP, Universite´ de Poitiers, 40 avenue du Recteur Pineau, 86022 Poitiers Cedex, France article info Article history: Available online 30 July 2009 1. The Omo group research expedition Studying the earliest human expansions outside Africa is a two- tailed question. As future main advances will certainly come from paleoenvironmental, biological, and cultural data found in Eurasia, a detailed understanding of the African context is a prerequisite for building any large scale scenario. In this regard, the Shungura Formation (Lower Omo Valley, south-western Ethiopia) constitutes a major source of primary and contextual data. It is located in the Arabo-African rift system (Fig. 1), in regional proximity to one of the putative pathways toward Eurasia, the Bab-el-Mandeb strait. The Shungura Formation is one of the most complete Plio-Pleis- tocene continental sequences, with ca. 800 m of interstratified volcanic tuffs and fluviatile to fluvio-lacustrine sediments, depos- ited almost continuously between 3.6 Ma and 1.0 Ma (Fig. 1; Heinzelin, 1983). Previous research by the International Omo Research Expedition (IORE), between 1967 and 1976, defined a detailed chronostratigraphic framework, with more than 25 marker levels precisely dated. The IORE unearthed numerous hominid remains among ca. 50,000 fossil vertebrates (Howell and Coppens, 1974; Coppens, 1977), as well as one of the oldest stone tool industries (Chavaillon, 1976; Merrick and Merrick, 1976). Since then, the gathered data has been used as a primary source for studying the impact of environmental changes on human evolu- tion (see, e.g., Bobe et al., 2007), initially theorized by Coppens (1975) as the (H)Omo event. Thirty years later, several aspects of the Shungura fossil and cultural record call for reconsideration. For this purpose, field research in the Shungura Formation was resumed in 2006 by the Omo Group Research Expedition (Boisserie et al., 2008). The long- term ambition is to compare the relative impacts of regional and global environmental factors (tectonics, climate) on hominid morphological adaptations, behaviour, and dispersal dynamics between 3 Ma and 1 Ma. The approach is multidisciplinary, and the team includes a dozen archeologists, geologists, paleoecologists, and paleontologists from France, Ethiopia, USA, and Chad. Field work was performed in 2006, 2007, and 2008. It involved 18–25 participants every year. Whereas most previous collections indi- cated localities at best, this field methodology allows the recording of fossil and artefact assemblages with high spatial and strati- graphic accuracy (metric to centimetric scale), as well as with detailed contextual information (taphonomy, sedimentology). The preparation and laboratory work takes place at the National Museum of Ethiopia (Addis Ababa), where all findings are curated. 2. Fieldwork goals and initial results 2.1. Geology Using the unique chronostratigraphic framework defined by the IORE (Heinzelin, 1983), the focus is on two poorly understood aspects of the Shungura geology, critical for reconstructing paleo- environmental evolution. Preliminary large scale geological obser- vations indicate that major and minor tectonic events were previously not described. Rifting in the northern Turkana Basin will be carefully studied, notably the chronological sequence and inten- sity of faulting events. Their impact on landscape evolution (notably shaping of the palaeohydrographic network) needs to be assessed. The spatiotemporal dynamics of sedimentary depositional environments and processes also need to be investigated, using * Corresponding author at. Institut de pale ´ oprimatologie et pale ´ ontologie humaine, e ´ volution et pale ´oenvironnements, UMR CNRS 6046 – IPHEP, Universite ´ de Poitiers, 40 avenue du Recteur Pineau, 86022 Poitiers Cedex, France. Tel.: þ33 549453753; fax: þ33 549454017. E-mail addresses: jean.renaud.boisserie@univ-poitiers.fr (J.-R. Boisserie), a.delagnes@ipgq.u-bordeaux1.fr (A. Delagnes), ybeyene@ethionet.et (Y. Beyene), mathieu.schuster@univ-poitiers.fr (M. Schuster). Contents lists available at ScienceDirect Quaternary International journal homepage: www.elsevier.com/locate/quaint 1040-6182/$ – see front matter Ó 2009 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2009.07.013 Quaternary International 223-224 (2010) 426–428