ScienceDaily (June 21, 2010) — Meet "Lucy's" Great-Grandfather. Cleveland Museum of Natural History Curator and Head of Physical Anthropology Dr. Yohnannes Haile-Selassie led an international team that discovered and analyzed a 3.6 million-year-old partial skeleton found in Ethiopia. The early hominid is 400,000 years older than the famous "Lucy" skeleton and is significantly larger in size. Research on the new specimen reveals that advanced human-like, upright walking occurred much earlier in the evolutionary timeline than previously thought.
Anatomically arranged elements of partial skeleton KSD-VP-1/1. The male Australopithecus afarensis specimen found in Ethiopia was nicknamed "Kadanuumuu."
(Credit: Yohannes Haile-Selassie, Liz Russell, Cleveland Museum of Natural History. Used with permission from the Proceedings of the National Academy of Sciences.)
The partial skeleton belongs to "Lucy's" species, Australopithecus afarensis. It was found in the Woranso-Mille area of Ethiopia's Afar region by a team led by Haile-Selassie that excavated of the skeleton over five years following the discovery in 2005 of the lower arm bone. The team recovered the most complete clavicle and one of the most complete shoulder blades ever found in the human fossil record. A significant portion of the rib cage was also found.
The specimen was nicknamed "Kadanuumuu" (kah-dah-nuu-muu) by the authors. This means "big man" in the Afar language and reflects its large size. The male hominid stood between 5 to 5 ½ feet tall, while "Lucy" stood only 3 ½ feet tall.
"This individual was fully bipedal and had the ability to walk almost like modern humans," said Haile-Selassie. "As a result of this discovery, we can now confidently say that 'Lucy' and her relatives were almost as proficient walking on two legs as we are, and that the elongation of our legs came earlier in our evolution that previously thought."
He explained, "All of our understanding of Australopithecus afarenis' locomotion was dependent on 'Lucy.' Because she was an exceptionally small female with absolutely short legs, this gave some researchers the impression that she was not fully adapted to upright walking. This new skeleton falsifies that impression because if 'Lucy's' frame had been as large as this specimen, her legs would also have been proportionally longer."
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Yohannes Haile-Selassie a,b,c,1, Bruce M. Latimer a,b,c, Mulugeta Alene d, Alan L. Deino e, Luis Gibert e,
Stephanie M. Melillo f, Beverly Z. Saylor g, Gary R. Scott e, and C. Owen Lovejoy a,h,1
-Author Affiliations
aThe Cleveland Museum of Natural History, Cleveland, OH 44106;
bDepartment of Anthropology,
cThe Institute for the Science of Origins, and
gDepartment of Geological Sciences, Case Western Reserve University, Cleveland, OH 44106;
dDepartment of Earth Sciences, Addis Ababa University, Addis Ababa, Ethiopia 1176;
e Berkeley Geochronology Center, Berkeley, CA 94709;
fDepartment of Biology, Stanford University, Stanford, CA 94305; and
hDepartment of Anthropology, School of Biomedical Sciences, Kent State University, Kent, OH 44242
Contributed by C. Owen Lovejoy, April 16, 2010 (sent for review February 22, 2010)
Abstract
Only one partial skeleton that includes both forelimb and hindlimb elements has been reported for Australopithecus afarensis. The diminutive size of this specimen (A.L. 288-1 ["Lucy"]) has hampered our understanding of the paleobiology of this species absent the potential impact of allometry. Here we describe a large-bodied (i.e., well within the range of living Homo) specimen that, at 3.58 Ma, also substantially antedates A.L. 288–1. It provides fundamental evidence of limb proportions, thoracic form, and locomotor heritage inAustralopithecus afarensis. Together, these characteristics further establish that bipedality in Australopithecus was highly evolved and that thoracic form differed substantially from that of either extant African ape.
bipedality human evolution upright walking hominid thorax
Footnotes
1To whom correspondence may be addressed. E-mail: olovejoy@aol.com oryhailese@cmnh.org.
Author contributions: Y.H.-S., B.M.L., M.A., A.L.D., L.G., B.Z.S., G.R.S., and C.O.L. designed research; Y.H.-S., B.M.L., M.A., A.L.D., L.G., S.M.M., B.Z.S., and C.O.L. performed research; Y.H.-S., B.M.L., M.A., A.L.D., L.G., B.Z.S., G.R.S., and C.O.L. analyzed data; and Y.H.-S., B.M.L., A.L.D., L.G., B.Z.S., and C.O.L. wrote the paper.
The authors declare no conflict of interest.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1004527107/-/DCSupplemental.
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