The genesis, evolution and fate of Homo erectus have been explored palaeontologically since the taxon's recognition in the late nineteenth century. Current debate1 is focused on whether early representatives from Kenya and Georgia should be classified as a separate ancestral species ('H. ergaster')2, 3, 4, and whether H. erectus was an exclusively Asian species lineage that went extinct5, 6. Lack of resolution of these issues has obscured the place of H. erectus in human evolution. A hominid calvaria and postcranial remains recently recovered from the Dakanihylo Member of the Bouri Formation, Middle Awash, Ethiopia, bear directly on these issues. These 1.0-million-year (Myr)-old Pleistocene sediments contain abundant early Acheulean stone tools and a diverse vertebrate fauna that indicates a predominantly savannah environment. Here we report that the 'Daka' calvaria's metric and morphological attributes centre it firmly within H. erectus. Daka's resemblance to Asian counterparts indicates that the early African and Eurasian fossil hominids represent demes of a widespread palaeospecies. Daka's anatomical intermediacy between earlier and later African fossils provides evidence of evolutionary change. Its temporal and geographic position indicates that African H. erectus was the ancestor of Homo sapiens. The Early Pleistocene Dakanihylo ('Daka') Member comprises 22 to 45 m of sediments unconformably atop the Pliocene Hatayae Member of the Bouri Formation7 (Fig. 1). These deposits contain abundant archaeological and palaeontological remains embedded in primarily alluvial deposits relating to lakeside beaches or shallow water deposits in distributary channels8. Initial interpretations identified Daka sediments as postdating hominid remains and Acheulean artefacts from Bodo9. However, the Daka artefacts clearly antedate those at Bodo, and single-crystal 40Ar/39Ar dating of a pumiceous unit at the base of the Member gave an age of 1.042 0.009 Myr (ref. 8). The entire Dakanihylo Member is of reverse magnetic polarity, so the minimum age of its palaeoanthropological contents is 0.8 Myr.