The oldest direct evidence of stone tool manufacture comes from Gona (Ethiopia) and dates to between 2.6 and 2.5 million years (Myr) ago1. At the nearby Bouri site several cut-marked bones also show stone tool use approximately 2.5 Myr ago2. Here we report stone-tool-inflicted marks on bones found during recent survey work in Dikika, Ethiopia, a research area close to Gona and Bouri. On the basis of low-power microscopic and environmental scanning electron microscope observations, these bones show unambiguous stone-tool cut marks for flesh removal and percussion marks for marrow access. The bones derive from the Sidi Hakoma Member of the Hadar Formation. Established 40Ar–39Ar dates on the tuffs that bracket this member constrain the finds to between 3.42 and 3.24 Myr ago, and stratigraphic scaling between these units and other geological evidence indicate that they are older than 3.39 Myr ago. Our discovery extends by approximately 800,000 years the antiquity of stone tools and of stone-tool-assisted consumption of ungulates by hominins; furthermore, this behaviour can now be attributed to Australopithecus afarensis.
We thank the Authority for Research and Conservation of Cultural Heritage, the National Museum of Ethiopia, the Ministry of Tourism and Culture and the Afar regional government for permits and support; C. Mesfin, Z. Bedaso, T. Gebreselassie, Mesfin Mekonnen, H. Defar, A. Zerihun, G. Senbeto, Mogues Mekonnen, W. Aberra, T. Yifru and the people of the Dikika area for field assistance. We also thank the administration of Adaytu town and members of the Ethiopian armed forces. Funds for the 2009 field season were provided by the California Academy of Sciences. Travel expenses for D.G., S.P.M., D.R. and J.G.W. were covered by their respective institutions. C.W.M. and H.A.B. acknowledge the assistance of the research professionals in the John M. Cowley Center for High Resolution Electron Microscopy, LE-CSSS, ASU in conducting the ESEM imaging, and J. Thompson and S. Lansing for participating in the blind test. Z.A. thanks P. Mollard and K. Berge for assistance during fieldwork preparations.
This file contains Supplementary Information comprising: 1 Survey Methodology; 2 Faunal list; 3 Stratigraphic and palaeoenvironmental context; 4 Surface modifications on the fossil specimens; Supplementary Figures 1- 23 with legends; Supplementary Tables 1- 3 and References.