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SnakebyteXX
03-07-2005, 02:30 PM
The fossilised skeleton of a four million-year-old human ancestor able to walk on two legs could provide clues as to how humans' upright walk evolved. The remains, found in north-east Ethiopia, are the oldest yet discovered of an upright hominid, scientists told a press conference in Addis Ababa, Ethiopia, on Saturday.

Several fossils from one individual have been discovered at the site, including parts of the ribs, vertebrae, pelvis, shoulder blade and thighbone. But it is the ankle joint that is most interesting, showing that it walked on two legs.

"This skeleton helps us to understand what happened in the joints, how walking upright occurred - what we never had before," says Bruce Latimer of the Natural History Museum in Cleveland, Ohio, who made the discovery together with Yohannes Haile Selassie of the National Museum in Addis Ababa.

Modern ankles
The discovery was made about 60 kilometres (37 miles) from where the fossilised remains of a hominid called Lucy were found in 1974. At about three million years old and with modern ankles, Lucy was the oldest example of a hominid able to walk upright discovered for many years. These newly discovered fossils are much older, and so may reveal more of the evolution process.

A study of a six million-year-old hominid thighbone in 2004 revealed walking habits closer to humans than chimpanzees, but scientists hope the ankle bone of the new find could reveal exactly how the as yet unclassified creature walked. "Normally, you find one bone or two from an individual and you are happy. Now we have found parts of a skeleton, this is very rare," adds Latimer.

Despite being older than Lucy, the skeleton is also bigger, with longer legs, which has surprised the scientists and remains unexplained. But they hope and expect that further work will reveal more of how humans evolved. "This is the world's oldest biped," says Latimer. "It will revolutionise the way we see human evolution."


link (http://www.newscientist.com/article.ns?id=dn7102)