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Science 2 October 2009:
Vol. 326. no. 5949, pp. 71, 71e1-71e6
DOI: 10.1126/science.1175831
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Research Articles

The Pelvis and Femur of Ardipithecus ramidus: The Emergence of Upright Walking

C. Owen Lovejoy,1,* Gen Suwa,2 Linda Spurlock,3 Berhane Asfaw,4 Tim D. White5

The femur and pelvis of Ardipithecus ramidus have characters indicative of both upright bipedal walking and movement in trees. Consequently, bipedality in Ar. ramidus was more primitive than in later Australopithecus. Compared with monkeys and Early Miocene apes such as Proconsul, the ilium in Ar. ramidus is mediolaterally expanded, and its sacroiliac joint is located more posteriorly. These changes are shared with some Middle and Late Miocene apes as well as with African apes and later hominids. However, in contrast to extant apes, bipedality in Ar. ramidus was facilitated by craniocaudal shortening of the ilium and enhanced lordotic recurvature of the lower spine. Given the predominant absence of derived traits in other skeletal regions of Ar. ramidus, including the forelimb, these adaptations were probably acquired shortly after divergence from our last common ancestor with chimpanzees. They therefore bear little or no functional relationship to the highly derived suspension, vertical climbing, knuckle-walking, and facultative bipedality of extant African apes.

1 Department of Anthropology, School of Biomedical Sciences, Kent State University, Kent, OH 44242–0001, USA.
2 The University Museum, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
3 Cleveland Museum of Natural History, Cleveland, OH 44106–4930, USA.
4 Rift Valley Research Service, Post Office Box 5717, Addis Ababa, Ethiopia.
5 Human Evolution Research Center and Department of Integrative Biology, 3101 Valley Life Sciences Building, University of California at Berkeley, Berkeley, CA 94720, USA.

* To whom correspondence should be addressed. E-mail: olovejoy{at}aol.com

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Ardipithecus ramidus and the Paleobiology of Early Hominids.
T. D. White, B. Asfaw, Y. Beyene, Y. Haile-Selassie, C. O. Lovejoy, G. Suwa, and G. WoldeGabriel (2009)
Science 326, 64-64, 75-86
   Abstract »    Full Text »    PDF »
The Ardipithecus ramidus Skull and Its Implications for Hominid Origins.
G. Suwa, B. Asfaw, R. T. Kono, D. Kubo, C. O. Lovejoy, and T. D. White (2009)
Science 326, 68-68, 68e1-68e7
   Abstract »    Full Text »    PDF »
Careful Climbing in the Miocene: The Forelimbs of Ardipithecus ramidus and Humans Are Primitive.
C. O. Lovejoy, S. W. Simpson, T. D. White, B. Asfaw, and G. Suwa (2009)
Science 326, 70-70, 70e1-70e8
   Abstract »    Full Text »    PDF »
Combining Prehension and Propulsion: The Foot of Ardipithecus ramidus.
C. O. Lovejoy, B. Latimer, G. Suwa, B. Asfaw, and T. D. White (2009)
Science 326, 72-72, 72e1-72e8
   Abstract »    Full Text »    PDF »
Reexamining Human Origins in Light of Ardipithecus ramidus.
C. O. Lovejoy (2009)
Science 326, 74-74, 74e1-74e8
   Abstract »    Full Text »    PDF »


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