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Abstract

The origin of Australopithecus, the genus widely interpreted as ancestral to Homo, is a central problem in human evolutionary studies. Australopithecus species differ markedly from extant African apes and candidate ancestral hominids such as Ardipithecus, Orrorin and Sahelanthropus. The earliest described Australopithecus species is Au. anamensis, the probable chronospecies ancestor of Au. afarensis. Here we describe newly discovered fossils from the Middle Awash study area that extend the known Au. anamensis range into northeastern Ethiopia. The new fossils are from chronometrically controlled stratigraphic sequences and date to about 4.1–4.2 million years ago. They include diagnostic craniodental remains, the largest hominid canine yet recovered, and the earliest Australopithecus femur. These new fossils are sampled from a woodland context. Temporal and anatomical intermediacy between Ar. ramidus and Au. afarensis suggest a relatively rapid shift from Ardipithecus to Australopithecus in this region of Africa, involving either replacement or accelerated phyletic evolution.

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Acknowledgements

We thank the National Science Foundation (including the Revealing Hominid Origins Initiative/HOMINID program), the Institute of Geophysics and Planetary Physics of the University of California at Los Alamos National Laboratory (LANL), the Japan Society for the Promotion of Science, the Fondation Singer-Polignac, and the Philip and Elaina Hampton Fund for Faculty International Initiatives at Miami University for financial support of field and laboratory research. The Earth and Environmental Sciences Division Electron Microprobe laboratory at LANL assisted with access and use. We thank A. Ademassu, W. Amerga, A. Amzaye, A. Asfaw, G. Assefa, F. Bibi, M. Black, D. Brill, K. Brudvik, M. Chalachew, M. Chubachi, W. Demisse (in memoriam), N. Eldredge, H. Elema, E. Güleç, M. Haydera, R. Jabbour, A.-R. Jaouni, K. Kairento, F. Kaya, K. Kimeu, B. Kyongo, D. Kubo, W. Liu, S. Mahieu, W. Mangao, M. McCollum, E. Mekonnen, W. Mihel, L. Morgan, C. Pehlevan, P. Reno, G. Richards, B. Rosenman, M. Serrat, A. Shabel, L. Smeenk, B. Tegengne, A. Terrazas and S. Yoseph for fieldwork, laboratory work and discussion, and M. Leakey for collections access. We thank the Ministry of Youth, Sports and Culture, the Authority for Research and Conservation of the Cultural Heritage, and the National Museum of Ethiopia for permissions and facilitation. We also thank the Afar Regional Government, the Afar people of the Middle Awash, and many others for contributing directly to the research efforts.

Author information

Affiliations

  1. Human Evolution Research Center, Museum of Vertebrate Zoology, 3101 Valley Life Sciences Building, and

    • Tim D. White
    • , Jean-Renaud Boisserie
    • , Henry Gilbert
    •  & F. Clark Howell
  2. Department of Integrative Biology, University of California at Berkeley, Berkeley, California 94720, USA

    • Tim D. White
    • , Jean-Renaud Boisserie
    •  & Leslea J. Hlusko
  3. Hydrology, Geochemistry and Geology Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

    • Giday WoldeGabriel
  4. Rift Valley Research Service, P.O. Box 5717, Addis Ababa, Ethiopia

    • Berhane Asfaw
  5. Department of Anthropology, University of Illinois, Urbana, Illinois 61801, USA

    • Stan Ambrose
  6. Department of Anthropology and Archaeology, Authority for Research and Conservation of the Cultural Heritage, Ministry of Youth, Sports and Culture, P.O. Box 6686, Addis Ababa, Ethiopia

    • Yonas Beyene
  7. College of Medicine, Department of Anatomy, Laboratory of Evolutionary Biology, Howard University, Washington DC 20059, USA

    • Raymond L. Bernor
  8. Département Histoire de la Terre, USM 0203, UMR 5143 CNRS, Unité Paléobiodiversité et Paléoenvironnement, Muséum National d'Histoire Naturelle, Paris 75005, and Laboratoire de Géobiologie, Biochronologie et Paléontologie Humaine, UMR 6046, Université de Poitiers, 86022 Poitiers Cedex, France

    • Jean-Renaud Boisserie
  9. Department of Geology, Miami University, Oxford, Ohio 45056, USA

    • Brian Currie
    •  & William K. Hart
  10. Department of Physical Anthropology, Cleveland Museum of Natural History, 1 Wade Oval Drive, Cleveland, Ohio 44106, USA

    • Yohannes Haile-Selassie
  11. Department of Anthropology, National Science Museum, Hyakunincho, Shinjuku-ku, Tokyo 169-0073, Japan

    • Reiko T. Kono
  12. Palaeontology Section, Transvaal Museum, P.O. Box 413, Pretoria, South Africa

    • Thomas Lehmann
  13. Laboratoire Paléoenvironnements et Paléobiosphère, UMR 5125, Université Claude Bernard, Lyon 1, 69622 Villeurbanne Cedex, France

    • Antoine Louchart
  14. Department of Anthropology and Division of Biomedical Sciences, Kent State University, Kent, Ohio 44242, USA

    • C. Owen Lovejoy
  15. Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, and Department of Earth and Planetary Science, University of California at Berkeley, Berkeley, California 94720, USA

    • Paul R. Renne
  16. Institute of Natural and Environmental Sciences, University of Hyogo, Yayoigaoka, Sanda 669-1546, Japan

    • Haruo Saegusa
  17. Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06520, USA

    • Elisabeth S. Vrba
  18. Natural History Museum, Sierra College, Rocklin, California 95677, USA

    • Hank Wesselman
  19. The University Museum, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

    • Gen Suwa

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Competing interests

Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

Corresponding author

Correspondence to Tim D. White.

Supplementary information

PDF files

  1. 1.

    Supplementary Discussion 1

    Dental metric comparisons.

  2. 2.

    Supplementary Discussion 2

    Enamel thickness measurements.

  3. 3.

    Supplementary Discussion 3

    Cladistic relationships.

  4. 4.

    Supplementary Figure 1

    ASI paleosol carbonates.

  5. 5.

    Supplementary Figure 2

    Comparative dental morphology.

  6. 6.

    Supplementary Figure 3

    Argon-argon results.

  7. 7.

    Supplementary Table 1

    Hominid fossils.

  8. 8.

    Supplementary Table 2

    Isotopic composition of paleosol carbonates.

  9. 9.

    Supplementary Table 3

    Faunal list.

  10. 10.

    Supplementary Table 4

    Radioisotopic dating results.

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https://doi.org/10.1038/nature04629

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