June 23, 2010

Lucy’s Hominid Forebears Were Upright Walkers

Kadanuumuu. Photo:
Yohannes Haile-Selassie,
Liz Russell, Cleve. Museum
of Natural History. Used with
permission from Proceedings
of the Natl. Academy of Sciences.

The famous hominid fossil Lucy has family. An announcement Monday in the early online edition of the Proceedings of the National Academy of Science (PNAS) says the relative — although 400,000 years older — was, like Lucy, an advanced upright walker.

Three Case Western Reserve University researchers: Yohannes Haile-Selassie, Bruce Latimer and Beverly Saylor, were among an international team of scientists who reported the most complete skeleton so far of a 3.6 million-year-old Lucy species, Australopithecus afarensis.

Other researchers were from the Cleveland Museum of Natural History, Kent State University, Addis Ababa University and Berkeley Geochronology Center, and researchers from Sweden and France.

Latimer, interim director of the CWRU Center for Human Origins — a component center of the Institute for the Science of Origins — and an adjunct professor of anatomy at the School of Medicine, co-directed the Woranso-Mille Paleontological Project with Haile-Selassie, the lead investigator of the study reported in PNAS.

The finding is nicknamed “Kadanuumuu,” which means big man, because of his height, determined to range from 5 feet to 5 feet 6 inches tall. In comparison, Lucy, found in 1974, was determined to be a small female about 40 inches tall.

Kadanuumuu provides a glimpse into the evolution of man, generating new information about locomotion, shoulder morphology and the rib cage.

According to the researchers, nearly 1 million years before stone tools were made, Kadanuumuu already had long legs like the modern human. This overturns the theory that man developed long legs to walk miles during persistent hunting.

The bones were among 4,500 fossil mammalian specimens found. Some 95 fossil hominid specimens, as old as 3.8 million years, are among those discovered.

“As a result of this discovery, we now know Lucy and her relatives better than ever,” said Haile-Selassie, the curator and head of physical anthropology at the Cleveland Museum of Natural History and a fellow of the Center for Human Origins.

“Partial skeletons are rare, which is why they are so valuable,” Latimer said. “This particular skeleton preserves portions of the shoulder and thoracic cage — elements not previously found together in an associated individual.”

He added that Kadanuumuu‘s shoulder complex was more like humans’ and not at all like chimpanzees’, which are knuckle-walkers.

“The idea that humans went through a knuckle-walking phase can now be discarded,” Latimer said.

Collaborating as the project’s geologist and dating the soils surrounding the fossil skeleton was Saylor, associate professor of geological sciences in the College of Arts and Sciences.

Through early indicators in the soil around the fossil remains, Saylor estimates the hominid’s age at approximately 3.6 million years, making it the oldest specimen in the group of Australopithecus afarensis.

The species was named after the Afar region of Ethiopia. Lucy was found in the Hadar in the Afar region.

For more information contact Kevin Mayhood, 216.368.4442.

Posted by: Kimyette Finley, June 23, 2010 09:12 AM | News Topics: Faculty, Research, School of Medicine

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