April 12, 2006

Ancient fossils fill gap in early human evolution

By Patricia Reaney

LONDON (Reuters) - An international team of scientists have
discovered 4.1 million year old fossils in eastern Ethiopia
that fill a missing gap in human evolution.

The teeth and bones belong to a primitive species of
Australopithecus known as Au. anamensis, an ape-man creature
that walked on two legs.

The Australopithecus genus is thought to be an ancestor of
modern humans. Seven separate species have been named. Au.
anamensis is the most primitive.

"This new discovery closes the gap between the fully blown
Australopithecines and earlier forms we call Ardipithecus,"
said Tim White, a leader of the team from the University of
California, Berkeley.

"We now know where Australopithecus came from before 4
million years ago."

Found and analyzed by scientists from the United States,
Ethiopia, Japan and France, the fossils were unearthed in the
Middle Awash area in the Afar desert of eastern Ethiopia.

The area, about 140 miles northeast of Addis Ababa, has the
most continuous record of human evolution, according to the

The remains of the hominid that had a small brain, big
teeth and walked on two legs, fits into the one million-year
gap between the earlier Ardipithecus and Australopithecus
afarensis which includes the famous fossil skeleton known as
Lucy, which lived between 3.6 and 3.3 million years ago and was
found in 1974.

"It is fair to say that some species of Ardipithecus gave
rise to Australopithecus," said White, who reported the
discovery in the journal Nature.

The fossils from about eight individuals include the
largest hominid canine found so far, the earliest known thigh
bone of the species and hand and foot bones.

The finding also extends the range of Au. anamensis in
Ethiopia. Previous remains of the species were found in Kenya.

White said the large teeth suggest the hominid was able to
eat fibrous foods and roots, compared to earlier species of
Ardipithecus that had smaller teeth which restricted their

Along with the hominid fossils, the scientists discovered
hundreds of remains of pigs, birds, rodents and monkeys as well
as hyenas and big cats which gave them an idea of the habitat
in which they existed.

"Here, in a single Ethiopian valley, we have nearly a
mile-thick stack of superimposed sediments and twelve horizons
yielding hominid fossils. These discoveries confirm the Middle
Awash study area as the world's best window on human
evolution," White added.