Letters to Nature

Nature 412, 178-181 (12 July 2001) | doi:10.1038/35084063; Received 19 February 2001; Accepted 15 May 2001

Late Miocene hominids from the Middle Awash, Ethiopia

Yohannes Haile-Selassie

  1. Department of Integrative Biology and Laboratory for Human Evolutionary Studies, Museum of Vertebrate Zoology, 3060 VLSB, University of California, Berkeley, California 94720, USA

Correspondence to: Yohannes Haile-Selassie Correspondence and requests for materials should be addressed to Y.H.-S. (e-mail: Email: ethio@uclink4.berkeley.edu).

Molecular studies suggest that the lineages leading to humans and chimpanzees diverged approximately 6.5–5.5 million years (Myr) ago, in the Late Miocene1, 2, 3. Hominid fossils from this interval, however, are fragmentary and of uncertain phylogenetic status, age, or both4, 5, 6. Here I report new hominid specimens from the Middle Awash area of Ethiopia that date to 5.2–5.8 Myr and are associated with a wooded palaeoenvironment7. These Late Miocene fossils are assigned to the hominid genus Ardipithecus and represent the earliest definitive evidence of the hominid clade. Derived dental characters are shared exclusively with all younger hominids. This indicates that the fossils probably represent a hominid taxon that postdated the divergence of lineages leading to modern chimpanzees and humans. However, the persistence of primitive dental and postcranial characters in these new fossils indicates that Ardipithecus was phylogenetically close to the common ancestor of chimpanzees and humans. These new findings raise additional questions about the claimed hominid status of Orrorin tugenensis 8, recently described from Kenya and dated to approx6 Myr9.