Scientists Find Fossils of Man's Earliest Relative
Reuters- Wednesday July 11 2:15 PM ET
By Patricia Reaney
LONDON (Reuters) - An international team of scientists said Wednesday they had dug up bones and teeth of an early pre-human that could help fill the gaps in mankind's evolutionary tree.
The fossils of a new subspecies of an early relative of humans were found 140 miles northeast of Addis Ababa in Ethiopia. They are about 5.4 to 5.7 million years old, about a million years older the previous oldest known hominid, according to the researchers.
``It is the earliest hominid. We are pushing back the hominid record by more than a million years,'' Yohannes Haile-Selassie, a researcher at the University of California at Berkeley who discovered the fossils, told Reuters.
Before the latest discovery, the earliest known fossils definitively placed on the human side of the evolutionary tree were 4.4 million years old.
Hominids are creatures more closely related to humans than chimpanzees. Scientists suspect the evolutionary line that led to humans diverged from the line leading to our closest ape relatives about five to six million years ago.
The jaw, collar, feet and arm bones are from about five individuals of the new subspecies of Ardipithecus. They were found among fossils of other mammals including elephants, horses and rats and come from creatures the size of a chimpanzee.
``We now know that the split with chimpanzees did not happen five million years ago because we have hominids that are 5.5 or 5.6 million years old,'' Haile-Selassie explained.
YOUNGER THAN ``MILLENNIUM MAN''
The specimens are about 2.5 million years older than Lucy, the most famous fossil remains of an early hominid, but slightly younger than so-called ``Millennium Man,'' or Orrorin, which French and Kenyan scientists unearthed in Kenya last year and claimed were mankind's earliest known relative.
But Haile-Selassie said that until more fossils were found and further analysis was completed it would be unclear whether ''Millennium Man'' was the earliest hominid, the last common relative of humans and chimpanzees, the earliest chimpanzee or an ape that become extinct.
He and his colleagues found the fossil remains of Ardipithecus in the Middle Awash region of Ethiopia which is today a harsh desert. It would have been a wooded habitat when the creatures roamed the area.
They say their findings, which are published in the science journal Nature, suggest the earliest hominids lived in wooded, wet environments and did not venture into more wide-open spaces until about 4.4 million years ago.
A toe bone indicates the Ardipithecus subspecies walked on two feet when on the ground.
In a commentary on the research Henry Gee, a senior editor at Nature, said both ``Millennium Man'' and Ardipithecus are thought to lie close to the point in the family tree at which the ancestries of chimpanzees and humans diverged.
But he added that the early evolutionary relationship between chimpanzees and early hominids will remain murky because bones and teeth are all scientists have to go on.
``Uncertainty is likely to reign for some time, leaving the nature of the latest common ancestor – and the general course of early hominid evolution -- as mysterious as ever,'' he said.